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Author name code: jefferies-john
ADS astronomy entries on 2022-09-14
author:"Jefferies, John T."
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Title: Frank Quimby Orrall (15 October 1925 - 4 February 2000).
Authors: Jefferies, J. T.; Zirker, J. B.
2000SoPh..194..185J Altcode:
No abstract at ADS
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Title: A legendary polyglot... and lovely days
Authors: Jefferies, John T.
1998ASSL..222...96J Altcode: 1998ream.conf...96J
No abstract at ADS
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Title: A Stochastic Model of the Solar Atmosphere
Authors: Gu, Yeming; Jefferies, John T.; Lindsey, Charles; Avrett,
E. H.
1997ApJ...484..960G Altcode:
We present a model for the lower solar atmosphere based on continuum
observations of the Sun spanning the 2-1200 μm wavelength range. We
have shown that the data, in particular the center-to-limb brightness
profiles at 50-350 μm, cannot be accounted for by any model which
is plane-parallel and homogeneous in the height range in which this
radiation is formed. We accordingly set out to develop a two-component
model as the natural generalization. Making use of a theory for
radiation transfer in a stochastic multi-component atmosphere, we find
that one can indeed obtain an inhomogeneous model which satisfies
center-to-limb data over the 2-1200 μm range. This composite model
is made up of hot “flux tubes” randomly embedded in a cool medium,
the flux tubes expanding to occupy an increasing proportion of the
atmosphere as we move up in height. <P />The cool ambient component
shows a monotonic decrease in temperature in the range defined by the
data. The temperature in the hot component is constant at about 6500 K
up to about 400 km and increases monotonically above that height. The
center-to-limb observations demand that the gas in the interiors of
the flux tubes be recessed downward with respect to a hydrostatic
equilibrium distribution of density. This appears to constitute a
chromospheric Wilson depression consistent with a magnetic field
of about 120 G in the flux-tube interior at a height of about 600
km. <P />The new model is shown to be consistent with other spectral
measurements independent of those used to define it. It gives a
very good fit to the 0.5 μm continuum intensities across the disk,
and provides an excellent accounting for the disk-center brightness
temperature in the center of the 3-2 R14 CO line at 4.667 μm. A
boundary temperature of less than about 3000 K in the cold component
is suggested from the limb-darkening data available for this line. <P
/>In an appendix we mention a procedure for an analogous study based on
the intensities of multiplet lines, which may hold promise for modeling
over a wider range of heights that can be spanned by the IR data.
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Title: Radiative Transfer in Stochastic Media
Authors: Gu, Yeming; Lindsey, Charles; Jefferies, John T.
1995ApJ...450..318G Altcode:
We review some basic concepts arising in the study of radiative
transfer in a stochastic atmosphere and consider their application
to realistic atmospheric models. In particular, we examine the theory
of Lindsey and Jefferies which deals with multicomponent atmospheres
whose stochastic nature is entailed in the morphology of a network of
boundaries separating different atmospheric components. This theory
is based on the Markov assumption, that the probability, per unit path
length along a ray, for transition into another component 15 independent
of the distance already traveled in the current component. We examine
the applicability of the theory to models that are non-Markovian,
paying particular attention to the assignment of transition rates
of such atmospheres. We consider in detail transition probabilities
for spherical, tubular, conical, and other fluted structures, and
show how the effects of overlap are to be incorporated for the case
of a two-component atmosphere. Comparisons of results obtained from
the theory of Lindsey and Jefferies with those found from Monte Carlo
calculations, for models based on identical structures randomly embedded
into an ambient medium, show that the Markov assumption promises to
be a good approximation for the determination of the statistics of
radiative transfer in a wide variety of stochastic atmospheres, even
when they are markedly non-Markovian.
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Title: Infrared Applications for Radiative Transport in Stochastic
Media
Authors: Lindsey, C.; Gu, Y.; Jefferies, J. T.
1995itsa.conf..313L Altcode:
No abstract at ADS
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Title: Radiative Transfer in Stochastic Atmospheres
Authors: Gu, Y.; Lindsey, C.; Jefferies, J. T.
1994AAS...185.0702G Altcode: 1994BAAS...26Q1316G
We describe a general statistical perspective for the study of
radiative transfer through inhomogeneous media and apply it to
simple stochastic atmospheric models. The particular context for our
applications considers a stochastic atmosphere to be a multi-component
medium in which any individual component of the medium is locally
smooth. The stochastic nature of the atmosphere resides in the
statistical character of the complex network of boundaries that
separate various species of media one from another. We illustrate the
theory with simple atmospheric models based on an ambient medium into
which are randomly embedded structural elements containing alternative
species of medium. We consider structures of various shapes and sizes,
ranging from simple spheres to elongated or fluted structures with
preferred orientation. An important distinctive quality of a stochastic
atmosphere is whether the medium contains structures that individually
may be optically thick. Atmospheres containing only optically thin
structures tend to be statistically amenable to representation by
equivalent smooth atmospheres. The theory we have developed is fully
applicable to atmospheres that contain optically thick elements as
well as optically thin ones. Such conditions apply to a broad variety
of radiative transfer problems in astrophysics and stellar physics,
for example, to emission from interstellar gas clouds, from solar
or stellar chromospheres or from photospheres that contain heated
magnetic flux tubes. In this work we concentrate on a formalism that
rests on the Markov assumption, which states that the probability of
encountering a transition from one type of medium, A, to another,
B, is independent of the cumulative distance since the transition
into medium A, as one proceeds along the optical path. We examine the
importance of this assumption and its utility as a first approximation
by illustrating the consequences of its application to atmospheric
models that are non-Markovian.
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Title: Overview of Infrared Solar Physics
Authors: Jefferies, J. T.
1994IAUS..154....1J Altcode:
No abstract at ADS
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Title: Infrared solar physics: proceedings of the 154th Symposium
of the International Astronomical Union, held in Tucson, Arizona,
U.S.A., March 2-6, 1992.
Authors: Rabin, D. M.; Jefferies, John T.; Lindsey, C.
1994IAUS..154.....R Altcode:
No abstract at ADS
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Title: An active solar prominence in 1.3 MM radiation
Authors: Harrison, R. A.; Carter, M. K.; Clark, T. A.; Lindsey, C.;
Jefferies, J. T.; Sime, D. G.; Watt, G.; Roellig, T. L.; Becklin,
E. E.; Naylor, D. A.; Tompkins, G. J.; Braun, D.
1993A&A...274L...9H Altcode:
We present new millimetre-wavelength observations of an active solar
prominence. Observations made over a two-day period with the James
Clerk Maxwell Telescope on Manna Kea, Hawaii, give a unique view in
1.3 mm radiation of the spectacular prominence that appeared on the
west solar limb in the total solar eclipse of 11 July 1991.
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Title: Measurement of the Height of the Solar CO Layer During the
11 July 1991 Eclipse
Authors: Clark, T. A.; Naylor, D. A.; Tompkins, G. J.; Lindsey, C. A.;
Becklin, E. E.; Jefferies, J. T.; Harrison, R. A.; Roellig, T. L.;
Carter, M.; Braun, D. C.; Watt, G.
1992AAS...181.8108C Altcode: 1992BAAS...24.1253C
No abstract at ADS
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Title: Extreme-infrared brightness profile of the solar chromosphere
obtained during the total eclipse of 1991
Authors: Lindsey, C.; Jefferies, J. T.; Clark, T. A.; Harrison, R. A.;
Carter, M. K.; Watt, G.; Becklin, E. E.; Roellig, T. L.; Braun, D. C.;
Naylor, D. A.
1992Natur.358..308L Altcode:
THE solar chromosphere is a thin layer of gas that is several thousand
degrees hotter than the underlying photosphere, and responsible for
most of the Sun's ultraviolet emission. The mechanism by which it is
heated to temperatures exceeding 10,000 K is not understood. Millimetre
and submillimetre radiometry can be used to obtain the chromospheric
temperature profile, but the diffraction-limited resolution for the
largest telescopes is at best 17 arcsec, or ~12,500 km at the Sun's
distance. This is greater than the thickness of the quiet chromosphere
itself. The total eclipse of July 1991, which passed over the Mauna
Kea Observatory in Hawaii, provided a rare opportunity to make limb
occultation observations with a large submillimetrewavelength telescope,
the 15-m James Clerk Maxwell Telescope, and in this way we obtained a
temperature profile in 1.3-mm radiation with ~300 km resolution at the
Sun. Our observations indicate that spicules (magnetically entrained
funnels of gas) reach a temperature of 8,000 K at 3,000-4,000 km above
the photosphere, a temperature lower than those of many spicule models.
