Physical Sciences and Mathematics Commons^™

State-To-State Rate Coefficients For Hcs+In Rotationally Inelastic Collisions With H2at Low Temperatures, Otoniel Denis-Alpizar, Ernesto Quintas-Sánchez, Richard Dawes

Chemistry Faculty Research & Creative Works

HCS⁺ ions have been detected in several regions of the interstellar medium (ISM), but an accurate determination of the chemical-physical conditions in the molecular clouds where this molecule is observed requires detailed knowledge of the collisional rate coefficients with the most common colliders in those environments. In this work, we study the dynamics of rotationally inelastic collisions of HCS⁺ + H₂ at low temperature, and report, for the first time, a set of rate coefficients for this system. We used a recently developed potential energy surface for the HCS⁺-H₂ van der Waals complex and …

Untangling The Formation Of Methoxymethanol (Ch3Och2Oh) And Dimethyl Peroxide (Ch3Ooch3) In Star-Forming Regions, Cheng Zhu, Robert Frigge, Alexandre Bergantini, Ryan C. Fortenberry, Ralf I. Kaiser

Faculty and Student Publications

© 2019. The American Astronomical Society. All rights reserved.. Methoxymethanol (CH3OCH2OH) was recently detected toward the MM1 core in the high-mass star-forming region NGC 6334I. However, the underlying formation mechanisms of this complex organic molecule (COM) as well as its structural isomers ethylene glycol (HOCH2CH2OH) and the hitherto unobserved dimethyl peroxide (CH3OOCH3) are still elusive. Here, we report the very first confirmed synthesis of dimethyl peroxide - at various deuteration levels within interstellar analogous ices of D3-methanol (CD3OH) exposed to ionizing radiation at ultralow temperatures of 5 K. The discrimination of specific isomers is achieved by exploiting reflectron time-of-flight mass …

Detection Of A Substantial Molecular Gas Reservoir In A Brightest Cluster Galaxy At Z = 1.7, Tracy M.A. Webb, James Lowenthal, Min Yun, Allison G. Nobel, Adam Muzzin, Gillian Wilson, H.K.C. Yee, Ryan Cybulski, D. H. Hughes

Astronomy: Faculty Publications

We report the detection of CO(2–1) emission coincident with the brightest cluster galaxy (BCG) of the high- redshift galaxy cluster SpARCS1049+56, with the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT). We confirm a spectroscopic redshift for the gas of z = 1.7091 ± 0.0004, which is consistent with the systemic redshift of the cluster galaxies of z = 1.709. The line is well fit by a single-component Gaussian with an RSR-resolution-corrected FWHM of 569 ± 63kms−1. We see no evidence for multiple velocity components in the gas, as might be expected from the multiple image components seen …

Polycyclic Aromatic Hydrocarbons With Aliphatic Sidegroups: Intensity Scaling For The C-H Stretching Modes And Astrophysical Implications, Xuejuan Yang, Aigen Li, Rainer Glaser, Jianxin Zhong

Chemistry Faculty Research & Creative Works

The so-called unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm ubiquitously seen in a wide variety of astrophysical regions are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. Astronomical PAHs may have an aliphatic component, as revealed by the detection in many UIE sources of the aliphatic C-H stretching feature at 3.4 mm. The ratio of the observed intensity of the 3.4 mm feature to that of the 3.3 μm aromatic C-H feature allows one to estimate the aliphatic fraction of the UIE carriers. This requires knowledge of the intrinsic oscillator strengths of the 3.3 …

The C-H Stretching Features At 3.2-3.5 Μm Of Polycyclic Aromatic Hydrocarbons With Aliphatic Sidegroups, Xuejuan Yang, Aigen Li, Rainer Glaser, Jianxin Zhong

