Author name code: avery ADS astronomy entries on 2022-09-14 author:"Avery, Lorne W." ------------------------------------------------------------------------ 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. Bibcode: 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 A ∼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. 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. Bibcode: 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. 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 Bibcode: 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. Title: Excitation Analysis of SO and SO2 in the Proto-Planetary Nebula OH 231.8+4.2 Authors: Claude, S. M. X.; Avery, L. W.; Matthews, H. E. Bibcode: 2000ApJ...545..379C Altcode: In the nebula OH 231.8+4.2 we have observed SO and SO2 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 SO2 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 SO2 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. 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. Bibcode: 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 Ne=2500 and 4000 cm-3 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 Ne=20,000 cm-3 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. 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. Bibcode: 2000BAAS...32..378A Altcode: No abstract at ADS 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. Bibcode: 2000IAUTA..24..281W Altcode: No abstract at ADS Title: Canadian participation in the Atacama Large Millimetre Array. Authors: Avery, L. W.; Wilson, C. D. Bibcode: 1999JRASC..93..179A Altcode: No abstract at ADS 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. Bibcode: 1999JRASC..93..182M Altcode: No abstract at ADS 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. Bibcode: 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-1. 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 Lsolar and a total mass of 1.8-4.6 Msolar. 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. 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. Bibcode: 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 Msolar) 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 Msolar, while the inner arc breaks up into a number of individual clumps, some of which are previously identified protostars. 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 Bibcode: 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. Title: Enhanced Chemical Abundances in the L1157 Outflow: SiO and CH 3OH Observations Authors: Avery, L. W.; Chiao, M. Bibcode: 1996ApJ...463..642A Altcode: Millimeter and submillimeter wavelength spectral lines of CH3OH 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 CH3OH emission in the blueshifted lobe peak at the same position as the CO J = 1-0 line The SiO and CH3OH lines originate from warm gas. The temperature deduced from the methanol observations matches the laboratory temperature at which pure CH3OH ice separates from an H2O:CH3OH 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 105 relative to quiescent, dark cloud values. The slower gas is somewhat cooler and less dense, with an SiO abundance enhancement factor of 106, well above that seen in the Orion KL outflow. The CH3OH abundance, relative to H2, is 1.5 x 10-7, and its emission originates in gas with Tkin ≥ 100 K. A number of outflows are now known that show strong abundance enhancements in SiO and/or CH3OH 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 CH3OH. 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. Bibcode: 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 H13CN 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 H13CN and HC15N J = 8-7 lines indicates 200 K, 109 cm-3 gas either with an H2 column density of ∼2 × 1024 cm-2 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. 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. Bibcode: 1994JRASC..88R.265M Altcode: No abstract at ADS 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. Bibcode: 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 1012/sq cm and N(SiH2) equal to or less than 3.5 x 1015. 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 1011/sq cm, which corresponds to X(HCO(+)) = 1.8 x 10-11 for a mass-loss rate of 4 x 10-5 solar mass/yr. This is an order of magnitude lower than the predicted theoretical abundance of X(HCO(+)) = 4.5 x 10-10 (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 (0330), (111d0), (1200), and (011d1) 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. Title: C3S and C5S in IRC +10216 Authors: Bell, M. B.; Avery, L. W.; Feldman, P. A. Bibcode: 1993ApJ...417L..37B Altcode: No abstract at ADS Title: New heavy molecules in the envelope of IRC+10216. Authors: Bell, M. B.; Avery, L. W.; MacLeod, J. M.; Watson, J. K. G. Bibcode: 1993JRASC..87Q.175B Altcode: No abstract at ADS 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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. Title: Cloud-Cloud Collision in the High-Latitude Cloud MBM 55? Authors: Koempe, C.; Vallee, J. P.; Avery, L. W. Bibcode: 1992AGAb....7...34K Altcode: No abstract at ADS 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. Bibcode: 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. Title: Warm Molecular Gas in the Nucleus of IC 342: The CO ( J = 32) Distribution Authors: Irwin, Judith A.; Avery, L. W. Bibcode: 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. 