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Title: Chromospheric Dynamics Based on Infrared Solar Brightness
Variations
Authors: Kopp, G.; Lindsey, C.; Roellig, T. L.; Werner, M. W.; Becklin,
E. E.; Orrall, F. Q.; Jefferies, J. T.
1992ApJ...388..203K Altcode:
The NASA Kuiper Airborne Observatory was used to observe far-infrared
continuum brightness fluctuations in the lower chromosphere due to
solar 5 minute oscillations on the quiet sun. Brightness measurements
made at 50, 100, 200, and 400 microns show a strong correlation with
visible-line Doppler measurements from photospheric and chromospheric
altitudes. The motion of the chromosphere is nearly in phase over a
large range of heights, while the infrared brightness lags the Doppler
velocity by phases varying from significantly less than 90 deg at low
altitudes to nearly 90 deg at higher altitudes. It is proposed that
this is the result of a nonadiabatic response of the chromospheric
gas to compression and may indicate an important mechanism for wave
dissipation. Thermal relaxation times ranging from about 40 s at
340 km above the tau(5000) = 1 photosphere to about 300 s at 600 km
are proposed.
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Title: The Solar Chromospheric Supergranular Network in 850 Micron
Radiation
Authors: Lindsey, Charles A.; Jefferies, John T.
1991ApJ...383..443L Altcode:
The first submillimeter solar observations are examined of the
chromospheric supergranular network, made on the 15-m James Clerk
Maxwell Telescope on Mauna Kea in 850-micron radiation. These
observations are useful for thermal diagnostics of the low and middle
chromospheres of the quiet-sun and magnetic regions, where mechanical
heating of the atmospheric medium first becomes manifest. The models
of Vernazza, Avrett and Loeser appear to be consistent with these
observations.
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Title: Submillimeter Solar Limb Profiles Determined from Observations
of the Total Solar Eclipse of 1988 March 18
Authors: Roellig, T. L.; Becklin, E. E.; Jefferies, J. T.; Kopp,
G. A.; Lindsey, C. A.; Orrall, F. Q.; Werner, M. W.
1991ApJ...381..288R Altcode:
Observations were made of the extreme solar limb in six far-infrared
wavelength bands ranging from 30 to 670 micron using the Kuiper
Airborne Observatory during the total eclipse of the sun on 1988 March
18. By observations of the occultation of the solar limb by the moon,
it was possible to obtain a spatial resolution of 0.5 arcsec normal
to the limb. The solar limb was found to be extended with respect
to the visible limb at all of these wavelengths, with the extension
increasing with wavelength. Limb brightening was observed to increase
slightly with increasing wavelength, and no sign of a sharp emission
spike at the extreme limb was found at any of these wavelengths. The
observations can be well fitted by a chromospheric model incorporating
cool dense spicules in the lower chromosphere.
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Title: The Solar MG i Spectrum from ATMOS. I. Identification and
Preliminary Discussion
Authors: Jefferies, John T.
1991ApJ...377..337J Altcode:
As an initial step in a program to understand some puzzling aspects of
the infrared solar Mg I spectrum, the set of high-resolution, high SNR
lines of this spectrum are examined in the 1985 ATMOS experiment on
Spacelab 3. Wavenumbers were obtained for the Mg I transitions lying
in or near the range covered by ATMOS, namely 650 to 4800/cm. Lines
involving principal quantum numbers up to n = 10 are seen in the data;
some striking features of the Mg I spectrum are described and some
directions of interest for future analytical studies and for future
flights of the experiment are indicated.
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Title: On the Inference of Magnetic Field Vectors from Stokes Profiles
Authors: Jefferies, John T.; Mickey, Donald L.
1991ApJ...372..694J Altcode:
A study is made of the range of applicability of the weak-field
approximation for the inference of magnetic field vectors from the
profiles of the Stokes parameters. It is shown that, for typical solar
lines in the visible, this approximation may be applied with an accuracy
of 20 percent for field strengths as great as 3500/gL G (where gL is
the Lande factor) in the line wings. A systematic underestimate of
the field strength seems to occur for strong fields - observations in
several related spectral lines may allow a calibration of this effect,
and so for an increase in accuracy of the inferences. The procedures
have been tested using solar data obtained in two lines of Fe I, near
6300 A, with the Stokes Polarimeter at the Mees Solar Observatory of
the University of Hawaii.
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Title: Physics of the infrared spectrum.
Authors: Deming, Drake; Jennings, Donald E.; Jefferies, John; Lindsey,
Charles
1991sia..book..933D Altcode:
The authors describe the diagnostic value and principal results
derived from solar studies at wavelengths exceeding 1.6 μm. The
infrared is a favorable region to conduct studies of the solar
magnetic field. The high-n emission lines in the 12-μm spectrum are
of special interest. However, the LTE or NLTE nature of the lines,
and the mechanism of their excitation, remain poorly understood. The
far-infrared continuum is an excellent thermometer for the upper
photosphere and chromosphere, allowing study of the average thermal
state and the compressional effects of wave motions. Observations
of limb brightening at far-infrared wavelengths have shown that the
structure of the chromosphere is spatially inhomogeneous, even at
the lowest chromospheric altitudes. Time-series observations in the
far-infrared show that the chromosphere exhibits a substantial thermal
response to the 5-min oscillations. Further progress in far-infrared
studies will result from the new generation of large-aperture
submillimeter telescopes, and from the development of the theory of
radiative transfer in inhomogeneous media.
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Title: Direct inference of magnetic field vectors from Stokes
profiles.
Authors: Jefferies, J. T.; Mickey, D. L.
1991sopo.work..373J Altcode:
No abstract at ADS
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Title: Submillimeter Observations of the Sun from the James Clerk
Maxwell Telescope
Authors: Lindsey, Charles A.; Yee, Selwyn; Roellig, Thomas L.; Hills,
Richard; Brock, David; Duncan, William; Watt, Graeme; Webster, Adrian;
Jefferies, John T.
1990ApJ...353L..53L Altcode:
The first submillimeter solar observations from the 15 m James
Clerk Maxwell Telescope (JCMT) on Mauna Kea are reported. The JCMT
submillimeter heterodyne receiver is used to observe the sun in 850
micron radiation. These are the first submillimeter observations of
features on the size scale of the chromospheric supergranular network
and of sunspots. A comparison is made between 850 micron images and
calcium K line images of the chromospheric supergranular network in
the quiet sun and in plage. Images of sunspots are given, noting that
their 850 micron brightness is comparable to, or somewhat greater than,
that of the quiet sun.
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Title: Far-Infrared Intensity Variations Caused by 5 Minute
Oscillations
Authors: Lindsey, C.; Kopp, G.; Becklin, E. E.; Roellig, T.; Werner,
M. W.; Jefferies, J. T.; Orrall, F. Q.; Braun, D.; Mickey, D. L.
1990ApJ...350..475L Altcode:
Observations of solar IR intensity variations at 50, 100, and
200 microns were made simultaneously and cospatially with Doppler
measurements in the sodium D1 line at 5896 A. Brightness temperature
variations of several K in amplitude are highly correlated with five
minute Doppler oscillations. The brightness variations are attributed
to work done on the chromospheric medium by compression, driven by the
five minute oscillations. The Doppler oscillations lead the brightness
variations by about 47 deg in phase at 50 and 100 microns and by about
72 deg in phase at 200 microns.
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Title: Statistical Concepts in Radiative Transfer through
Inhomogeneous Media
Authors: Lindsey, C.; Jefferies, J. T.
1990ApJ...349..286L Altcode:
The theory of radiative transfer in inhomogeneous media is extended
to handle transfer for scale lengths small compared to the scale
size of the inhomogeneity. This is called the microscopic domain of
inhomogeneous radiative transfer. A concept called the vector intensity
distribution is introduced to characterize the statistical properties
of radiation in various species of medium. Radiative transfer in an
inhomogeneous atmosphere is expressed in terms of the evolution of
this vector intensity distribution and its various moments along the
optical path.
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Title: Transfer of Line Radiation in a Magnetic Field
Authors: Jefferies, John; Lites, Bruce W.; Skumanich, A.
1989ApJ...343..920J Altcode:
Using a classical approach, the transfer equations are derived for
spectral-line radiation in a medium which is permeated by a magnetic
field. Consideration is given to solutions of these equations for
the 'weak-field' case, when the Zeeman splitting is a fraction of
the Doppler width, and the range of validity of such solutions. Some
approximate expressions allow a simple inference of the vector-field
characteristics directly from the line profiles.
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Title: Profiles of the Extreme Solar Limb at Far Infrared and
Submillimeter Wavelengths
Authors: Roellig, T. L.; Werner, M. W.; Kopp, G.; Becklin, E. E.;
Lindsey, C.; Orrall, F. Q.; Jefferies, J. T.
1989BAAS...21..765R Altcode:
No abstract at ADS
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Title: Radiative Transfer in Inhomogeneous Atmospheres: A Statistical
Approach
Authors: Jefferies, John T.; Lindsey, Charles A.