Chemistry Faculty Research & Creative Works

The so-called "unidentified" infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm are ubiquitously seen in a wide variety of astrophysical regions. The UIE features are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials, e.g., polycyclic aromatic hydrocarbon (PAH) molecules. The 3.3 μm aromatic C-H stretching feature is often accompanied by a weaker feature at 3.4 μm. The latter is generally thought to result from the C-H stretch of aliphatic groups attached to the aromatic systems. The ratio of the observed intensity of the 3.3 μm aromatic C-H feature to that of the 3.4 …

The Upper Limit For Ch4 In The Protostellar Disk Toward Hl Tauri, E L. Gibb, T Rettig, Sean D. Brittain, R Haywood, Theodore Simon, C Kulesa

Sean D Brittain

We used high-resolution infrared spectra of the heavily embedded T Tauri star HL Tau to search for evidence of absorption due to the R0, R1, and R2 gas-phase CH4 ν3 lines near 3.3 μm. From this, we report a 3 σ upper limit of 1.3 × 1015 cm-2 for the CH4 gas column density toward HL Tau. Our results are compared to those found for CO gas toward this source and to the recent model for chemistry in the inner (10 AU) disks around T Tauri stars by Markwick et al. We find that the upper limit of methane ice+gas …

Herschel/Pacs Observations Of Young Sources In Taurus: The Far-Infrared Counterpart Of Optical Jets, L Podio, I Kamp, D Flower, C Howard, G Sandell, A Mora, G Aresu, Sean D. Brittain, W.R.F. Dent, C Pinte, G J. White

Sean D Brittain

Context. Observations of the atomic and molecular line emission associated with jets and outflows emitted by young stellar objects provide sensitive diagnostics of the excitation conditions, and can be used to trace the various evolutionary stages they pass through as they evolve to become main sequence stars. Aims. To understand the relevance of atomic and molecular cooling in shocks, and how accretion and ejection efficiency evolves with the evolutionary state of the sources, we will study the far-infrared counterparts of bright optical jets associated with Class I and II sources in Taurus (T Tau, DG Tau A, DG Tau B, …

The Carriers Of The Interstellar Unidentified Infrared Emission Features: Constraints From The Interstellar C-H Stretching Features At 3.2-3.5 Μm, Xuejuan Yang, Rainer Glaser, Aigen Li, Jianxin Zhong

Chemistry Faculty Research & Creative Works

The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm, commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules, have recently been ascribed to mixed aromatic/aliphatic organic nanoparticles. More recently, an upper limit of <9% was placed on the aliphatic fraction (i.e., the fraction of carbon atoms in aliphatic form) of the UIE carriers based on the observed intensities of the 3.4 μm and 3.3 μm emission features by attributing them to aliphatic and aromatic C-H stretching modes, respectively, and assuming A _3.4/A _3.3 ≈ 0.68 derived from a small set of aliphatic and aromatic compounds, where A _3.4 and A _3.3 are, respectively, the band strengths of the 3.4 μm aliphatic and 3.3 μm aromatic C-H bonds. To improve the estimate of the aliphatic fraction of the UIE carriers, here we analyze 35 UIE sources exhibiting both the 3.3 μm and …

Basecol2012: A Collisional Database Repository And Web Service Within The Virtual Atomic And Molecular Data Centre (Vamdc), M.-L Duberne, M. H. Alexander, Y. A. Ba, N. Balakrishnan, C. Balança, C. Ceccarelli, J. Cernicharo, F. Daniel, F. Dayou, M. Doronin, F. Dumouchel, A. Faure, N. Feautrier, D. R. Flower, A. Grosjean, P. Halvick, J. Kłos, F. Lique, G. C. Mcbane, S. Marinakis, N. Moreau, R. Moszynsk, D. A. Neufeld, E. Roueff, P Schilke, A. Spielfiedel, P. C. Stancil, T. Stoecklin, J. Tennyson, B. Yang, A.-M. Vasserot, L. Wiesenfeld

