Author name code: reid
ADS astronomy entries on 2022-09-14
author:"Reid, Aaron"
------------------------------------------------------------------------
Title: Constraining the magnetic vector in the quiet solar photosphere
and the impact of instrumental degradation
Authors: Campbell, R. J.; Shelyag, S.; Quintero Noda, C.; Mathioudakis,
M.; Keys, P. H.; Reid, A.
Bibcode: 2021A&A...654A..11C
Altcode: 2021arXiv210701519C
Context. With the advent of next generation high resolution telescopes,
our understanding of how the magnetic field is organized in the
internetwork (IN) photosphere is likely to advance significantly.
Aims: We aim to evaluate the extent to which we can retrieve accurate
information about the magnetic vector in the IN photosphere using
inversion techniques.
Methods: We use a snapshot produced from
high resolution three-dimensional magnetohydrodynamic (MHD) simulations
and employ the Stokes Inversions based on Response functions (SIR) code
to produce synthetic observables in the same near infrared spectral
window as observed by the GREGOR Infrared Spectrograph (GRIS), which
contains the highly magnetically sensitive photospheric Fe I line pair
at 15 648.52 Å and 15 652.87 Å. We then use a parallelized wrapper to
SIR to perform nearly 14 million inversions of the synthetic spectra to
test how well the `true' MHD atmospheric parameters can be constrained
statistically. Finally, we degrade the synthetic Stokes vector
spectrally and spatially to GREGOR resolutions and examine how this
influences real observations, considering the impact of stray light,
spatial resolution and signal-to-noise (S/N) in particular.
Results: We find that the depth-averaged parameters can be recovered
by the inversions of the undegraded profiles, and by adding simple
gradients to magnetic field strength, inclination, and line of sight
velocity we show that an improvement in the χ2 value
is achieved. We also evaluate the extent to which we can constrain
these parameters at various optical depths, with the kinematic and
thermodynamic parameters sensitive deeper in the atmosphere than
the magnetic parameters. We find the S/N and spatial resolution both
play a significant role in determining how the degraded atmosphere
appears. At the same time, we find that the magnetic and kinematic
parameters are invariant upon inclusion of an unpolarized stray
light. We compare our results to recent IN observations obtained
by GREGOR. We studied a linear polarization feature which resembles
those recently observed by GRIS in terms of appearing as `loop-like'
structures and exhibiting very similar magnetic flux density. Thus,
we demonstrate that realistic MHD simulations are capable of showing
close agreement with real observations, and the symbiosis between them
and observations continues to prove essential. We finally discuss the
considerations that must be made for DKIST-era observations.
Title: Flare-induced Sunquake Signatures in the Ultraviolet as
Observed by the Atmospheric Imaging Assembly
Authors: Quinn, Sean; Mathioudakis, Mihalis; Nelson, Christopher J.;
Milligan, Ryan O.; Reid, Aaron; Jess, David B.
Bibcode: 2021ApJ...920...25Q
Altcode: 2021arXiv210505704Q
Sunquakes (SQs) have been routinely observed in the solar photosphere,
but it is only recently that signatures of these events have been
detected in the chromosphere. We investigate whether signatures of
SQs are common in ultraviolet (UV) continua that sample the solar
plasma several hundred km above where SQs are typically detected. We
analyze observations from the Solar Dynamics Observatory's Atmospheric
Imaging Assembly (SDO/AIA) 1600 and 1700 Å passbands, for SQ signatures
induced by the flares of Solar Cycle 24. We base our analysis on the
62 SQs detected in the recent statistical study presented by Sharykin
& Kosovichev. We find that 9 out of 62 SQ candidates produced a
response that is clearly detected in running-difference images from
the AIA 1600 and 1700 Å channels. A binary frequency filter with a
width of 2 mHz, centered on 6 mHz, was applied to the data. The first
signature of each SQ was detected at distances between 5.2 and 25.7
Mm from the associated flare ribbon. Time-distance and regression
analysis allowed us to calculate the apparent transverse velocities
of the SQs in the UV data sets and found maximum velocities as high
as 41 km s-1, 87 Mm away from the SQ source. Our analysis
shows that flare-induced SQ signatures can be detected in the SDO/AIA
1600 and 1700 Å passbands, hinting at their presence in the lower
chromosphere. There was no apparent correlation between GOES flare
classification and the appearance of the SQ at these heights.
Title: Temporal evolution of small-scale internetwork magnetic fields
in the solar photosphere (Corrigendum)
Authors: Campbell, R. J.; Mathioudakis, M.; Collados, M.; Keys, P. H.;
Asensio Ramos, A.; Nelson, C. J.; Kuridze, D.; Reid, A.
Bibcode: 2021A&A...652C...2C
Altcode:
No abstract at ADS
Title: Flare-induced Photospheric Velocity Diagnostics
Authors: Monson, Aaron J.; Mathioudakis, Mihalis; Reid, Aaron;
Milligan, Ryan; Kuridze, David
Bibcode: 2021ApJ...915...16M
Altcode: 2021arXiv210502199M
We present radiative-hydrodynamic simulations of solar flares generated
by the RADYN and RH codes to study the perturbations induced in
photospheric Fe I lines by electron beam heating. We investigate how
variations in the beam parameters result in discernible differences
in the induced photospheric velocities. Line synthesis revealed a
significant chromospheric contribution to the line profiles resulting
in an apparent red asymmetry by as much as 40 m s-1 close
to the time of maximum beam heating, which was not reflective of the
upflow velocities that arose from the radiative-hydrodynamic simulations
at those times. The apparent redshift to the overall line profile was
produced by significant chromospheric emission that was blueshifted
by as much as 400 m s-1 and fills in the blue side of
the near-stationary photospheric absorption profile. The velocity
information that can be retrieved from photospheric line profiles during
flares must therefore be treated with care to mitigate the effects of
higher parts of the atmosphere providing an erroneous velocity signal.
Title: Temporal evolution of small-scale internetwork magnetic fields
in the solar photosphere
Authors: Campbell, R. J.; Mathioudakis, M.; Collados, M.; Keys, P. H.;
Asensio Ramos, A.; Nelson, C. J.; Kuridze, D.; Reid, A.
Bibcode: 2021A&A...647A.182C
Altcode: 2021arXiv210200942C
Context. While the longitudinal field that dominates in photospheric
network regions has been studied extensively, small-scale transverse
fields have recently been found to be ubiquitous in the quiet
internetwork photosphere and this merits further study. Furthermore,
few observations have been able to capture how this field evolves.
Aims: We aim to statistically characterize the magnetic vector in
a quiet Sun internetwork region and observe the temporal evolution of
specific small-scale magnetic features.
Methods: We present
two high spatio-temporal resolution observations that reveal the
dynamics of two disk-centre internetwork regions taken by the new GREGOR
Infrared Spectrograph Integral Field Unit with the highly magnetically
sensitive photospheric Fe I line pair at 15648.52 Å and 15652.87
Å. We record the full Stokes vector and apply inversions with the
Stokes inversions based on response functions code to retrieve the
parameters characterizing the atmosphere. We consider two inversion
schemes: scheme 1 (S1), where a magnetic atmosphere is embedded in
a field free medium, and scheme 2 (S2), with two magnetic models
and a fixed 30% stray light component.
Results: The magnetic
properties produced from S1 inversions returned a median magnetic
field strength of 200 and 240 G for the two datasets, respectively. We
consider the median transverse (horizontal) component, among pixels
with Stokes Q or U, and the median unsigned longitudinal (vertical)
component, among pixels with Stokes V, above a noise threshold. We
determined the former to be 263 G and 267 G, and the latter to be 131
G and 145 G, for the two datasets, respectively. Finally, we present
three regions of interest, tracking the dynamics of small-scale magnetic
features. We apply S1 and S2 inversions to specific profiles of interest
and find that the latter produces better approximations when there is
evidence of mixed polarities. We find patches of linear polarization
with magnetic flux density of the order of 130−150 G and find that
linear polarization appears preferentially at granule-intergranular
lane boundaries. The weak magnetic field appears to be organized in
terms of complex `loop-like' structures, with transverse fields often
flanked by opposite polarity longitudinal fields.
Title: Nonthermal electrons revealed by LOFAR
Authors: Zucca, Pietro; Pellizzoni, Alberto; Krankowski, Andrzej;
Rothkaehl, Hanna; Mann, Gottfried; Vocks, Christian; Magdalenic,
Jasmina; Marque, Christophe; Jackson, Bernard; Fallows, Richard;
Tomasik, Lukasz; Hamish; Reid, A. S.; Gallagher, Peter; Vourlidas,
Angelos; Bisi, Mario M.; Carley, Eoin; Matyjasiak, Barbara; Kozarev,
Kamen; Dabrowski, Bartosz; Morosan, Diana; Tiburzi, Caterina; Chang,
Peijin
Bibcode: 2021cosp...43E1065Z
Altcode:
During solar flares and CMEs, the corona is heated, plasma motion,
waves and shocks are ignited, and particles are accelerated. The
accelerated particles propagate through the solar corona causing a
variety of plasma instabilities that lead to enhanced non-thermal
radio emission, known as "radio bursts". By studying radio-bursts'
characteristics we can gain insight into the properties of energetic
particles and the ambient coronal plasma, and the properties of particle
acceleration mechanisms, such as magnetic reconnection and/or shocks
in the solar atmosphere. The Low Frequency aRray (LOFAR) can be used
to study the fundamental plasma physics of solar radio bursts with
unprecedented time resolution in dynamic spectra, as well as with
both interferometric imaging and tied array imaging. In this talk, an
overview of recent results obtained with the LOFAR telescope will be
given, including observations of a different variety of radio bursts
such as type II, III and IV. These observations were performed with
simultaneous beam formed and interferometric imaging, resulting in
unprecedented special resolution with baselines up to ~120 km. Finally,
we will present the plan for future observations and the remaining
challenges of solar-heliospheric low-frequency observations.
Title: Results from the LOFAR coordination with PSP
Authors: Zucca, Pietro; Pellizzoni, Alberto; Krankowski, Andrzej;
Rothkaehl, Hanna; Mann, Gottfried; Vocks, Christian; Magdalenic,
Jasmina; Marque, Christophe; Jackson, Bernard; Fallows, Richard;
Tomasik, Lukasz; Miteva, Rositsa; Hamish; Reid, A. S.; Gallagher,
Peter; Vourlidas, Angelos; Bisi, Mario M.; Carley, Eoin; Matyjasiak,
Barbara; Kozarev, Kamen; Dabrowski, Bartosz; Morosan, Diana; Tiburzi,
Caterina; Zhabngm, Peijin
Bibcode: 2021cosp...43E.945Z
Altcode:
Understanding and modelling the complex state of the Sun-solar
wind-magnetosphere-ionosphere-thermosphere system, requires a
comprehensive set of multiwavelength observations. LOFAR has unique
capabilities in the radio domain. Some examples of these include: a)
the ability to take high-resolution solar dynamic spectra and radio
images of the Sun; b) observing the scintillation (interplanetary
scintillation - IPS) of distant, compact, astronomical radio sources
to determine the density, velocity and turbulence structure of the
solar wind; and c) the use of Faraday rotation as a tool to probe
the interplanetary magnetic-field strength and direction. However, to
better understand and predict how the Sun, its atmosphere, and more
in general the Heliosphere works and impacts Earth, the combination
of in-situ spacecraft measurements and ground-based remote-sensing
observations of coronal and heliospheric plasma parameters is extremely
useful. Ground-based observations can be used to infer a global
picture of the inner heliosphere, providing the essential context into
which in-situ measurements from spacecraft can be placed. Conversely,
remote-sensing observations usually contain information from extended
lines of sight, with some deconvolution and modelling necessary to build
up a three-dimensional (3-D) picture. Precise spacecraft measurements,
when calibrated, can provide ground truth to constrain these models. The
PSP mission is observing the solar corona and near-Sun interplanetary
space. It has a highly-elliptical orbit taking the spacecraft as close
as nearly 36 solar radii from the Sun centre on its first perihelion
passage, and subsequent passages ultimately reaching as close as 9.8
solar radii. Four instruments are on the spacecraft's payload: FIELDS
measuring the radio emission, electric and magnetic fields, Poynting
flux, and plasma waves as well as the electron density and temperature;
ISOIS measuring energetic electrons, protons, and heavy ions in the
energy range 10 keV-100 MeV; SWEAP measuring the density, temperature,
and flow speed of electrons, protons, and alphas in the solar wind;
and finally, WISPR imaging coronal streamers, coronal mass ejections
(CMEs), their associated shocks, and other solar wind structures in the
corona and near-Sun interplanetary space, and provide context for the
other three in-situ instruments. In this talk, several results of the
joint LOFAR/PSP campaign will be presented, including fine structures
of radio bursts, localization and kinematics of propagating radio
sources in the heliosphere, and the challenges and plans for future
observing campaigns including PSP and Solar Orbiter.
Title: Non-LTE inversions of a confined X2.2 flare. I. The vector
magnetic field in the photosphere and chromosphere
Authors: Vissers, G. J. M.; Danilovic, S.; de la Cruz Rodríguez,
J.; Leenaarts, J.; Morosin, R.; Díaz Baso, C. J.; Reid, A.; Pomoell,
J.; Price, D. J.; Inoue, S.
Bibcode: 2021A&A...645A...1V
Altcode: 2020arXiv200901537V
Context. Obtaining an accurate measurement of magnetic field vector
in the solar atmosphere is essential for studying changes in field
topology during flares and reliably modelling space weather.
Aims: We tackle this problem by applying various inversion methods to a
confined X2.2 flare that occurred in NOAA AR 12673 on 6 September 2017
and comparing the photospheric and chromospheric magnetic field vector
with the results of two numerical models of this event.
Methods:
We obtained the photospheric magnetic field from Milne-Eddington
and (non-)local thermal equilibrium (non-LTE) inversions of Hinode
SOT/SP Fe I 6301.5 Å and 6302.5 Å. The chromospheric field was
obtained from a spatially regularised weak-field approximation (WFA)
and non-LTE inversions of Ca II 8542 Å observed with CRISP at the
Swedish 1 m Solar Telescope. We investigated the field strengths
and photosphere-to-chromosphere shear in the field vector.
Results: The LTE- and non-LTE-inferred photospheric magnetic field
components are strongly correlated across several optical depths in
the atmosphere, with a tendency towards a stronger field and higher
temperatures in the non-LTE inversions. For the chromospheric field,
the non-LTE inversions correlate well with the spatially regularised
WFA, especially in terms of the line-of-sight field strength and field
vector orientation. The photosphere exhibits coherent strong-field
patches of over 4.5 kG, co-located with similar concentrations
exceeding 3 kG in the chromosphere. The obtained field strengths
are up to two to three times higher than in the numerical models,
while the photosphere-to-chromosphere shear close to the polarity
inversion line is more concentrated and structured.
Conclusions:
In the photosphere, the assumption of LTE for Fe I line formation
does not yield significantly different magnetic field results in
comparison to the non-LTE case, while Milne-Eddington inversions
fail to reproduce the magnetic field vector orientation where Fe
I is in emission. In the chromosphere, the non-LTE-inferred field
is excellently approximated by the spatially regularised WFA. Our
inversions confirm the locations of flux rope footpoints that have
been predicted by numerical models. However, pre-processing and lower
spatial resolution lead to weaker and smoother field in the models than
what our data indicate. This highlights the need for higher spatial
resolution in the models to better constrain pre-eruptive flux ropes.
Title: An Introduction to Photospheric Flare Line Diagnostics
Authors: Monson, A.; Mathioudakis, M.; Milligan, R.; Reid, A.;
Kuridze, D.
Bibcode: 2020AGUFMSH057..04M
Altcode:
In preparation for solar cycle 25, we present radiative hydrodynamic
flare models from the F-CHROMA archive constructed using the RADYN and
RH codes. We simulate potential observable perturbations seen in the
line-of-sight velocity and heating induced in the photosphere during
a flare. Many works have focused on the recreation of chromospheric
spectral line profiles as the atmosphere rapidly heats and expands
due to the injection of energy from magnetic reconnection. This
extreme heating mechanism can permeate through the upper atmosphere
and affect the lowest levels of the solar atmosphere. This results
in an observable brightening and Doppler shifting of spectral lines
formed in the deepest regions, though the extent of this photospheric
reaction is still not fully characterised. We investigate how variations
in the properties of a solar flare-accelerated electron beam result in
discernible asymmetries in the flaring profiles of several deep forming
Fe I spectral lines. Through analysis of the contribution functions
and response functions of these lines during a flare, we have found
an unprecedented level of high velocity chromospheric contribution
which significantly alters the emergent profile of these lines. This
comparatively weak, high velocity surplus contributing region of
the chromosphere can result in false red shifts and/or significantly
adds to the flaring Doppler shifted profile, resulting in a greater
blue shift of the line core, which had previously been assumed as a
purely photospheric velocity diagnostic. Based on this evidence, it
is concluded that any future work using these photospheric lines to
diagnose properties of the photosphere in a flaring atmosphere must
be carefully analysed to mitigate effect of higher forming regions
providing a surplus velocity signal.
Title: Chromospheric Bubbles in Solar Flares
Authors: Reid, A.; Zhigulin, B.; Carlsson, M.; Mathioudakis, M.
Bibcode: 2020ApJ...894L..21R
Altcode: 2020arXiv200510586R
We analyze a grid of radiative hydrodynamic simulations of solar flares
to study the energy balance and response of the atmosphere to nonthermal
electron beam heating. The appearance of chromospheric bubbles is one
of the most notable features that we find in the simulations. These
pockets of chromospheric plasma get trapped between the transition
region and the lower atmosphere as it is superheated by the particle
beam. The chromospheric bubbles are seen in the synthetic spectra,
appearing as an additional component to Balmer line profiles with high
Doppler velocities as high as 200 km s-1. Their signatures
are also visible in the wings of Ca II 8542 Å line profiles. These
bubbles of chromospheric plasma are driven upward by a wave front that
is induced by the shock of energy deposition, and require a specific
heating rate and atmospheric location to manifest.
