explanation blue bibcodes open ADS page with paths to full text
Author name code: avery
ADS astronomy entries on 2022-09-14
author:"Avery, Lorne W."
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Title: Sensitive observations of radio recombination lines in Orion
and W51: the data and detection of systematic recombination line
blueshifts proportional to impact broadening
Authors: Bell, M. B.; Avery, L. W.; MacLeod, J. M.; Vallée, J. P.
2011Ap&SS.333..377B Altcode: 2011arXiv1102.5057B; 2011Ap&SS.tmp...84B
Sensitive spectral observations made in two frequency bands near
6.0 and 17.6 GHz are described for Orion and W51. Using frequency
switching we were able to achieve a dynamic range in excess of 10,000
without fitting sinusoidal or polynomial baselines. This enabled us
to detect lines as weak as T <SUB> A </SUB>∼1 mK in these strong
continuum sources. Hydrogen recombination lines with Δ n as high as
25 have been detected in Orion. In the Orion data, where the lines
are stronger, we have also detected a systematic shift in the line
center frequencies proportional to linewidth that cannot be explained
by normal optical depth effects.
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Title: Gravitational deformation of a reflector antenna measured
with single-receiver holography
Authors: Legg, T. H.; Avery, L. W.; Matthews, H. E.; Vallée, J. P.
2004ITAP...52...20L Altcode:
Holographic measurements of deformations in a large antenna reflector
are described. The deformations were brought about by changing elevation
angle and gravitational loading. A phase-switching arrangement was used,
which allowed a single, already installed and operating receiver to be
shared by both the main antenna signal and a reference signal. Natural
H2O masers in our galaxy were used as signal sources, and a reference
antenna was attached rigidly to the antenna under test so as to move
with it. Observing techniques are described that accommodate changes
in source elevation angles and antenna feed position while acquiring
a data set.
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Title: HARP-B: a 350-GHz 16-element focal plane array for the James
Clerk Maxwell telescope
Authors: Smith, Henry; Hills, Richard E.; Withington, Stafford;
Richer, Johnathan; Leech, Jamie; Williamson, Ross; Gibson, Hugh; Dace,
Roger; Ananthasubramanian, P. G.; Barker, Robert W.; Baldwin, Robert;
Stevenson, Howard; Doherty, Peter; Molloy, Dennis; Quy, Victor; Lush,
Chris; Hales, Sally; Dent, William R. F.; Pain, Ian; Wall, Robert;
Hastings, Peter R.; Graham, Brenda; Baillie, Thomas E. C.; Laidlaw,
Ken; Bennett, Richard J.; Laidlaw, Ian; Duncan, William; Ellis,
Maureen A.; Redman, Russell O.; Wooff, Robert; Yeung, Keith K.;
Fitzsimmons, Joeleff T.; Avery, Lorne; Derdall, Dennis; Josephson,
Dean; Anthony, Andre; Atwal, Raj; Chylek, Tomas; Shutt, Dean J.;
Friberg, Per; Rees, Nicholas P.; Philips, Robin; Kroug, Matthias;
Klapwijk, Teun M.; Zijlstra, Tony
2003SPIE.4855..338S Altcode:
A 350GHz 4 × 4 element heterodyne focal plane array using SIS detectors
is presently being constructed for the JCMT. The construction is
being carried out by a collaborative group led by the MRAO, part of
the Astrophysics Group, Cavendish Laboratory, in conjunction with
the UK-Astronomy Technology Centre (UK-ATC), The Herzberg Institute
of Astrophysics (HIA) and the Joint Astronomy Center (JAC). The Delft
Institute of Microelectronics & Sub-micron Technology (DIMES) is
fabricating junctions for the SIS mixers that have been designed at
MRAO. Working in conjunction with the 'ACSIS' correlator & imaging
system, HARP-B will provide 3-dimensional imaging capability with high
sensitivity at 325 to 375GHz. This will be the first sub-mm spectral
imaging system on JCMT - complementing the continuum imaging capability
of SCUBA - and affording significantly improved productivity in terms
of speed of mapping. The core specification for the array is that the
combination of the receiver noise temperature and beam efficiency,
weighted optimally across the array will be <330K SSB for the
central 20GHz of the tuning range. In technological terms, HARP-B
synthesizes a number of interesting and innovative features across
all elements of the design. This paper presents both a technical and
organizational overview of the HARP-B project and gives a description
of all of the key design features of the instrument. 'First light'
on the instrument is currently anticipated in spring 2004.
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Title: Excitation Analysis of SO and SO<SUB>2</SUB> in the
Proto-Planetary Nebula OH 231.8+4.2
Authors: Claude, S. M. X.; Avery, L. W.; Matthews, H. E.
2000ApJ...545..379C Altcode:
In the nebula OH 231.8+4.2 we have observed SO and SO<SUB>2</SUB>
millimeter-wave emission lines having a wide range of excitation
energy. The extent of the SO emission was also mapped. Rotation diagrams
were derived from these observations, and we deduced the rotation
temperatures and relative abundances of SO and SO<SUB>2</SUB> for three
different velocity ranges corresponding to the spherical mass-loss
envelope and the blue and red lobes of the bipolar outflow. The rotation
temperatures for SO and SO<SUB>2</SUB> are higher in the expanding
envelope than in the outflow lobes. Subject to modeling uncertainties,
the relative abundances of both molecules in the lobes are slightly
enhanced by factors 2-5 times relative to the values in the envelope.
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Title: A New Technique for Measuring Impact-broadened Radio
Recombination Lines in HII Regions: Confrontation with Theory at
High Principal Quantum Numbers
Authors: Bell, M. B.; Avery, L. W.; Seaquist, E. R.; Vallée, J. P.
2000PASP..112.1236B Altcode:
New, low-noise receivers have allowed detection, in several giant H
II regions, of Rydberg-Rydberg transitions of hydrogen that cover
a large range of Δn-values in a single observing window. This,
in turn, allows lines covering a large range in principal quantum
number n to be detected simultaneously with the same antenna beam. We
have employed a new frequency-switching technique which allows a very
precise determination of the line widths. We have used this technique
with the NRAO 140 foot telescope to observe lines in W51 and Orion A
near 6 GHz, with Δn-values that vary by a factor of ~21 (Δn=1-~21)
and corresponding n-values that vary by a factor of 2.7 (n=102-274). By
generating Voigt line profiles using Griem's theory of impact broadening
by electrons, inserting them into a telescope data file, and processing
them in a manner identical to that of the telescope data, we have been
able to examine how the observing and reduction techniques affect both
the line widths and line areas as n increases. For n<=180, Δn<=6,
our restored line widths and areas give densities of N<SUB>e</SUB>=2500
and 4000 cm<SUP>-3</SUP> in W51 and Orion A, respectively. These
densities are higher than reported previously with a 5' beamwidth. For
higher n-values we are unable to fit our data using Griem's theory. For
n>180, Δn>6, our telescope-measured line widths fall rapidly
below predicted values, while the line areas simultaneously increase
above predicted values. This behavior of the line area as the line
widths decrease is inconsistent with Griem's theory or an instrumental
effect. Observations of Orion A at 17.6 GHz, with a 1.7‧ beamwidth,
require a density in excess of N<SUB>e</SUB>=20,000 cm<SUP>-3</SUP>
to fit. Although the detected lines cover a range in n and Δn from
71 to 177 and 1 to 17, respectively, there is no evidence for a line
width decrease at the high Δn-values. We conclude from this that the
line narrowing seen at 6 GHz is related to the principal quantum number.
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Title: National Research Council of Canada, Herzberg Institute of
Astrophysics, James Clerk Maxwell Telescope Group, 5071 West Saanich
Road, Victoria, British Columbia, Canada V8X 4M6. Report for the
period 1 Apr 1998 - 31 Mar 1999.
Authors: Avery, L.
2000BAAS...32..378A Altcode:
No abstract at ADS
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Title: Working Group on Astrochemistry: (Groupe de Travail Pour
L'Astrochimie)
Authors: Williams, D. A.; Avery, L. W.; Black, J. H.; Buch, V.;
Dalgarno, A.; Greenberg, J. M.; Henkel, C.; Irvine, W. M.; Maier,
J. P.; Menten, K. M.; Minh, Y. C.; Ohishi, M.; Rowe, B.; Singh, P. D.;
Snyder, L. E.; van Dishoeck, E. F.; Zeng, Q.
2000IAUTA..24..281W Altcode:
No abstract at ADS
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Title: Canadian participation in the Atacama Large Millimetre Array.
Authors: Avery, L. W.; Wilson, C. D.
1999JRASC..93..179A Altcode:
No abstract at ADS
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Title: Large SCUBA images of the Rho Ophiuchi and Orion B molecular
clouds.