Peer Reviewed Articles

The BASECOL2012 database is a repository of collisional data and a web service within the Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu). It contains rate coefficients for the collisional excitation of rotational, ro-vibrational, vibrational, fine, and hyperfine levels of molecules by atoms, molecules, and electrons, as well as fine-structure excitation of some atoms that are relevant to interstellar and circumstellar astrophysical applications. Submissions of new published collisional rate coefficients sets are welcome, and they will be critically evaluated before inclusion in the database. In addition, BASECOL2012 provides spectroscopic data queried dynamically from various spectroscopic databases using the VAMDC technology. …

The Nature Of The H2-Emitting Gas In The Crab Nebula, C. T. Richardson, J. A. Baldwin, Gary J. Ferland, E. D. Loh, C. A. Kuehn, A. C. Fabian, Philippe Salomé

Physics and Astronomy Faculty Publications

Understanding how molecules and dust might have formed within a rapidly expanding young supernova remnant is important because of the obvious application to vigorous supernova activity at very high redshift. In previous papers, we have mapped the Crab nebula (the Crab) in a rotovibrational H₂emission line, and then measured the molecular excitation temperature for a few of the brighter H₂-emitting knots that we have found to be scattered throughout the Crab's filaments. We found that H₂ emission is often quite strong, correlates with optical low-ionization emission lines and has a surprisingly high excitation temperature. Here, …

High­- Accuracy Quartic Force Field Calculations For The Spectroscopic Constants And Vibrational Frequencies Of 11A′ L-­C3H-­: A Possible Link To Lines Observed In The Horsehead Nebula Pdr, Ryan C. Fortenberry, Xinchuan Huang, T. D. Crawford, Timothy J. Lee

Ryan C. Fortenberry

It has been shown that rotational lines observed in the Horsehead nebula photodissociation region (PDR) are probably not caused by l-C₃H⁺, as was originally suggested. In the search for viable alternative candidate carriers, quartic force fields are employed here to provide highly accurate rotational constants, as well as fundamental vibrational frequencies, for another candidate carrier: 1¹ A' C₃H^–. The ab initio computed spectroscopic constants provided in this work are, compared to those necessary to define the observed lines, as accurate as the computed spectroscopic constants for many of the known interstellar …

Spectroscopic Constants And Vibrational Frequencies For L­-C3H+ And Isotopologues From Highly­Accurate Quartic Force Fields: The Detection Of L­-C3H+ In The Horsehead Nebula Pdr Questione, Xinchuan Huang, Ryan C. Fortenberry, Timothy J. Lee

Ryan C. Fortenberry

Very recently, molecular rotational transitions observed in the photon-dominated region of the Horsehead nebula have been attributed to l-C₃H⁺. In an effort to corroborate this finding, we employed state-of-the-art and proven high-accuracy quantum chemical techniques to compute spectroscopic constants for this cation and its isotopologues. Even though the B rotational constant from the fit of the observed spectrum and our computations agree to within 20 MHz, a typical level of accuracy, the D rotational constant differs by more than 40%, while the H rotational constant differs by three orders of magnitude. With the likely errors in …

Co Abundance Variations In The Orion Molecular Cloud, F. Ripple, M.H. Heyer, R. A. Gutermuth, R.L. Snell, C.M. Brunt

Robert A. Gutermuth

Infrared stellar photometry from the Two Micron All-Sky Survey (2MASS) and spectral line imaging observations of 12CO and 13CO J = 1–0 line emission from the Five College Radio Astronomy Observatory (FCRAO) 14-m telescope are analysed to assess the variation of the CO abundance with physical conditions throughout the Orion A and Orion B molecular clouds. Three distinct Av regimes are identified in which the ratio between the 13CO column density and visual extinction changes corresponding to the photon-dominated envelope, the strongly self-shielded interior, and the cold, dense volumes of the clouds. Within the strongly self-shielded interior of the Orion …

Theoretical Electronic And Rovibrational Studies For Anions Of Interest To The Dibs, Ryan C. Fortenberry

Ryan C. Fortenberry

The dipole-bound excited state of the methylene nitrile anion (CH2CN−) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN− and the similar methylene enolate anion, CH2CHO−. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist …

Herschel/Pacs Observations Of Young Sources In Taurus: The Far-Infrared Counterpart Of Optical Jets, L Podio, I Kamp, D Flower, C Howard, G Sandell, A Mora, G Aresu, Sean D. Brittain, W.R.F. Dent, C Pinte, G J. White

Publications

Context. Observations of the atomic and molecular line emission associated with jets and outflows emitted by young stellar objects provide sensitive diagnostics of the excitation conditions, and can be used to trace the various evolutionary stages they pass through as they evolve to become main sequence stars. Aims. To understand the relevance of atomic and molecular cooling in shocks, and how accretion and ejection efficiency evolves with the evolutionary state of the sources, we will study the far-infrared counterparts of bright optical jets associated with Class I and II sources in Taurus (T Tau, DG Tau A, DG Tau B, …

On The Electronic Spectroscopy Of Closed Shell Cations Derived From Resonance Stabilized Radicals: Insights From Theory And Franck-Condon Analysis, T. P. Troy, S. H. Kable, T. W. Schmidt, Scott Reid

Chemistry Faculty Research and Publications

Context. Recent attention has been directed on closed-shell aromatic cations as potential carriers of the diffuse interstellar bands. The spectra of mass-selected, matrix-isolated benzylium, and tropylium cations were recently reported. The visible spectrum of benzylium exhibits a large Franck-Condon (FC) envelope, inconsistent with diffuse interstellar band carriers.

Aims. We perform a computational analysis of the experimentally studied benzylium spectrum before extending the methods to a range of larger, closed-shell aromatic cations to determine the potential for this class of systems as diffuse interstellar band carriers.

Methods. Density functional theory (DFT), time-dependent ((TD)DFT), and multi-configurational self-consistent field second-order perturbation theory (MRPT2) …

Molecular Outlfows Identified In The Fcrao Co Survey Of The Taurus Molecular Cloud, Gopal Narayanan, Ronald Snell, Ashley Bemis

Gopal Narayanan

Jets and outflows are an integral part of the star formation process. While there are many detailed studies of molecular outflows towards individual star-forming sites, few studies have surveyed an entire star-forming molecular cloud for this phenomenon. The 100-deg2 Five College Radio Astronomy Observatory CO survey of the Taurus Molecular Cloud provides an excellent opportunity to undertake an unbiased survey of a large, nearby, molecular cloud complex for molecular outflow activity. Our study provides information on the extent, energetics and frequency of outflows in this region, which are then used to assess the impact of outflows on the parent molecular …

H2 Temperatures In The Crab Nebula, E. D. Loh, J. A. Baldwin, Gary J. Ferland, Z. K. Curtis, C. T. Richardson, A. C. Fabian, P. Salomé

Physics and Astronomy Faculty Publications

We used K-band spectra to measure the H₂ excitation temperatures in six molecular knots associated with the filaments in the Crab Nebula. The temperatures are quite high – in the range T∼ 2000–3000 K, just below the H₂ dissociation temperature. This is the temperature range over which the H₂ 1–0 S(1) line at λ2.121 μm has its maximum emissivity per unit mass, so there may be many additional H₂ cores with lower temperatures that are too faint to detect. We also measured the electron density in adjacent ionized gas, which on the assumption of …

Aztec 1.1 Mm Observations Of The Mbm12 Molecular Cloud, M. J. Kim, S. Kim, S. Youn, M. S. Yun, Grant Wilson, I. Aretxaga, J. P. Williams, D. H. Hughes, A. Humphrey, J. E. Austermann, T. A. Perera, P. D. Mauskopf, L. Magnani, Y.-W. Kang