Title: Internal consistency of neutron coherent scattering length
measurements from neutron interferometry and from neutron gravity
reflectometry
Authors: Snow, W. M.; Apanavicius, J.; Dickerson, K. A.; Devaney,
J. S.; Drabek, H.; Reid, A.; Shen, B.; Woo, J.; Haddock, C.; Alexeev,
E.; Peters, M.
Bibcode: 2020PhRvD.101f2004S
Altcode: 2019arXiv191014271S
Many theories beyond the Standard Model postulate short-range
modifications to gravity which produce deviations of Newton's
gravitational potential from a strict 1 /r dependence. It is common to
analyze experiments searching for these modifications using a potential
of the form V'(r )=-G/M m r [1 +α exp (-r /λ ) ] . The best
present constraints on α for λ <100 nm come from neutron scattering
and often employ comparisons of different measurements of the coherent
neutron scattering amplitudes b . We analyze the internal consistency
of existing data from two different types of measurements of low-energy
neutron scattering amplitudes: neutron interferometry, which involves
squared momentum transfers q2=0 , and neutron gravity
reflectometry, which involves squared momentum transfers q2=8
m Vopt where m is the neutron mass and Vopt
is the neutron optical potential of the medium. We show that the
fractional difference Δ/b |b | averaged over the seven elements where
high precision data exist on the same material from both measurement
methods is [2.2 ±1.4 ]×10-4. We also show that Δ/b |b |
for these data is insensitive both to exotic Yukawa interactions and
also to the electromagnetic neutron-atom interactions proportional to
the neutron-electron scattering length bn e and the neutron
polarizability scattering amplitude bpol. This result will
be useful in any future global analyses of neutron scattering data
to determine bn e and bound α and λ . We also discuss
how various neutron interferometric and scattering techniques with
cold and ultracold neutrons can be used to improve the precision of
b measurements and make some specific proposals.
Title: High-resolution spectropolarimetric observations of the
temporal evolution of magnetic fields in photospheric bright points
Authors: Keys, P. H.; Reid, A.; Mathioudakis, M.; Shelyag, S.;
Henriques, V. M. J.; Hewitt, R. L.; Del Moro, D.; Jafarzadeh, S.;
Jess, D. B.; Stangalini, M.
Bibcode: 2020A&A...633A..60K
Altcode: 2019arXiv191108436K
Context. Magnetic bright points (MBPs) are dynamic, small-scale
magnetic elements often found with field strengths of the order of a
kilogauss within intergranular lanes in the photosphere.
Aims:
Here we study the evolution of various physical properties inferred from
inverting high-resolution full Stokes spectropolarimetry data obtained
from ground-based observations of the quiet Sun at disc centre.
Methods: Using automated feature-tracking algorithms, we studied
300 MBPs and analysed their temporal evolution as they evolved to
kilogauss field strengths. These properties were inferred using
both the NICOLE and SIR Stokes inversion codes. We employ similar
techniques to study radiative magnetohydrodynamical simulations
for comparison with our observations.
Results: Evidence was
found for fast (∼30-100 s) amplification of magnetic field strength
(by a factor of 2 on average) in MBPs during their evolution in our
observations. Similar evidence for the amplification of fields is seen
in our simulated data.
Conclusions: Several reasons for the
amplifications were established, namely, strong downflows preceding
the amplification (convective collapse), compression due to granular
expansion and mergers with neighbouring MBPs. Similar amplification of
the fields and interpretations were found in our simulations, as well
as amplification due to vorticity. Such a fast amplification will have
implications for a wide array of topics related to small-scale fields
in the lower atmosphere, particularly with regard to propagating wave
phenomena in MBPs.
Title: Hydrogen Emission in Type II White-light Solar Flares
Authors: Procházka, Ondřej; Reid, Aaron; Mathioudakis, Mihalis
Bibcode: 2019ApJ...882...97P
Altcode: 2019arXiv190710888P
Type II white-light flares (WLFs) have weak Balmer line emission
and no Balmer jump. We carried out a set of radiative hydrodynamic
simulations to understand how the hydrogen radiative losses vary with
the electron-beam parameters and more specifically with the low-energy
cutoff. Our results have revealed that for low-energy beams, the excess
flare Lyman emission diminishes with increasing low-energy cutoff as
the energy deposited into the top chromosphere is low compared to the
energy deposited into the deeper layers. Some Balmer excess emission is
always present and is driven primarily by direct heating from the beam
with a minor contribution from Lyman continuum backwarming. The absence
of Lyman excess emission in electron-beam driven models with high
low-energy cutoff is a prominent spectral signature of type II WLFs.
Title: The magnetic properties of photospheric magnetic bright points
with high-resolution spectropolarimetry
Authors: Keys, Peter H.; Reid, Aaron; Mathioudakis, Mihalis; Shelyag,
Sergiy; Henriques, Vasco M. J.; Hewitt, Rebecca L.; Del Moro, Dario;
Jafarzadeh, Shahin; Jess, David B.; Stangalini, Marco
Bibcode: 2019MNRAS.488L..53K
Altcode: 2019MNRAS.tmpL..98K; 2019MNRAS.tmpL..95K; 2019arXiv190607687K
Magnetic bright points (MBPs) are small-scale magnetic elements
ubiquitous across the solar disc, with the prevailing theory suggesting
that they form due to the process of convective collapse. Employing a
unique full Stokes spectropolarimetric data set of a quiet Sun region
close to disc centre obtained with the Swedish Solar Telescope, we look
at general trends in the properties of magnetic bright points. In total
we track 300 MBPs in the data set and we employ NICOLE inversions to
ascertain various parameters for the bright points such as line-of-sight
magnetic field strength and line-of-sight velocity, for comparison. We
observe a bimodal distribution in terms of maximum magnetic field
strength in the bright points with peaks at ∼480 G and ∼1700 G,
although we cannot attribute the kilogauss fields in this distribution
solely to the process of convective collapse. Analysis of MURAM
simulations does not return the same bimodal distribution. However,
the simulations provide strong evidence that the emergence of new flux
and diffusion of this new flux play a significant role in generating
the weak bright point distribution seen in our observations.
Title: The Chromospheric Response to the Sunquake Generated by the
X9.3 Flare of NOAA 12673
Authors: Quinn, Sean; Reid, Aaron; Mathioudakis, Mihalis; Nelson,
Christoper; Krishna Prasad, S.; Zharkov, Sergei
Bibcode: 2019ApJ...881...82Q
Altcode: 2019arXiv190608545Q
Active region NOAA 12673 was extremely volatile in 2017 September,
producing many solar flares, including the largest of solar cycle 24,
an X9.3 flare of 2017 September 06. It has been reported that this flare
produced a number of sunquakes along the flare ribbon. We have used
cotemporal and cospatial Helioseismic and Magnetic Imager (HMI) line of
sight (LOS) and Swedish 1 m Solar Telescope (SST) observations to show
evidence of the chromospheric response to these sunquakes. Analysis
of the Ca II 8542 Å line profiles of the wavefronts revealed that
the crests produced a strong blue asymmetry, whereas the troughs
produced at most a very slight red asymmetry. We used the combined
HMI, SST data sets to create time-distance diagrams and derive the
apparent transverse velocity and acceleration of the response. These
velocities ranged from 4.5 to 29.5 km s-1 with a constant
acceleration of 8.6 × 10-3 km s-2. We employed
NICOLE inversions, in addition to the center-of-gravity method to
derive LOS velocities ranging from 2.4 km s-1-3.2 km
s-1. Both techniques show that the crests are created by
upflows. We believe that this is the first chromospheric signature of
a flare induced sunquake.
Title: Mapping the Magnetic Field of Flare Coronal Loops
Authors: Kuridze, D.; Mathioudakis, M.; Morgan, H.; Oliver, R.; Kleint,
L.; Zaqarashvili, T. V.; Reid, A.; Koza, J.; Löfdahl, M. G.; Hillberg,
T.; Kukhianidze, V.; Hanslmeier, A.
Bibcode: 2019ApJ...874..126K
Altcode: 2019arXiv190207514K
Here, we report on the unique observation of flaring coronal loops at
the solar limb using high-resolution imaging spectropolarimetry from
the Swedish 1 m Solar Telescope. The vantage position, orientation,
and nature of the chromospheric material that filled the flare loops
allowed us to determine their magnetic field with unprecedented accuracy
using the weak-field approximation method. Our analysis reveals coronal
magnetic field strengths as high as 350 G at heights up to 25 Mm above
the solar limb. These measurements are substantially higher than a
number of previous estimates and may have considerable implications
for our current understanding of the extended solar atmosphere.
Title: Coronal and chromospheric observations of pre- and post-flare
plasma evolution
Authors: Long, David; Reid, Aaron; Harra, Louise; Mathioudakis, Mihalis
Bibcode: 2018csc..confE..16L
Altcode:
Solar flares are among the most energetic and spectacular events
occurring in our solar system, produced by the release of stored
magnetic energy in the solar atmosphere through the reconnection
of twisted magnetic fields. Although the magnetic field itself is
difficult to observe in the solar atmosphere, we can gain vital
insights into the reconnection process by studying the evolution
of solar plasma prior to and following the flare. Here we present
contemporaneous spectroscopic and imaging observations of an X9.3 solar
flare from 2017-September-6. This was the largest flare of the current
solar cycle to date, and was well observed in the corona by SDO/AIA
and Hinode/EIS as well as in the chromosphere by instruments at the
ground-based Swedish Solar Telescope. This combination of observations
provides spectroscopic information throughout the solar atmosphere,
giving a unique insight into the evolution of plasma in the lead-up
to and following the flare.
Title: Signatures of quiet Sun reconnection events in Ca II, Hα,
and Fe I
Authors: Shetye, J.; Shelyag, S.; Reid, A. L.; Scullion, E.; Doyle,
J. G.; Arber, T. D.
Bibcode: 2018MNRAS.479.3274S
Altcode: 2018MNRAS.tmp.1509S; 2017arXiv170310968S
We use observations of quiet Sun (QS) regions in the Hα 6563 Å, Ca II
8542 Å, and Fe I 6302 Å lines. We observe brightenings in the wings
of the Hα and Ca II combined with observations of the interacting
magnetic concentrations observed in the Stokes signals of Fe I. These
brightenings are similar to Ellerman bombs (EBs), i.e. impulsive
bursts in the wings of the Balmer lines that leave the line cores
unaffected. Such enhancements suggest that these events have similar
formation mechanisms to the classical EBs found in active regions,
with the reduced intensity enhancements found in the QS regions due to
a weaker feeding magnetic flux. The observations also show that the
quiet Sun Ellerman bombs are formed at a higher height in the upper
photosphere than the photospheric continuum level. Using simulations,
we investigate the formation mechanism associated with the events and
suggest that these events are driven by the interaction of magnetic
field lines in the upper photospheric regions. The results of the
simulation are in agreement with observations when comparing the light
curves, and in most cases, we found that the peak in the Ca II 8542
Å wing occurred before the peak in Hα wing. Moreover, in some cases,
the line profiles observed in Ca II are asymmetrical with a raised core
profile. The source of heating in these events is shown by the MURaM
simulations and is suggested to occur 430 km above the photosphere.
Title: Reproducing Type II White-light Solar Flare Observations with
Electron and Proton Beam Simulations
Authors: Procházka, Ondřej; Reid, Aaron; Milligan, Ryan O.; Simões,
Paulo J. A.; Allred, Joel C.; Mathioudakis, Mihalis
Bibcode: 2018ApJ...862...76P
Altcode: 2018arXiv180600249P
We investigate the cause of the suppressed Balmer series and the origin
of the white-light continuum emission in the X1.0 class solar flare on
2014 June 11. We use radiative hydrodynamic simulations to model the
response of the flaring atmosphere to both electron and proton beams,
which are energetically constrained using Ramaty High Energy Solar
Spectroscopic Imager and Fermi observations. A comparison of synthetic
spectra with the observations allows us to narrow the range of beam
fluxes and low energy cutoff that may be applicable to this event. We
conclude that the electron and proton beams that can reproduce the
observed spectral features are those that have relatively low fluxes
and high values for the low energy cutoff. While electron beams shift
the upper chromosphere and transition region to greater geometrical
heights, proton beams with a similar flux leave these areas of the
atmosphere relatively undisturbed. It is easier for proton beams to
penetrate to the deeper layers and not deposit their energy in the
upper chromosphere where the Balmer lines are formed. The relatively
weak particle beams that are applicable to this flare do not cause
a significant shift of the τ = 1 surface and the observed excess WL
emission is optically thin.
Title: Penumbral Waves Driving Solar Fan-shaped Chromospheric Jets
Authors: Reid, A.; Henriques, V. M. J.; Mathioudakis, M.; Samanta, T.
Bibcode: 2018ApJ...855L..19R
Altcode:
We use Hα imaging spectroscopy taken via the Swedish 1 m Solar
Telescope to investigate the occurrence of fan-shaped jets at the solar
limb. We show evidence for near-simultaneous photospheric reconnection
at a sunspot edge leading to the jets appearance, with upward velocities
of 30 km s-1, and extensions up to 8 Mm. The brightening at
the base of the jets appears recurrent, with a periodicity matching that
of the nearby sunspot penumbra, implying running penumbral waves could
be the driver of the jets. The jets’ constant extension velocity
implies that a driver counteracting solar gravity exists, possibly
as a result of the recurrent reconnection erupting material into the
chromosphere. These jets also show signatures in higher temperature
lines captured from the Solar Dynamics Observatory, indicating a very
hot jet front, leaving behind optically thick cool plasma in its wake.
Title: Penumbral Waves driving Solar chromospheric fan-shaped jets
Authors: Reid, A.; Henriques, V. M. J.; Mathioudakis, M.; Samanta, T.
Bibcode: 2018arXiv180207537R
Altcode:
We use H$\alpha$ imaging spectroscopy taken via the Swedish 1-m Solar
Telescope (SST) to investigate the occurrence of fan-shaped jets at
the solar limb. We show evidence for near-simultaneous photospheric
reconnection at a sunspot edge leading to the jets appearance, with
upward velocities of 30\ks, and extensions up to 8~Mm. The brightening
at the base of the jets appears recurrent, with a periodicity matching
that of the nearby sunspot penumbra, implying running penumbral waves
could be the driver of the jets. The jets' constant extension velocity
implies that a driver counteracting solar gravity exists, possibly
as a result of the recurrent reconnection erupting material into the
chromosphere. These jets also show signatures in higher temperature
lines captured from the Solar Dynamics Observatory (SDO), indicating
a very hot jet front, leaving behind optically thick cool plasma in
its wake.
Title: Modelling of Electron and Proton Beams in a White-light
Solar Flare
Authors: Procházka, O.; Reid, A.; Milligan, R. O.; Allred, J. C.;
Mathioudakis, M.
Bibcode: 2017AGUFMSH41A2756P
Altcode: 2017AGUFMSH41A2756M
Observations of an X1 class WL solar flare on 2014 June 11 showed a
surprisingly weak emission in both higher order Balmer and Lyman
lines and continua. The flare was observed by RHESSI but low
energy cut-off of non-thermal component was indeterminable due to
the unusually hard electron spectrum (delta = 3). An estimate of
power in non-thermal electron beams together with an area of WL
emission observed by HMI yielded to an upper and lower estimate of
flux 1E9 and 3E10 erg/cm2/s, respectively. We performed a grid of
models using a radiative hydrodynamic code RADYN in order to compare
synthetic spectra with observations. For low energy cut-off we chose
a range from 20 to 120 keV with a step of 20 keV and delta parameter
equal to 3. Electron beam-driven models show that higher low energy
cut-off is more likely to produce an absorption Balmer line profile,
if the total energy flux remains relatively low. On the other hand a
detectable rise of HMI continuum (617 nm) lays a lower limit on the
beam flux. Proton beam-driven models with equivalent fluxes indicate a
greater penetration depth, while the Balmer lines reveal significantly
weaker emission. Atmospheric temperature profiles show that for higher
values of low energy cut-off the energy of the beam is deposited lower
in chromosphere or even in temperature minimum region. This finding
suggests, that suppressed hydrogen emission can indicate a formation
of white-light continuum below chromosphere.
Title: IRIS Burst Spectra Co-spatial to a Quiet-Sun Ellerman-like
Brightening
Authors: Nelson, C. J.; Freij, N.; Reid, A.; Oliver, R.; Mathioudakis,
M.; Erdélyi, R.
Bibcode: 2017ApJ...845...16N
Altcode: 2017arXiv170705080N
Ellerman bombs (EBs) have been widely studied over the past two
decades; however, only recently have the counterparts of these events
been observed in the quiet-Sun. The aim of this article is to further
understand small-scale quiet-Sun Ellerman-like brightenings (QSEBs)
through research into their spectral signatures, including investigating
whether the hot signatures associated with some EBs are also visible
co-spatial to any QSEBs. We combine Hα and Ca II 8542 Å line scans at
the solar limb with spectral and imaging data sampled by the Interface
Region Imaging Spectrograph (IRIS). Twenty-one QSEBs were identified
with average lifetimes, lengths, and widths measured to be around 120 s,
0.″63, and 0.″35, respectively. Three of these QSEBs displayed clear
repetitive flaring through their lifetimes, comparable to the behavior
of EBs in active regions. Two QSEBs in this sample occurred co-spatial
to increased emission in SDO/AIA 1600 Å and IRIS slit-jaw imager 1400
Å data; however, these intensity increases were smaller than those
reported co-spatially with EBs. One QSEB was also sampled by the IRIS
slit during its lifetime, displaying increases in intensity in the
Si IV 1393 Å and Si IV 1403 Å cores, as well as the C II and Mg II
line wings, analogous to IRIS bursts (IBs). Using RADYN simulations,
we are unable to reproduce the observed QSEB Hα and Ca II 8542 Å
line profiles, leaving the question of the temperature stratification
of QSEBs open. Our results imply that some QSEBs could be heated to
transition region temperatures, suggesting that IB profiles should be
observed throughout the quiet-Sun.
Title: Chromospheric Inversions of a Micro-flaring Region
Authors: Reid, A.; Henriques, V.; Mathioudakis, M.; Doyle, J. G.;
Ray, T.