1988ApJ...335..372J Altcode:
A procedure is presented for calculating the statistical properties
of the radiation which emerges from a multicomponent gas when the
absorption and emission coefficients vary statistically along the
direction of propagation. A relation describing the evolution of
the intensity distribution through the gas is derived, and, from
that, a transfer equation for the expected value of the intensity is
obtained which is analogous to the standard transfer equation for a
continuous medium and to which it reduces in the limit of a homogeneous
medium. General solutions for this transfer equation, and the analogous
transfer equation for the variance, are found for a special class of
situations. As a representative example, consideration is given to
the transfer of radiation through a spherical atmosphere consisting of
radial structures, with an exponential height distribution, which are
immersed according to a given probability distribution in an ambium,
itself inhomogeneous, whose properties also vary with height.
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Title: Submillimeter Observations of the Extreme Solar Limb by
Occultation in the Total Solar Eclipse of 18 March 1988
Authors: Roellig, T. R.; Werner, M. W.; Kopp, G.; Becklin, E. E.;
Lindsey, C.; Orrall, F. Q.; Jefferies, J. T.
1988BAAS...20..689R Altcode:
No abstract at ADS
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Title: Modeling the Solar Chromosphere by Airborne Solar Eclipse
Observations
Authors: Orrall, F. Q.; Becklin, E. E.; Lindsey, C.; Roellig, T. R.;
Werner, M. W.; Kopp, G.; Jefferies, J. T.
1987BAAS...19.1014O Altcode:
No abstract at ADS
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Title: Observations of Far-Infrared Solar Continuum Variations Due
to Compression Waves
Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.;
Roellig, T. R.; Kopp, G.; Jefferies, J. T.
1987BAAS...19S1014L Altcode:
No abstract at ADS
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Title: Extreme Limb Profiles of the Sun at Far-Infrared and
Submillimeter Wavelengths
Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.;
Jefferies, J. T.; Gatley, I.
1986ApJ...308..448L Altcode:
Thirty, 50, 100, and 200 microns solar limb intensity profiles
determined with arcsecond resolution from airborne observations of
the occultation of the solar limb during the total eclipse of July
31, 1981, are presented. Two points of particular importance emerge:
(1) the longer-wavelength (100 and 200 micron) limbs are significantly
brighter than disk center. At 200 microns the extreme limb is about 1.22
times the brightness of disk center. This is consistent with the 6000 K
temperature-plateau structure of the model chromospheres of Vernazza,
Avrett, and Loeser (1973, Ap. J., 184, 605; 1981; Ap. J. Suppl., 45,
635); and (2) the longer wavelength limbs are extended significantly
further above the visible limb than Vernazza, Avrett, and Loeser
predict. These results provide a strong basis for modeling of the solar
chromosphere free from the assumption of gravitational-hydrostatic
equilibrium.
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Title: Extreme limb profiles of the sun at far-infrared and
submillimeter wavelengths
Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.;
Jefferies, J. T.; Gatley, I.
1986STIN...8632375L Altcode:
Thirty, 50, 100, and 200 microns solar limb intensity profiles
determined with arcsecond resolution from airborne observations of
the occultation of the solar limb during the total eclipse of 1981
July 31 are presented. Two points of particular importance emerge:
(1) the longer-wavelength (100 and 200 micron) limbs are significantly
brighter than disk center. At 200 microns the extreme limb is about 1.22
times the brightness of disk center. This is consistent with the 6000 K
temperature-plateau structure of the model chromospheres of Vernazza,
Avrett, and Loeser (1973, Ap. J., 184, 605; 1981; Ap. J. Suppl., 45,
635;) and (2) the longer wavelength limbs are extended significantly
further above the visible limb than Vernazza, Avrett, and Loeser
predict. These results provide a strong basis for modeling of the solar
chromosphere free from the assumption of gravitational-hydrostatic
equilibrium.
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Title: The SHIRSOG Workshop. Proceedings of a workshop on prospects
for a new synoptic high resolution spectroscopic observing facility,
held at the National Solar Observatory, National Optical Astronomy
Observatories, Tucson, Arizona, USA, 3 September 1986.
Authors: Giampapa, M. S.; Jefferies, J. T.; Linsky, J. L.
1986swpw.book.....G Altcode:
No abstract at ADS
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Title: Extreme limb profiles of the sun at far infrared and
submillimeter wavelengths.
Authors: Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Jefferies, J. T.;
Werner, M.; Gatley, I.
1985NASCP2353...58B Altcode:
The authors present results of analysis of 30 to 200 μm observations
of the occultation of the solar limb during the total solar eclipse
of 1981 July 31. The observations were made from the Kuiper Airborne
Observatory. The 30 to 200 μm continuum radiation from the solar
limb originates in the lower and middle chromosphere. By measuring the
brightness profiles, one is able to fix important constraints on both
the temperature of the material and its density structure.
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Title: Extreme limb profiles of the Sun at far infrared and
submillimeter wavelengths
Authors: Becklin, E. E.; Lindsey, C.; Orrall, F. Q.; Jefferies, J. T.;
Werner, M. W.; Gatley, I.
1984abas.symp...58B Altcode:
Limb intensity profiles at 30, 50, 100, and 200 microns, determined
from Kuiper airborne observatory (KAO) observations of the occultation
of the solar limb during the total eclipse of July 31, 1981, are
presented. Significant but gradual limb brightening was found at the
longer wavelengths consistent with the 6000 K temperature-plateau
structure of the model chromospheres of Vernazza, Avrett, and
Loeser. The 100 and 200 micrometers limbs are extended significantly
further above the visible limb than the Vernazza, Avrett, and Loeser
model predicts. These results show that the solar chromosphere is
strongly perturbed from gravitational-hydrostatic equilibrium to heights
as low as 1000 km. These profiles can serve as a powerful diagnostic
for modeling the temperature and density of chromospheric structure
free from the assumption of gravitational-hydrostatic equilibrium.
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Title: Extreme Limb Profiles of the Sun at Far Infrared and
Submillimeter Wavelengths
Authors: Lindsey, C.; Becklin, E. E.; Orrall, F. Q.; Werner, M. W.;
Jefferies, J. T.; Gatley, I.
1984BAAS...16..992L Altcode:
No abstract at ADS
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Title: In Memoriam: R. G. Giovanelli
Authors: Jefferies, John T.
1984SoPh...94....1J Altcode:
No abstract at ADS
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Title: Observations of the brightness profile of the sun in the
30-200 micron continuum
Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.;
Werner, M. W.; Gatley, I.
1984ApJ...281..862L Altcode:
The authors observed the brightness profile of the quiet Sun in
broad continuum passbands centered at 30, 50, 100, and 200 μm with
a resolution of 2arcmin. Weak radial darkening was seen at all four
wavelengths near disk center. This reverses to brightening toward the
limb in the 100 and 200 μm continuum. Radial darkening at 100 and
200 μm is not expected from smooth model chromospheres consistent
with absolute brightness measurements. These results do not support
a homogeneous model of the low chromosphere, where the temperature
reversal occurs.
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Title: Coronal and chromospheric physics
Authors: Jefferies, J. T.; Landman, D. A.; Orrall, F. Q.
1983huha.rept.....J Altcode:
Achievements and completed results are discussed for investigations
covering solar activity during the solar maximum mission and the solar
maximum year; other studies of solar activity and variability; infrared
and submillimeter photometry; solar-related atomic physics; coronal
and transition region studies; prominence research; chromospheric
research in quiet and active regions; solar dynamics; eclipse studies;
and polarimetry and magnetic field measurements. Contributions were
also made in defining the photometric filterograph instrument for the
solar optical telescope, designing the combined filter spectrograph,
and in expressing the scientific aims and implementation of the solar
corona diagnostic mission.
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Title: Submillimeter extensions of the solar limb determined from
observations of the total eclipse of 1981 July 31
Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.;
Werner, M. W.; Gatley, I.
1983ApJ...264L..25L Altcode:
The authors present first results of observations of a lunar occultation
of the solar limb made from the Kuiper Airborne Observatory in the
30, 50, 100, and 200 μm continuum during the total solar eclipse
of 1981 July 31. The solar limb is found to be extended at the
longer wavelengths up to 1000 km higher than predicted from smooth
plane-parallel chromospheric models. Results at both second and third
contact show the infrared limb extensions to be approximately 0arcsec.8,
1arcsec.5, 2arcsec.5, and 3arcsec.0 above the visible limb in the 30,
50, 100, and 200 μm bands, respectively.
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Title: Submillimeter extensions of the solar limb determined from
observations of the total eclipse of 1981 July 31
Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.;
Werner, M. W.; Gatley, I.
1982STIN...8314047L Altcode:
First results are presented of observations of a lunar occultation
of the solar limb made from the Kuiper Airborne Observatory in the
30 micrometr, 50 micrometer, 100 micrometer, and 200 micrometer
continuum during the total solar eclipse of 1981 July 31. The solar
limb was extended at the longer wavelengths up to 1000 km higher than
predicted from smooth plane-parallel chromospheric models. Results at
both second and third contact show the infrared limb extensions to
be approximately 0".8, 1"5, 2".5 and 3".0 above the visible limb in
the observed bands, respectively. A possible interpretation proposes
chromospheric fine structure inhomogeneities of greater density than
presently incorporated in models of the middle chromosphere.