Authors: Mitchell, G.; Avery, L.; Knee, L.; Matthews, H.;
Moriarty-Schieven, G.; Basu, S.; Fiege, J.; Matthews, B.; Pudritz,
R.; Wilson, C.; Fich, M.; Johnstone, D.; Joncas, G.
1999JRASC..93..182M Altcode:
No abstract at ADS
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Title: A Jet-driven, Extreme High-Velocity Outflow Powered by a Cold,
Low-Luminosity Protostar near NGC 2023
Authors: Sandell, G.; Avery, L. W.; Baas, F.; Coulson, I.; Dent,
W. R. F.; Friberg, P.; Gear, W. P. K.; Greaves, J.; Holland,
W.; Jenness, T.; Jewell, P.; Lightfoot, J.; Matthews, H. E.;
Moriarty-Schieven, G.; Prestage, R.; Robson, E. I.; Stevens, J.;
Tilanus, R. P. J.; Watt, G. D.
1999ApJ...519..236S Altcode:
We have discovered an extreme high-velocity bipolar CO outflow in
the vicinity of NGC 2023, with total outflow velocities of ~200 km
s<SUP>-1</SUP>. At very high velocities this outflow is jetlike with
an opening angle <=4°, while it shows a separate outflow lobe at
low velocities. The outflow is bipolar and exhibits a clear mirror
symmetry, which suggests that the source powering the outflow is
episodic or precessing. The dynamical timescales for the outflow are
<=3000 yr. We identify the source driving the CO jet with a deeply
embedded low-luminosity submillimeter double source (separation ~23"),
where the primary component lies on the symmetry axis of the outflow and
has all the signatures of a “class 0” protostellar object. Analysis
of molecular data and (sub)millimeter photometry suggests that the
driving source is cold and compact, with a luminosity of <~10
L<SUB>solar</SUB> and a total mass of 1.8-4.6 M<SUB>solar</SUB>. It
has no near-IR counterpart, it drives an extremely young outflow,
and it emits a large fraction of its luminosity in the submillimeter
regime. Both millimeter sources have low dust emissivity, β~0.8-1.3,
similar to what is found for other class 0 objects, while the
surrounding molecular cloud core appears to have a β~2.0, the canonical
value for “normal” interstellar dust in the submillimeter regime.
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Title: Submillimeter Continuum Emission in the ρ Ophiuchi Molecular
Cloud: Filaments, Arcs, and an Unidentified Far-Infrared Object
Authors: Wilson, Christine D.; Avery, Lorne W.; Fich, Michel;
Johnstone, Doug; Joncas, Gilles; Knee, Lewis B. G.; Matthews, Henry E.;
Mitchell, George F.; Moriarty-Schieven, Gerald H.; Pudritz, Ralph E.
1999ApJ...513L.139W Altcode: 1999astro.ph..1133W
New wide-field images of the ρ Ophiuchi molecular cloud at 850 and
450 μm obtained with the Submillimeter Common-User Bolometer Array on
the James Clerk Maxwell Telescope reveal a wide variety of large-scale
features that were previously unknown. Two linear features, each 4'
(0.2 pc) in length, extend to the north of the bright emission
region containing SM1 and VLA 1623. These features may correspond
to the walls of a previously unidentified outflow cavity or the
boundary of a photon-dominated region powered by a nearby B star. A
previously unidentified source is located in the northeast region
of the image. The properties of this source (diameter ~5000 AU, mass
~0.3-1 M<SUB>solar</SUB>) suggest that it is a preprotostellar core. Two
arcs of emission are seen in the direction of the northwest extension
of the VLA 1623 outflow. The outer arc appears relatively smooth at
850 μm and is estimated to have a mass of ~0.3 M<SUB>solar</SUB>,
while the inner arc breaks up into a number of individual clumps,
some of which are previously identified protostars.
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Title: 345-GHz facility SIS receiver for the JCMT
Authors: Cunningham, Charles T.; Avery, L. W.; Bergeron, C. R.; Claude,
S.; Feldman, P. A.; Fletcher, J. R.; Gao, Jian-Rong; Hayward, R. H.;
Jegers, J. B.; Klapwijk, Teun M.; MacLeod, J. M.; Matheson, D. N.;
Mirza, A.; Redman, R. O.; van de Stadt, Herman
1998SPIE.3357..620C Altcode:
Receiver B3 is a common-user facility instrument for the JCMT and was
commissioned in December 1996. It includes the following features:
(1) Frequency coverage of 315 to 372 GHz with optimum performance at
345 GHz. (2) Two spatially- coincident channels with orthogonal linear
polarizations. (3) An IF of 4 GHz with an instantaneous bandwidth
of 1.7 GHz in each channel. (4) Single side-band capability with the
rejected side-band terminated on a cold load. (5) High- efficiency,
frequency-independent optics. (6) Independent adjustment of the local
oscillator power to the two mixers. (7) Internal ambient and cold
loads for accurate receiver calibration. (8) Fully automated operation.
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Title: Enhanced Chemical Abundances in the L1157 Outflow: SiO and
CH 3OH Observations
Authors: Avery, L. W.; Chiao, M.
1996ApJ...463..642A Altcode:
Millimeter and submillimeter wavelength spectral lines of
CH<SUB>3</SUB>OH and SiO have been observed in the remarkable
outflow source L1157. Statistical equilibrium analyses indicate
that the abundances of both compounds are enhanced greatly in the
blueshifted, southern lobe which is known to show evidence of active
shock heating. Both the SiO and CH<SUB>3</SUB>OH emission in the
blueshifted lobe peak at the same position as the CO J = 1-0 line
The SiO and CH<SUB>3</SUB>OH lines originate from warm gas. The
temperature deduced from the methanol observations matches the
laboratory temperature at which pure CH<SUB>3</SUB>OH ice separates
from an H<SUB>2</SUB>O:CH<SUB>3</SUB>OH mixture, and sublimates rapidly
into the gas phase. The SiO shows evidence of kinematically distinct
regions, with the higher velocity gas being more highly clumped, warmer,
and enriched in SiO abundance by a factor of more than 10<SUP>5</SUP>
relative to quiescent, dark cloud values. The slower gas is somewhat
cooler and less dense, with an SiO abundance enhancement factor of
10<SUP>6</SUP>, well above that seen in the Orion KL outflow. The
CH<SUB>3</SUB>OH abundance, relative to H<SUB>2</SUB>, is 1.5 x
10<SUP>-7</SUP>, and its emission originates in gas with T<SUB>kin</SUB>
≥ 100 K. A number of outflows are now known that show strong abundance
enhancements in SiO and/or CH<SUB>3</SUB>OH due to evaporation of grain
mantles or dust destruction due to shocks. This probably occurs in the
bow shocks associated with supersonic jets, and the resulting abundance
enhancements may be relatively short-lived after cessation of the jet,
due to depletion back onto the grains and gas-phase chemical processing
of CH<SUB>3</SUB>OH.
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Title: The 685--692 GHz Spectrum of the Orion Core
Authors: Harris, A. I.; Avery, L. W.; Schuster, K. -F.; Tacconi,
L. J.; Genzel, R.
1995ApJ...446L..85H Altcode:
We used the new Max Planck Institute for Extraterrestrial Physics
submillimeter spectrometer to measure the 685-692 GHz (438-434 μm)
spectrum of the Orion core in the James Clerk Maxwell Telescope's 7"
beam. We detected 13 lines from the "Compact Ridge" and "Plateau"
outflow over this 7 GHz wide band. Our map of the H<SUP>13</SUP>CN J =
8-7 line shows that the densest part of the outflow is more compact
(4" FWHM) than the SO-emitting region (∼12"). Observation of both
H<SUP>13</SUP>CN and HC<SUP>15</SUP>N J = 8-7 lines indicates 200
K, 10<SUP>9</SUP> cm<SUP>-3</SUP> gas either with an H<SUB>2</SUB>
column density of ∼2 × 10<SUP>24</SUP> cm<SUP>-2</SUP> or with
modestly enhanced HCN abundances in the warm and dense core of the
outflow. Although the true continuum level is clearly present between
the lines, the lines are still strong and contribute up to 50% of the
total flux in this relatively crowded part of the spectrum.
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Title: Detection of extended J = 6→5 CO emission from the outflow
lobes of IRAS 04368 in Taurus.
Authors: MacLeod, J. M.; Avery, L. W.; Harris, A.
1994JRASC..88R.265M Altcode:
No abstract at ADS
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Title: Submillimeter Molecular Line Observations of IRC +10216:
Searches for MgH, SiH 2, and HCO +, and Detection of Hot HCN
Authors: Avery, L. W.; Bell, M. B.; Cunningham, C. T.; Feldman, P. A.;
Hayward, R. H.; McLeod, J. M.; Matthews, H. E.; Wade, J. D.