Bibcode: 2017ApJ...845..100R
Altcode: 2017arXiv170700029R
We use spectropolarimetric observations of the Ca II 8542 Å line, taken
from the Swedish 1 m Solar Telescope, in an attempt to recover dynamic
activity in a micro-flaring region near a sunspot via inversions. These
inversions show localized mean temperature enhancements of ∼1000
K in the chromosphere and upper photosphere, along with co-spatial
bi-directional Doppler shifting of 5-10 km s-1. This heating
also extends along a nearby chromospheric fibril, which is co-spatial
to 10-15 km s-1 downflows. Strong magnetic flux cancellation
is also apparent in one of the footpoints, and is concentrated in the
chromosphere. This event more closely resembles that of an Ellerman
Bomb, though placed slightly higher in the atmosphere than what is
typically observed.
Title: Solar Ellerman Bombs in 1D Radiative Hydrodynamics
Authors: Reid, A.; Mathioudakis, M.; Kowalski, A.; Doyle, J. G.;
Allred, J. C.
Bibcode: 2017ApJ...835L..37R
Altcode: 2017arXiv170104213R
Recent observations from the Interface Region Imaging Spectrograph
appear to show impulsive brightenings in high temperature lines,
which when combined with simultaneous ground-based observations in
Hα, appear co-spatial to Ellerman Bombs (EBs). We use the RADYN
one-dimensional radiative transfer code in an attempt to try and
reproduce the observed line profiles and simulate the atmospheric
conditions of these events. Combined with the MULTI/RH line synthesis
codes, we compute the Hα, Ca II 8542 Å, and Mg II h and k lines for
these simulated events and compare them to previous observations. Our
findings hint that the presence of superheated regions in the
photosphere (>10,000 K) is not a plausible explanation for the
production of EB signatures. While we are able to recreate EB-like
line profiles in Hα, Ca II 8542 Å, and Mg II h and k, we cannot
achieve agreement with all of these simultaneously.
Title: Ellerman bombs in 1-D radiative hydrodynamics
Authors: Reid, Aaron
Bibcode: 2017psio.confE..44R
Altcode:
No abstract at ADS
Title: Magnetic Flux Cancellation in Ellerman Bombs
Authors: Reid, A.; Mathioudakis, M.; Doyle, J. G.; Scullion, E.;
Nelson, C. J.; Henriques, V.; Ray, T.
Bibcode: 2016ApJ...823..110R
Altcode: 2016arXiv160307100R
Ellerman Bombs (EBs) are often found to be co-spatial with bipolar
photospheric magnetic fields. We use Hα imaging spectroscopy along with
Fe I 6302.5 Å spectropolarimetry from the Swedish 1 m Solar Telescope
(SST), combined with data from the Solar Dynamic Observatory, to study
EBs and the evolution of the local magnetic fields at EB locations. EBs
are found via an EB detection and tracking algorithm. Using NICOLE
inversions of the spectropolarimetric data, we find that, on average,
(3.43 ± 0.49) × 1024 erg of stored magnetic energy
disappears from the bipolar region during EB burning. The inversions
also show flux cancellation rates of 1014-1015
Mx s-1 and temperature enhancements of 200 K at the detection
footpoints. We investigate the near-simultaneous flaring of EBs due to
co-temporal flux emergence from a sunspot, which shows a decrease in
transverse velocity when interacting with an existing, stationary area
of opposite polarity magnetic flux, resulting in the formation of the
EBs. We also show that these EBs can be fueled further by additional,
faster moving, negative magnetic flux regions.
Title: Ellerman Bombs with Jets: Cause and Effect
Authors: Reid, A.; Mathioudakis, M.; Scullion, E.; Doyle, J. G.;
Shelyag, S.; Gallagher, P.
Bibcode: 2015ApJ...805...64R
Altcode: 2015arXiv150305359R
Ellerman Bombs (EBs) are thought to arise as a result of photospheric
magnetic reconnection. We use data from the Swedish 1 m Solar
Telescope to study EB events on the solar disk and at the limb. Both
data sets show that EBs are connected to the foot points of forming
chromospheric jets. The limb observations show that a bright structure
in the Hα blue wing connects to the EB initially fueling it, leading
to the ejection of material upwards. The material moves along a loop
structure where a newly formed jet is subsequently observed in the
red wing of Hα. In the disk data set, an EB initiates a jet which
propagates away from the apparent reconnection site within the EB
flame. The EB then splits into two, with associated brightenings in
the inter-granular lanes. Micro-jets are then observed, extending
to 500 km with a lifetime of a few minutes. Observed velocities of
the micro-jets are approximately 5-10 km s-1, while their
chromospheric counterparts range from 50 to 80 km s-1. MURaM
simulations of quiet Sun reconnection show that micro-jets with
properties similar to those of the observations follow the line of
reconnection in the photosphere, with associated Hα brightening at
the location of increased temperature.
Title: Chromospheric Diagnostics from IRIS and DST
Authors: Cauzzi, Gianna; Reardon, Kevin P.; Jaeggli, Sarah A.;
Reid, Aaron
Bibcode: 2014AAS...22430201C
Altcode:
Using data obtained during a coordinated observing campaign in
September 2013, we compare the spectral and imaging diagnostics from
IRIS and the instruments at the Dunn Solar Telescope (DST). We focus
on a small active region observed for approximately one hour with IRIS
(NUV, FUV, and SJI) in conjunction with IBIS, FIRS, and ROSA from the
DST.In particular, we examine the line widths and intensities in the
different chromospheric lines (H-alpha, Ca II 8542, Mg II) and the
temporal evolution of these different diagnostics. This allows us to
better relate the views from new window provided by IRIS to previous
studies of the chromosphere.
Title: Radio and X-ray Diagnostics of Electron Beams in Solar Flares
Authors: Vilmer, Nicole; Kontar, Eduard; Hamish; Reid, A. S.;
Maksimovic, Milan
Bibcode: 2014cosp...40E3526V
Altcode:
Solar flares are associated with efficient production of energetic
particles at all energies. While energetic electrons and ions
interacting with the solar atmosphere produce high energy X-rays
and gamma-rays, the energetic electrons escaping to the corona and
interplanetary medium produce coherent radio emissions (in particular
type III bursts) and may be directly detected by experiments aboard
spacecraft. We shall present the results of two statistical studies
combining X-ray observations from RHESSI and of type III bursts observed
in the decimeter/meter range and imaged by the Nançay Radioheliograph
We shall show how the combination of X-ray and radio observations
allows for some events to deduce the characteristics of the electron
beam acceleration sites (height and size). We shall also present the
results of a recent study on the percentage of decimetric/metric
type III bursts observed with Nançay which have a counterpart at
lower frequencies (namely in the range 14 to 1 MHz ) observed with
Wind/Waves. This study is based on a list of events for which X-ray
emission (by RHESSI) is also observed in connection with the type III
bursts. We shall discuss the different reasons which could explain
the extent or not of the metric type III burst to the hectometric range.
Title: Alfvén Waves in Simulations of Solar Photospheric Vortices
Authors: Shelyag, S.; Cally, P. S.; Reid, A.; Mathioudakis, M.
Bibcode: 2013ApJ...776L...4S
Altcode: 2013arXiv1309.2019S
Using advanced numerical magneto-hydrodynamic simulations of the
magnetized solar photosphere, including non-gray radiative transport and
a non-ideal equation of state, we analyze plasma motions in photospheric
magnetic vortices. We demonstrate that apparent vortex-like motions in
photospheric magnetic field concentrations do not exhibit "tornado"-like
behavior or a "bath-tub" effect. While at each time instance the
velocity field lines in the upper layers of the solar photosphere show
swirls, the test particles moving with the time-dependent velocity
field do not demonstrate such structures. Instead, they move in a
wave-like fashion with rapidly changing and oscillating velocity field,
determined mainly by magnetic tension in the magnetized intergranular
downflows. Using time-distance diagrams, we identify horizontal
motions in the magnetic flux tubes as torsional Alfvén perturbations
propagating along the nearly vertical magnetic field lines with local
Alfvén speed.
Title: Proterozoic rejuvenation of the Archean Crust tracked by U
Pb and Hf-isotopes in Detrital Zircon
Authors: Belousova, E. A.; Reid, A. J.; Griffin, W. L.; O'Reilly, S. Y.
Bibcode: 2006GeCAS..70R..44B
Altcode:
No abstract at ADS
Title: Petrography and Geochemistry of Upper Eocene Spherules from
709C (Indian Ocean) and DSDP 612 (NW Atlantic)
Authors: Rajmon, D.; Reid, A. M.; Copeland, P.
Bibcode: 2006LPI....37.2201R
Altcode:
Spherules from ODP 709c (Indian ocean) diplay petrographic and
geochemical characteristics similar to spherules from ODP 216 and 292
(SE Asia). The data, however, neither strongly support nor reject the
hypothesis of a third Upper Eocene ejecta layer in SE Asia.
Title: Argon isotopic analysis of breccia veins from the Roter Kamm
crater, Namibia, and implications for their thermal history
Authors: Rajmon, D.; Copeland, P.; Reid, A. M.
Bibcode: 2005M&PS...40..841R
Altcode:
No abstract at ADS
Title: Potential of Radar Imaging and Sounding Methods in Mapping
Heavily Eroded Impact Craters: Mapping Some Structural Elements of
the Hico Crater, TX
Authors: Heggy, E.; Horz, F.; Reid, A. M.; Hall, S. A.; Chan, C.
Bibcode: 2004LPI....35.1462H
Altcode:
SRTM data combined with a GPR field survey of the area north Hico
central Texas, suggest that the Hico disturbed area is an impact
structure with a minimum diameter around 5 km, and that its concentric
rings are structurally controlled by faults.
Title: Magnetic Investigations of Breccia Veins and Basement Rocks
from Roter Kamm Crater and Surrounding Region, Namibia
Authors: Rajmon, D.; Hall, S. A.; Reid, A. M.; McG. Miller, R.;
Robertson, D. J.
Bibcode: 2004LPI....35.1867R
Altcode:
The target rocks from Roter Kamm crater retained NRM components related
to the Kalahari APWP for ~1.1 0.9, ~0.7 0.6 and ~0.5 Ga. There is no
evidence for re-magnetization of the Roter Kamm samples at ~300 Ma or
during the impact at 3.7 Ma.
Title: ``Pseudotachylytes'' that Never Melted: A Thermal Story from
Roter Kamm Crater, Namibia
Authors: Rajmon, D.; Copeland, P.; Reid, A. M.
Bibcode: 2002LPI....33.1944R
Altcode:
The rim rocks of the 2.5 km Roter Kamm crater in southwest
Namibia are cut by breccia veins that macroscopically resemble
pseudotachylytes. 40Ar/39Ar data, coupled to
other published data, show that these veins never approached melting
temperatures and only attained temperatures of 250-330 °C.
Title: Metamorphosed Antarctic LL Chondrites: Pyroxene Thermometry
Authors: Reid, A. M.; Dussaud, E. A.
Bibcode: 2000LPI....31.1751R
Altcode:
No abstract at ADS
Title: Radio study of X-ray clusters. (Thesis abstract).
Authors: Reid, A. D.
Bibcode: 2000PASA...17..285R
Altcode:
No abstract at ADS
Title: Geology and Stratigraphy of Mare Tranquillitatis
Authors: Rajmon, D.; Reid, A. M.; Spudis, P.
Bibcode: 1999M&PSA..34R..96R
Altcode:
No abstract at ADS
Title: Temperature and Formation of Pseudotachylytic Impact Breccias,
Roter Kamm Crater, Southwestern Namibia
Authors: Rajmon, D.; Copeland, P.; Reid, A. M.; Lavigne, J. -F.
Bibcode: 1999M&PSA..34...95R
Altcode:
No abstract at ADS
Title: Heterogeneity of Silicates in Antarctic LL4 Chondrites
Authors: Aoyama, H.; Reid, A. M.
Bibcode: 1999LPI....30.1791A
Altcode:
LL4 Antarctic chondrites contain a mix of relict primary and metamorphic
secondary characteristics. The metamorphic effects probably relate to
short-lived high temperature impact events rather than to prolonged
burial metamorphism.
Title: Radio study of X-ray clusters of galaxies -- II. A1300:
a post-merger cluster at z=0.31 containing a halo and a relic
Authors: Reid, A. D.; Hunstead, R. W.; Lemonon, L.; Pierre, M. M.
Bibcode: 1999MNRAS.302..571R
Altcode:
As part of an extensive radio--IR--optical--X-ray study of ROSAT
clusters of galaxies in the Hydra region we have observed the Abell
cluster A1300, one of the most distant (z~= 0.31) and X-ray luminous
(L_X~ 1.7 x 10^45 erg s^-1 cm^-2, 0.1--2.4 keV) clusters in the
sample, with the Molonglo Observatory Synthesis Telescope at 843 MHz
and the Australia Telescope Compact Array at 1.34, 2.4, 4.8 and 8.6
GHz. Previous results in the X-ray and optical have suggested that
A1300 is in a post-merging phase. We present further evidence of this
with the discovery of two diffuse radio sources projected within the
extended X-ray emission of A1300. These may be among the most distant
radio halo and relic sources yet found. We argue that the halo source,
which is seen in projection near the centre of the cluster and coincides
with an extension in the X-ray surface brightness distribution, is
the result of a cluster-wide process related to the merger.
Title: Memorial for Elbert Aubrey King, Jr.
Authors: Reid, A.
Bibcode: 1999M&PS...34..677R
Altcode:
No abstract at ADS
Title: ASCA/ROSAT observations of the radio source MRC 0625-536
Authors: Otani, C.; Brinkmann, W.; Boehringer, H.; Reid, A.;
Siebert, J.
Bibcode: 1998A&A...339..693O
Altcode:
We present the results of ROSAT/ASCA observations of the bright
southern radio source MRC 0625-536. The majority of the X-ray emission
originates from the surrounding cluster Abell 3391. The best fit
temperature for the cluster gas is kT = 5.8(+0.4}_{-0.3) keV with
an abundance of 0.36+/- 0.10 times the solar value. We determined
the radial mass profile and extrapolating the data out to 3 Mpc, and
we find that the total mass of the cluster is (0.4 - 1.6) x 10(15)
M_sun. Up to about 10% of the X-ray flux could originate from the
central dumbbell galaxy. A comparison of the X-ray contours with the
complex 13cm radio structure reveals strong interactions between the
radio jets and the surrounding matter. MRC 0625-536 is thus another
object where the interaction between the otherwise invisible matter
of the cluster and the activity of the central radio galaxy can be
studied by combining data from the radio and the X-ray regimes.
Title: Lewis Cliff 88701: A Partly Equilibrated LL4 Chondrite
Authors: Reid, A. M.; Ayoyama, H.
Bibcode: 1998M&PSA..33Q.128R
Altcode:
No abstract at ADS
Title: Time-dependent structure in ultraviolet absorption lines of
the rapid rotators HD 64760 (B0Ib) and HD 93521 (O9.5V)
Authors: Howarth, Ian D.; Townsend, R. H. D.; Clayton, M. J.;
Fullerton, A. W.; Gies, D. R.; Massa, D.; Prinja, R. K.; Reid, A. H. N.
Bibcode: 1998MNRAS.296..949H
Altcode:
Cross-correlation provides an effective line-averaging function
for spectra containing many line features, a result which can
be exploited in order to perform time-series and spatial-domain
analyses of absorption-line variability in data of (relatively) poor
quality. We apply this method to high-resolution IUE spectra. For
the known non-radial pulsator HD 93521 (O9.5V), time-series analysis
of the cross-correlation function recovers two periods that are
confirmed in independent optical data (P_1=1.77 h, P_2=2.90 h); there
is no statistically significant excess power at these frequencies
in lines formed in the stellar wind. By comparing phase information
from the time-series analysis with results from pulsation models we
estimate l~=10+/-1 and 6+/-1 as the harmonic degrees for P_1 and P_2,
respectively, with l+m<~2 for each mode (where m is the azimuthal
order of the mode). We also present evidence for absorption-line
variability in HD 64760 (HR3090 B0.5 Ib), finding marginally significant
signals with P_1=8.9 h (or, possibly, 14.2 h) and P_2=29 h. The longer
period is present, with a strong signal, in wind-formed lines. We
consider possible circumstellar and (quasi-)photospheric origins for
P_2, and conclude that this signal probably does not arise through
rotational modulation (with the corollary that the stellar-wind signal
also does not arise in corotating structures, contrary to previous
suggestions). The phase behaviour of the signals is consistent with
non-radial pulsation models characterized by l=5+/-1 (P_1) and 2+/-1
(P_2), with l+m<=1, supporting a previous suggestion by Baade that
both low- and higher-order modes are present; the wind modulation at P_2
may then result from leakage of pulsation energy into the supersonic
outflow. The lack of significant photometric variability is a serious
difficulty for this model (any sinusoidal photometric variability at P_2
has semiamplitude <2 mmag at lambda_eff=1575Angstroms, with 95 per
cent confidence), but this may itself be a consequence of wave leakage.
Title: Radio study of X-ray clusters of galaxies - I. A3528: a
pre-merging cluster in the core of the Shapley Supercluster
Authors: Reid, A. D.; Hunstead, R. W.; Pierre, M. M.
Bibcode: 1998MNRAS.296..531R
Altcode: 1997astro.ph.11330R
As part of an extensive radio-IR-optical-X-ray study of ROSAT
clusters of galaxies in the Hydra region we have observed the bimodal
Abell cluster A3528, located in the core of the Shapley Supercluster
(z~=0.053), with the Molonglo Observatory Synthesis Telescope at 843MHz
and the Australia Telescope Compact Array at 1.4 and 2.4GHz. This is
part I in a series of papers which looks at the relationship between
the radio and X-ray emission in samples of ROSAT selected clusters. The
radio source characteristics - tailed morphologies and steep spectra -
are consistent with the effects of a dense intracluster medium and
the pre-merging environment of A3528. In particular, we present
evidence that the minor member of the radio-loud dumbbell galaxy
located at the centre of the northern component of A3528 is on a
plunging orbit. We speculate that this orbit may have been induced by
the tidal interactions between the merging components of A3528. In
addition, the radio source associated with the dominant member of
the dumbbell galaxy exhibits many of the characteristics of compact
steep spectrum sources. We argue that the radio emission from this
source was triggered ~10^6 yr ago by tidal interactions between the
two members of the dumbbell galaxy, strengthening the argument that
compact steep spectrum (CSS) sources are young. Re-analysis of archive
pointed Position Sensitive Proportional Counter (PSPC) data using
multiresolution filtering suggests the presence of an AGN and/or a
cooling flow in the southern component of A3528.