Grant Wilson

We present 1.1 mm observations of the dust continuum emission from the MBM12 high-latitude molecular cloud observed with the Astronomical Thermal Emission Camera (AzTEC) mounted on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. We surveyed a 6.34 deg$^2$ centered on MBM12, making this the largest area that has ever been surveyed in this region with submillimeter and millimeter telescopes. Eight secure individual sources were detected with a signal-to-noise ratio of over 4.4. These eight AzTEC sources can be considered to be real astronomical objects compared to the other candidates based on calculations of the false detection rate. The …

Rotationally Warm Molecular Hydrogen In The Orion Bar, Gargi Shaw, Gary J. Ferland, W. J. Henney, P. C. Stancil, N. P. Abel, E. W. Pellegrini, J. A. Baldwin, P. A. Van Hoof

Physics and Astronomy Faculty Publications

The Orion Bar is one of the nearest and best-studied photodissociation or photon-dominated regions (PDRs). Observations reveal the presence of H₂ lines from vibrationally or rotationally excited upper levels that suggest warm gas temperatures (400-700 K). However, standard models of PDRs are unable to reproduce such warm rotational temperatures. In this paper, we attempt to explain these observations with new comprehensive models which extend from the H⁺ region through the Bar and include the magnetic field in the equation of state. We adopt the model parameters from our previous paper which successfully reproduced a wide variety of spectral …

Large-Scale Structure Of The Molecular Gas In Taurus Revealed By High Linear Dynamic Range Spectral Line Mapping, Paul F. Goldsmith, Mark Heyer, Gopal Narayanan, Ronald Snell, Di Li, Chris Brunt

Gopal Narayanan

We report the results of a 100 deg2 survey of the Taurus molecular cloud region in 12CO and 13CO J = 1→ 0. The image of the cloud in each velocity channel includes simeq3 × 106 Nyquist-sampled pixels on a 20'' grid. The high sensitivity and large spatial dynamic range of the maps reveal a very complex, highly structured cloud morphology, including filaments, cavities, and rings. The axes of the striations seen in the 12CO emission from relatively diffuse gas are aligned with the direction of the magnetic field. We have developed a statistical method for analyzing the pixels in …

The Upper Limit For Ch4 In The Protostellar Disk Toward Hl Tauri, E L. Gibb, T Rettig, Sean D. Brittain, R Haywood, Theodore Simon, C Kulesa

Publications

We used high-resolution infrared spectra of the heavily embedded T Tauri star HL Tau to search for evidence of absorption due to the R0, R1, and R2 gas-phase CH4 ν3 lines near 3.3 μm. From this, we report a 3 σ upper limit of 1.3 × 1015 cm-2 for the CH4 gas column density toward HL Tau. Our results are compared to those found for CO gas toward this source and to the recent model for chemistry in the inner (10 AU) disks around T Tauri stars by Markwick et al. We find that the upper limit of methane ice+gas …

Luminosity Profiles Of Merger Remnants, J E. Hibbard, Min S. Yun

Min S. Yun

Using published luminosity and molecular gas profiles of the late-stage mergers NGC 3921, NGC 7252, and Arp 220, we examine the expected luminosity profiles of the evolved merger remnants, especially in light of the massive CO complexes that are observed in their nuclei. For NGC 3921 and NGC 7252, we predict that the resulting luminosity profiles will be characterized by an r1/4 law. In view of previous optical work on these systems, it seems likely that they will evolve into normal elliptical galaxies as regards their optical properties. Due to a much higher central molecular gas column density, Arp 220 …

Co (J = 4 → 3) And 650 Micron Continuum Observations Of The Z = 0.93 Hyperluminous Infrared Galaxy Fsc 15307+3252, Min S. Yun, N Z. Scoville

Min S. Yun

We report the results of our CO J = 4 → 3 line and rest-frame 650 μm continuum observations of the z = 0.93 hyperluminous infrared galaxy FSC 15307+3252 using the Owens Valley Millimeter Array. No line or continuum emission was detected, but the derived limits provide a useful constraint on the temperature, emissivity, and mass of the cold dust associated with FSC 15307+3252 and its molecular gas content. The 3 σ upper limit on the velocity-integrated CO (4-3) line flux is 1.6 Jy km s-1 (for ΔV = 300 km s-1). This corresponds to a surprisingly small total molecular …