1994ApJ...426..737A Altcode:
Sensitive searches have been carried out under good observing conditions
for submillimeter-wavelength lines of MgH and SiH2 in the circumstellar
envelope of IRC +10216. Upper limits for the column densities are
N(MgH-24) equal to or less than 6 x 10<SUP>12</SUP>/sq cm and N(SiH2)
equal to or less than 3.5 x 10<SUP>15</SUP>. A deep search has also
been made without success for HCO(+). The upper limit for the column
density is N(HCO(+)) equal to or less than 1.4 x 10<SUP>11</SUP>/sq
cm, which corresponds to X(HCO(+)) = 1.8 x 10<SUP>-11</SUP> for
a mass-loss rate of 4 x 10<SUP>-5</SUP> solar mass/yr. This is an
order of magnitude lower than the predicted theoretical abundance of
X(HCO(+)) = 4.5 x 10<SUP>-10</SUP> (Glassgold et al. 1987). The J =
4-3 rotational lines have been observed from four vibrational states
of HCN, all with higher excitation energies than have previously
been reported. These are the (03<SUP>3</SUP>0), (11<SUP>1d</SUP>0),
(12<SUP>0</SUP>0), and (01<SUP>1d</SUP>1) states, with excitation
energies of 3000, 4000, 5100, and 5800 K, respectively. The line
profiles are narrower than that of the HC(15)N ground-state line which
was observed simultaneously. This suggests the hot HCN emission is
not cospatial with the lower excitation lines.
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Title: C3S and C5S in IRC +10216
Authors: Bell, M. B.; Avery, L. W.; Feldman, P. A.
1993ApJ...417L..37B Altcode:
No abstract at ADS
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Title: New heavy molecules in the envelope of IRC+10216.
Authors: Bell, M. B.; Avery, L. W.; MacLeod, J. M.; Watson, J. K. G.
1993JRASC..87Q.175B Altcode:
No abstract at ADS
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Title: HCO+ emission in the HH7-11 region: the slowest component of
the outflow?
Authors: Dent, W. R. F.; Cunningham, C.; Hayward, R.; Davies, S. R.;
Wade, D.; Avery, L. W.; Mayer, C. J.; Masuda, N. T.
1993MNRAS.262L..13D Altcode:
Results of mapping of the region of high-velocity outflow in HH7-11
in the J = 4-3 transition of HCO(+) are compared with published
optical, CO, and J = 1-0 HCO(+) maps are presented. Unlike the
latter interferometric data, a bright compact source associated with
the exciting star, plus weaker emission throughout the region, is
observed. Extended emission surrounds the line of HH objects, and has a
structure very similar to that of the blueshifted CO outflow. Spectra
of the J = 4-3 and 3-2 lines in selected positions within the flow
region indicate two physical components: cool gas at a density of a
few million per cu cm at the velocity of SSV13 and the ambient cloud,
and warm (35 K) gas at a few hundred thousand per cu cm blueshifted
by about 1 km/s. The close agreement between the HCO(+) and higher
velocity CO suggests that the former arises from the densest, slowest
component of the molecular flow. The structure appears to favor a
confined jet rather than a shocked cloudlet model.
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Title: A Spectral-Line Survey of W51 from 17.6 to 22.0 GHz
Authors: Bell, M. B.; Avery, L. W.; Watson, J. K. G.
1993ApJS...86..211B Altcode:
The complete centimeter-wave spectrum between 17.57 and 22.04 GHz of
the W51Main/South complex has been surveyed with the NRAO 140 foot
telescope with channel spacings of 0.3125 MHz and down to a 1 alpha
level between T(A) = 1-5 mK. Approximately 224 lines were detected,
of which 94 are hydrogen or helium recombination lines, 11 are ammonia
lines, 19 are coincident with known molecular transitions, and 100 are
unidentified. Observations obtained with longer integration times,
but over very limited frequency ranges, indicate that many of the
known molecules might be detectable in this source with only a few
hours of integration time. The carbon chain molecules more common in
other sources (CnH, CnN, HCnN, etc.) are not strong, although HC3N,
HC5N and several nonlinear molecules containing C3 appear to have
been detected. Based on the high signal-to-noise ratio obtained for
C3H2 lines, and the fact that the off-axis C-13 isotopomer was also
detected, we have concluded that W51 is probably an excellent source
in which to search for propargylene, the nearly linear version of
this molecule. Eleven transitions of ammonia from (4,2) to (14,11 )
were also detected in the survey and appear to show an increase in
excitation temperature with both J and (J- K) for this molecule.
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Title: A Spectral Line Survey of IRC +10216 at Millimeter and
Submillimeter Wavelengths
Authors: Avery, L. W.; Amano, T.; Bell, M. B.; Feldman, P. A.; Johns,
J. W. C.; MacLeod, J. M.; Matthews, H. E.; Morton, D. C.; Watson,
J. K. G.; Turner, B. E.; Hayashi, S. S.; Watt, G. D.; Webster, A. S.
1992ApJS...83..363A Altcode:
Results of a spectral survey of IRC+10216 using the James Clerk
Maxwell Telescope are presented. A total of 46 spectral lines were
detected from 11 different identified molecules and isotopomers, and
an additional eight weak features are unidentified. The excitation
temperatures between different Ka ladders of SiCC range from 145 to
227 K, suggesting that excitation by IR radiation is important for
this molecule. The total column density of SiCC is found to be 2.8 x
10 exp 15/sq cm.
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Title: The Excitation Temperature of HC 9N in the Circumstellar
Envelope of IRC +10216
Authors: Bell, M. B.; Avery, L. W.; MacLeod, J. M.; Matthews, H. E.
1992ApJ...400..551B Altcode:
We have observed six relatively low energy transitions of HC9N in the
circumstellar envelope of IRC + 10216. We find this long carbon-chain
molecule to have a mean excitation temperature of Tex = 12 +/- 3
K which is similar to the values reported previously for HC3N and
HC5N. If this cool HC9N gas extends to a radius of about 25 arcsec,
we calculate a column density of N about 4.0 x 10 exp 13/sq cm. We
also report detection of the N = 2-1 transition of C3N.
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Title: Cloud-Cloud Collision in the High-Latitude Cloud MBM 55?
Authors: Koempe, C.; Vallee, J. P.; Avery, L. W.
1992AGAb....7...34K Altcode:
No abstract at ADS
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Title: A Sensitive Search for Rotational Lines of Vibrationally
Excited HC 5N in IRC +10 degrees 216
Authors: Bell, M. B.; Feldman, P. A.; Avery, L. W.
1992ApJ...396..643B Altcode:
The results of a search for nu(11) and nu(10) lines of HC5N (both the J
= 9-8 and J = 11-10 transitions in the molecular envelope of the carbon
star IRC + 10 deg 216 are reported. The J = 11-10 observations are the
first obtained with the new NRAO 30 GHz receiver. No vibrational lines
were detected to a level of 2 percent of the ground state lines. Using
new and published intensities for the ground-state lines, evidence of
HC5N at two temperatures is found. By assuming that the warmer HC5N
gas is contained in the inner half of a thick shell similar to HC5N,
an excitation analysis reveals that its mean excitation temperature
is about 25 K. Although it is conceivable that some of the HC3N gas at
the inner edge of the shell may have an excitation temperature as high
as about 30 K, this is found to be too low to produce vibrational
lines above the present limit of detectability. The cooler gas,
which extends to a radius of about 25 arcsec is characterized by an
excitation temperature of about 13 K. The density of the warm ground
state HC5N gas is found to be about 3.7 x 10 exp 14/sq cm.
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Title: Warm Molecular Gas in the Nucleus of IC 342: The CO ( J =
32) Distribution
Authors: Irwin, Judith A.; Avery, L. W.
1992ApJ...388..328I Altcode:
We have extensively mapped the nuclear molecular bar of the nearby,
face-on galaxy, IC 342, in ^12^CO(J = 3 - 2) using the JCMT. The
emission is centrally peaked with a weaker maximum to the north, and
there is evidence for both circular and noncircular motions in this
region. A comparison of the CO(J = 3 - 2)/CO(J = 2 - 1) and CO(J = 2 -
1)/CO(J = 1 - 0) line ratios from both the JCMT and IRAM telescopes,
together with a large velocity gradient model, shows that the emission
is generally due to warm gas of mean density 2 x 10^3^ cm^-3^, and
moderate optical thickness. CO abundances are lower than in Galactic
dark clouds, especially in the central, active, star-forming regions,
possibly due to UV photodissociation. A north-south ridge of higher
excitation is observed to the east of the nucleus and may be associated
with shocks. We estimate a total H_2_ mass of 10^7^ - 10^8^ M_sun_
in the bar; the molecular mass is likely a substantial fraction of
the dynamical mass within the central 170 pc.