Title: Characterization of Experimental Shock Effects in Calcite
and Dolomite by X-Ray Diffraction
Authors: Bell, M. S.; Horz, F.; Reid, A.
Bibcode: 1998LPI....29.1422B
Altcode:
No abstract at ADS
Title: LL Chondrites and Prior's Rules
Authors: Komatsu, M.; Reid, A. M.
Bibcode: 1998LPI....29.1224K
Altcode:
No abstract at ADS
Title: VizieR Online Data Catalog: Probing the LHS Catalog (Gizis+
1997)
Authors: Gizis, J. E.; Reid; I. N.
Bibcode: 1997yCat..61090849G
Altcode:
We present moderate resolution spectroscopy of 111 cool dwarf stars
to supplement the observations we have already presented in the
Palomar/MSU Nearby-Star Spectroscopic Survey. The sample consists of
71 suspected nearby stars added to the Preliminary Third Catalog of
Nearby Stars since 1991 as well as 40 faint red stars selected from
the LHS catalog. The study was aimed at identifying interesting red
dwarfs, particularly new nearby, ultracool dwarfs, and very metal-poor
stars. The observations were made using the Palomar 60-inch,
the Hale 200-inch and the Las Campanas 100-inch telescopes between
June 1995 and January 1996. The spectral resolution is approximately
3 Angstroms per pixel with wavelength coverage from 6200 to 7500
Angstroms. Table 2 contains bandstrengths for TiO, CaH, and CaOH
indices. (4 data files).
Title: X-ray/optical analysis of the cluster of galaxies Abell 1300:
indications of a post-merger at z=0.31.
Authors: Lemonon, L.; Pierre, M.; Hunstead, R.; Reid, A.; Mellier,
Y.; Boehringer, H.
Bibcode: 1997A&A...326...34L
Altcode: 1997astro.ph..4065L
We present ROSAT PSPC and HRI observations of the distant cluster
A 1300 (z=0.3071) in conjunction with optical data, to investigate
the physics of the intra-cluster medium and the dynamical state
of the cluster. By means of a multi-resolution wavelet analysis,
we find evidence for structures in the X-ray emission of this very
luminous (L_X_~1.7x10^45^erg/s in the 0.1-2.4keV band) and massive
(M_tot_~1.3x10^15^Msun_ at a radius ~2.2Mpc) cluster. This
cluster is significant as we appear to be witnessing the end of a
merger which occurred at an early epoch.
Title: Petrology of Allende dark inclusions
Authors: Buchanan, P. C.; Zolensky, M. E.; Reid, A. M.
Bibcode: 1997GeCoA..61.1733B
Altcode:
Bulk compositions acquired by neutron activation analysis are reported
for eight Allende dark inclusions (DIs) and compared with compositions
of five DIs previously reported in the literature. Enrichments of
the elements Na, K, Br, Ba, Au, and As are generally correlated with
increased proportions of porous aggregates predominantly composed
of fine-grained, platy to fibrous olivine. These aggregates have
been interpreted by some workers as chondrules and inclusions that
first were exposed to aqueous alteration, converting anhydrous
silicates to phyllosilicates, and later were dehydrated by thermal
metamorphism, converting phyllosilicates to olivine. Our data support
this interpretation and suggest that the aqueous alteration was open
system in character. Feldspathoid grains intergrown with platy to
fibrous olivines in porous, olivine-rich aggregates and inclusions of
sodalite, nepheline, pentlandite, ilmenite, and spinel in these olivines
suggest that phyllosilicates produced during aqueous alteration could
accommodate Na, K, Ni, S, etc and are most consistent with a mixture
of both saponite and serpentine. Dehydration of saponite would require
that the temperature of thermal metamorphism was higher than previously
suggested and may have been as high as 800°-900°C. Nonporous rims
containing Ca-rich minerals (andradite, hedenbergite) surrounding dark
inclusions containing highest proportions of porous, olivine-rich
aggregates and slight to moderate depletions of these clasts in Ca
relative to bulk Allende suggest that these rims were also the result
of redistribution of some elements during dehydration of these clasts
caused by thermal metamorphism.
Title: Petrography and Mineral Chemistry of the Pipliya Eucrite
Authors: Buchanan, P. C.; Goetzee, S. H.; Reimold, W. U.; Reid, A. M.
Bibcode: 1997LPI....28..167B
Altcode:
The texture and mineralogy of the Pipliya meteorite are reported. The
meteorite is a brecciated eucrite and is distinctive because of its
high proportion of lithic clasts compared to the amount of brecciate
matrix and because lithology A (fine-grained and containing pyroxenes
similar in composition to those in 'main group' eucrites) and lithology
B (similar to A in mineralogy but medium-grained) are similar in
pyroxene mineralogy but different in texture and grain size. The
texture of the matrix material suggests that the breccia may have
undergone late stage metamorphism.
Title: Olivine and Pyroxene Compositions in LL6 Chondrites from
Antarctica
Authors: Reid, A.
Bibcode: 1997LPI....28.1155R
Altcode:
No abstract at ADS
Title: Antarctic LL Chondrites
Authors: Reid, A. M.
Bibcode: 1997pbnm.work...50R
Altcode: 1997LPITR9702...50R
No abstract at ADS
Title: A first glimpse into ISM/ICM connections at z=0.2 with ISOCAM.
Authors: Pierre, M.; Aussel, H.; Altieri, B.; Bernard, J. P.; Biviano,
A.; Boulade, O.; Cesarsky, C.; Cesarsky, D.; Elbaz, D.; Hunstead,
R.; Lemonon, L.; Reid, A.; Vigroux, L.
Bibcode: 1996A&A...315L.297P
Altcode:
Although it is well established that the cluster environment affects
the gas content and massive star formation in galaxies, the mechanisms
have not yet been unambiguously identified. In order to elucidate
some of the processes responsible, an ISO Core Programme - DEEPXSRC -
is dedicated to deep observations of medium redshift rich clusters
of galaxies. We present here the first results from this programme,
obtained by correlating our ISOCAM observations ( at 7.5 and 15μm)
of the cluster A1732 with radio, optical and X-ray images. Some 10
distant IR galaxies are detected in an 8'x8' field and are the faintest
extragalactic sources detected by ISO so far.
Title: Optical time-series spectroscopy of the O4 supergiant ζ
Puppis.
Authors: Reid, A. H. N.; Howarth, I. D.
Bibcode: 1996A&A...311..616R
Altcode:
We present time-resolved echelle spectroscopy of the O4 I(n)f supergiant
ζ Puppis. Variations are observed in all absorption-line profiles,
with typical peak-to-peak amplitudes of ~2% of the continuum intensity
(~4% in He II λ5411A). All observed absorption lines (He I, He II,
N IV, and C IV) show the same gross characteristics, with `bumps' and
`dips' moving blue-to-red through the profiles, with no detectable
line-to-line velocity shifts in the variability pattern (<15km/s)
although there are differences in the relative amplitudes across the
lines. The time dependence of the variability is investigated by using
a 2-D clean power-spectrum analysis. Significant power is found at a
period of ~8.54hr; the underlying signal is marginally consistent with
sectorial, prograde non-radial pulsations with l=-m=2, although this
does not account for all the observed variability. The blue emission
wing of Hα was included in the echellograms, and, in contrast to the
absorption lines, shows features moving red-to-blue with a period of
8.5hr (the absorption-line period). The Hα data also show features
at a period of 19.6hr (the recurrence time of the `discrete absorption
features' observed in UV P-Cygni resonance lines), moving blue-to-red
at velocities more positive than -280km/s and red-to-blue at more
negative velocities. The temporal behaviour of Hα provides the first
direct evidence for a dynamical response of a radiation-driven wind
to basal velocity fields.
Title: Breccias resembling melt bombs from the Roter Kamm Crater
Authors: Degenhardt, J. J.; Miller, R. McG.; Reimold, W. U.; Reid,
A. M.
Bibcode: 1996M&PS...31..413D
Altcode:
Irregular, dark green to black, glassy-looking boulders are locally
common in the northwest portion of the rim of the Roter Kamm impact
crater in southern Namibia. Their smooth surfaces, flow-like textures,
presence of folds, and their similarity to melt bombs have led to
the interpretation that these are molten impact ejecta. However, the
samples we have examined are all fine-grained breccias composed of
angular fragments that show no evidence of melting. Meltlike surface
textures of these rim breccias are largely a consequence of surface
wind polishing of fine-grained rocks in a desert environment. These
mono-mict breccias were produced by impact-related brecciation of
Gariep sediments (carbonaceous, siliceous shales) previously modified
by low-grade Damaran metamorphism. Secondary quartz within the breccias
is attributed to fluid activity that postdates the impact.
Title: Analysis of Dark Inclusions from Allende
Authors: Buchanan, P. C.; Zolensky, M. E.; Wentworth, S. J.; Reid,
A. M.
Bibcode: 1996LPI....27..177B
Altcode:
Fruland et al. described dark inclusions found in the meteorite Allende
as "black to light gray lithic inclusions (xenoliths) that have been
found to be different from the bulk meteorite, both petrographically
and chemically." Similar dark inclusions have been described from
other CV3 meteorites (e.g., Leoville and Vigarano). Most authors
have concluded that these clasts are petrogenetically related to the
meteorites in which they occur, even though textures can be strikingly
different. These inclusions apparently represent materials that have
been affected by different processes from those that affected typical
CV3 meteorites, or by the same processes either in a different sequence
or to different degrees. This abstract reports and interprets new
geochemical and mineralogical data for several of these clasts.
Title: Non-Chondritic Inclusions in the LL Chondrite DOM85505
Authors: Peterson, K. C. A.; Reid, A. M.; Mittlefehldt, D. W.
Bibcode: 1996LPI....27.1027P
Altcode:
DOM85505 is a 31g LL Antarctic chondrite that was noted in the
preliminary description to contain inclusions lacking chondritic
texture. Angular inclusions in the host chondrite (LL5, S4) do
not resemble any of the common achondrites in texture or mineral
composition. The non-chondritic inclusions have similar bulk
compositions and the same mineral compositions as the host chondrite
and appear to be have formed as cumulates from an LL chondrite
melt. Texturally similar non-chondritic inclusions in the L6 Yamato
meteorites 75097 and 793241 derive from an H chondrite source but are
also cumulates that have reacted with the host chondrite following
incorporation.
Title: Petrology of Allende Dark Inclusions
Authors: Buchanan, P. C.; Zolensky, M. E.; Reid, A. M.
Bibcode: 1996M&PSA..31Q..23B
Altcode:
No abstract at ADS
Title: Petrology of the polymict eucrite Petersburg
Authors: Buchanan, P. C.; Reid, A. M.
Bibcode: 1996GeCoA..60..135B
Altcode:
The polymict eucrite Petersburg contains eucritic and diogenitic
materials which span a broad range of compositions. The present
study focuses on four eucritic clasts for which bulk compositions and
mineralogical data were acquired; the broad compositional range of
these clasts documents the diversity of the parent regolith. Clast
A is REE-rich (~26 × chondrite) and magnesian (Mg# = 48.7);
composition of this clast can best be explained by partial melting of
a source region distinctly different from that of other noncumulate
eucrites. Composition of eucritic clast B is similar to compositions
of cumulate eucrites in REE and Sr abundances, but it has a much
lower Mg# than Moore County. Clasts C and D are similar in texture,
mineralogy, and composition to main group eucrites. The presence of
anomalous clast A in the same polymict breccia as typical eucrite
clasts C and D emphasizes the variability of source materials from
which eucritic melts were derived on the HED parent body(ies). After
final accretion, this breccia apparently was exposed to a minor episode
of thermal metamorphism causing ~30 μm wide alteration rims around
larger pyroxene fragments and causing alteration of pyroxenes at the
edges of eucritic clasts. This metamorphism completely altered the Mg#
of smaller matrix pyroxenes, less than 40-60 μm in size, to values
closer to the bulk Mg# of the meteorite.
Title: Multi-Wavelength Study of ROSAT Clusters of Galaxies
Authors: Reid, A. D.; Hunstead, R. W.; Pierre, M. M.
Bibcode: 1996IAUS..175..353R
Altcode:
No abstract at ADS
Title: Recovery of three ordinary chondrites, Rooikop 001-003,
from the Namib Desert in Western Namibia
Authors: Reid, A. M.; Jakes, O.; Zolensky, M. E.; Miller, R. Mcg.
Bibcode: 1995Metic..30..781R
Altcode:
No abstract at ADS
Title: Features Resembling Pseudotachylyte at Enchanted Rock
Batholith, Texas
Authors: Buchanan, P. C.; Degenhardt, J. J., Jr.; Reid, A. M.
Bibcode: 1995Metic..30R.492B
Altcode:
Enchanted Rock batholith in central Texas is a granitic pluton of ~250
km^2 area [1]. The batholith intrudes Precambrian metamorphic rocks and
is dated by Rb-Sr at 1,048+/-34 m.y. [2]. Plutonic rocks are exposed in
a series of exfoliation domes located along the southeastern edge of the
batholith. Numerous subvertical fractures occur along the outer margins
of the intrusion and, in a few cases, between exfoliation domes. A
number of these fractures contain veins described as pseudotachylytes
by Barnes [3]. In hand specimen, the veins resemble pseudotachylytes,
forming a branching network and containing angular fragments of local
country rock in a fine-grained matrix that locally exhibits an apparent
flow texture. Some smaller veins appear to have been injected into
host rock. The veins range in width up to ~30 cm with boundaries which
are sharp and smooth with undulating surfaces. Thin (~4-5 cm) aplite
dikes cut the granite and generally show small amounts of displacement
where intersected by the fracture veins (maximum measured apparent
displacement ~75 cm). Matrix material in veins includes fragments of
quartz, feldspar, biotite, and opaques. Matrix biotite is generally
associated with opaques and occurs as numerous, tiny, oriented flakes
between fragments of feldspar and quartz in areas which are darker
than surrounding matrix. The flow-like textures of matrix materials
are defined by these darker areas which are elongated subparallel
to fracture direction. The finer-grained matrix biotite apparently
derives from comminution of larger grains from host rock. Larger clasts
include rock fragments and fragments of alkali feldspar and quartz,
with a tendency for the larger fragments to concentrate in the centers
of veins. Clasts are irregular in shape and are commonly angular and
rarely contorted. Rock fragments are derived from host rock and also
include "breccia within breccia" fragments. Single-mineral fragments
display evidence of strain; quartz commonly shows undulatory extinction,
mosaic texture, and multiple fractures. Feldspar twins commonly are
deformed. None of the samples show PDF's in quartz or any evidence
for the former presence of glass or quenched melt which might have
formed by frictional melting. Fracture vein materials from Enchanted
Rock pluton are not pseudotachylytes sensu stricto, in that there is
no evidence of frictional melting. The presence of small, comminuted
flakes of apparently unaltered biotite in these veins suggests that
temperatures did not exceed ~400 degrees-800 degrees C for appreciable
periods of time [4, 5, 6] and limits the amount of frictional heating
which could have affected these breccias. However, some characteristic
features of these rocks are similar to those of pseudotachylytes,
including narrow vein-like form, flow-like texture, very fine-grained
brecciated nature, extensive deformation of constituent minerals, and
localized derivation. These veins represent narrow zones of moderately
intense deformation related to the latter stages of emplacement of the
pluton or to later tectonic activity. The deformation is not related
to impact processes or to fault zones involving any significant
displacement. References: [1] Hutchison R. M. (1956) Bull. GSA, 67,
763-806. [2] Garrison J. R. Jr. et al. (1979) Contrib. Mineral. Petrol.,
69, 361-374. [3] Barnes V. E. (1940) Texas Univ. Publ. 3945,
645-656. [4] Vedder W. and Wilkins R. W. T. (1969) Am. Mineral., 54,
482-509. [5] Sanz J. et al. (1983) Phys. Chem. Mineral., 9, 14-18. [6]
Spray J. G. (1992) Tectonophys., 204, 205-221.
Title: High resolution radio maps of quasars from the Jodrell Bank
966MHz survey.
Authors: Reid, A.; Shone, D. L.; Akujor, C. E.; Browne, I. W. A.;
Murphy, D. W.; Pedelty, J.; Rudnick, L.; Walsh, D.
Bibcode: 1995A&AS..110..213R
Altcode:
Radio maps are presented of quasars from the Jodrell Bank 966MHz
survey. The maps are made from observations at 408MHz with MERLIN,
1464/1666MHz with the VLA/MERLIN and at 5GHz with the VLA. The core
radio spectra at the three frequencies are shown for nearly all the
sources, showing that although a majority of core spectra are flat,
some sources have steep-spectrum cores.
Title: 'Melt' Breccias from the Roter Kamm Impact Crater, Namibia
Authors: Degenhardt, J. J., Jr.; Reid, A. M.; Buchanan, P. C.; Miller,
R. Mcg.
Bibcode: 1995LPI....26..323D
Altcode:
No abstract at ADS
Title: Recovering Parental Magma Compositions: A Single-Blind Test
of the Method and an Analysis of a Kilauean Parental Magma
Authors: Woronow, A.; Reid, A. M.; Jones, J. H.
Bibcode: 1995LPI....26.1521W
Altcode:
No abstract at ADS
Title: Book Review: New perspectives on stellar pulsation and
pulsating variable stars (IAU colloquium 139) / Cambridge U Press,
1993
Authors: Reid, A.