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Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii 96822. Report.
Authors: Jefferies, J. T.
1982BAAS...14..177J Altcode:
No abstract at ADS
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Title: Astronomical studies of the major planets, natural satellites
and asteroids using the 2.24 M telescope
Authors: Jefferies, J. T.
1982huha.reptR....J Altcode:
Ground based detection of east-west asymmetries in the Jovian torus,
three dimensional models of the plasma conditions in the Jovian torus,
rotational variations in methane band images of Neptune, Io's rapid
flickering, thermophysical models, the diameters and albedos of the
satellites of Uranus from radiometric observations, the diameters of
Pluto and Triton, standard stars are discussed.
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Title: Research in planetary astronomy and operation of Mauna Kea
Observatory
Authors: Jefferies, J. T.
1982huha.reptS....J Altcode:
Highlights of the programs including the major planets, satellites,
asteroids, and comets are presented. The operation of the 2.24 m
telescope is discussed.
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Title: Astronomical studies of the major planets, natural satellites
and asteroids using the 2.24 M telescope
Authors: Jefferies, J. T.
1982huha.reptQ....J Altcode:
Directional features in the Jovian sodium torus, high quality CCD
images of the major planets, methane bands in the spectrum of Triton,
the central wavelength of the SO2 absorption band on Io, a component
on the icy surfaces of the satellites of Uranus, fluctuation of Io's
volcanic radiation, standard stars, and thermal radiation from the
four brightest satellites of Uranus are discussed.
---------------------------------------------------------
Title: Submillimeter observations of solar limb-brightening in the
total solar eclipse of 31 July 1981
Authors: Becklin, E. E.; Jefferies, J. T.; Lindsey, C.; Orrall, F.;
Gatley, I.; Werner, M.
1981huha.rept.....B Altcode:
Eight flights of the Kuiper Airborne Observatory (KAO) were devoted to
solar observation. The successful observation of a total solar eclipse
was accomplished. The observations were made simultaneously at 30,
50, 100, and 200 microns. The successful adaptation of the KAO for
solar observations thus provided the most detailed data to date in
this spectral band. The results from a preliminary analysis of the KAO
data are summarized: (1) the 200 micron limb is extended about 3 arc
sec above the 30 micron limb, indicating the prescence of cool dense
material up to the altitudes of spicules; (2) strong radial darkening
of the quiet sun intensity profile appeared at 200 microns, probably an
indication that hot material in the low chromosphere is recessed into
vertical magnetic flux tubes embedded in a cooler nonmagnetic substrate,
which obscures the heated material approaching the limb; (3) active
regions were observed to undergo a strong increase in contrast above the
quiet sun background at wave lengths of 100 microns and longer; and (4)
the moon was mapped for use as a photometric standard for determining
the absolute intensity of the sun in all four wavelength bands.
---------------------------------------------------------
Title: Submillimeter Continuum Observations of Solar Plages
Authors: Jefferies, J. T.; Becklin, E. E.; Lindsey, C.; Orrall, F. Q.;
Gatley, I.; Werner, M.
1981BAAS...13Q.881J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of the Center-to-Limb Intensity of the Quiet
Sun at 30-200 μm
Authors: Orrall, F. Q.; Becklin, E. E.; Jefferies, J. T.; Lindsey,
C.; Gatley, I.; Werner, M.
1981BAAS...13..880O Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Submillimeter Observations of the Extreme Solar Limb Obtained
in the Total Eclipse of 1981 July 31
Authors: Lindsey, C.; Becklin, E. E.; Jefferies, J. T.; Orrall, F. Q.;
Gatley, I.; Werner, M.
1981BAAS...13..880L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Comprehensive Study of the Sun in the Submillimeter Continuum
Authors: Becklin, E. E.; Jefferies, J. T.; Lindsey, C.; Orrall, F. Q.;
Gatley, I.; Werner, M.
1981BAAS...13..880B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Institute for Astronomy, University of Hawaii, Honolulu,
Hawaii 96822. Report.
Authors: Jefferies, J. T.
1981BAAS...13..177J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Hawaii, University-Of
Authors: Jefferies, J. T.
1980BAAS...12..117J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ca II emission from stellar chromospheres.
Authors: Cram, L. E.; Krikorian, R.; Jefferies, J. T.
1979A&A....71...14C Altcode:
Measurements are presented of the separations of the K2 peaks and
the K1 dips of the emission core of the Ca II K line observed on
high-dispersion spectra of 33 late-type stars. These separations
(called W1 and W2) are compared with the emission core width W which
satisfies the Wilson-Bappu correlation. With some qualifications, it
is found that W is directly proportional to the 1.3 power of W1 and
the 1.06 power of W2. Some consequences of this result are discussed.
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii 96822. Report.
Authors: Jefferies, J. T.
1979BAAS...11..115J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Requests for Observing Time on the CFHT
Authors: Locke, J. L.; Jefferies, J. T.
1979BCFHT...2....3L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii. Observatory report.
Authors: Jefferies, J. T.
1977BAAS....9..106J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High resolution atlas of the solar spectrum 2678-2931 A
Authors: Allen, M. S.; McAllister, H. C.; Jefferies, J. T.
1977STIN...7831029A Altcode:
A portion of the ultraviolet solar spectrum is presented in this
high resolution atlas. The data, originating from a rocket echelle
spectrogram obtained on 19 June 1974 of a quiet area near the center
of the solar disk, extend from 2678 to 2931 A. The instrument had
a nominal resolving power of 200,000 at these wavelengths and the
rms precision of the rectified wavelength scale is 15 mA. Absolute
intensities are computed by calibration to the absolute measurements
of Kohl and Parkinson.
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii. Observatory report.
Authors: Jefferies, J. T.
1976BAAS....8...99J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The abundance determination in a stellar atmosphere. I. LTE
experimentation using an artificial non-LTE spectrum.
Authors: Dumont, S.; Heidmann, N.; Jefferies, J. T.; Pecker, J. -C.
1975A&A....40..127D Altcode:
It is shown that the classical LTE analysis of an atomic spectrum
of a solar-like star leads to values of the abundance (A) which may
be different from the real values. Various uncertainties affect the
results derived from neutral lines. However, proper selection of
the observational data, for instance use of ion lines, can lead, in
similar cases at least, to good values of A. These conclusions concern
the solar-like case; however, they emphasize that, in all cases,
the effect of departures from LTE needs very careful discussion.
---------------------------------------------------------
Title: High-Resolution Solar Spectra in the 2900 A and the 1700
A Range
Authors: McAllister, Howard C.; Smith, Peter H.; Jefferies, John T.
1975BAAS....7..365M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Linear Polarization of Continuum Radiation in Sunspots
Authors: Finn, G. D.; Jefferies, J. T.
1975BAAS....7..349F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii. Observatory report.
Authors: Jefferies, J. T.
1975BAAS....7...62J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Polarization of Continuum Radiation in Sunspots. I:
Rayleigh and Thomson Scattering
Authors: Finn, G. D.; Jefferies, J. T.
1974SoPh...39...91F Altcode:
Expressions are derived for the Stokes parameters of light scattered by
a layer of free electrons and hydrogen atoms in a sunspot. A physically
reasonable sunspot model was found so that the direction of the
calculated linear polarization agrees reasonably with observations. The
magnitude of the calculated values of the linear polarization agrees
generally with values observed in the continuum at 5830 Å. Circular
polarization in the continuum also accompanies electron scattering in
spot regions; however for commonly accepted values of the longitudinal
magnetic field, the predicted circular polarization is much smaller
than observed.
---------------------------------------------------------
Title: Fine Structure of the Upper Chromosphere
Authors: Jefferies, J. T.
1974IAUS...56...71J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Non-LTE Profiles of the A1 I Autoionization Lines
Authors: Finn, G. D.; Jefferies, J. T.
1974SoPh...34...57F Altcode:
A non-LTE formulation is given for the transfer of radiation in the
autoionizing lines of neutral aluminum at λ1932 and λ1936 through both
the Bilderberg and Harvard-Smithsonian model atmospheres. Numerical
solutions for the common source function of these lines and their
theoretical line profiles are calculated and compared with the
corresponding LTE profiles. Our results show that the non-LTE profiles
provide a better match with the observations. They also indicate that
the continuous opacity of the standard solar models should be increased
in this wavelength region if the center-limb variations of observed and
theoretical profiles of these lines are to be in reasonable agreement.
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii. Observatory report.
Authors: Jefferies, J. T.
1974BAAS....6...48J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Inversion of the Solar Limb-darkening Equation in the Presence
of Noise
Authors: Kunasz, C. V.; Jefferies, J. T.; White, O. R.