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Title: Sub-Millimetre Observations of Sicc in IRC 10216(CP)
Authors: Avery, L. W.; Amano, T.; Bell, M. B.; Feldman, P. A.; Johns,
J. W. C.; MacLeod, J. M.; Mathews, H. E.; Morton, D. C.; Watson,
J. K. G.; Turner, B. E.; Hyashi, S. S.; Watt, G. D.; Webster, A. S.
1992IAUS..150..399A Altcode:
No abstract at ADS
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Title: Warm molecular gas in the nucleus of IC 342.
Authors: Irwin, J. A.; Avery, L. W.
1991JRASC..85..191I Altcode:
No abstract at ADS
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Title: Impact broadening of hydrogen recombination lines with Δn
≤ 17 in Orion and W51.
Authors: Bell, M.; Avery, L.; Moore, T.; MacLeod, J.
1991JRASC..85..200B Altcode:
No abstract at ADS
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Title: The Scientific Case for Molecular Line Observations at K-band
Frequencies with the Radio Schmidt Telescope
Authors: Avery, L. W.
1991rst..work...81A Altcode:
No abstract at ADS
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Title: The high-velocity gas in L723 - one outflow or two?
Authors: Avery, L. W.; Hayashi, S. S.; White, G. J.
1990JRASC..84..421A Altcode:
No abstract at ADS
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Title: The Unusual Morphology of the High-Velocity Gas in L723:
One Outflow or Two?
Authors: Avery, L. W.; Hayashi, S. S.; White, Glenn J.
1990ApJ...357..524A Altcode:
The molecular outflow in L723 in the CO J = 2-1 line was mapped. The
unusual morphology of the flow which has been revealed in earlier CO
J = 1-0 maps is very marked in the present data. The present maps of
the emission integrated over the entire line wings reveal a striking
quadrupolar morphology. It has been suggested that this structure could
be due to two separate outflow sources which are virtually coincident
or to a single, nonsteady source which is precessing. However, in the
maps made of the more optically thin emission arising from only the
higher velocity intervals in the line wings, the quadrupolar structure
transforms into two continuous, roughly semicircular arcs, one on each
side of the IRAS source 1915 + 1907. These arcs are interpreted to be
the limb-brightened walls of evacuated cavities swept clear by a wind
from the IRAS source. Consequently, it appears that L723 contains a
single, rather conventional bipolar outflow with an axis oriented from
northeast to southwest.
---------------------------------------------------------
Title: New CO observations of the high-latitude molecular cloud MBM
55, near IRAS 230604+145055.
Authors: Vallee, J. P.; Avery, L. W.
1990A&A...233..553V Altcode:
Two spatially and kinematically distinct clumps of molecular gas were
discovered in the vicinity of the point source IRAS 2306 + 1451 in
the MBM 55. The two clumps are red and blue-shifted with respect to
the narrow (C-13)O line core velocity, and are located on opposite
sides of the IRAS source. The separation of 3 arcmin between the
peaks of the red and blue emission corresponds to less than 0.16 pc,
uncorrected for an unknown projection effect.
---------------------------------------------------------
Title: Collisional Rate Coefficients of C 3H 2 and the Determination
of Physical Conditions in Molecular Clouds
Authors: Avery, L. W.; Green, Sheldon
1989ApJ...337..306A Altcode:
Collisional excitation rates for C3H2, calculated using the coupled
states approximation at temperatures of 10-30 K, are presented. C3H2
produces a number of spectral line pairs whose members are close
together in frequency but arise from levels with different excitation
energies. The rates are used in statistical equilibrium calculations
to illustrate the excitation properties and density-dependent behavior
of various C3H2 line ratios.
---------------------------------------------------------
Title: A Study of C 3HD in Cold Interstellar Clouds
Authors: Bell, M. B.; Avery, L. W.; Matthews, H. E.; Feldman, P. A.;
Watson, J. K. G.; Madden, S. C.; Irvine, W. M.
1988ApJ...326..924B Altcode:
The 1(10)-1(01) transition of C3HD was detected at 19.418 GHz at twelve
positions in cold, dark clouds, and the D hyperfine components were
resolved in two sources (L1498 and TMC-1C) well enough to derive values
for the D quadrupole coupling constants. Simultaneous observations
of C3H2 in each source yield relative integrated line intensities in
the range 0.10-0.18, from which relative C3HD/C3H2 abundances in the
range 0.05-0.15 were derived. These are among the highest deuteration
ratios yet observed. Within the limits of the observational and modeling
uncertainties, it is possible to explain the derived C3HD/C3H2 ratios
by ion-molecule chemistry if e is equal to about 3 x 10 to the -7th.
---------------------------------------------------------
Title: Newly Detected Molecules in Dense Interstellar Clouds
Authors: Irvine, William M.; Avery, L. W.; Friberg, P.; Matthews,
H. E.; Ziurys, L. M.
1988inma.conf...15I Altcode:
This paper is also published in Astrophys. Lett. Commun. See 45.131.139.
---------------------------------------------------------
Title: Newly Detected Molecules in Dense Interstellar Clouds
Authors: Irvine, William M.; Avery, L. W.; Friberg, P.; Matthews,
H. E.; Ziurys, L. M.
1988ApL&C..26..167I Altcode: 1988ApL....26..167I
Several new interstellar molecules have been identified including
C<SUB>2</SUB>S, C<SUB>3</SUB>S, C<SUB>5</SUB>H, C<SUB>6</SUB>H and
(probably) HC<SUB>2</SUB>CHO in the cold, dark cloud TMC-1; and the
discovery of the first interstellar phosphorus-containing molecule, PN,
in the Orion "plateau" source. Further results include the observations
of <SUP>13</SUP>C<SUB>3</SUB>H<SUB>2</SUB> and C<SUB>3</SUB>HD, and
the first detection of HCOOH (formic acid) in a cold cloud.
---------------------------------------------------------
Title: Newly detected molecules in dense interstellar clouds.
Authors: Irvine, W. M.; Avery, L. W.; Friberg, P.; Matthews, H. E.;
Ziurys, L. M.
1988imgh.conf...15I Altcode:
This paper is also published in Astrophys. Lett. Commun. See 45.131.139.
---------------------------------------------------------
Title: CO J=3-2 and J=2-1 spectroscopy and mapping of ten high
velocity molecular outflow sources.
Authors: Phillips, J. P.; White, G. J.; Rainey, R.; Avery, L. W.;
Richardson, K. J.; Griffin, M. J.; Cronin, M. J.; Monteiro, T.;
Hilton, J.
1988A&A...190..289P Altcode:
The authors have mapped high velocity outflows associated with
the sources K3-50, CRL 2591, W3, S88, NGC 2264, NGC 2024, S140,
G 35.2-0.74, NGC 1333 (HH 7-11), and NGC 1333 (IRAS 1) in the J =
2-1 and J = 3-2 transitions of CO. The line core and wing excitation
properties are discussed in detail, and an approximate relation dv/dr
≅ 2.5×10<SUP>-4</SUP>n (H<SUB>2</SUB>)<SUP>3/2</SUP>km s<SUP>-1</SUP>
pc<SUP>-1</SUP> determined, whereby most of the nebulae appear to
depart considerably from the régime of free-fall collapse, or thermal,
turbulent, and rotational stability.
---------------------------------------------------------
Title: Submillimetre CO observations of the Cepheus A outflow.
Authors: Richardson, K. J.; White, Glen J.; Avery, L. W.; Woodsworth,
A. W.
1987A&A...174..197R Altcode:
The authors have carried out spectral mapping of the Cep A region in
the J = 3-2 transition of CO. The high velocity wings symptomatic of
outflowing gas are evident over a region ≡6×6 arc min in extent
(≡1.3×1.3 pc). There appear to be 2 outflows, as found also
for HCO<SUP>+</SUP> by Loren et al. (1985). The CO J = 3-2 red wing
intensity is enhanced relative both to lower transition CO data and to
HCO<SUP>+</SUP> J = 1-0, particularly to the south and east of Cep A,
a result which suggests the presence of hot, optically thin gas in the
flow. No such significant enhancement is seen, however, in the blue
wing. The data are discussed in terms of a 2 component outflow in which
the HCO<SUP>+</SUP> emission originates mainly from dense clumps in
the flow while a less dense (but >4×10<SUP>4</SUP>cm<SUP>-3</SUP>)
interclump medium is responsible for most of the <SUP>12</SUP>CO
emission.
---------------------------------------------------------
Title: Co/ J=3-2 and J=4-3 Observations of Molecular Clouds
Authors: White, G. J.; Rainey, R.; Avery, L.; Phillips, J. P.; Griffin,
M.; Monteiro, T.; Richardson, K.; Cronin, N.; Harten, R.