Bibcode: 1995Obs...115...44R
Altcode: 1995Obs...115...44N
No abstract at ADS
Title: Two Modes of Pulsation in the Rapidly Rotating O9.5 Dwarf,
HD 93521
Authors: Reid, A. H. N.; Bohlender, D.; Bolton, C. T.; Fullerton,
A. W.; Howarth, I. D.; Manz, C.; Smith, K. C.; Townsend, R. H. D.
Bibcode: 1995ASPC...83..309R
Altcode: 1995aasp.conf..309R; 1995IAUCo.155..309R
No abstract at ADS
Title: Recovery of Three Ordinary Chondrites from the Namib Desert
in Western Namibia
Authors: Reid, A. M.; Jakeš, P.; Zolensky, M. E.; McG. Miller, R.
Bibcode: 1995mfch.work...57R
Altcode: 1995LPITR9502...57R
No abstract at ADS
Title: Locating New Meteorite Recovery Areas
Authors: Zolensky, M. E.; Schutt, J. W.; Reid, A. M.; Jakeš, P.;
Martinez de Los Rios, E.; Miller, R. M.
Bibcode: 1995mfch.work...78Z
Altcode: 1995LPITR9502...78Z
No abstract at ADS
Title: Multi-wavelength study of ROSAT clusters of galaxies.
Authors: Pierre, M.; Hunstead, R.; Reid, A.; Robertson, G.; Mellier,
Y.; Soucail, G.; Böhringer, H.; Ebeling, H.; Voges, W.; Cesarsky,
C.; Oukbir, J.; Sauvageot, J. -L.; Vigroux, L.
Bibcode: 1994Msngr..78...24P
Altcode:
No abstract at ADS
Title: The Subsurface Character of the Marquez Impact Crater in Leon
County, Texas, as Determined from Gravity and Well Log Data
Authors: Wong, A. M.; Reid, A. M.; Hall, S. A.; Sharpton, V. L.
Bibcode: 1994Metic..29R.552W
Altcode:
The Marquez Dome in northwest Leon County, Texas is a shallow buried
complex impact crater. Exposure of Cretaceous sediments in a 1.2
km diameter disturbed zone, surrounded by shallow dipping Tertiary
sediments, led early investigators to interpret the structure as the
uplift overlying a salt dome. Subsequent drilling and seismic reflection
data within the area have ruled out a salt diapiric origin. Gibson and
Sharpton [1], and Sharpton and Gibson [2] reinterpreted the disturbed
zone as the central uplift of a complex crater, based on the absence
of salt above 5000 m below sea level, from well log information, on
the presence, from seismic reflection data, of continuous flat-lying
reflectors beneath the structure, and on examination of the rocks from
the central uplift. Shatter cones were found associated with the uplift
and planar deformation features occur in quartz grains collected at
the Marquez Dome [2]. Sharpton and Gibson [2] estimated the age of
the structure at 58 m.y., and that age has recently been confirmed
by apatite fission track dating [3]. In an attempt to understand the
geometry of the Marquez Dome, which is only exposed within the region
of the central uplift, we have combined limited surface mapping with
available geophysical well logs, and with gravity data that combines
a new detailed survey with earlier regional gravity data. Structure
maps were constructed by well log correlation for five stratigraphic
horizons that were disrupted by the impact. The extent of the crater was
estimated by mapping the small negative gravity anomaly that surrounds
the central uplift. Depths to the breccia lens surrounding the uplift
were estimated using empirical scaling laws. The revised model for the
Marquez Structure yields a diameter estimate of 12.7 km with an uplift
of at least 1120 m at the center of the structure. Subsurface structure
maps show decreasing deformation with depth, consistent with an impact
origin. From the well log and gravity data we have constructed a three
dimensional model of the central uplift to a depth of around 2000 m,
where there is no further evidence of deformation associated with
the central uplift. The predictions of this model, at least for the
shallow horizons, will be tested with the completion of two shallow
drill holes, sited just off the central uplift and midway to the
proposed crater rim. Core will be recovered selectively from both these
holes. References: [1] Gibson J. W. Jr. and Sharpton V. L. (1989) EOS,
70-15, 383. [2] Sharpton V. L. and Gibson J. W. Jr. (1990) LPS XXI,
1136-1137. [3] McHone J. F. and Sorkhabi R. B. (1994) LPS XXV, 881-882.
Title: Lithic Clasts in the Polymict Eucrite Petersburg
Authors: Buchanan, P. C.; Reid, A. M.
Bibcode: 1994Metic..29S.450B
Altcode:
The polymict eucrite Petersburg is a regolith breccia containing
significant proportions of matrix pyroxenes with compositions
interrnediate between those found in diogenites and noncumulate
eucrites. Possible sources of these intennediate composition pyroxenes
include cumulate eucrites, noncumulate eucrites more magnesian than
"main group" eucrites, cores of zoned pyroxenes from unequilibrated
eucntes, and eucritic materials affected by metamorphic redistribution
of Fe/Mg. Abundant eucritic clasts in Petersburg allow examination of
materials from which matrix minerals were derived. The majority of
Petersburg lithic clasts represent Fe-rich, equilibrated eucrites
similar to Juvinas. Clast pyroxenes within 20-30 micrometers of
clast edges have significantly higher Mg# than interior pyroxenes;
this is apparently the result of subsolidus alteration after clast
formation. Fe-rich alteration rims of similar thickness are present
on matrix pyroxenes of diogenitic composition. Fe/Mg exchange
during lithification of howardites and polymict eucrites has been
reported previously [l,2]. Based on matrix textures, Hewins [3,4]
has inferred thermal metamorphism of the Petersburg breccia under a
hot breccia blanket or lava flow. The uniform width and ubiquity of
Petersburg alteration rims suggests formation during a single thermal
event after final breccia accumulation. Less common among Petersburg
eucrite clasts are more magnesian compositions. Mittlefehldt [5]
reported data from Petersburg clast RC03 with bulk Mg# of 46 and
REE abundances of ~13x chondrite. We have analyzed Petersburg clast
A, a medium-grained (average grain size ~l mm), subophitic clast
predominantly composed of lath-shaped plagioclase (44%) and elongate
to equant pyroxene (44%) with mesostasis (10%) and minor opaques
(2%). Pyroxenes are unzoned with respect to Mg/Fe and are dominantly
composed of low-Ca clinopyroxene with fine (<1 micrometer thick)
augite exsolution lamellae that causes electron microprobe analyses
to range in apparent composition from Wo(sub)2.0En(sub)46.5 to
Wo(sub)32.7En(sub)33 7. These compositions are distinctly more
magnesian than pyroxene in "main group" eucrites [6]. Plagioclase
composition ranges from An77.4 to An88.7. REE abundances are
~26x chondrite with a signifilcant negative Eu anomaly. Electron
microprobe analyses of fused beads indicate that bulk Mg# of this
clast is ~49. Given the narrow width of alteration rims on Petersburg
eucrite clasts, the large size of clast A (>0.6 g), and the fact
that INAA and fused bead samples were obtained from the interior of
clast A, bulk clast compositions were unaffected by the metamorphic
redistribution of Fe/Mg described above. Stolper [7] suggested that
eucrites Stannern and Sioux County represented increasing degrees
of partial melting of similar source areas; other eucrites (e.g.,
Nuevo Laredo) represented fractionation of Sioux County-like liquids
(Fig. l). Later studies demonstrated the presence of eucritic materials
that could not easily be explained by this interpretation. Clast RC03
from Petersburg [5] and clast CF3 from Kapoeta [8] were interpreted
as derived from different source regions than other noncumulate
eucrites, based on major and trace element compositions. Hewins [4]
came to a similar conclusion for eucritic clasts in Petersburg based
on anomalously high Ni/Co ratio of clast metal. Warren et al.[9],
however, interpreted the REE-rich -21x chondrite), but magnesian
(Mg# ~45) eucrite Pomozdino as a partial cumulate, a mixture of
Stannern-like melt and cumulate material. Such an interpretation is
difficult to reconcile with data for clast A from Petersburg, since
bulk composition is more REE rich and yet more magnesian than that of
Pomozdino. Assuming Binda-like cumulate material, modeling of this
composition requires mixture with liquid that is more REE rich than
any eucritic matenal yet analyzed. Clast A may represent a very low
proportion partial melt of a source that has chondritic REE abundances,
but is significantly more magnesian than the source from which the
"main group" eucrites were derived. Intermediate-composition matrix
pyroxenes in Petersburg are derived at least in part from materials
that have trace element compositions similar to Stannern, but are more
magnesian. Some smaller (<60 micrometers) matrix pyroxene grains
probably have compositions that are largely the result of redistribution
of Fe/Mg during metamorphism after breccia accumulation. There is
no evidence that any of the intermediate-composition pyroxenes in
the matrix of Petersburg were derived from zoned pyroxenes similar
to those in Pasamonte. References: [l] Labotka T. C. and Papike
J. J. (1980) Proc. LPSC 11th, 1103-1130. [2] Fuhrman M. and Papike
J. J. (1981) Proc. LPSC 12th, 1257-1279. [3] Hewins R. H. (1979)
LPS X, 543-545. [4] Hewins R. H. (1979) GCA, 43, 1663-1673. [5]
Mittlefehldt D. W. (1979) GCA, 43, 1917-1935. [6] BVSP (1981)
Basaltic Volcanism on the Terrestrial Planets, Pergamon. [7]
Stolper E. (1977) GCA, 41, 587-611. [8] Smith M. R. (1982) Ph.D
dissertation, Oregon State University. [9] Warren P. H. et al. (1990)
Proc. LPSC 20th, 281-297. [10] Christophe Michel-Levy M. et al. (1987)
Bull. Mineral., 110, 449-458. [11] Hamet J. et al. (1978) Proc. LPSC,
9th, 1115-1136. [12] Jerome D. Y. (1970) Ph.D. dissertation, University
of Oregon. [13] McCarthy T. S. et al. (1973) EPSL, 18, 433-442. [14]
Palme H. et al. (1978) Proc. LPSC, 9th, 25-57. [15] Wanke H. et
al. (1974) Proc. LSC, 3rd, 1251-1268. [16] Warren P. H. and Jerde
E. A. (1987) GCA, 51, 713-725.
Title: Parental Magma Compositions of Basalts Using an Artificial
Neural Network: Theory
Authors: Woronow, A.; Reid, A. M.; Jones, J. H.; Pingitore, N. E., Jr.
Bibcode: 1994LPI....25.1513W
Altcode:
No abstract at ADS
Title: Time-series analysis of the O4 supergiant Zeta Puppis
Authors: Reid, A.
Bibcode: 1994IAUS..162..112R
Altcode:
No abstract at ADS
Title: Carbonaceous Chondrite Clasts in the Howardites Bholghati
and EET87513
Authors: Buchanan, P. C.; Zolensky, M. E.; Reid, A. M.
Bibcode: 1993Metic..28..659B
Altcode:
Twenty-two carbonaceous chondrite clasts from the two howardites
Bholghati and EET87513 were analyzed. Clast N from EET87513 is a
fragment classified as CM2 material on the basis of texture, bulk
composition, mineralogy, and bulk O isotopic composition. Carbonaceous
chondrite clasts from Bholghati, for which less data are available
because of their small size, can be divided into two petrologic
types: C1 and C2. C1 clasts are composed of opaque matrix with
rare coarse-grained silicates as individual mineral fragments;
textures resemble CI meteorites and some dark inclusions from CR
meteorites. Opaque matrix is predominantly composed of flaky saponite;
unlike typical CI and CR meteorites, serpentine is absent in the samples
we analyzed. C2 clasts contain chondrules, aggregates, and individual
fragments of coarse-grained silicates in an opaque matrix principally
composed of saponite and anhydrous ferromagnesian silicates with flaky
textures similar to phyllosilicates. These anhydrous ferromagnesian
silicates are interpreted as the product of heating of pre-existing
serpentine. The carbonaceous chondrite clasts we have studied from these
two howardites are, with one notable exception (clast N from EET87513),
mineralogically distinct from typical carbonaceous chondrites. However,
these clasts have very close affinities to carbonaceous chondrites
and have also experienced thermal metamorphism and aqueous alteration,
but to different degrees.
Title: Time-Series Observations of O Stars. II. Optical Observations
of zeta Ophiuchi
Authors: Reid, A. H. N.; Bolton, C. T.; Crowe, R. A.; Fieldus, M. S.;
Fullerton, A. W.; Gies, D. R.; Howarth, I. D.; McDavid, D.; Prinja,
R. K.; Smith, K. C.
Bibcode: 1993ApJ...417..320R
Altcode:
We present photopolarimetry and extensive high-resolution,
high-signal-to-noise optical spectroscopy of the rapidly rotating late
O-type star Ζ Ophiuchi (HD 149757). The polarimetric data show no
substantial variability over 1 week (σp < 0.04%), while
the spectroscopic data show characteristic line-profile variations in
the form of "bumps" migrating from blue to red on typical time scales
of several hours. These variations are relatively strong (amplitude
∼1% of the continuum level) in He I λ4471, and Si III λλ4552,
4567, 4575. They are seen at lower amplitudes in Mg II λ4481, but
are almost undetectable (amplitude ≲0.3%) in He II λλ4541, 4686
and N III λλ4511, 4515, 4518. We attribute this to a combination
of equatorial gravity darkening and a latitudinally confined origin
of the variations. Using a Fourier CLEAN technique, it is shown
that the line-profile variations can be adequately represented as
a set of sinusoids. The periods, combined with an estimate of the
rotational period, lead us to rule out rotational modulation as the
origin of the variability. The phase changes of the sinusoids across the
line-profiles indicate a repetitive pattern, consistent with sectorial
(1 = -m) nonradial pulsation. We find four periods: P = 3.339 hr (|m|
= 4), 2.435 hr (|m| = 5 or 6), 1.859 hr (|m| = 9±1), and either 1.366
or 1.292 hr (|m| = 11±1). The "superperiods," P|m|, may be nearly
commensurate (at ∼13-14 hr), but that commensurability is not exact.
Title: Time-Series Observations of O Stars. III. IUE and HST
Spectroscopy of zeta Ophiuchi and Implications for the ``Photospheric
Connection''
Authors: Howarth, Ian D.; Bolton, C. T.; Crowe, R. A.; Ebbets, D. C.;
Fieldus, M. S.; Fullerton, A. W.; Gies, D. R.; McDavid, D.; Prinja,
R. K.; Reid, A. H. N.; Shore, S. N.; Smith, K. C.
Bibcode: 1993ApJ...417..338H
Altcode:
Stellar-wind variability in the archetypal nonradially pulsating O star
ζ Oph (09.5 V) is discussed on the basis of new time-series lUE and HST
spectroscopy and archival results. Time-variable "discrete absorption
components" are first observed at high velocities (≳ 103
km s-1 ≃ 0.8υ∞) and then migrate blueward;
the recurrence time scale for the phenomenon is ∼20 hr. This is
the first record of this type of variability in a luminosity-class V
star and provides support for the previously inferred ubiquity of such
behavior across the 0-star regime. The accelerations are slower than
predicted by steady state wind models and are unlikely to represent
the time-averaged velocity law of the outflow. The UV results are
discussed in the context of simultaneous optical observations (Paper
II); no evidence is found to suggest that nonradial pulsations have any
direct role in determining the gross observational characteristics of
discrete absorption components, on either long (years) or short (hours)
time scales. The line-driven instability provides a promising mechanism
to account for variability observed in the UV P Cygni profiles of ζ
Oph, and, by extension, in all other O stars.
Title: Limits on mode identifications in rotating, non-radially
pulsating stars.
Authors: Reid, A. H. N.; Aerts, C.
Bibcode: 1993A&A...279L..25R
Altcode:
We present CLEAN time-series analysis of synthetic line profiles
obtained from a non-radially pulsating stellar model which incorporates
effects of rotation. Two models (a low-degree l = 2, m = -1; and
a high degree l = -m = 8) were calculated for a rapidly rotating
late O-type star, where the prograde oscillation frequency in the
corotating frame of the star is twice that of the stellar rotation
frequency. An interpretation of the results based upon the usual
slow-rotation assumptions gives a mis-identification of both period
and mode of oscillation for the low-degree model, but correctly
identifies the non-radial pulsation (NRP) characteristics of the
sectorial model. The mis-identification of the low-degree model has
possible implications for previous mode identifications, and we urge
caution when analyzing the line profile variations of rapidly-rotating,
non-radially pulsating stars.
Title: Original Size of the Vredefort Structure, South Africa
Authors: Therriault, A. M.; Reid, A. M.; Reimold, W. U.
Bibcode: 1993LPI....24.1419T
Altcode:
The Vredefort structure is located approximately 120 km southwest of
Johannesburg, South Africa, and is deeply eroded. Controversies remain
on the origin of this structure with the most popular hypotheses being:
(1) by impact cratering about 2.0 Ga; (2) as a cryptoexplosion structure
about 2.0 Ga; and (3) by purely tectonic processes starting at about
3.0 Ga and ending with the Vredefort event at 2.0 Ga. In view of recent
work in which the granophyre dikes are interpreted as the erosional
remants of a more extensive impact melt sheet, injected downward
into the underlying country rocks, the impact origin hypothesis for
Vredefort is adopted. In order to estimate the original dimensions of
the Vredefort impact structure, it is assumed that the structure was
initially circular, that its predeformation center corresponds to the
center of the granitic core, and that the pre-Vredefort geology of the
area prior to approximately 2.0 Ga ago is as suggested by Fletcher and
Reimold. The spatial relationship between shock metamorphic effects,
the shock pressures they record, and the morphological features of the
crater were established for a number of large terrestrial craters. The
principles of crater formation at large complex impact structures
comparable in size to Vredefort were also established, although many
details remain unresolved. An important conclusion is that the transient
crater, which is formed directly by excavation and displacement by the
shock-induced cratering flow-field (i.e., the particle velocity flow
field existing in the region of the transient crater but behind the
initial outgoing shock front), is highly modified during the late stage
processes. The original transient crater diameter lies well within the
final rim of the crater, which is established by structural movements
during late-stage cavity modification.
Title: Characterization of the Marquez Dome buried impact crater
using gravity and magnetic data
Authors: Wong, A. M.; Reid, A. M.; Hall, S. A.; Sharpton, V. L.