1973A&A....28...15K Altcode:
Summary. We discuss the formulation and application of the
Phillips-Twomey method for inverting the integral equation of solar
limb darkening in the presence of noise. We show, through numerical
experiments, that the method can be successfully applied to real data
and that it has clear advantages over those standard methods that
rely on the expression of the source function in an analytic form. In
addition, we briefly discuss some potentially interesting methods
of a different kind, which are still under examination. Key words:
solar limb-darkening - Phillips-Twomey inversion - source function
---------------------------------------------------------
Title: Inversion of the Limb Darkening Equation in the Presence
of Noise
Authors: Kunasz, Chela V.; Jefferies, J. T.; White, O. R.
1973BAAS....5S.274K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Analysis of Si II Solar UV Emission Lines
Authors: McAllister, H. C.; Jefferies, J. T.
1973BAAS....5T.276M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii. Observatory report for the period July 1971 through June 1972.
Authors: Jefferies, J. T.
1973BAAS....5..120J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Temperature Distribution in a Stellar Atmosphere, Diagnostic
Basis
Authors: Jefferies, John T.; Morrison, Nancy D.
1973NASSP.317....3J Altcode: 1973stch.coll....3J; 1973IAUCo..19....3J
No abstract at ADS
---------------------------------------------------------
Title: Solar activity (Activité solaire).
Authors: Jefferies, J. T.; Simon, P.; Beckers, J. M.; McLean, D. J.
1973IAUTA..15...75J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Hawaii's Mauna Kea Observatory Today
Authors: Morrison, David; Jefferies, John T.
1972S&T....44..361M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Interpretation of Total Line Intensities from Optically
Thin Gases. III: Application to Coronal Forbidden Line Spectra
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1972SoPh...22..327J Altcode:
The diagnostic method developed in the two preceding papers of this
series is applied to coronal forbidden line intensity data obtained at
eclipses in 1952, 1961, 1965, 1966, and 1970. The application of the
method is limited by the nature of the data but allows a first inference
of the relationship between electron density and temperature in the
condensations observed at these eclipses, and of the distribution of
the electrons within the temperature range samples by the observations
effectively 10<SUP>6</SUP> to 2.4 × 10<SUP>6</SUP> K. We determine the
relative abundance of nickel to iron in the corona, finding a value in
agreement with latest photospheric determinations and with a similar
(factor of two) uncertainty. We are also able to set lower limits to
the abundance of iron with respect to hydrogen, again finding values
consistent with recent photospheric determinations.
---------------------------------------------------------
Title: The Interpretation of Total Line Intensities from Optically
Thin Gases. II: The Coronal Forbidden Lines
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1972SoPh...22..317J Altcode:
We discuss the application of a general diagnostic procedure, developed
in the preceding paper of this series, to the inference of the physical
state of coronal condensations from a knowledge of their forbidden
line emission. We consider the limitations set on such an analysis by
inadequacies in existing data and indicate the additional observations
in the infrared and ultraviolet, as well as the visible, which will
be needed for development of the full power of the diagnostic method.
---------------------------------------------------------
Title: The Interpretation of Total Line Intensities from Optically
Thin Gases. I: A General Method
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1972SoPh...22..307J Altcode:
We describe a general method for inferring, from the line emission of an
optically thin medium, the physical state of the gas along the column in
the line of sight which is sampled by the observations. Since it is not
possible to infer the distribution of the physical state parameters with
position in the line of sight - any arbitrary rearrangement of material
giving equivalent line emission - we seek instead to specify the
state in another way. A unique specification is found in terms of the
bivariate distribution function μ (n, T), describing the partitioning
of the matter in the gas over the density and temperature. We show
that, given sufficient observational data, it is in principle possible
to determine both μ (n, T), and the chemical composition. With less
complete data the acuity of the analysis is correspondingly reduced.
---------------------------------------------------------
Title: University of Hawaii, Institute for Astronomy, Honolulu,
Hawaii. Observatory report for the period July 1970 through June 1971.
Authors: Jefferies, J. T.
1972BAAS....4...45J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Guest Investigators at the Mauna Kea Observatory
Authors: Jefferies, John T.
1971PASP...83..693J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Population Inversion in the Outer Layers of a Radiating Gas
Authors: Jefferies, J. T.
1971A&A....12..351J Altcode:
On the basis of solutions to the coupled radiative transfer equations
for multiplet lines, we present simple physical arguments on the
expected distribution of population among closely spaced energy levels
in the ground, or a low-lying state, of an atom or molecule. It is
shown that, because uncoupling of multiplet lines will occur in the
outer layers of a radiating gas, population "anomalies" will occur in
the fine structure states associated with the upper and/or lower levels
of the multiplet transitions. Order of magnitude estimates suggest
that the mechanism is able to account for some aspects of the 18 cm OH
emission, though better solutions of the coupled transfer equations
are needed before proper observational comparison is possible. It is
suggested that atoms with p and p2 configurations may be expected to
have inverted populations among the ground state levels in the outer
layers of an optically thick gas. A list is given of infrared and
submillimetric atomic lines which may show amplification in astronomical
sources. Two lines of C T are accessible to ground based (high altitude)
instrumentation, and these may merit a diligent search. Key words:
population inversion - radiative transfer
---------------------------------------------------------
Title: The spectrum of the chromosphere and corona from lambda 3000
to lambda 7000 on March 7, 1970.
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1971BAAS....3Q.262J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Coronal models and coronal chemical abundances.
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1971BAAS....3..261J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Population inversion in the outer layers of radiating gas.
Authors: Jefferies, J. T.
1971JQSRT..11..545J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Spectrum of the Inner Corona Observed during the Total
Solar Eclipse of 30 May, 1965
Authors: Jefferies, John T.; Orrall, Frank Q.; Zirker, J. B.
1971SoPh...16..103J Altcode:
A series of spectrograms of the inner solar corona were obtained at
the total solar eclipse of 30 May 1965 using a fast spectrograph with
a circular slit that recorded the spectrum from λ3000 to λ9000 at all
position angles around the limb simultaneously. In this paper absolute
intensity is given as a function of position angle for the stronger
lines and the continuum. In the coronal enhancement or condensation
centered at heliocentric position angle 293°, absolute intensity is
given for 34 forbidden emission lines and the continuum.
---------------------------------------------------------
Title: Formation of Line Spectra—A Review
Authors: Jefferies, J. T.
1970PASA....1..356J Altcode: 1970PASAu...1..356J
A typical stellar spectrogram shows a vast number of spectral
lines. Each of these has its characteristic shape and strength which
must, in some way, reflect the structure of the atmosphere in which the
radiation arose. It seems reasonable that from all this profile data we
should be able (and with considerable redundancy) to infer a good deal
about the physical structure of the radiating gas, and a major effort
has correspondingly been devoted to clarifying the physical basis of
spectral line formation, i.e., exactly how the atmospheric structure
and the atomic properties are reflected in the line profiles. This
problem, however, is far from solved : Few, if any, of the profiles
of strong lines can be predicted in detail from model atmospheres,
nor have analyses of the profiles yielded unambiguous data on the
atmospheric structure. Indeed, as recently as 1967, the participants
at a conference in Bilderberg (Holland) concluded that no data at
all which had been obtained from line profile analyses was worthy of
inclusion in specifying the solar atmospheric model. Evidently, then,
the problem of line formation is not trivial ; in this paper we discuss
some of the difficulties and review the not inconsiderable progress
which has been made in this area of astrophysical research.
---------------------------------------------------------
Title: Institute for Astronomy, University of Hawaii, Honolulu,
Hawaii. Report 1968-1969.
Authors: Jefferies, J. T.
1970BAAS....2...49J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Models for Coronal Condensations
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1969BAAS....1Q.246J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: 22. Eission Line Spectrum of the Solar Corona
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1969LIACo..15..235J Altcode: 1969MSRSL..17..235J
No abstract at ADS
---------------------------------------------------------
Title: 21. Forbidden Lines in the Solar Corona, Introductory Report
Authors: Jefferies, J. T.
1969LIACo..15..213J Altcode: 1969MSRSL..17..213J
No abstract at ADS
---------------------------------------------------------
Title: Emission line spectrum of the solar corona.
Authors: Jefferies, J. T.; Orrall, F. Q.; Zirker, J. B.
1969MSRSL..25..235J Altcode: 1969tisa.conf..235J
No abstract at ADS
---------------------------------------------------------
Title: Forbidden lines in the solar corona.
Authors: Jefferies, J. T.
1969MSRSL..25..213J Altcode: 1969tisa.conf..213J
No abstract at ADS
---------------------------------------------------------
Title: Studies in spectral line formation. III. Non-linear multi-level
atom problems.
Authors: Finn, G. D.; Jefferies, J. T.
1969JQSRT...9..469F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Stellar aerodynamics. Introductory remarks.
Authors: Jefferies, J. T.
1969JQSRT...9..191J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Progress at Mauna Kea Observatory
Authors: Jefferies, John T.; Sinton, William M.