1987IAUS..115..172W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Submillimetre Wavelength Spectrum of Orion-A
Authors: White, G. J.; Monteiro, T.; Rainey, R.; Richardson, K.;
Griffin, M.; Avery, L.
1987IAUS..115..153W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Globules and Dark Clouds in the CO J = 3--2
and J = 2--1 Lines
Authors: Avery, L. W.; White, Glenn J.; Williams, I. P.; Cronin, N.
1987ApJ...312..848A Altcode:
In a search for embedded molecular outflows, nine globules and compact
dark clouds, including the known outflow sources B335 and L723, were
observed in the (C-12)O J = 2-1 and J = 3-2 lines, and a Monte Carlo
radiative transfer code utilizing a combination of microturbulent and
velocity gradient line broadening was used to model the flows. Both
the known sources are found to be of relatively low density and modest
energy. It is found that n(H2) = 3000/cu cm in B335 and 1000/cu cm in
the L723 high-velocity gas. None of the other seven clouds show clear
evidence of bipolar outflows. Models of the globules B68 and B361
suggest efficient carbon isotope fractionation, with the (C-12)O and
(C-13)O abundance ratios being 14 and 25, respectively.
---------------------------------------------------------
Title: Radio and millimetre observations of larger molecules.
Authors: Avery, L. W.
1987IAUS..120..187A Altcode:
The number of known interstellar molecules has increased steadily
since 1970 and stands presently at 68. Of the molecules discovered in
recent years more than half contain three or more heavy elements. The
number of sources where HC<SUB>5</SUB>N or HC<SUB>3</SUB>N has been
detected now includes 21 dark clouds, four circumstellar shells, two
bipolar nebulae, the line of sight to the Cas A supernova remnant,
and possibly a comet. The more abundant large molecules are useful
diagnostic probes, and preliminary statistical equilibrium calculations
of the widespread new ring, C<SUB>3</SUB>H<SUB>2</SUB>, are presented
which indicate its usefulness as an indicator of H<SUB>2</SUB> density.
---------------------------------------------------------
Title: Detection of Deuterated Cyclopropenylidene (C 3HD) in TMC-1
Authors: Bell, M. B.; Feldman, P. A.; Matthews, H. E.; Avery, L. W.
1986ApJ...311L..89B Altcode:
The authors report the detection of a spectral line at 19418.7 MHz
in the direction of the dense molecular cloud TMC-1. As a result of
laboratory work recently made available they can now assign this line
to the 1<SUB>10</SUB> → 1<SUB>01</SUB> transition of C<SUB>3</SUB>HD
(deuterated cyclopropenylidene) and use the observations to derive the
column densities of C<SUB>3</SUB>HD and C<SUB>3</SUB>H<SUB>2</SUB>
in TMC-1 as ≡4×10<SUP>12</SUP>cm<SUP>-2</SUP> and
≡1×10<SUP>14</SUP>cm<SUP>-2</SUP>, respectively. The chemistry
leading up to the production of C<SUB>3</SUB>HD is discussed and
evaluated.
---------------------------------------------------------
Title: Multi-level study of C3H2: The first interstellar hydrocarbon
ring
Authors: Madden, S. C.; Irvine, W. M.; Matthews, H. E.; Avery, L. W.
1986inpr.conf..155M Altcode:
Cyclic species in the interstellar medium have been searched for almost
since the first detection of interstellar polyatomic molecules. Eleven
different C3H2 rotational transitions were detected; 9 of which
were studied in TMC-1, a nearby dark dust cloud, are shown. The
1<SUB>10</SUB> yields 1<SUB>01</SUB> and 2<SUB>20</SUB> yields
2<SUB>11</SUB> transitions were observed with the 43 m NRAO telescope,
while the remaining transitions were detected with the 14 m antenna
of the Five College Radio Observatory (FCRAO). The lines detected in
TMC-1 have energies above the ground state ranging from 0.9 to 17.1
K and consist of both ortho and para species. Limited maps were made
along the ridge for several of the transitions. The HC3N J = 2 yields
1 transition were mapped simultaneously with the C3H2 1<SUB>10</SUB>
yields 1<SUB>01</SUB> line and therefore can compare the distribution
of this ring with a carbon chain in TMC-1. C3H2 is distributed along a
narrow ridge with a SE - NW extension which is slightly more extended
than the HC2N J = 2 yields 1. Gaussian fits gives a FWHP extension of
8'5 for C3H2 while HC3N has a FWHP of 7'. The data show variations
of the two velocity components along the ridge as a function of
transition. Most of the transitions show a peak at the position of
strongest HC3N emission while the 2<SUB>21</SUB> yields 2<SUB>10</SUB>
transition shows a peak at the NH3 position.
---------------------------------------------------------
Title: C3H2 observations as a diagnostic probe for molecular clouds
Authors: Avery, L. W.
1986inpr.conf...19A Altcode:
Recently the three-membered ring molecule, cyclopropenylidene, C3H2,
has been identified in the laboratory and detected in molecular
clouds by Thaddeus, Vrtilek and Gottlieb (1985). This molecule
is wide-spread throughout the Galaxy and has been detected in 25
separate sources including cold dust clouds, circumstellar envelopes,
HII regions, and the spiral arms observed against the Cas supernova
remnant. In order to evaluate the potential of C3H2 as a diagnostic
probe for molecular clouds, and to attempt to identify the most useful
transitions, statistical equilibrium calculations were carried out for
the lowest 24 levels of the ortho species and the lowest 10 levels of
the para species. Many of the sources observed by Matthews and Irvine
(1985) show evidence of being optically thick in the 1(10)-1(01)
line. Consequently, the effects of radiative trapping should be
incorporated into the equilibrium calculations. This was done using
the Large Velocity Gradient approximation for a spherical cloud of
uniform density. Some results of the calculations for T(K)=10K are
given. Figures are presented which show contours of the logarithm of
the ratio of peak line brightness temperatures for ortho-para pairs of
lines at similar frequencies. It appears that the widespread nature
of C3H2, the relatively large strength of its spectral lines, and
their sensitivity to density and molecular abundance combine to make
this a useful molecule for probing physical conditions in molecular
clouds. The 1(10)-1(01) and 2(20)-2(11) K-band lines may be especially
useful in this regard because of the ease with which they are observed
and their unusual density-dependent emission/absorption properties.
---------------------------------------------------------
Title: The C 3H 2 2 20--2 11 Transition: Absorption in Cold Dark
Clouds
Authors: Matthews, H. E.; Madden, S. C.; Avery, L. W.; Irvine, W. M.
1986ApJ...307L..69M Altcode:
The first observations of the 2(20)-2(11) transition of
cyclopropenylidene (C3H2) at 21.6 GHz are described. The most
significant finding is that the 2(20)-2(11) transition line is always
seen in absorption, in contrast to the 18.3-GHz 1(10)-1(01) resonance
line of the ortho species which always appears in emission in cold
dust clouds. Thus the former must have an excitation temperature less
than the brightness temperature of the universal microwave background
and becomes only the second molecule to exhibit such 'refrigeration'
below this temperature in cold, dark dust clouds.
---------------------------------------------------------
Title: Submillimeter Wavelength Molecular Spectroscopy of the Orion
Molecular Cloud
Authors: White, Glenn J.; Avery, L. W.; Richardson, K. J.; Lesurf,
J. C. G.
1986ApJ...302..701W Altcode:
A submillimeter wavelength spectroscopic study of the Orion molecular
cloud has been made in the J = 4-3 HCN, HC-13N, HCO(+), HC-13O(+),
and J = 7-6 CS molecular transitions. Densities of up to a few times
10 to the 6th/cu cm are found coupled with high inferred brightness
temperatures, indicating kinetic temperatures of 120 K. Evidence for
lower densities in the surrounding ambient molecular cloud is presented
along with maps of HCN and HCO(+) emission. The maps indicate different
spatial distributions in the two lines. The abundances of HCN and HCO(+)
in the plateau source are found to be enhanced relative to those in
the surrounding molecular cloud, and there is a suggestion that a
number of small-angular-diameter clumps may be present. The present
observations do not confirm the previously reported detection of CO(+)
in the interstellar medium.
---------------------------------------------------------
Title: The structure and kinematics of the DR 21 region.
Authors: Richardson, K. J.; White, G. J.; Phillips, J. P.; Avery, L. W.