Bibcode: 1993LPI....24.1533W
Altcode:
The buried impact crater, Marquez Dome, located in Leon County in
east central Texas, is an approximately 15 km diameter structure whose
central uplift is now partially exposed due to headward erosion of the
post-impact cover. The central uplift is approximately 3 km in diameter
and the rocks within it have been uplifted more than 1200 m above their
regional level. The crater rim remains buried and previous attempts
to determine its location have had to rely on seismic reflection data
and geologic well logs. These attempts have been somewhat successful
in mapping the extent of the disturbed zone around Marquez Dome,
but more limited in their ability to image the shallow buried rim. In
an attempt to define accurately the whole Marquez Dome structure and
assist in the selection of drilling sites, a geophysical investigation
involving gravity and magnetic data over the central uplift and the
surrounding area has been undertaken.
Title: EET87513 Clast N: A CM2 Fragment in an HED Polymict Breccia
Authors: Buchanan, P. C.; Zolensky, M. E.; Reid, A. M.; Barrett, R. A.
Bibcode: 1993LPI....24..209B
Altcode:
Xenoliths of material resembling carbonaceous chondrites have been
found in several HED polymict breccias. Most workers concluded that
these clasts are related to CM2 meteorites on the basis of texture, bulk
composition, and mineralogy. Data on clast N, a carbonaceous chondrite
fragment from the howardite EET87513 large enough (approximately 4x5mm
on the surface of the slab from which it was separated) to extract
bulk samples for INAA and oxygen isotope analysis and to provide
a thin section for electron microprobe, SEM, and TEM analysis is
reported. Preliminary data for this clast were previously reported. INAA
was performed at Oregon State University and bulk oxygen isotopic
composition was determined at the University of Chicago. These data
confirm that EET87513 clast N is a fragment of CM2 material.
Title: Origin of the Vredefort Structure, South Africa: Impact Model
Authors: Therriault, A. M.; Reid, A. M.; Reimold, W. U.
Bibcode: 1993LPI....24.1421T
Altcode:
A model is presented for the evolution of the Vredefort structure, based
on reasoned constraints on the original size of the Vredefort structure
from observational data and comparison with other terrestrial impact
craters. The models for complex craters (ring and multi-ring basins)
of Croft, Grieve, and co-workers, and Schultz and co-workers, were
used to reconstruct the Vredefort impact event, using a final crater
diameter of 300 km, as estimated by Therriault. The sequence of events
(stages 2-5) is illustrated diagramatically. The stages are: initial
penetration, excavation and compression, dynamic rebound and uplift,
maximum radial growth and collapse, and final crater form.
Title: Time-Series Spectroscopy of Sigma Ophiuchi
Authors: Reid, A. H. N.; et al.
Bibcode: 1993npsp.conf..190R
Altcode: 1993IAUCo.139..190R
No abstract at ADS
Title: Impactite and pseudotachylite from Roter Kamm Crater, Namibia
Authors: Degenhardt, J. J., Jr.; Buchanan, P. C.; Reid, A. M.
Bibcode: 1992lmip.conf...20D
Altcode:
Pseudotachylite is known to occur in a variety of geologic settings
including thrust belts (e.g., the Alps and the Himalayas) and impact
craters such as Roter Kamm, Namibia. Controversy exists, however, as
to whether pseudotachylite can be produced by shock brecciation as
well as by tectonic frictional melting. Also open to debate is the
question of whether pseudotachylites form by frictional fusion or
by cataclasis. It was speculated that the pseudotachylite at Roter
Kamm was formed by extensional settling and adjustment of basement
blocks during 'late modification stage' of impact. The occurrence
of pseudotachylite in association with rocks resembling quenched
glass bombs and melt breccias in a relatively young crater of known
impact origin offers a rare opportunity to compare features of these
materials. Petrographic, x-ray diffraction, and electron microprobe
analyses of the impactites and pseudotachylites are being employed to
determine the modes of deformation and to assess the role of frictional
melting and comminution of adjacent target rocks.
Title: Mg/Si in the Earth, Planets, and Meteorites
Authors: Jakes, P.; Reid, A. M.
Bibcode: 1992Metic..27R.239J
Altcode:
The "primitive materials," i.e., carbonaceous chondrites (CV,CI,CM) [1]
and interplanetary dust particles [2,3] have Mg/Si ratios similar to
those of the solar photosphere [1]. The bulk composition of the Earth
and that of the terrestrial planets are believed to have higher than
"primitive" Mg/Si ratios [4], whereas ordinary and enstatite chondrites
have lower than primitive Mg/Si ratios [5]. The separation of Mg from
Si may result from reduction of silicon into a metallic phase through
the reaction of silicates with C or H2(6) or through temperature-induced
reduction of silicates (oxygen volatilization) [7,8]. Reduction leads to
the formation of a residuum with higher than original Mg/Si ratios. High
temperatures may also cause the vaporization of silicon and also lead
to higher Mg/Si ratios in the residual phase [4]. Lower Mg/Si ratios
could result from partial melting of a primitive material in which
Si preferentially enters the melt, leaving a high Mg/Si residuum. The
recrystallization of silicon- bearing metal in the presence of silicates
may also provide a mechanism to decrease Mg/Si ratios. This process
is documented by the presence of silica/silicates in the meteoritic
metals (CV3 Leoville and Efremovka and other chondrites, e.g., Renazzo,
ALH85085 [9]). Since Mg/Si fractionation may result from the extreme
temperatures, the other siderophile and volatile element abundances must
also be considered. The high contents of volatile elements in enstatite
chondrites exclude the possibility of such high-temperature processes,
and condensation under highly reducing conditions best explains
the observed abundances. The aubrites, i.e., enstatite achondrites,
however, all have attributes of high-T, low f[O(sub)2] processing and
may have formed through the recrystallization of superheated highly
fractionated (planetary processed?) material. An explanation of the
Earth's higher than primitive Mg/Si was sought in the differences
of volatility of Si and Mg, and hence in the thermal regime during
the formation of the early solar system [4] and in the siderophile
behavior of Si under reducing conditions [10]. Since Palme and Nickel
[5] have shown that the Mg number (Mg/Si ratio) in the upper mantle of
the Earth relates to the degree of fractionation of the mantle, e.g.,
to Ca/Al ratios. The explanation of different Mg/Si ratios between
the primitive chondrites and Earth's mantle could be found in mantle
fractionation, i.e., the formation of the Earth's crust. We argue for
the chondritic composition of the Earth in respect of Mg/Si and that
the ancient upper mantle was significantly fractionated prior to 3.9 AE
[11,12,13]. The early fractionation is reflected in the high Mg/Si of
the present peridotitic mantle. The upper mantle has been fractionated
throughout geologic time due to the formation of the basaltic melts
that contribute to the growth of the Earth's crust. These melts
are rich in Si relative to Mg, whereas the residuum is rich in Mg
relative to Si. The early melts were either erupted on the surface
or retained within the mantle. The erupted portion may be returned to
the mantle in the form of eclogite in the same way that recent oceanic
"basaltic" crust (with eclogite mineralogy) is recycled to the mantle
[14]. Since the eclogites do not completely homogenize with the upper
mantle and retain their petrological and geochemical identity [15],
the formation of basalts (eclogites) strongly influences the Mg/Si
ratio of the noneclogitic, i.e., peridotite mantle (residual mantle has
higher Mg/Si whereas basalt has lower Mg/Si than the original parent
rock). The "lost" crustal component [11] (3.9 AE old) may be present
in the upper mantle (transition) zone in its eclogitic (or griquaitic)
form. We suggest therefore that sampling of the upper mantle through the
analysis of pristine peridotites does not represent the bulk mantle but
represents only one major mantle component. Mantle sampling is biased
toward the rocks we interpret as primitive. The Earth's upper mantle may
well be chondritic in respect to Mg/Si, if the eclogites present are
added back into the estimates of mantle composition. References. [1]
Anders E. and Grevesse N. (1989), Geochim. Cosmochim. Acta, 53,
197-214. [2] Rietmeijer F.J.M. (1987), Abs. LPSC 18, 832-833. [3] Dikov
P.Yu. et al. (1990), Geokhimiya, 789-795. [4] Ringwood A.E. (1989),
Earth Planet. Sci. Lett., 95, 1-7. [5] Palme H. and Nickel K.G. (1985),
Geochim. Cosmochim. Acta, 49, 2123-2132. [6] Baedecker P.A and Wasson
J.T. (1975), Geochim. Cosmochim. Acta, 39, 735-765. [7] Jakes P. et
al., (1992), Abs. LPSC 23, 599-600. [8] Dickinson T.L. et al.,
(1992), Abs. LPSC 23, 309-310. [9] Zanda B. (1992), Abs. LPSC 23,
1569-1570. [10] Wanke H.(1981), Phil. Trans. R. Soc. Lond., A 303,
287-302. [11] Harper C.L. and Jacobsen S.B. (1992), EOS, 323. [12]
Collerson K.D. et al. (1991), Nature, 349, 209-214. [13] Galer S.G.G
and Goldstein S.L. (1991), Geochim. Cosmochim. Acta, 55, 227-239. [14]
Ringwood A.E. [15] Hatton C.J. and Gurney J.J. (1987), in Mantle
xenoliths P.H. Nixon ed., John Wiley & Sons.
Title: Time Series Observations of O Stars. I. IUE Observations of
Variability in the Stellar Wind of zeta Puppis
Authors: Prinja, R. K.; Balona, L. A.; Bolton, C. T.; Crowe, R. A.;
Fieldus, M. S.; Fullerton, A. W.; Gies, D. R.; Howarth, I. D.; McDavid,
D.; Reid, A. H. N.
Bibcode: 1992ApJ...390..266P
Altcode:
Stellar wind variability in Zeta Pup (O4 I(n)f) is described based on
31 high-resolution IUE observations secured over 5 1/2 days in 1989
April. Extensive changes are evident in the absorption regions of Si
IV 1393.76, 1402.77A and N IV 1718.55A P Cygni profiles. Both lines
exhibit similar patterns of variability, which are characterized by the
development and subsequent blueward migration, of discrete absorption
components. The formation of four discrete features is identified
over about 2.2 days of intensive observations, with a recurrence
time of about 15 hr. The time scales, velocities, and accelerations
of the progressive absorption enhancements are determined. These
changes are accompanied by fluctuations of up to about 200 km/s in
the maximum observed blue edge velocities in saturated C IV and N V
P Cygni profiles.
Title: Matrix Pyroxenes in Howardites and Polymict Eucrites
Authors: Buchanan, P. C.; Reid, A. M.
Bibcode: 1992LPI....23..173B
Altcode:
No abstract at ADS
Title: Mineralogy of Dark Clasts in CT Chondrites, Encrites and
Howardites
Authors: Zolensky, M. E.; Weisberg, M. K.; Buchanan, P. C.; Prinz,
M.; Reid, A.; Barrett, R. A.
Bibcode: 1992LPI....23.1587Z
Altcode:
No abstract at ADS
Title: Excess Heat and the Early Planet Evolution
Authors: Jakes, P.; Reid, A. M.; Casanova, I.
Bibcode: 1992LPI....23..597J
Altcode:
No abstract at ADS
Title: Silicate Melts at Super Liquidus Temperatures: Reduction
and Volatilization
Authors: Jakes, P.; Sen, S.; Matsuishi, K.; Reid, A. M.; King, E. A.;
Casanova, I.
Bibcode: 1992LPI....23..599J
Altcode:
No abstract at ADS
Title: Three New Chondrites from Namibia
Authors: Reid, A. M.; Jakes, P.; Zolensky, M. E.; Miller, R.
Bibcode: 1992LPI....23.1135R
Altcode:
No abstract at ADS
Title: A Magnetic Survey Across the Roter Kamm Impact Crater, Namibia
Authors: Reimold, W. U.; Reid, A. M.; Jakes, P.; Zolensky, M. E.;
Miller, R.
Bibcode: 1992LPI....23.1143R
Altcode:
No abstract at ADS
Title: "Bronzite" Granophyre: New Insight on Vredefort
Authors: Therriault, A. M.; Reid, A. M.
Bibcode: 1992LPICo.790...72T
Altcode:
No abstract at ADS
Title: Impactite and Pseudotachylite from Roter Kamm Crater, Namibia
Authors: Degenhardt, J. J., Jr.; Buchanan, P. C.; Reid, A. M.
Bibcode: 1992LPICo.790...20D
Altcode:
No abstract at ADS
Title: Bronzite Granophyre: New insight on Vredefort
Authors: Therriault, A. M.; Reid, A. M.
Bibcode: 1992lmip.conf...72T
Altcode:
The Vredefort Dome is located near the center of the Witwatersrand
Basin, about 120 km southeast of Johannesburg, South Africa. Its
origin is enigmatic, ranging from a major impact event to endogenous
processes, either igneous or tectonic. A unique melt rock, the
'Bronzite' Granophyr, occurs in the Vredefort structure as vertical
ring dikes along the contact between sedimentary collar and core of
Archaean granites, and as vertical dikes extending northwest-southeast
and northeast-southwest in the granitic core. The granophyre rocks
have an unusual composition and high content of recrystallized
sedimentary inclusions compared to common intrusive igneous rocks
with similar SiO2 content (61 to 70 percent by weight). The unique
nature of the granophyre has been underlined in previous studies
and origin hypotheses as an impact melt or as a highly contaminated
intrusive mafic magma have also been discussed. We present new results
obtained from a recent detailed petrographic and geochemical study of
a very large and texturally diverse suite of 'Bronzite' Granophyre,
representing all dikes occurring at Vredefort.
Title: Eucrite and Diogenite Clasts in Three Antarctic Achondri2tes
Authors: Buchanan, P. C.; Reid, A. M.
Bibcode: 1991LPI....22..149B
Altcode:
No abstract at ADS
Title: The Bholghati howardite: Petrography and mineral chemistry
Authors: Reid, A. M.; Buchanan, Paul; Zolensky, M. E.; Barrett, R. A.
Bibcode: 1990GeCoA..54.2161R
Altcode:
A 10 g sample of the Bholghati howardite was disaggregated in order
to separate two eucrite clasts, several small carbonaceous clasts,
fragments of diogenitic pyroxene, and bulk matrix. The eucrite clasts
show evidence of moderately rapid cooling from a melt, followed
by prolonged subsolidus annealing. The carbonaceous clasts mostly
resemble CM2 carbonaceous chondrites with low-iron silicates and
Fe-Ni sulphides in a fine grained dark matrix. One clast, however,
is mineralogically, petrographically, and compositionally similar
to a CI 1 chondrite. Both carbonaceous and eucritic clasts have a
complex history prior to incorporation into the howardite matrix
with no evidence of significant metamorphism since assembly. Most
clasts in the howardite breccia are monomineralic, with pyroxene
and plagioclase pre-dominant. Pyroxenes range from 'diogenitic' to
'eucritic' with diogenitic compositions most abundant; a significant
number of intermediate compositions are present, consistent with
derivation from a series of rocks related by fractionation.
Title: Clast Populations in Three Antarctic Achondrites
Authors: Buchanan, B. C.; Reid, A. M.; Schwarz, C.
Bibcode: 1990LPI....21..141B
Altcode:
No abstract at ADS
Title: Observations on Granitic Clasts in Granphyre from the Vredefort
Dome, South Africa
Authors: Reimold, W. U.; Reid, A. M.; Therriault, A. M.
Bibcode: 1990LPI....21.1009R
Altcode:
No abstract at ADS
Title: Carbonaceous fragments in the Bholghati howardite
Authors: Reid, A. M.; Buchanan, P. C.; Barrett, R. A.; Zolensky, M. E.
Bibcode: 1989Metic..24R.319R
Altcode:
No abstract at ADS
Title: Four Year Modulation of Periodic Radio Outbursts from LSI
+61 degrees 303
Authors: Gregory, P. C.; Xu, Huang-Jian; Backhouse, C. J.; Reid, A.
Bibcode: 1989ApJ...339.1054G
Altcode:
New 6 cm observations of the binary radio, X-ray, and gamma-ray
star LSI + 61 deg 303 obtained in August 1984 and September 1986
are presented. The data accumulated to date provide evidence for a
strong modulation in the amplitude of the 26.496 day periodic radio
outbursts. The modulation occurs on a time scale of 4 yr. Two possible
explanations are considered: (1) variable beaming from a precessing
relativistic jet and (2) variable accretion due to quasi-cyclic Be
star envelope variations.
Title: The Bholghati Howardite: Petrography and Mineral Chemistry
Authors: Reid, A. M.; Buchanan, P.
Bibcode: 1989LPI....20..892R
Altcode:
No abstract at ADS
Title: Carbonaceous Fragments in the Bholghati Howardite
Authors: Reid, A. M.; Buchanan, P. C.; Barrett, R. A.; Zolensky, M. E.
Bibcode: 1989LPICo.712..206R
Altcode:
No abstract at ADS
Title: Pink Spanel Troctolites in Apollo 14 Breccias
Authors: Collins, D. T.; Reid, A. M.
Bibcode: 1989mtak.conf...26C
Altcode: 1989LPITR8903...26C
No abstract at ADS
Title: The Bholghati Consortium: Preliminary Chemical and Petrologic
Characterization of the Bholghati Howardite
Authors: Gosselin, D. C.; Laul, J. C.; Smith, M. R.; Reid, A. M.
Bibcode: 1988Metic..23Q.270G
Altcode:
No abstract at ADS
Title: Dynamic Crystallization Experiments on Chondrule Melts of
Porphyritic Olivine Composition: Comparison of Olivine Compositions
from Natural and Experimentally Produced Chondrules
Authors: Lofgren, G. E.; Reid, A. M.
Bibcode: 1988LPI....19..688L
Altcode:
No abstract at ADS
Title: The Bholghati Consortium: Preliminary Chemical and Petrologic
Characterization of the Bholghati Howardite
Authors: Gosselin, D. C.; Laul, J. C.; Smith, M. R.; Reid, A. M.
Bibcode: 1988LPICo.665E..13G
Altcode:
No abstract at ADS
Title: Composition of gold grains in the Vaal Placer, Klerksdorp,
South Africa
Authors: Reid, A. M.; Le Roex, A. P.; Minter, W. E. L.