1968S&T....36..140J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Chromospheric Spectrum at the 1962 Eclipse
Authors: Dunn, R. B.; Evans, J. W.; Jefferies, J. T.; Orrall, F. Q.;
White, O. R.; Zirker, J. B.
1968ApJS...15..275D Altcode:
A joint expedition of the High Altitude Observatory, Sacramento Peak
Observatory, and the National Bureau of Standards obtained slitless
spectrograms of the flash spectrum at the February 5,1962, total eclipse
of the Sun. The spectrograms covered the wavelength range of about
3200 to 9100 A with a height resolution of 100 km. The spectrographic
equipment, the observations, the photometric calibration procedures,
and the methods adopted to reduce the large quantity of data are
described. The results are presented in a set of tables that show the
wavelength and identification (where known) of each of the 3500 lines
recorded. A separate set of tables lists the intensity of each line at
each height. The latter tables are ordered according to the element,
ionization stage, and multiplet number associated with the line.
---------------------------------------------------------
Title: Formation and Analysis of Line Spectra-A Review of Some
Recent Progress.
Authors: Jefferies, John T.
1968AJS....73R..65J Altcode:
Within the past five years substantial progress has been made in the
self- consistent (or non-LTE) theory of line formation. The current
situation is reviewed, and outstanding questions raised, both in the
"analytical" problem of deriving an atmospheric structure from an
observed line spectrum, and in the "synthetic" problem of computing the
spectrum emitted by a gas of given physical properties. The emphasis
throughout is on the physical meaning of the results rather than on the
mathematical problems. A brief discussion of basic principles is given
to illustrate the fundamental role played by the score function. The
successes and shortcomings of the work of the 1950's is then briefly
summarized. A major limitation in earlier work lay in its restriction
to a two-level atom which was, in turn, associated with numerical
difficulties encountered in the solution of two-point boundary value
problems or, equivalently in this case, of the integral equations for
the line source functions. The different methods developed to overcome
these problems will be sketched and some representative results given
for some multilevel configurations. The physical interpretation of
the results will be stressed, especially as concerns the predicted
relationships between the different spectral line profiles arising
from a given configuration of levels. On this basis the concepts of
thermalization length and net-radiative bracket are examined. The
analysis of an observed spectrum introduces different but related
problems. It is shown how predictions from the self-consistent
theory of line formation can be applied to allow a solution of the
analytical problem and how and why this analysis differs from the LTE
case. Limitations to the general analytical procedure are outlined.
---------------------------------------------------------
Title: Spectral line formation
Authors: Jefferies, John T.
1968slf..book.....J Altcode: 1968QB465.J4.......
No abstract at ADS
---------------------------------------------------------
Title: The Analysis of Spectral-Line Profiles. I. a. Generalized
Theory for the Solar Case
Authors: Jefferies, J. T.; White, O. R.
1967ApJ...150.1051J Altcode:
Recent studies of spectral-line formation are shown to provide a basis
for the analysis of profiles of multiplet lines in the "solar case," i
e., when limb-darkening data are available. The theoretical foundation
is more general than that assuming local thermodynamic equilibrium,
which is included as a special case. A detailed analytical procedure
is given along with a discussion of its shortcomings and limitations.
---------------------------------------------------------
Title: The Analysis of Spectral-Line Profiles. II. an Application
to the Solar Sodium D-Lines
Authors: Curtis, G. W.; Jefferies, J. T.
1967ApJ...150.1061C Altcode:
On the basis of general principles set down in the first paper of this
series, an analysis is made of Waddell's solar D-line observations
The results show a large measure of seff-consistency and, among
other conclusions, suggest that the temperature minimum in the solar
atmosphere lies above T5 10- , and that to a factor of order 2 the
solar abundance of sodium is that given by LTE analyses.
---------------------------------------------------------
Title: The Solar Observatory of the University of Hawaii
Authors: Jefferies, J. T.
1967SoPh....2..369J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Inference of Velocities from Line Asymmetries
Authors: Kulander, John L.; Jefferies, John T.
1966ApJ...146..194K Altcode:
Synthetic line profiles are generated for a variety of model atmospheres
containing linear and quadratic velocity fields. Both weak and strong
lines are considered. Comparison of the actual velocity structures with
those inferred from the bisector shifts of the asymmetrical profiles
show qualitative agreement only in the line cores and in general only
for velocities small compared with the thermal velocity. Approximate
expressions relating the observed profile parameters to atmospheric
velocity parameters, for small linear velocities, are obtained and
tested. Observed rms displacements in the solar Ha line are used to
infer the amplitude of the oscillatory velocity field in that region
of the solar chromosphere where the core is formed.
---------------------------------------------------------
Title: Loop Prominences and Coronal Condensations. III. The Abundances
of Iron and Calcium
Authors: Jefferies, J. T.; Orrall, F. Q.
1966ApJ...145..231J Altcode:
Measured total intensities of the continuum and of the red, green,
and yellow forbidden coronal lines emitted by discrete features of a
sporadic coronal condensation are shown to yield firm lower limits to
the abundances of iron and calcium. These strict lower limits exceed
the photospheric abundances (derived by curve-of-growth analysis of
Fraunhofer lines) by a factor of 3 for iron and 12 for calcium; the
actual coronal abundance will be higher still.
---------------------------------------------------------
Title: Eclipse Determination of Chemical Abundances in the Solar
Corona.
Authors: Curtis, G. W.; Jefferies, J. T.; Orrall, F. Q.
1966AJ.....71S.382C Altcode:
Chemical abundance determinations from observations of the coronal
emission spectrum (particularly for iron) have consistently exceeded
those determined from curve of growth analyses of photospheric
absorption lines. Although the coronal abundances are somewhat
uncertain because they depend on uncertain coronal models and uncertain
theories of coronal ionization and excitation, Jefferies and Orrall
(Astrophy. J. 1966, to be published) have shown that it is possible
to set rigorous lower limits to the abundances that are insensitive to
these uncertainties. Applying this method to coronagraph observations
of the red, yellow, and green coronal lines they found lower limits
to the calcium and iron abundances in excess of the photospheric
values by factors of 2 or 3. We have applied this method to the very
complete observations of the coronal spectrum between A3000 and A9000
obtained by the University of Hawaii- Sacramento Peak Observatory
expedition to observe the eclipse of 30 May 1965. Emission lines
arising from 15 different ions were studied. The resulting lower
limits to the coronal abundances are given below, along with the photo
spheric abundances taken from the careful curve of growth studies by
C. R. Cowley (Astrophys. J. 143, 352, 1966) for Ni, and E. A. Mu~ller
and J. P. Mutschlecner (Astrophys. J. Suppl. 9, No. 85, 1964) for the
remainder of the elements. Abundance per 106 protons Element V Cr Mn
Fe Co Ni Corona (lower limit) 0.22 1.0 0.042 5.0 1.1 1.1 Photosphere
0.013 0.12 0.065 5.0 0.026 0.49 The coronal abundances shown are
strict lower limits. The actual values can be that low only if there
is a specially favorable temperature distribution to make ionization a
maximum and only if the local electron density is high enough that the
excitation is governed completely by collisions. But within the ions Fe
XI and Ni XIII, which give rise to two observable emission lines, it is
clear that both radiation and collision processes enter to determine
the degree of excitation. We conclude that the coronal abundances are
higher than the lower limits shown and that they therefore exceed the
photospheric values.
---------------------------------------------------------
Title: The Solar Abundance of Iron
Authors: Jefferies, J. T.
1966IAUS...26..207J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Survey of the Problem
Authors: Jefferies, J. T.
1965SAOSR.174....3J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Multilevel Problems
Authors: Jefferies, J. T.
1965SAOSR.174..177J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Loop Prominences and Coronal Condensations. I. Non-Thermal
Velocities Within Loop Prominences.
Authors: Jefferies, J. T.; Orrall, F. Q.
1965ApJ...141..505J Altcode:
Profiles of the Ha-line observed in loop prominences at the limb with
the coronagraph show much more extended wings than ordinary prominences,
and a detailed study of the profiles of the loop system of February
19, 1962, shows that these wings are caused neither by instrumental
effects nor by the Stark effect but arise from non-thermal motions of
emitting hydrogen atoms. The possibility that these fast neutral atoms
were produced by charge exchange or recombination from equally fast
protons is considered and rejected since the particles would produce
far too much heating. It is shown, however, that the observed wings
could reasonably be interpreted as a jetlike streaming, along the loops,
of matter accelerated from a region near their tops.
---------------------------------------------------------
Title: Loop Prominences and Coronal Condensations. II. The Source
of Mass and Energy and a Model of the Loop Prominence Mechanism.
Authors: Jefferies, J. T.; Orrall, F. Q.