1986MNRAS.219..167R Altcode:
Observations of the DR21/DR21(OH) region have been made in the molecular
lines CO J = 2-1, CO J = 3-2, HCN J = 4-3, HCO<SUP>+</SUP> J = 4-3,
H<SUP>13</SUP>CO<SUP>+</SUP> J = 4-3 and CS J = 7-6, supplemented
by continuum observations of DR21 and DR21(OH) at 350 μm and a
20 μm map of DR21. The CO observations show a high-velocity wing
region around DR21, which is blue shifted with respect to the -3 km
s<SUP>-1</SUP> central velocity of the source, and may be due to an
outflow. The CS, HCN, HCO<SUP>+</SUP> and H<SUP>13</SUP>CO<SUP>+</SUP>
intensities, spatial extents and line profiles, in addition to the
self-absorptions seen in some CO lines, can be understood on the basis
of a simple 2-component model similar to that of Norman & Silk and
consisting of dense (10<SUP>5</SUP> - 10<SUP>6</SUP>cm<SUP>-3</SUP>)
clumps surrounded by a less dense (≡10<SUP>3</SUP>cm<SUP>-3</SUP>)
interclump gas of higher temperature.
---------------------------------------------------------
Title: Submillimetre line and continuum observations of the S 255
molecular cloud.
Authors: Richardson, K. J.; White, G. J.; Gee, G.; Griffin, M. J.;
Cunningham, C. T.; Ade, P. A. R.; Avery, L. W.
1985MNRAS.216..713R Altcode:
The S255 molecular cloud has been observed using both continuum and
spectral line techniques at several submillimetre and millimetre
wavelengths. From photometry at 350, 760 and 1070 μm, the dust is
estimated to have a central temperature of 44K and an emissivity which
varies as λ<SUP>-1</SUP>. Spectral mapping of the source has been
carried out in the CO J = 2-1, CO J = 3-2 and HCN J = 4-3 molecular
lines, and central spectra obtained in the transitions HCO<SUP>+</SUP>
J = 4-3 and H<SUP>13</SUP>CO<SUP>+</SUP> J = 4-3. Many features of
the line observations can be modelled. Mapping at 350 μm has revealed
an elongated central structure, also suggested by the HCN mapping, in
which two clumps are separated by 1 arcmin along a north-south line. The
intensity ratios between the pairs of transitions CO J = 3-2, CO J =
2-1 and HCO<SUP>+</SUP> J = 4-3, H<SUP>13</SUP>CO<SUP>+</SUP> J = 4-3,
suggest that fragmentation has occurred in the cloud. An optically thin,
high-velocity component is detected in the CO J = 3-2 line, for which a
density of n(H<SUB>2</SUB>+He) ≡ 4 - 7×10<SUP>4</SUP>cm<SUP>-3</SUP>
and a size of ≡0.7 arcmin are deduced. This component is hotter
than the ambient cloud material and may originate from a high-velocity
molecular outflow.
---------------------------------------------------------
Title: Holographic measurements of the ARO 46-m telescope with
changing zenith angle.
Authors: Legg, T. H.; Avery, L. W.; Matthews, H. E.; Vallée, J. P.
1985JRASC..79..241L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: CO J = 3-2 observations of molecular line sources having
high-velocity wings.
Authors: Richardson, K. J.; White, G. J.; Avery, L. W.; Lesurf,
J. C. G.; Harten, R. H.
1985ApJ...290..637R Altcode:
Twelve molecular line sources which exhibit high-velocity wings in
the CO J = 1-0 rotational transition have been observed in the CO J =
3-2 line. The densities derived using observations of the transition
in combination with the lower lines can be considerably higher than
those derived purely from mapping the CO J = 1-0 transition, in some
cases by over an order of magnitude. This general conclusion tends to
increase the likelihood that the outflows are capable of supporting
clouds against free-fall gravitational collapse. Low values of apparent
CO fractional abundance per unit velocity gradient are derived, which
may be due to a depletion of CO in the outflow regions or alternatively,
to clumping of the outflowing molecular gas.
---------------------------------------------------------
Title: Observations of <SUP>12</SUP>CO Data and Models for the Dark
Cloud L183
Authors: Vedi, K.; Williams, I. P.; Avery, L.; White, G. S.; Cronin, N.
1985LNP...237...83V Altcode: 1985nmc..proc...83V
Observations of the C-12O J = 3-2 and J = 2-1 transitions for the dark
cloud L183 are presented, and theoretical modeling, using Avery's
(1983) Monte Carlo radiative transfer programs, which combine
velocity gradients and microturbulence, is carried out to fit the
observed antenna temperatures. Reasonable fits to the observations
were obtained with two models. The static model has a cold core with
hot outer layers and is a physically feasible model. The isothermal
model with a kinetic temperature of 15 K is easily accounted for by
the fragmentary hypothesis, and assumes that the lines are produced
from one of the denser clumps.
---------------------------------------------------------
Title: The detection of interstellar methyldiacetylene (CH3 C4 H).
Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W.
1984ApJ...282L..89M Altcode:
The CH3C4H interstellar molecule has been detected in the molecular
cloud TMC-1, with a total column density lying in the range of 2.0 x 10
to the 13th/sq cm to 3.1 x 10 to the 13th/sq cm for 4-6 K rotational
temperatures. By comparison with CH3C2H, the chemical process through
which two carbon atoms are added to the chain to produce CH3C4H yields
an abundance decrease of a factor of 2-4, as in the case for linear
cyanopolyynes. Since this relative abundance factor of approximately
3 is common to several different types of carbon chain molecules, it
is suggested to reflect the relative abundance of pure carbon chains
of different lengths.
---------------------------------------------------------
Title: The detection of interstellar methylcyanoacetylene
Authors: Broten, N. W.; MacLeod, J. M.; Avery, L. W.; Irvine, W. M.;
Hoglund, B.; Friberg, P.; Hjalmarson, A.
1984ApJ...276L..25B Altcode:
A new interstellar molecule, methylcyanoacetylene (CH3C3N), has been
detected in the molecular cloud TMC-1. The J = 8 to 7, J = 7 to 6, J =
6 to 5, and J = 5 to 4 transitions have been observed. For the first
three of these, both the K = 0 and K = 1 components are present,
while for J = 5 to 4, only the K = 0 line has been detected. The
observed frequencies were calculated by assuming a value of radial
velocity V(LSR) = 5.8 km/s for TMC-1, typical of other molecules in
the cloud. All observed frequencies are within 10 kHz of the calculated
frequencies, which are based on the 1982 laboratory constants of Moises
et al. (1982), so the identification is secure. The lines are broadened
by hyperfine splitting, and the J = 5 to 4, K = 0 transition shows
incipient resolution into three hyperfine components. The rotational
temperature determined from these observations is quite low, with T(rot)
in the range from 2.7 to 4 K. The total column density is approximately
5 x 10 to the 12th per sq cm.
---------------------------------------------------------
Title: The detection of interstellar methylcyanoacetylene.
Authors: Broten, N. W.; MacLeod, J. M.; Avery, L. W.; Irvine, W. M.;
Hoglund, B.; Hjalmarson, A.
1983BAAS...15Q.616B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Notes- Twenty-Second Meeting of the N.R.C. Associate Committee
on Astronomy
Authors: Avery, L. W.
1982JRASC..76..139A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A model of Taurus Molecular Cloud 1 based on HC3N observations
Authors: Avery, L. W.; MacLeod, J. M.; Broten, N. W.
1982ApJ...254..116A Altcode:
A Monte Carlo radiative transfer code is used to create a model
of the dark cloud TMC 1 which is consistent with the detection
of five rotational transitions of cyanoacetylene in recent
observations. Solutions are given for the interaction between radiative
trapping and population equilibrium in the cases of the 15 lowest
rotational levels of HC3N, assuming a cylindrical geometry for the
source. The model is characterized by a relatively high excitation
core and a lower excitation halo. It has proven impossible to fit the
observations well without invoking temperature enhancement, in addition
to density enhancement, in accounting for the higher excitation of
the core.
---------------------------------------------------------
Title: Detection of deuterated cyanodiacetylene (DC<SUB>5</SUB>N)
in Taurus Molecular Cloud 1.
Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W.
1981ApJ...251L..33M Altcode:
The J = 9-8 and J = 10-9 transitions of deuterated cyanodiacetylene
(DC5N) have been detected at 22.9 and 25.4 GHz in Taurus Molecular
Cloud 1. The abundance ratio DC5N/HC5N is found to lie in the range
0.006-0.016, which overlaps the range 0.013-0.017 observed for
DCO(+)/HCO(+), and is less than the range 0.02-0.08 determined for
DC3N/HC3N. The observation that R(DC5N) is approximately 0.5 R(DCO(+)),
is consistent with a model in which HC5N is formed on grains and
subsequently deuterated by reactions with H2D(+) in the gas phase.
---------------------------------------------------------
Title: The distribution of emission in TMC-1 from the strong
unidentified line at 85339 MHz.