Bibcode: 1988MinDe..23..211R
Altcode:
Separated gold grains from 94 samples of the Vaal Placer, Klerksdorp
gold field, South Africa have been analyzed for Au, Ag and Hg. Average
gold grain compositions in these samples range from 80 to 95 weight
percent Au, 4 to 18 weight percent Ag and 0.5 to 4 weight percent
Hg with an average composition around Au 90, Au 8, Hg 2. Individual
grains are homogeneous but significant differences exist between gold
grains from single small samples and also between average compositions
in separate samples. The data do not fit any simple model of gold
compositional control by provenance or by metamorphic homogenization.
Title: Variable radio source GT0116+622 is a possible counterpart
to Cas γ-1
Authors: Gregory, P. C.; Duric, N.; Reid, A.; Picha, J.; Stevenson, T.
Bibcode: 1986Natur.323..602G
Altcode:
Identification of celestial γ-ray sources has proved to be
very difficult because of the large positional uncertainties
(typically several degrees) and the transient nature of many of these
objects. Highly variable radio emission is a striking characteristic
of the most secure source of very high-energy radiation, Cygnus X-3
(ref. 1). Here we report the discovery of another highly variable
radio source which coincides in position with the transient TeV γ-ray
source Cas γ-1. We have obtained an accurate radio position with the
Very Large Array (VLA) telescope but no optical counterpart was found
on the Mount Palomar Sky Survey prints. We have also obtained upper
limits on radio emission from the binary X-ray pulsar, 4U0115+634,
another proposed identification for Cas γ-1.
Title: Compositions of 7 Allan Hills polymict eucrites and one
diogenite
Authors: Reid, A. M.; Le Roex, A. P.
Bibcode: 1984LPICo.537E..64R
Altcode:
No abstract at ADS
Title: Ferrobasalts from the Spiess Ridge segment of the Southwest
Indian Ridge
Authors: le Roex, A. P.; Dick, H. J. B.; Reid, A. M.; Erlank, A. J.
Bibcode: 1982E&PSL..60..437L
Altcode:
Highly vesicular, microporphyritic basaltic rocks have been dredged
from the slow-spreading Spiess Ridge segment of the Southwest Indian
Ridge. All the samples recovered are hyalocrystalline with plagioclase,
clinopyroxene and olivine as phenocryst and microphenocryst
phases. Titanomagnetite occurs as euhedral microphenocrysts in
some of the more evolved samples. In terms of bulk rock and quench
glass chemistry the lavas are characterised by highly evolved
compositions(e.g. FeO*=10.3-14.2%;TiO 2=2.0-3.4%;K
2O=0.50-1.1%;MgO=6.0-3.5%;Zr=160-274ppm;Nb=14-32ppm)
and can be classified as ferrobasalts. Isotopic and
incompatible element ratios of the lavas(e.g. 87Sr/
86Sr=0.70325-0.70333;Zr/Nb=8.4-11.3;Y/Nb=2.3-1.4)
indicate their strongly "enriched" nature (see also Dickey et
al. [6]). Quantitative major and trace element modelling indicates
that most of the compositional variations observed can be attributed to
low-pressure fractional crystallisation of plagioclase, clinopyroxene
and minor olivine and titanomagnetite. The range in composition can
be accounted for by up to 65% fractional crystallisation. We suggest
that the extreme differentiation of the Spiess Ridge lavas is related
not to spreading rate, but to rate of magma supply. The basaltic
melts appear to have evolved in a newly established zone of magmatic
activity, associated with the most recent northward jump of the Bouvet
triple junction, where they were effectively isolated from significant
admixture of primitive magmas.
Title: Analysis of palaeomagnetic inclination data
Authors: McFadden, P. L.; Reid, A. B.
Bibcode: 1982GeoJ...69..307M
Altcode: 1982GeoJI..69..307M
No abstract at ADS
Title: Descriptions of stony meteorites
Authors: Score, R.; King, T. V. V.; Schwarz, C. M.; Reid, A. M.;
Mason, B.
Bibcode: 1982mvla.rept...19S
Altcode:
The individual specimens, arranged by class are described. Within the
chondrites, the specimens are grouped according to the Van Schmus-Wood
classification, and the descriptions follow the order of increasing
petrographic type. The original weight of the specimen is given to
the nearest gram (nearest 0.1 gram for specimens weighing less than
100 grams). Material on al characterized meteorites collected together
with descriptions of some meteorites is included. Specimens weighing
less than 100 grams are listed without descriptions, unless they show
distinctive features.
Title: Basaltic Achondrite Meteorites from the Antarctic
Authors: Reid, A. M.
Bibcode: 1982AntJ...16...65R
Altcode:
No abstract at ADS
Title: Overview of Antarctic achondrites
Authors: Reid, A. M.
Bibcode: 1982mvla.rept...59R
Altcode:
The distribution of achondrite classes in the Antarctic and
non-Antarctic collections are compared. The numbers in the non-Antarctic
column are an unreliable guide to the real distribution of achondrite
types in the total terrestrial infall because of the vagaries of
observation, recognition, and recovery. The Antarctic meteorites
provide a better guide since they are more easily recognized and are
all carefully studied and cataloged. There remarked differences between
the Antarctic and non-Antarctic achondrite collections. Diogenites
are more abundant inthe Antarctic collection, comprising over half
the classified samples.
Title: Igneous Layering in an Achondritic Meteorite
Authors: McSween, H. Y., Jr.; Reid, A. M.
Bibcode: 1981Metic..16Q.359M
Altcode:
No abstract at ADS
Title: Major Element Compositions and Rb-Sr, Sm-Nd Isotopic
Systematics of Allan Hills Polymict Eucrites
Authors: Wooden, J. L.; Brown, R.; Bansal, B.; Shih, C. -Y.; Wiesmann,
H.; Nyquist, L. E.; Reid, A. M.
Bibcode: 1981Metic..16..404W
Altcode:
No abstract at ADS
Title: A preliminary report on the achondrite meteorites in the 1979
U. S. Antarctic meteorite collection
Authors: Reid, A.; Score, R.
Bibcode: 1981PolRe..20...33R
Altcode:
Seventy-three meteorite samples were collected in Antarctica during
the austral summer of 1979-80. A description is presented of the seven
achondrites found among the meteorite samples. The achondrites described
include an ALHA79017-polymict eucrite, an EETA79001-shergottite,
an EETA79002-diogenite, an EETA79004-eucrite, an EETA79005-polymict
eucrite, an EETA79006-howardite, and an EETA79011-polymict eucrite. The
most exciting single aspect of the 1979 collection is undoubtedly the
discovery of a new member of the shergottite group of meteorites. Sample
EETA79001 is just under 8 kg and should thus provide ample material
for detailed studies. In addition to the achondrites, a unique iron
meteorite with abundant silicate (orthopyroxene) inclusions and a
large diogenite is also discussed.
Title: Chemical and Isotopic Studies of the Allan Hills Polymict
Eucrites
Authors: Wooden, J.; Reid, A.; Brown, R.; Bansal, B.; Wiesmann, H.;
Nyquist, L.
Bibcode: 1981LPI....12.1203W
Altcode:
No abstract at ADS
Title: Summary Statistics of 1977 and 1978 Antarctic Meteorite
Collections and a Glimpse of the 1979 Collection
Authors: King, T. V. V.; Score, R.; Schwarz, C.; Reid, A. M.; Mason,
B. H.
Bibcode: 1980Metic..15..315K
Altcode:
No abstract at ADS
Title: Antarctic polymict eucrites
Authors: Reid, A. M.; Schwarz, C. M.
Bibcode: 1980LPICo.412..104R
Altcode:
No abstract at ADS
Title: Petrogenetic Models for Eucrite Genesis
Authors: Reid, A. M.; Duncan, A. R.; Le Roex, A.
Bibcode: 1979LPI....10.1022R
Altcode:
No abstract at ADS
Title: Unequilibrated and Equilibrated Eucrites
Authors: Reid, A. M.; Barnard, B. M.
Bibcode: 1979LPI....10.1019R
Altcode:
No abstract at ADS
Title: Major element composition in Luna 20 glasses.
Authors: Warner, J. L.; Reid, A. M.; Ridley, W. I.; Brown, R. W.
Bibcode: 1979rhrm.conf..420W
Altcode:
No abstract at ADS
Title: Abundance and composition of phases in the Luna 20 regolith
45 - 125 µm fraction.
Authors: Reid, A. M.; Warner, J. L.; Ridley, W. I.; Brown, R. W.
Bibcode: 1979rhrm.conf..372R
Altcode:
No abstract at ADS
Title: Non-Mare "Igneous" Clasts in Apollo 15 Breccias
Authors: Reid, A. M.; Richardson, S. H.; Duncan, A. R.
Bibcode: 1977LPI.....8..801R
Altcode:
No abstract at ADS
Title: In search of LKFM (low K Fra Mauro basalt).
Authors: Reid, A. M.; Duncan, A. R.; Richardson, S. H.
Bibcode: 1977LPSC....8.2321R
Altcode:
The term Low K Fra Mauro Basalt (LKFM) was first used by Reid et
al. (1972) in connection with a study of glass compositions in the
less than 1 mm fraction of three Apollo 15 soils. If the glass data
have been interpreted correctly, then rocks of LKFM composition are a
major component of the lunar crust. This interpretation is supported
by the orbital X-ray and gamma-ray data which are consistent with the
LKFM composition for several areas of the lunar surface. A description
is presented of a search of Apollo 15 breccia samples for clasts which
have igneous textures and are not obviously mare basalts. The objectives
of this search were to assess the nature of nonmare igneous rocks in
the Apollo 15 breccias and, in particular, to search for evidence of
the elusive igneous LKFM. Reasonable evidence is found that rocks with
the composition of LKFM are a major constituent of the lunar crust.
Title: A description of two automated control systems for the
electron microprobe
Authors: Frost, M. T.; O'Hara, K.; Suddaby, P.; Grant, G.; Reid,
A. F.; Wilson, A. F.; Zuiderwyk, M.
Bibcode: 1976XRS.....5..180F
Altcode:
No abstract at ADS
Title: Characterization of crust formation on a parent body of
achondrites and the moon by pyroxene crystallography and chemistry.
Authors: Takeda, H.; Miyamoto, M.; Ishii, T.; Reid, A. M.
Bibcode: 1976LPSC....7.3535T
Altcode:
Single crystal X-ray diffraction and electron microprobe techniques
were used to study lunar crustal pyroxenes in a cataclastic norite,
a pyroxene-rich clast, and anorthosite lunar samples, and also
in meteorites including diogenites, eucrites, and the Yamoto (1)
howardite. The crystallographic and chemical characteristics of
pyroxenes in these materials are compared and are discussed in terms
of the lower stability limit of pigeonite. A mechanical mixing model
of howardite is proposed.
Title: Aioun EL Atrouss: A New Hypersthene Achondrite with Eucritic
Inclusions
Authors: Lomena, I. S. M.; Toure, F.; Gibson, E. K., Jr.; Clanton,
U. S.; Reid, A. M.
Bibcode: 1976Metic..11...51L
Altcode:
Preliminary investigations have been made on two separate pieces
from the Aioun el Atrouss meteorite that fell on April 17, 1974
in southeast Mauritania. The major portion of the meteorite is a
brecciated hypersthene achondrite with orthopyroxene (En74) as the
major phase. Clasts of eucrite, up to 7 per cent in volume within
a single slice, occur within the hypersthene achondrite host. No
evidence has been found of reaction between the two meteorite types,
nor of the presence of any materials intermediate in composition.
Title: Cristallographic and chemical studies of a bronzite and
chromite in the Yamato (B) achondrite.
Authors: Takeda, H.; Reid, A. M.; Yamanaka, T.
Bibcode: 1976Metic..11..183T
Altcode:
No abstract at ADS
Title: The Nakhlites Part I: Petrography and Mineral Chemistry
Authors: Bunch, T. E.; Reid, A. M.
Bibcode: 1975Metic..10..303B
Altcode:
The two Nakhlite meteorites (Nakhla and Lafayette) are described,
and their possible origin is discussed. It is shown that both objects
are cumulates of clinopyroxene with augite as the major mineral and
with lesser abundances of olivine, plagioclase, K-feldspar, Fe-Ti
oxides, FeS, pyrite, chalcopyrite, and possibly iddingsite. Also,
both meteorites are unbrecciated, and their texture is dominated by
elongate subhedral to euhedral prisms of clinopyroxene. The data are
shown to be compatible with the Nakhlites' being cumulative rocks from
a common basaltic parent liquid. It is established that these objects
are not of lunar origin, and it is concluded that the position of the
parent body relative to other planetary bodies remains to be determined.
Title: The Nakhlites Part II: Where, When and How
Authors: Reid, A. M.; Bunch, T. E.
Bibcode: 1975Metic..10..317R
Altcode:
The Nakhla and Lafayette meteorites are pyroxenite cumulates that
show no simple relation to chondrites, basaltic achondrites, or lunar
rocks. They present evidence of magma tic activity occurring on a
highly differentiated parent body relatively late in the history of
the solar system similar in some respects to the Earth.
Title: A Geochemical and Petrographic Study of 1-2mm Fines from
Apollo 17
Authors: Blanchard, D. P.; Korotev, R. L.; Brannon, J. C.; Jacobs,
J. W.; Haskin, L. A.; Reid, A. M.; Donaldson, C. H.; Brown, R. W.
Bibcode: 1975LPI.....6...57B
Altcode:
No abstract at ADS
Title: A geochemical and petrographic study of 1 - 2 mm fines from
Apollo 17.
Authors: Blanchard, D. P.; Korotev, R. L.; Brannon, J. C.; Jacobs,
J. W.; Haskin, L. A.; Reid, A. M.; Donaldson, C. H.; Brown, R. W.
Bibcode: 1975LPSC....6.2321B
Altcode:
Samples of fines less than 1-mm and 155 1-2 mm particles from several
Apollo 17 sites were analyzed for Na, Sc, Cr, Mn, Fe, Co, Ni, Hf,
Ta, Th, and REE. Products of comminution and construction are present
in the 1-2 mm particles, and the compositions of the rock fragments
clearly indicate the general chemical characteristics of their parent
rock types. The likely sources of materials for the glassy particles
are considered. Glasses are enriched over their parent soils in Fe,
Sc, Mn, and Cr, and are relatively enriched in light REE, so that some
chemical fractionation accompanies glass-forming processes. Elements
were determined by instrumental neutron activation analysis.
Title: Crystallographic and chemical studies of a bronzite and
chromite in the Yamato (B) achondrite.
Authors: Takeda, H.; Reid, A. M.; Yamanaka, T.
Bibcode: 1975MNIPR...5...83T
Altcode:
No abstract at ADS
Title: The Nakhlites.
Authors: Bunch, T. E.; Reid, A. M.
Bibcode: 1975Metic..10...92B
Altcode:
No abstract at ADS
Title: Phase chemistry of Apollo 14 soil sample 14259.
Authors: Aitken, F. K.; Anderson, D. H.; Bass, M. N.; Brown, R. W.;
Butler, P., Jr.; Heiken, G.; Jakes, P.; Reid, A. M.; Ridley, W. I.;
Takeda, H.; Warner, J.; Williams, R. J.
Bibcode: 1974ModGe...5....1A
Altcode:
Optical, X-ray-diffraction and electron-microprobe techniques were used
to investigate 0.26 gm of Apollo 14 soil sample 14259. Major element
microprobe analyses were made of 470 mineral grains and 388 glass
grains. The mineral abundances in the soil are 45% plagioclase, 41%
pyroxene, 7% olivine, 3% oxides, 2% K-feldspar; 1% nickel-iron, and
less than 1% troilite. The glasses have a wide range of compositions
but preferred values are evident and are interpreted as representative
of rock types contributing to the soil at the Fra Mauro site. Eleven
per cent of the glasses have compositions like those of mare basalts
or mare soils and are believed to be mare-derived. Eighty-six per cent
of the glasses are equivalent in composition to basalts that have
higher Al, and lower Ca/Al and Fe/Mg ratios than mare basalts. The
most abundant compositional type is named Fra Mauro basaltic glass and
is subdivided into three related types. The other major glass type in
the soil corresponds in composition to anorthositic gabbro.
Title: Comparative Studies of Impact Glasses and Breccias
Authors: Fredriksson, K.; Brenner, P.; Nelen, J.; Noonan, A.; Dube,
A.; Reid, A.
Bibcode: 1974LPI.....5..245F
Altcode:
No abstract at ADS
Title: Comparisons of Crystallographic and Chemical Characteristics
of Pyroxenes Between Lunar Crustal Rocks and Achondrites
Authors: Takeda, H.; Ishii, T.; Reid, A. M.
Bibcode: 1974LPI.....5..764T
Altcode:
No abstract at ADS
Title: Chromium Partitioning Between Olivine and Pyroxene and the
Redox State of Lunar Rocks
Authors: Jakes, P.; Reid, A. M.
Bibcode: 1974LPI.....5..381J
Altcode:
No abstract at ADS
Title: A Refractory Glass Chondrule in the Vigarano Chondrite
Authors: Reid, A. M.; Williams, R. J.; Gibson, Everett K., Jr.;
Fredriksson, Kurt
Bibcode: 1974Metic...9...35R
Altcode:
Vigarano, a type 3 carbonaceous chondrite, contains a chondrule composed
of highly refractory Ca and Al rich glass with minor spinel. The
chondrule formed from material similar to the Ca, M, Ti-rich aggregates
that are common in Vigarano and other type 3 chondrites and formation
of these refractory aggregates must predate formation of some Vigarano
chondrules. Experiments with synthetic analogues and a comparison with
studies in the system CaO-MgO-Al2O3-SiO2 indicate a temperature for
formation of the chondrule at or above 1700 0Cfollowed by very rapid
coo ling.
Title: Luna 16 Revisited: The case for Aluminous Mare Basalts
Authors: Reid, A. M.; Jakes, P.