1965ApJ...141..519J Altcode:
Estimates of the mass and energy requirements of loop prominences
indicate difficulties in the generally accepted "condensation
process." An alternative process is considered in which super thermal
particles drift or are injected into the magnetic field of the loop. It
is found that all the mass required to maintain a loop (or quiescent)
prominence can be supplied in the form of particles moving at tO cm/sec
and that their energy will then just balance that lost by radiation
Since it is now known that loop prominences are associated with those
flares that produce copious amounts of fast plasma, it is suggested
that the loops arise naturally as a coronal configuration by which
this flare plasma is returned to the chromosphere The mass and energy
required to feed the loop are provided by the injection into the system
of fast particles of this plasma. The applicability of this mechanism
to other types of prominences is discussed.
---------------------------------------------------------
Title: The Theory of the Chromospheric Spectrum
Authors: Jefferies, John T.
1965ASSL....1..131J Altcode: 1965sosp.conf..131J
No abstract at ADS
---------------------------------------------------------
Title: Solar Flares and the Loop Prominence Mechanism
Authors: Jefferies, J. T.; Orrall, F. Q.
1964NASSP..50...71J Altcode: 1964psf..conf...71J
No abstract at ADS
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Title: On the Interpretation of Prominence Spectra.VI. Temperature
Determination and a Model for Quiescent Prominences.
Authors: Jefferies, J. T.; Orrall, F. Q.
1963ApJ...137.1232J Altcode:
Temperatures estimated from the widths of Balmer lines and from the
continuum intensities of q prominence emission have previously been
shown to be discordant. In this paper we show how the crepancy can
be accounted for in terms of a variable temperature model, and we
derive the characterisi of such a model. In particular, we show that,
to account for the observed emission, we can allow onl comparatively
small amount of material in the line of sight to be at temperatures
above 15000 K
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Title: The Structure of Regions of Coronal-Line Emission.
Authors: Jefferies, J. T.; Pecker, C. W.; Thomas, R. N.
1962ApJ...135..653J Altcode:
No abstract at ADS
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Title: On the Interpretation of Prominence Spectra. V. The Emission
Lines in Quiescent Prominences.
Authors: Jefferies, J. T.; Orrall, F. Q.
1962ApJ...135..109J Altcode:
Observations are presented of emission-line total intensities and
widths in the range XX for two quiescent prominences. In one of these
prominences, total intensities are also given for emission lines
in the range XX . From the total intensities it is found that (1)
the excitation temperature describing the populations of the energy
levels of Fe 1 is 3600 K; (2) the ratio of intensity of the 0 1 lines
at X 7775 and X 8446 (known to be variable in astronomical sources)
is 18(3) the electron kinetic temperature of the region emitting He
1 must be greater than 11000 K Estimates are made of the theoretical
strengths of one line of He 1 and five lines of Fe 1. The shapes of the
lines in the range XX 3600- 3800 are Gaussian to within the limit of
error of measurement except for the higher Balmer lines of H 1 and the
lines of He 1. These lines are all free from self-absorption. The line
widths of H i correspond to atom kinetic temperature of about 8200 K,
but this is an upper limit, since non-thermal motions also broaden
the lines It is shown that the usual method of employing the widths
of metal lines to correct for these non-thermal motions overcorrects
in quiescent prominences, yielding too low a temperature; however,
the hydrogen and metal line widths are consistent with atom kinetic
temperatures between 6500 and 8200 K. In Paper IV the electron kinetic
temperature was found to be 12500 K from continuum measures in one of
these same prominences. The difference between the temperatures given by
the two methods cannot be attributed to observational error. Although a
real difference between the atom and electron kinetic temperatures may
exist, it is suggested rather that these temperatures are averages over
steep temperature gradients and the averages are weighted differently
by the two methods.
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Title: On the Interpretation of Prominence Spectra.IV. The Balmer
and Paschen Continua in a Quiet Prominence.
Authors: Jefferies, J. T.; Orrall, F. Q.
1961ApJ...134..747J Altcode:
Observations of the Balmer and Paschen continua in a quiet prominence
are discussed. Their self- consistency is considered and the
observations analyzed for derivation of mean values of the electron
temperature and density. A graphical method is given for determining
these mean values from the magnitude of the Balmer or Paschen jump,
together with the emission per unit volume in the appropriate freebound
continuum. It is pointed out that, because of the relatively small
jump at the series limit, Paschen continuum observations are much
less useful than those at the Balmer limit The Balmer jump and total
emission is found to be consistent with the mean values T 12000 K and
n 8 X 1O . These results are compared with those derived previously in
the same way, for a flare-type loop, namely, T 15000 K and n, 2 X 1O ,
and for a chromospheric flare T __ 12000 K and n __ 3 X tO .
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Title: Vertical Velocities in the Solar Chromosphere
Authors: Giovanelli, R. G.; Jefferies, J. T.
1961AuJPh..14..212G Altcode:
No abstract at ADS
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Title: On the Interpretation of Prominence Spectra. II. The Line
and Continuous Spectrum of the Spray-Type Limb Event of March 7, 1959.
Authors: Jefferies, J. T.; Orrall, F. Q.
1961ApJ...133..946J Altcode:
The line and continuum emission of a limb flare of March 7, 1959, are
discussed. An analysis of the continuum emission near the almer limit
shows that the kinetic temperature of the flare must be considerably
less than 20000 K in that region where the hydrogen is excited. On
the assumption that the hydrogen emission is axially symmetric,
a model is derived for the temperature, electron density, and gas
pressure as a function of distance from the axis. The temperatures
so derived are much lower than those obtained from the usual methods
of line-width analysis, which, it is suggested, are of questionable
value in application to active limb events.
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Title: On the Interpretation of Prominence Spectra. III. The Line
and Continuous Spectrum of a Loop Prominence and Limb Flare.
Authors: Jefferies, J. T.; Orrall, F. Q.
1961ApJ...133..963J Altcode:
A detailed photometric study is presented of the line and continuous
spectrum of the limb flare of June 9, 1959. The electron temperature is
found to be certainly less than 24000 K in the bright, dense central
portion of the flare, where the hydrogen lines and continuum are
excited. The flare occurred as a condensation in an active coronal
region, yet the temperature is only slightly higher than that observed
in a spray-type flare that originated at the chromospheric level We
tentatively suggest temperatures of 10000 and 20000 K, respectively,
for "cool" and "hot" prominence classes suggested by Zirin and
Tandberg-Nanssen.
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Title: A Comment of the NRL Solar Lyman-Alpha Results.
Authors: Jefferies, J. T.; Thomas, R. N.
1961ApJ...133..606J Altcode:
Supplementary comments are made on the Morton-Widing analysis of the
NRL Ly-a observations; they serve to bring into sharper focus its
relation to current attempts at analysis of self-reversed emission
cores of collison-dominated lines for gradients of T , for chromospheric
structure, and for differential structure between quiet sun and plage,
sunspot and flare regions.
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Title: Source Function in a Non-Equilibrium Atmosphere.VI. The
Frequency Dependence of the Source Function for Resonance Line.
Authors: Jefferies, J. T.; White, O. R.
1960ApJ...132..767J Altcode:
The frequency dependence of the line source function is investigated
for the case of pure coherent scattering in the reference frame of
the atom. It is shown that the thermal redistribution due to Doppler
effect gives a form of scattering similar to complete redistribution
in the line core and coherency in the wings. Using a modified form for
this redistribution and allowing for some residual non-coherency due
to collisions in the frame of the atom, an algebraic solution of the
transfer equation is obtained, and emergent line profiles are computed,
for an isothermal atmosphere. It is shown that the line shape in the
transition region from line core to wing is strongly influenced by the
proportion of this residual non-coherency. It is finally suggested that,
until the strength of collisional perturbations is better understood
from theoretical or laboratory studies, theoretical work on line
spectra should adopt complete redistribution in scattering.
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Title: Source Function in a Non-Fquilibrium Atmosphere. VII. The
Interlocking Problem.
Authors: Jefferies, J. T.
1960ApJ...132..775J Altcode:
A general solution to the equations of statistical equilibrium
is presented and applied to the problem of determining the
influence of interlocking on the depth variation of line source
functions. Approximate uncoupled transfer equations are derived
for a simple three-level atom, and their quality is tested against
exact solutions. A discussion is given-exemplified by hydrogen-of
the influence of coupling for models consisting of larger numbers of
levels. The general form of the depth variation in the H and K lines
of Ca ii is shown to be little different from that derived in earlier
papers of this series where interlocking was neglected. It is shown,
however, that the strong coupling results in a common a given depth-of
the H and K line source functions.
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Title: The Source Function in a Non-Equilibrium
Atmosphere. V. Character of the Selfreversed Emission FO CA^{+}
H and K.
Authors: Jefferies, J. T.; Thomas, R. N.