Authors: Avery, L. W.; Broten, N. W.; MacLeod, J. M.
1981JRASC..75..245A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of Deuterated Cyanodiacetylene (DC<SUB>5</SUB>N)
in the Molecular Cloud TMC 1
Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W.
1981BAAS...13R.519M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of a complex new interstellar species with a
molecular weight of 99
Authors: Kroto, H. W.; Kirby, C.; Walton, D. R. M.; Avery, L. W.;
Broten, N. W.; McLeod, J. M.; Oka, T.
1980LIACo..21...83K Altcode: 1980smsl.conf...83K
In order to discover how large and complex the molecules in the
interstellar medium are, laboratory experiments have been carried out
on some long molecules with large dipole moments, and astronomical
measurements have been made. The Algonquin telescope in Canada
was used to search for H(C-triple bond-C)2CN and for H(C-triple
bond-C)3CN. The latter has been detected with intensities consistent
with an abundance between 1.5 and 3 times lower than that of the
former. These observations in the Heiles Cloud 2 imply that some highly
efficient synthetic processes are producing these species.
---------------------------------------------------------
Title: Long chain carbon molecules in the interstellar medium
Authors: Avery, L. W.
1980IAUS...87...47A Altcode:
The family of long chain carbon molecules known as the cyanopolyynes is
discussed with the aim of ascertaining their usefulness as astrophysical
probes. These carbons are the heaviest known interstellar molecules
and the longest linear molecules; they also have the largest moments of
inertia and the smallest rotational constants of the known interstellar
species. They are useful for molecular cloud studies because of the
sensitivity with which they reflect density and temperature. Studies
of the Taurus dark cloud complex, and more specifically of the small
condensation TCM1, have shown an enhanced abundance of cyanopolyynes;
these observations were computed using a two-component, core-halo
model. Other studies of TCM2 have conjectured that the clouds in Taurus
are potential star forming regions which are temporarily stable and
at high densities. This explanation may account for the presence of
cyanopolyynes in molecular clouds.
---------------------------------------------------------
Title: Radio observations of Heiles' Cloud 2.
Authors: Costain, C. H.; Avery, L. W.; Broten, N. W.; MacLeod, J. M.
1979JRASC..73..298C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Cyanodiacetylene (HC<SUB>5</SUB>N) in Heile's cloud 2.
Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W.
1979ApJ...233..584M Altcode:
The J = 4 3 transition of HC5N at 10.65 0Hz has been detected in a
narrow ridge of emission in Heiles's cloud 2 in Taurus. The relative
strengths of the three strongest hyperfine components are close to
the expected values for an optically thin molecular cloud in LTE. The
observed lines are very narrow, and show no detectable velocity
variation along the ridge. Statistical equilibrium calculations give
a total HC5N column density NL = 5 >c 1013 cm-2. Subject headings:
interstellar: molecules - nebulae: abundances - radio sources: lines
---------------------------------------------------------
Title: Failure to confirm the existence of interstellar methylamine-D
(CH<SUB>3</SUB>NHD).
Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W.; Oka, T.
1979ApJ...231..401M Altcode:
The probable detection of interstellar deuterated methylamine
through its 2(02) - 1(10) transition at 10,310.0 MHz has previously
been reported. On two separate occasions attempts were made without
success to confirm the existence of this spectral line. It does not
seem likely that the failure to observe the line can be attributed to
time variation, and it is concluded that interstellar CH3NHD has not
yet been detected.
---------------------------------------------------------
Title: Cyanodiacetylene (HC<SUB>5</SUB>N) in Sagittarius B2.
Authors: Avery, L. W.; Oka, T.; Broten, N. W.; MacLeod, J. M.
1979ApJ...231...48A Altcode:
Results are reported for observations of the J = 2-1 and 3-2
rotational lines of HC5N at 5.325 and 7.988 GHz, respectively, in Sgr
B2. Statistical-equilibrium calculations are performed to model the
physical conditions implied by the observations. A consistent model
of the Sgr B2 molecular cloud and continuum sources is obtained which
includes an extensive molecular cloud of very low density surrounding
the core and halo of the model proposed by Morris et al. (1976); this
cloud is assumed to have a diameter of 30 pc, an H2 density of about 100
per cu cm, and a kinetic temperature of approximately 20 K. A maximum
column density of 1.6 x 10 to the 14th per sq cm is estimated for HC5N
and shown to be equal to the column density for HC3N in the same source.
---------------------------------------------------------
Title: The detection of HC<SUB>9</SUB>N in interstellar space.
Authors: Broten, N. W.; Oka, T.; Avery, L. W.; MacLeod, J. M.; Kroto,
H. W.
1978ApJ...223L.105B Altcode:
With a molecular weight of 123 amu and 11 atoms, HC9N
(cyano-octatetra-yne) is the heaviest and largest molecule yet detected
in interstellar space. The J = 18-17 and J = 25-24 transitions have been
observed in Heiles's Cloud 2 by using a molecular constant obtained
by extrapolation from the lighter cyanopolyyne molecules. The column
density is estimated to be trillion per sq cm, down by a factor of 4
from that of HC9N in the same source.
---------------------------------------------------------
Title: Observations of CH in the direction of Sgr B2.
Authors: Andrew, B. H.; Avery, L. W.; Broten, N. W.
1978A&A....66..437A Altcode:
Observations of CH in the direction of Sgr B2 show the presence of all
three hyperfine components of the ground-state Lambda-doublet. There
are seven or more velocity components, some arising in the Sgr B2
cloud itself, others in the intervening medium. Column densities
are calculated and confirm that in dense clouds the abundance of CH
decreases relative to other molecules.
---------------------------------------------------------
Title: The detection of cyanohexatriyne, H(C≡ C)<SUB>3</SUB>CN,
in Heile's Cloud 2.
Authors: Kroto, H. W.; Kirby, C.; Walton, D. R. M.; Avery, L. W.;
Broten, N. W.; MacLeod, J. M.; Oka, T.
1978ApJ...219L.133K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A search for microwave emission from solar X-ray bright
point flares.
Authors: Avery, L. W.; Feldman, P. A.; Gaizauskas, V.; Roy, J. -R.;
Wolfson, C. J.
1977A&A....56..327A Altcode:
An attempt was made to detect 9.4-cm radio emission from flaring
X-ray bright points with the 46-m telescope at the Algonquin Radio
Observatory. Observations from the X-ray heliometer aboard OSO-8
were combined with optical and magnetic data to substantiate possible
events. Reduction of 52 h of radio data has revealed one event which
is a candidate for radio emission from a flaring X-ray bright point.
---------------------------------------------------------
Title: Detection of a Complex New Interstellar Molecule with a
Molecular Weight of 99.
Authors: Kroto, H. W.; Kirby, C.; Walton, D. R. M.; Avery, L. W.;
Broten, N. W.; MacLeod, J. M.; Oka, T.
1977BAAS....9..303K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Cyanodiacetylene in a dark dust cloud.
Authors: MacLeod, J. M.; Broten, N. W.; Avery, L. W.; Oka, T.
1977JRASC..71Q.396M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evidence for weak maser action in interstellar
cyanodiacetylene.
Authors: Broten, N. W.; MacLeod, J. M.; Oka, T.; Avery, L. W.; Brooks,
J. W.; McGee, R. X.; Newton, L. M.
1976ApJ...209L.143B Altcode:
The letter reports observations of the J = 1-0 and J = 8-7 rotational
transitions of cyanodiacetylene (HC5N) at the respective frequencies
of 2.663 GHz and 21.301 GHz in Sgr B2. A value of -4.12 + or 0.07
MHz for the HC5N quadrupole coupling constant is obtained from the
resolved hyperfine splitting of the J = 1-0 transition. Assuming thermal
equilibrium of the molecules at an excitation temperature of 30 K and
an optical depth of much less than unity, a total column density of
1.5 by 10 to the 14th power per sq cm is computed for both the J =
8-7 transition and the previously observed J = 4-3 transition. An
anomalously large intensity is found for the J = 1-0 transition in
HC5N, suggesting maser action in this molecule. Additional theoretical
evidence is cited in support of weak maser action in the J = 1-0 line
of HC5N.
---------------------------------------------------------
Title: Observations of quasiperiodic variations in the solar flux
at 10.7 GHz.
Authors: Avery, L. W.
1976SoPh...49..141A Altcode:
Observations of the continuum microwave flux at 2.8 cm from quiet
regions of the solar disc reveal low amplitude, quasiperiodic
fluctuations at periods of 234 s and 150 s. For oscillating elements
10 arc seconds in extent, the corresponding peak to peak temperature
variations are 230 K and 190 K. The energy flux in the oscillations is
estimated to be 2.5x10<SUP>2</SUP> ergs cm<SUP>2</SUP> s<SUP>−1</SUP>,
assuming they are caused by acoustic waves. If the oscillating elements
are ⩽ 1 arc second in extent, the energy flux is comparable to that
required for coronal heating.