Bibcode: 1974LPI.....5..627R
Altcode:
No abstract at ADS
Title: Rare Earth and Other Trace Elements in Some Individual 1-2MM
Fines From Apollo 16 and 17
Authors: Haskin, L. A.; Blanchard, D. P.; Jacobs, J. W.; Korotev,
R. L.; Herrmann, A. G.; Reid, A. M.
Bibcode: 1974LPI.....5..310H
Altcode:
No abstract at ADS
Title: Crystal Chemical Control of Element Partitioning for Coexisting
Pigeonite-Augite and Chromite-Ulvospinel
Authors: Takeda, H.; Miyamoto, M.; Reid, A. A.
Bibcode: 1974LPI.....5..766T
Altcode:
No abstract at ADS
Title: Apollo 16 1-2mm Fines, Sample 65702, Chemical and Petrographic
Correlations
Authors: Reid, A. M.; Donaldson, C.; Jakes, P.; Brown, R. W.
Bibcode: 1974LPI.....5..624R
Altcode:
No abstract at ADS
Title: Lunar petrology conference.
Authors: Ridley, W. I.; Reid, A. M.; Brett, P. R.
Bibcode: 1974EOSTr..55....4R
Altcode:
A Lunar Petrology Conference, sponsored by the Lunar Science Institute
under NASA contract NSR-09-051-001 and attended by nearly 100
scientists, was held from July 24 to 26, 1973, in Houston, Texas.The
principal aim of the conference was to bring together penologists and
geochemists active in lunar research to discuss the present status of
lunar petrology. The emphasis was placed on discussion with a minimum
of formal presentations. In each session two or three keynote speakers
reviewed present knowledge and highlighted problem areas in order to
encourage discussion. The 3-day meeting was characterized by lively,
broad-ranging, often humorous discussion of a variety of problems. The
following is a short synopsis of the major areas of discussion.
Title: Crystal chemical control of element partitioning for coexisting
chromite-ulvöspinel and pigeonite-augite in lunar rocks.
Authors: Takeda, H.; Miyamoto, M.; Reid, A. M.
Bibcode: 1974LPSC....5..727T
Altcode:
No abstract at ADS
Title: Feldspar basalts in lunar soil and the nature of the lunar
continents
Authors: Reid, A. M.; Ridley, W. I.; Harmon, R. S.; Warner, J.; Brett,
R.; Jakes, P.; Brown, R. W.
Bibcode: 1974lssf.book..122R
Altcode:
It is found that 25% on the Apollo-14 glasses have the same composition
as the glasses in two samples taken from the Luna-16 column. The
compositions are equivalent to feldspar basalt and anorthosite gabbro,
and are similar to the feldspar basalts identified from Surveyor-7
analysis for lunar continents.
Title: Apollo 17 Lunar Samples: Chemical and Petrographic Description
Authors: Apollo 17 Preliminary Examination Team; Gast, P. W.; Phinney,
W. C.; Duke, M. B.; Muehlberger, W. R.; Hubbard, N. J.; Butler, P.;
Laughon, R. B.; Annexstad, J. O.; Heiken, G. H.; Agrell, S.; Brett,
P. R.; Clanton, U. S.; Carrier, W. D.; Fruland, R.; Fryxell, R.;
Gooley, R.; Horz, F.; Jackson, E. D.; Lofgren, G. E.; Marvin, U. B.;
McKay, D. S.; Meyer, C.; Morrison, D. A.; Nagle, S.; Reid, A. M.;
Ridley, W. I.; Simonds, C. H.; Stuart-Alexander, D.; Warner, J. L.;
Williams, R. J.; Wilshire, H. G.; Bansal, B.; Bennett, L.; Clark,
R. S.; Eldridge, J. S.; Felix, W. D.; Gibson, E. K.; Keith, J. E.;
Lewis, C. F.; Moore, C. B.; Moore, G. W.; Northcutt, K. J.; O'Kelley,
G. D.; Perkins, R. W.; Portenier, W. R.; Rancitelli, L. A.; Reynolds,
M. A.; Rhodes, J. M.; Robbins, M. K.; Rogers, K. V.; Schonfeld, E.;
Simms, L. A.; Wainwright, J.; Wogman, N. A.
Bibcode: 1973Sci...182..659A
Altcode: 1973Sci...182..659G
No abstract at ADS
Title: Apollo 15 green glasses
Authors: Ridley, W. I.; Reid, A. M.; Warner, J. L.; Brown, R. W.
Bibcode: 1973PEPI....7..133R
Altcode:
Apollo 15 breccia 15427 and soils 15101, 15261 and 15301 contain
abundant spheres and fragments of a green glass that is remarkably
constant in composition. The glass is rich in Fe and Mg, and low in
Ti, unlike any known lunar basalt, and may be derived from material
of pyroxenitic composition in the Apennine Front.
Title: Major Element Composition of Glasses in two Apollo 16 Soils
and a Comparison with Luna 20 Glasses
Authors: Ridley, W. I.; Reid, A. M.; Warner, J.; Brown, R. W.; Gooley,
R.; Donaldson, C.
Bibcode: 1973LPI.....4..625R
Altcode:
No abstract at ADS
Title: Inverted Pigeonites from a Clast of Rock 15459
Authors: Takeda, H.; Ridley, W. I.; Reid, A. M.; Brett, R.
Bibcode: 1973LPI.....4..701T
Altcode:
No abstract at ADS
Title: Zirconolite (versus zirkelite) in Lunar Rocks
Authors: Wark, D. A.; Reid, A. F.; Lovering, J. F.; El Goresy, A.
Bibcode: 1973LPI.....4..764W
Altcode:
No abstract at ADS
Title: Coexisting bronzite and clinobronzite in the Steinbach
meteorite.
Authors: Reid, A. M.; Williams, R. J.; Takeda, H.
Bibcode: 1973Metic...8R..66R
Altcode:
No abstract at ADS
Title: The Apollo 16 Lunar Samples: Petrographic and Chemical
Description
Authors: Apollo 16 Preliminary Examination Team; Gast, P. W.;
Phinney, W. C.; Duke, M. B.; Jackson, E. K.; Hubbard, N. J.; Butler,
P.; Laughon, R. B.; Agrell, S. O.; Bass, M. N.; Brett, R.; Carrier,
W. D.; Clanton, U. S.; Eaton, A. L.; Head, J.; Heiken, G. H.; Horz,
F.; Lofgren, G. E.; McKay, D. S.; Morrison, D. A.; Muehlberger,
W. R.; Nagle, J. S.; Reid, A. M.; Ridley, W. I.; Simonds, C.;
Stuart-Alexander, D.; Warner, J. L.; Williams, R. J.; Wilshire, H.;
Bansal, B. M.; Brannon, J. A.; Landry, A. M.; Rhodes, J. M.; Rodgers,
K. V.; Wainwright, J. E.; Bennett, L.; Clark, R. S.; Keith, J. E.;
O'Kelley, G. D.; Perkins, R. W.; Rancitelli, L. A.; Portenier, W. R.;
Robbins, M. K.; Schonfeld, E.; Gibson, E. K.; Lewis, C. F.; Moore,
C. B.; Moore, D. R.
Bibcode: 1973Sci...179...23A
Altcode: 1973Sci...179...23G
No abstract at ADS
Title: Glass compositions in Apollo 16 soils 60501 and 61221
Authors: Ridley, W. I.; Reid, A. M.; Warner, J. L.; Brown, R. W.;
Gooley, R.; Donaldson, C.
Bibcode: 1973LPSC....4..309R
Altcode: 1973GeCAS...4..309R
No abstract at ADS
Title: Major Element Composition of Glasses in Three Apollo 15 Soils
Authors: Reid, A. M.; Warner, J.; Ridley, W. I.; Brown, R. W.
Bibcode: 1972Metic...7..395R
Altcode:
Approximately 180 glasses in each of three Apollo 15 soils have
been analyzed for nine elements. Cluster analysis techniques allow
the recognition of preferred glass compositions that are equated with
parent rock compositions. Green glass rich in Fe and Mg, poor in Al
and Ti may be derived from deep seated pyroxenitic material now present
at the A penn ine Front. Fra Mauro basalt (KREFP) is most abundant in
the LM soil and is tentatively identified as ray material from the
A ristillus-A u to lycu s area. High land basalt (anortho sitic gab
bro), believed to be derived from the lunar highlands, has the same
composition as at other landing sites, but is less abundant. The A
penn ine Front is probably not true highland material but may contain a
substantial amount of material with the composition of Fra Mauro basalt,
but lacking the high-K content. Glasses with mare basalt compositions
are present in the soils and four subgroups are recognized, one of which
is compositionally equivalent to the large Apollo 15 basalt samples.
Title: Petrology of Mare Fecunditatis
Authors: Jakes, P.; Ridley, W. I.; Reid, A. M.; Warner, J.; Harmon,
R. S.; Brett, R.; Brown, R. W.
Bibcode: 1972LPI.....3..430J
Altcode:
No abstract at ADS
Title: The Apollo 15 lunar samples: A preliminary description.
Authors: Gast, P. W.; Phinney, W. C.; Duke, M. B.; Silver, L. T.;
Hubbard, N. J.; Heiken, G. H.; Butler, P.; McKay, D. S.; Warner,
J. L.; Morrison, D. A.; Horz, F.; Head, J.; Lofgren, G. E.; Ridley,
W. I.; Reid, A. M.; Wilshire, H.; Lindsay, J. F.; Carrier, W. D.;
Jakes, P.; Bass, M. N.; Brett, P. R.; Jackson, E. D.; Rhodes, J. M.;
Bansal, B. M.; Wainwright, J. E.; Parker, K. A.; Rodgers, K. V.;
Keith, J. E.; Clark, R. S.; Schonfeld, E.; Bennett, L.; Robbins, M.;
Portenier, W.; Bogard, D. D.; Hart, W. R.; Hirsch, W. C.; Wilkin,
R. B.; Gibson, E. K.; Moore, C. B.; Lewis, C. F.
Bibcode: 1972Sci...175..363G
Altcode:
No abstract at ADS
Title: Chemistry of Highland and Mare Basalts as Inferred from
Glasses in the Lunar Soils
Authors: Reid, A. M.; Ridley, W. I.; Warner, J.; Harmon, R. S.; Brett,
R.; Jakes, P.; Brown, R. W.
Bibcode: 1972LPI.....3..640R
Altcode:
No abstract at ADS
Title: Apollo 15 glasses and the distribution of non-mare crustal
rock types.
Authors: Warner, J.; Ridley, W. I.; Reid, A. M.; Brown, R. W.
Bibcode: 1972afls.conf..179W
Altcode:
No abstract at ADS
Title: Microprobe analyses of glasses in lunar soils.
Authors: Brown, R. W.; Ridley, W. I.; Warner, J. L.; Reid, A. M.
Bibcode: 1972magl.book.....B
Altcode:
No abstract at ADS
Title: Preliminary Examination of Lunar Samples from Apollo 14
Authors: Anderson, D. H.; Bass, M. N.; Bennett, A. D.; Bogard, D. D.;
Brett, R.; Bromwell, L. G.; Butler, P., Jr.; Carrier, W. D., III;
Clark, R. S.; Cobleigh, T.; Duke, M. B.; Gast, P. W.; Gibson, E. K.,
Jr.; Hart, W. R.; Heiken, G. H.; Hirsch, W. C.; Hörz, F.; Jackson,
E. D.; Johnson, P. H.; Keith, J. E.; Lewis, C. F.; Lindsay, J. F.;
Martin, J. R.; Melson, W. C.; Mitchell, E. D.; Moore, C. B.; Morrison,
D. A.; Nance, W. B.; Phinney, W. C.; Reid, A. M.; Reynolds, M. A.;
Richardson, K. A.; Ridley, W. I.; Schonfeld, E.; Shepard, A. B.;
Sutton, R. L.; Trask, N. J.; Warner, J.; Wilkin, R. B.; Wilshire,
H. G.; Wones, D. R.; Lunar Sample Preliminary Examination Team (1)
Bibcode: 1971Sci...173..681A
Altcode:
No abstract at ADS
Title: Apollo 12 Igneous Rocks 12004, 12008, 12009, and 12022:
Metal Grains and their Relation to the Crystallization History
Authors: Brett, R.; Butler, P., Jr.; Meyer, C., Jr.; Reid, A. M.;
Takeda, H.; Williams, R. J.
Bibcode: 1971LPI.....2..212B
Altcode:
No abstract at ADS
Title: Apollo 12 igneous rocks 12004, 12008, 12009, and 12022:
A mineralogical and petrological study
Authors: Brett, R.; Butler, P., Jr.; Meyer, C., Jr.; Reid, A. M.;
Takeda, H.; Williams, R.
Bibcode: 1971LPSC....2..301B
Altcode:
No abstract at ADS
Title: Tranquillityite: A new silicate mineral from Apollo 11 and
Apollo 12 basaltic rocks
Authors: Lovering, J. F.; Wark, D. A.; Reid, A. F.; Ware, N. G.; Keil,
K.; Prinz, M.; Bunch, T. E.; El Goresy, A.; Ramdohr, P.; Brown, G. M.;
Peckett, A.; Phillips, R.; Cameron, E. N.; Douglas, J. A. V.; Plant,
A. G.
Bibcode: 1971LPSC....2...39L
Altcode:
No abstract at ADS
Title: Electron Microprobe, Fission Track and Activation Analysis
of Lunar Samples.
Authors: Frick, C.; Hughes, T. C.; Lovering, J. F.; Reid, A. F.;
Ware, N. G.; Wark, D. A.
Bibcode: 1971LPI.....2..205F
Altcode:
No abstract at ADS
Title: Apollo 11 samples: Major mineral chemistry
Authors: Reid, A. M.; Frazer, J. Z.; Fujita, H.; Everson, J. E.
Bibcode: 1970GeCAS...1..749R
Altcode: 1970LPSC....1..749R
No abstract at ADS
Title: A refractory glass chondrule in the Vigarano chondrite.
Authors: Reid, A. M.; Williams, R. J.; Gibson, E. K., Jr.; Fredriksson,
K.
Bibcode: 1970Metic...5R.218R
Altcode:
No abstract at ADS
Title: Phase Chemistry, Structure, and Radiation Effects in Lunar
Samples:
Authors: Arrhenius, G.; Asunmaa, S.; Drever, J. I.; Everson, J.;
Fitzgerald, R. W.; Frazer, J. Z.; Fujita, H.; Hanor, J. S.; Lal, D.;
Liang, S. S.; MacDougall, D.; Reid, A. M.; Sinkankas, J.; Wilkening, L.
Bibcode: 1970Sci...167..659A
Altcode:
Phase chemistry, structure, and radiation effects were studied in rock,
breccia, and soil samples. The regolith apparently developed in the
final stages of accretion and was modified by later impact processes
and radiation weathering. Exposure ages indicate transfer of buried
igneous rock fragments to the near surface late in lunar history. With
a few exceptions igneous rock fragments, soil, and breccia share the
same distinctive chemistry, probably acquired before accretion of the
moon. The igneous rocks texturally resemble basaltic achondrites, and
the soil and breccias contain glassy spheres analogous to chondrules.
Title: Crystal chemistry of high pressure polymorphs of ABO
3, AB 2O 4 and AB 4O
8 compounds, and their possible identifications with the
phases occurring in the mantle
Authors: Reid, A. F.
Bibcode: 1970PEPI....3..204R
Altcode:
No abstract at ADS
Title: Newly observed high pressure transformations in Mn
3O 4, CaAl 2O 4, and
ZrSiO 4
Authors: Reid, A. F.; Ringwood, A. E.
Bibcode: 1969E&PSL...6..205R
Altcode:
No abstract at ADS
Title: Composition of "irradiated" pyroxenes and feldspars in the
Kapoeta Howardite.
Authors: Wilkening, L.; Lal, D.; Reid, A. M.
Bibcode: 1969Metic...4Q.298W
Altcode:
No abstract at ADS
Title: High pressure transformations of spinels (I)
Authors: Ringwood, A. E.; Reid, A. F.
Bibcode: 1968E&PSL...5..245R
Altcode: 1969E&PSL...5..245R
The effects of high pressures (up to 200 kb) and high temperatures
(∼1000°C) upon 36 spinels have been investigated in an attempt to
define the principal patterns of spinel transformations. Fifteen
new transformations were found. Among A 2+B
3+2O 4 spinels, the most common
transformation mode is complete disproportionation into oxide
mixtures, AO + B 2O 3. In contrast, among A
2+2B 4+O 4 spinels,
the most common transformations are either to denser single A
2+2B 4+O 4 phases
or to mixtures of A 2+O (rocksalt) + A 2+B
4+O 3 (ilmenite) type phases. Two cases of
complete disproportionation into AO + BO 2 (rutile)
were observed. The bearing of these observations upon the probable
transformation mode of Mg 2SiO 4 (spinel-like
phase) in the Earth's mantle is discussed.
Title: High pressure polymorphs of olivines: The K 2NiF
4 type
Authors: Ringwood, A. E.; Reid, A. F.
Bibcode: 1968E&PSL...5...67R
Altcode: 1969E&PSL...5...67R
No abstract at ADS
Title: High pressure transformation of alkali aluminosilicates and
aluminogermanates
Authors: Ringwood, A. E.; Reid, A. F.; Wadsley, A. D.
Bibcode: 1967E&PSL...3...38R
Altcode:
No abstract at ADS
Title: Radiocarbon from Cosmic Radiation
Authors: Anderson, E. C.; Libby, W. F.; Weinhouse, S.; Reid, A. F.;
Kirshenbaum, A. D.; Grosse, A. V.
Bibcode: 1947Sci...105..576A
Altcode:
No abstract at ADS
Title: New Comet Reid (1927b)
Authors: Reid
Bibcode: 1927IAUC..135....1R
Altcode:
Observatory Capetown telegraphs: Comet Reid 8m0 January 26th 19h43m5
U.T. R.A. = 22 30 40.15 Decl. = -57 49 5 dRA = +44s dDecl. = -4'
discovered January 25th. As cipher preceding seconds of right ascension
and north polar distance in the telegram from Cape the cipher 7 is
used. Thus the position should be apparent (see "Important notice"
Circular No. 125).