1960ApJ...131..695J Altcode:
The methodology of Paper III is applied to delineate the principal
parameters affecting the characteristics of the self-reversed emission
cores of Ca+ H and K, in order to clarify whether current discussions
in terms only of are adequate. We find two additional factors to be
significant-c and the Te gradient. The factor E provides an effect in
the correct direction to interpret the Wilson-Bappu effect, but of too
small a size, subject to a more complete treatment of the region outside
the Doppler core. The effect of the T6 gradient seems more significant,
particularly as a basis for interpreting the observed solar variations.
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Title: Thermally Broadened Stark Profiles of Some High Balmer Lines.
Authors: Jefferies, J. T.
1960ApJ...131..690J Altcode:
Results are given of some computations of the thermally broadened Stark
profiles of the Balmer lines H12, H16, H18, and H26. The calculations
are made for ion densities and kinetic temperatures likely to be
of interest in solar prominences and flares. The degree of overlap
between 1126 and H27 is also computed as a function of ion density
and mean random atomic velocity.
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Title: The line and continuous emission observed in two limb flares
Authors: Dunn, R. B.; Jefferies, J. T.; Orrall, F. Q.
1960Obs....80...31D Altcode:
No abstract at ADS
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Title: Source Function in a Non-Equilibrium Atmosphere. III. The
Influence of a Chromosphere.
Authors: Jefferies, John T.; Thomas, Richard N.
1959ApJ...129..401J Altcode:
We apply the methods developed in the preceding two papers to
investigate the depth dependence of the source function for resonance
lines in an atmosphere having a chromospheric distribution of T,
superposed upon a photospheric one. The derived behavior of SL( )
for the neutral and ionized metals differs and mimics the observed
behavior of such lines. The hydrogen Balmer lines should behave like
the neutral metals, and the predicted behavior agrees with our earlier
empirical results.
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Title: The nova outburst: III. The ionization of hydrogen gas by an
exciting star
Authors: Jefferies, J.; Pottasch, S.
1959AnAp...22..318J Altcode:
No abstract at ADS
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Title: The Flare of September 18, 1957.
Authors: Jefferies, J. T.; Smith, E. V. P.; Smith, H. J.
1959ApJ...129..146J Altcode:
A set of spectra of the disk flare of September 18,1957, is
discussed. The spectra, covering simultaneously a wave-length range of
XX 390() 7200 at a dispersion of 2 A/mm, cover the period through the
maximum phase. The Balmer lines reached a central intensity in excess of
three times the neighboring continuum and were at that time exceedingly
wide. Several helium lines were in emission,including X 4686 of He II,
as well as the prominent neutral lines. The data indicate that the
excitation conditions in the visible flare vary rapidly with depth
and suggest that the flare is merely an extension of a more powerful
excitation. The Balmer series wing shapes are shown to be compatible
either with Stark effect or with a particular form of velocity field
of macroscopic or microscopic motions.
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Title: The Source Function in a Non-Equilibrium Atmosphere. II. The
Depth Dependence of the Source Function for Resonance and Strong
Subordinate Lines.
Authors: Jefferies, John T.; Thomas, Richard N.
1958ApJ...127..667J Altcode:
We obtain an algebraic solution for the depth variation of the source
function 8L (r) for resonance and strong subordinate lines by using the
Eddington approximation plus the method of discrete ordinates. We show
that if an observed line profile, produced in an atmosphere with the
above SL (r), is analyzed under the assumption of local thermodynamic
equilibrium, an underestimate of T.(r) in the outer atmospheric layer
results. The derived SL(r) agrees in qualitative behavior with the
source function found empirically by Athay and Thomas for the early
Balmer lines of hydrogen.
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Title: On the Interpretation of Prominence Spectra. I. Balmer Series
Line Widths.
Authors: Jefferies, J. T.; Orrall, F. Q.
1958ApJ...127..714J Altcode:
Line widths, derived from a set of high-dispersion spectra in
Balmer series Ha-H have been used to show that the assumption of a
constant-source function for Ha in prominences is not, in general,
correct. It is pointed out that, with our present ignorance of
prominence conditions, very little information can be obtained from
the Ha line alone but that, when coupled with spectra in other Balmer
lines, the Ha line may possibly provide a basis for inferring the run
of physical conditions with depth. It is suggested that the common
procedure of determining a kinetic temperature and turbulence from
hydrogen and helium lines may also be erroneous.
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Title: The interpretation of Balmer line profiles in solar
prominences.
Authors: Jefferies, John T.; Orrall, Frank Q.
1957AJ.....62..143J Altcode:
In the past, it has been the usual practice to interpret prominence
observations on the assumption that the observed radiation is the
intrinsic radiation of the prominence itself. It has been recently
pointed out, however, that a major component of the observed
radiation-at least in Ha should be scattered disk radiation;
the prominence thus acting as a diffuser as well as an emitter. In
order to get a better understanding of the process of line formation
in prominences as well as to obtain a consistent approach to the
determination of prominence temperatures, high dispersion profiles
have been obtained of the hydrogen Balmer lines Ha through HE and
the helium lines X5876 and X447I in prominences showing a minimum
of internal motions. The prominences were observed, at the limb,
with the i6-inch coronagraph at Sacramento Peak. Several years ago,
Conway (1952) and Ellison (1952) observed that Ha prominence line
profiles could be fitted very well to theoretical profiles computed
on the assumption of a source function constant in frequency across
the line and constant in depth in the prominence. The same remarkable
agreement has been obtained for our observations, except of course,
for those cases where the Ha line is self-reversed. For subordinate
lines like these, it is almost certain that the source function is in
fact frequency independent. The good agreement obtained between the
observed profiles, and those computed on the assumption of a source
function constant in depth, however, is probably largely fortuitous. It
seems that almost any monotonic source function could be fitted by
one of the family of curves. In any case, the occurrence of double-
peaked profiles in Ha shows that for this line the assumption is not
generally valid. In order to test this assumption further, the optical
depth at the center of the Ha line has been computed from the run of
widths of the Balmer lines H~ through HE. This method was found to give
a higher optical depth than that implied by the shape of the Ha line
using the assumption of a source function constant in depth. It seems
clear that the usual method of estimating prominence temperatures from
the Ha profile is very unreliable. Conway, M. 1955, Contr. Dunsink
Obs. No. 3. Ellison, M. A. 1952, Pub. Royal Obs. Edinburgh I,
No. 5. Sacramento Peak Observatory, Sunspot, N. Mex.
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Title: Temperatures and electron densities in flares as derived from
spectroscopic data
Authors: Jefferies, J. T.
1957MNRAS.117..493J Altcode:
It is shown that model ares with electron concentrations and
temperatures in the ranges 5Xio11-io13cm-3 and io4- .K respectively
have emissions consistent with the observed hydrogen and helium line
intensities in solar flare spectra. Some difficulties are shown to
exist in interpreting the observed great line width of H and a possible
solution is given.
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Title: The D<SUB>3</SUB> emission of prominences
Authors: Jefferies, J. T.
1956MNRAS.116..629J Altcode:
The computed emission of H and D3 from an isothermal slab model
prominence is shown to give agreement with observational data of
Bruck and Moss when the model has helium abundance one fifth that
of hyd gen, thickness z X I0 km, temperature between X 1o deg. K and
2.0 X I0 deg. K and electron concentration between 1010 cm-3 to 5 X
1010 . Some evidence has been found that the higher temperatures are
generally associated with lower electron concentrations. Comparison of
the present computations with earlier results obtained by the author
from an analysis of the contour of the H emission of prominences shows
that the ratio of the abundances of helium and hydrogen atoms in solar
prominences lies in the range to 04. As for H , the self emission
in D3 is generally small compared with the diffusely reflected and
transmitted component.
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Title: The High Temperature Excitation of Helium
Authors: Jefferies, J. T.
1955AuJPh...8..335J Altcode:
No abstract at ADS
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Title: The Hα emission of prominences
Authors: Jefferies, J. T.
1955MNRAS.115..617J Altcode:
It is shown that M radiation from the solar disk is strongly reflected
by prominences and is an important component of their radiation. An
analysis of their observed Ha emission at the limb indicates a range
of kinetic temperatures of about io4 to z X i04 deg. K and electron
concentrations of about i010 to X 1010 cm-3 for stable prominences. Two
alternative explanations are given for the double peaked profiles
of Ha sometimes observed in solar prominences, depending on whether
scattering is coherent or incoherent.
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Title: The Emission of Radiation from Model Hydrogen Chromospheres. II
Authors: Jefferies, J. T.; Giovanelli, R. G.
1954AuJPh...7..574J Altcode:
No abstract at ADS
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Title: The Albedo for the Atomic Scattering of Optical Radiation
Authors: Giovanelli, R. G.; Jefferies, J. T.
1954AuJPh...7..570G Altcode:
No abstract at ADS
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Title: Some Electron Collision Cross Sections of CaII
Authors: Jefferies, J. T.
1954AuJPh...7...22J Altcode:
No abstract at ADS
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Title: Emission of Radiation from Model Hydrogen Chromospheres
Authors: Jefferies, J. T.
1953AuJPh...6...22J Altcode:
No abstract at ADS