---------------------------------------------------------
Title: Total Solar Eclipses in Canada: 1963-2024 AD
Authors: Gaizauskas, V.; Avery, L. W.
1976JRASC..70..135G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of the heavy interstellar molecule cyanodiacetylene.
Authors: Avery, L. W.; Broten, N. W.; MacLeod, J. M.; Oka, T.; Kroto,
H. W.
1976ApJ...205L.173A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of the heavy interstellar molecule cyanodiacetylene.
Authors: Avery, L.; Broten, N. W.; McLeod, J. M.; Oka, T.
1976BAAS....8..394A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Comet Kobayashi-Berger-Milon (1975h)
Authors: Avery, L. W.; Andrew, B. H.; Borngen, F.; Lochno, P.; Kirsch,
K.; Bortle, J.
1975IAUC.2838....1A Altcode:
L. W. Avery and B. H. Andrew, Herzberg Institute of Astrophysics, report
the detection of emission at 3335.48 MHz from the rotational ground
state of CH. Using the 46-m Algonquin radio telescope they measured an
antenna temperature of 0.04 +/- 0.01 K for the 1 -> 1 line of the
{2}pi_{1/2} J = 1/2 state on Sept. 7, 8 and 9. F. Borngen, Tautenburg
Observatory, reports that he, assisted by P. Lochno and K. Kirsch,
took eight long exposures with the 134-cm f/3 Schmidt telescope on five
nights between July 31 and Aug. 6. He writes: "The length of the main
tail is more than 2o on all the plates, which range in sensitivity
from ultraviolet to red. Numerous details, such as faint cloud-like
condensations, are apparent. The main tail is generally flanked on both
sides by several fainter thread-like streamers, which are straight and
of various lengths. These streamers come directly from the head or
branch off from the main tail farther from the nucleus. There is to
some extent evidence of screw-like and turbulent motions in the tail
material." J. Bortle, Brooks Observatory, writes that he was able to
detect the comet in the morning sky on Sept. 4.39 UT and provides the
following total visual magnitude estimates, coma diameters and tail
information, obtained using 10 x 50 binoculars: Sept. 11.40, 4.9, 2',
-; 13.40, 4.9, > 2', 10' in p.a. 340o; 14.40, 5.1, 1'.5, 1o in 320o;
15.39, 5.0, 1'.3, 1o in 320o.
---------------------------------------------------------
Title: Continuum Observations of Comet Kohoutek (1973f)
Authors: Andrew, B. H.; Avery, L. W.
1975ApL....16..125A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Continuum observations of comet Kohoutek /1973f/
Authors: Andrew, B. H.; Avery, L. W.
1975ApL....16Q.125A Altcode:
Observations of comet Kohoutek on several occasions in December 1973
and January 1974 revealed no detectable continuum radio emission
at 2.8 cm wavelength; yet on January 10, 1974, Hobbs et al. (1975)
observed 20 mJy at 3.7 cm and 34 mJy at 2.8 cm. The icy-grain halo
model of the cometary nuclear region seems a likely explanation of
the observations, as suggested by Hobbs et al., but the radio emission
they observed may be a relatively rare phenomenon.
---------------------------------------------------------
Title: Continuum observations of Comet Kohoutek /1973f/
Authors: Andrew, B. H.; Avery, L. W.
1975ApL....16R.125A Altcode:
Observations of Comet Kohoutek on several occasions in December 1973
and January 1974 revealed no detectable continuum radio emission
at 2.8-cm wavelength, yet on January 10, 1974, Hobbs et al (1975)
observed 20 mJy at 3.7 cm and 34 mJy at 2.8 cm. The icy grain halo
model of the cometary nuclear region seems a likely explanation of
the observations, as suggested by Hobbs et al. (1975), but the radio
emission they observed may be a relatively rare phenomenon.
---------------------------------------------------------
Title: Search for microwave line emission from comet Kohoutek (1973f).
Authors: Avery, L. W.; Andrew, B. H.
1974AJ.....79.1322A Altcode:
Attempts to detect line emission from Comet Kohoutek (1973f) were
carried out at several frequencies over the period from Dec. 2,
1973, to Jan. 12, 1974. Upper limits for antenna temperature of the
6<SUB>16-5</SUB> sub 23 line of H2O and the 85 alpha line of H imply
that the rate of H2O production by Comet Kohoutek at a heliocentric
distance of 0.3 AU was less than 6 x 10 to the 32nd molecules/sec/ster,
and that the beam averaged electron density in the coma was less
than 500,000 per cu cm. The H2O observations are consistent with a
fluid-dynamic model of the coma and a nucleus of radius smaller than
42 km. Upper limits were also obtained for emission from ammonia and
methylene cyanide.
---------------------------------------------------------
Title: Non-detection of Interstellar Isothiocyanic Acid (HNCS)
Authors: Andrew, B. H.; Avery, L. W.
1974A&A....35..295A Altcode:
Key words: interstellar molecules Summary. We searched unsuccessfully
for radio emission at 23.458 GHz from the 202- 10i transition of
isothiocyanic acid. The 3 upper limits to the brightness temperatures
were 0.13 K, 0.16 K and 0.22 K in Sgr. B 2, W 51, and Orion A
respectively.
---------------------------------------------------------
Title: Comparison of Impulsive Optical and Radio Emission Features
of an Energetic Subflare
Authors: Gaizauskas, V.; Avery, L. W.
1974BAAS....6Q.287G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Orbital Data for Comet Kohoutek (1973f)
Authors: Avery, Lorne
1973JRASC..67L..25A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Predictions of Local Circumstances Across Canada of the Total
Solar Eclipse of July 10, 1972
Authors: Gaizauskas, V.; Avery, L. W.; Manning, F. D.
1971JRASC..65..107G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The formation of the Ca ii K line in a spinning spicule
Authors: Avery, Lorne W.
1970SoPh...13..301A Altcode:
The emission of the Ca II K line from a spinning cylindrical spicule
model is considered. In order to reproduce the observed spicule K
line profiles, the model must have both radial and axial gradients
in N<SUB>e</SUB> and T<SUB>e</SUB>. The rotating spicule model is
optically thin at all heights and is hotter and more dense than a
stationary model computed in a previous paper. It is proposed that
the so-called Type I and Type II spicules may be structurally the same
features, with different rotational velocities.
---------------------------------------------------------
Title: A Solar Spicule Model Based Upon Calcium II K Line Radiative
Transfer Studies
Authors: Avery, Lorne W.; House, Lewis L.
1969SoPh...10...88A Altcode:
Monte Carlo radiative transfer techniques are used to develop a
height-dependent spicule model based upon a more realistic configuration
than has hitherto been considered. The spicule is represented by a
uniform cylinder, of finite length, standing vertically upon a plane
chromosphere. The observed, limb-darkened, anisotropic chromospheric
flux incident upon the cylinder is incorporated into the transfer
calculations.
---------------------------------------------------------
Title: Radiative transport in finite homogeneous cylinders by the
Monte Carlo technique.
Authors: Avery, L. W.; House, L. L.; Skumanich, A.
1969JQSRT...9..519A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Monte Carlo technique applied to radiative transfer.
Authors: House, L. L.; Avery, L. W.
1969JQSRT...9.1579H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Monte Carlo Calculation of Radiative Transfer in Cylinders
with Application to Solar Spicules.
Authors: Avery, Lorne Wallace
1969PhDT.........2A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Monte Carlo Technique Applied to Radiative Transfer
Authors: House, L. L.; Avery, L. W.
1968rla..conf..133H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An Investigation of Resonance-Line Scattering by the Monte
Carlo Technique
Authors: Avery, Lorne W.; House, Lewis L.
1968ApJ...152..493A Altcode:
The problem of photon diffusion through a purely scattering atmosphere
is investigated by means of the Monte Carlo technique for two types of
scattering: (1) complete redistribution and (2) coherent scattering
in the rest frame of the atom which leads to partially coherent
scattering in the external frame. The Monte Carlo techniques are
applied to Lyman-a photons generated at a point source at the center
of a plane-parallel slab of large optical thickness. The mean number
of scatterings required for escape, (N), is computed for both types
of scattering. For thick slabs (N) is found to be much greater under
partially coherent conditions. As a result the source function should
approach the equilibrium value at smaller optical depths than one
predicts under complete redistribution. In addition it is found that,
under partially coherent scattering, photons tend to diffuse more
easily in space, but less easily in frequency than under complete
redistribution. Thus for complete redistribution the photons are more
likely to remain in the vicinity of their origin until they escape
from the atmosphere as the result of a single, large frequency shift