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. Bibcode: 1992IAUS..150..399A Altcode: No abstract at ADS Title: Warm molecular gas in the nucleus of IC 342. Authors: Irwin, J. A.; Avery, L. W. Bibcode: 1991JRASC..85..191I Altcode: No abstract at ADS Title: Impact broadening of hydrogen recombination lines with Δn ≤ 17 in Orion and W51. Authors: Bell, M.; Avery, L.; Moore, T.; MacLeod, J. Bibcode: 1991JRASC..85..200B Altcode: No abstract at ADS Title: The Scientific Case for Molecular Line Observations at K-band Frequencies with the Radio Schmidt Telescope Authors: Avery, L. W. Bibcode: 1991rst..work...81A Altcode: No abstract at ADS Title: The high-velocity gas in L723 - one outflow or two? Authors: Avery, L. W.; Hayashi, S. S.; White, G. J. Bibcode: 1990JRASC..84..421A Altcode: No abstract at ADS 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1988ApL&C..26..167I Altcode: 1988ApL....26..167I Several new interstellar molecules have been identified including C2S, C3S, C5H, C6H and (probably) HC2CHO 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 13C3H2 and C3HD, 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. Bibcode: 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. Bibcode: 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 ≅ 2.5×10-4n (H2)3/2km s-1 pc-1 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. Bibcode: 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+ 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+ 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+ emission originates mainly from dense clumps in the flow while a less dense (but >4×104cm-3) interclump medium is responsible for most of the 12CO 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 HC5N or HC3N 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, C3H2, are presented which indicate its usefulness as an indicator of H2 density. Title: Detection of Deuterated Cyclopropenylidene (C 3HD) in TMC-1 Authors: Bell, M. B.; Feldman, P. A.; Matthews, H. E.; Avery, L. W. Bibcode: 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 110 → 101 transition of C3HD (deuterated cyclopropenylidene) and use the observations to derive the column densities of C3HD and C3H2 in TMC-1 as ≡4×1012cm-2 and ≡1×1014cm-2, respectively. The chemistry leading up to the production of C3HD 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. Bibcode: 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 110 yields 101 and 220 yields 211 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 110 yields 101 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 221 yields 210 transition shows a peak at the NH3 position. Title: C3H2 observations as a diagnostic probe for molecular clouds Authors: Avery, L. W. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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+ J = 4-3, H13CO+ 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-1 central velocity of the source, and may be due to an outflow. The CS, HCN, HCO+ and H13CO+ 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 (105 - 106cm-3) clumps surrounded by a less dense (≡103cm-3) 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. Bibcode: 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-1. 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+ J = 4-3 and H13CO+ 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+ J = 4-3, H13CO+ 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(H2+He) ≡ 4 - 7×104cm-3 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. Bibcode: 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. Bibcode: 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 12CO Data and Models for the Dark Cloud L183 Authors: Vedi, K.; Williams, I. P.; Avery, L.; White, G. S.; Cronin, N. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 (DC5N) in Taurus Molecular Cloud 1. Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W. Bibcode: 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. Bibcode: 1981JRASC..75..245A Altcode: No abstract at ADS Title: Detection of Deuterated Cyanodiacetylene (DC5N) in the Molecular Cloud TMC 1 Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1979JRASC..73..298C Altcode: No abstract at ADS Title: Cyanodiacetylene (HC5N) in Heile's cloud 2. Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W. Bibcode: 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 (CH3NHD). Authors: MacLeod, J. M.; Avery, L. W.; Broten, N. W.; Oka, T. Bibcode: 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 (HC5N) in Sagittarius B2. Authors: Avery, L. W.; Oka, T.; Broten, N. W.; MacLeod, J. M. Bibcode: 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 HC9N in interstellar space. Authors: Broten, N. W.; Oka, T.; Avery, L. W.; MacLeod, J. M.; Kroto, H. W. Bibcode: 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. Bibcode: 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)3CN, 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 2.5x102 ergs cm2 s−1, 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1975ApL....16..125A Altcode: No abstract at ADS Title: Continuum observations of comet Kohoutek /1973f/ Authors: Andrew, B. H.; Avery, L. W. Bibcode: 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. Bibcode: 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. Bibcode: 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 616-5 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. Bibcode: 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. Bibcode: 1974BAAS....6Q.287G Altcode: No abstract at ADS Title: Orbital Data for Comet Kohoutek (1973f) Authors: Avery, Lorne Bibcode: 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. Bibcode: 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. Bibcode: 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 Ne and Te. 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. Bibcode: 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. Bibcode: 1969JQSRT...9..519A Altcode: No abstract at ADS Title: The Monte Carlo technique applied to radiative transfer. Authors: House, L. L.; Avery, L. W. Bibcode: 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 Bibcode: 1969PhDT.........2A Altcode: No abstract at ADS Title: The Monte Carlo Technique Applied to Radiative Transfer Authors: House, L. L.; Avery, L. W. Bibcode: 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. Bibcode: 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