Molecular Gas In The Inner 100 Parces Of M51, N Z. Scoville, Min S. Yun, L Armus, H Ford

Min S. Yun

We report imaging of CO (2-1) emission in the nucleus of M51 at 1'' (47 pc) resolution. Molecular gas is found closely associated with the nuclear radio jet and the X-shaped dust absorption feature seen in the Hubble Space Telescope images. The CO emission lies along the side of the nuclear radio continuum "jet." The strongest molecular emission is not symmetric in either position or velocity with respect to the nucleus—the dominant feature is at redshifted velocities and peaks 1'' to the west of the radio/optical nucleus. The CO (2-1) emission has an integrated flux implying a molecular gas mass …

Effects Of Interaction Induced Activities In Hickson Compact Groups: Co And Fir Study, L Verdes-Montenegro, Min S. Yun, J Perea, A Del Olmo, P T P Ho

Min S. Yun

A study of 2.6 mm CO J = 1 → 0 and far-infrared (FIR) emission in a distance-limited (z < 0.03) complete sample of Hickson compact group (HCG) galaxies was conducted in order to examine the effects of their unique environment on the interstellar medium of component galaxies and to search for a possible enhancement of star formation and nuclear activity. Ubiquitous tidal interactions in these dense groups would predict enhanced activities among the HCG galaxies compared to isolated galaxies. Instead, their CO and FIR properties (thus, "star formation efficiency") are surprisingly similar to isolated spirals. The CO data for 80 HCG galaxies presented here (including 10 obtained from the literature) indicate that the spirals globally show the same H2 content as the isolated comparison sample, although 20% are deficient in CO emission. Because of their large optical luminosity, low metallicity is not likely the main cause for the low CO luminosity. The CO deficiency appears linked with the group evolution, and gas exhaustion through past star formation and removal of the external gas reserve by tidal stripping of the outer H I disk offer a possible explanation. The IRAS data for the entire redshift-limited complete sample of 161 HCG galaxies were reanalyzed using ADDSCAN/SCANPI, improving the sensitivity by a factor of 3-5 over the existing Point Source Catalog (PSC) and resolving better the contribution from individual galaxies. The new analysis of the IRAS data confirms the previous suggestion that FIR emission in HCG galaxies is similar to isolated, Virgo Cluster, and weakly interacting galaxies. Their H2 and FIR characteristics yield a star formation efficiency that is similar to that of these comparison samples. A factor 2 enhancement in the 25-100 μm flux ratio among the HCG spirals is found, which suggests intense localized nuclear starburst activity similar to that of H II galaxies. A number of early-type galaxies in HCGs are detected in CO and FIR, lending further support to the idea that tidal interactions and tidally induced evolution of the groups and member galaxies are important in our sample.

Co J = 3-2 Emission In The Radio Galaxy 53w002 At Z = 2.394, N Z. Scoville, Min S. Yun, R A. Windhorst, W C. Keel, L Armus

Min S. Yun

We report a sensitive search for redshifted CO J = 3-2 emission from the weak radio galaxy 53W002 at z = 2.394. Maps at resolutions of 3'' and 235 km s-1 show a significant emission peak within 0farcs5 of the optical and radio continuum peaks. The measured narrowband flux is approximately 10 times the extrapolated centimeter-wavelength nonthermal radio continuum expected at 101.9 GHz and exhibits a spectral profile implying a 540 km s-1 width (FWHM) at a systemic redshift z = 2.394 ± 0.001 for CO (3-2). This emission has a total integrated flux of 1.51 ± 0.2 Jy km …

Resolution And Kinematics Of Molecular Hydrogen In The Cloverleaf Gravitational Lens, Min S. Yun, N Z. Scoville, J J. Carrasco, R D. Blandford

Min S. Yun

Gravitational lenses have long been advertised as primitive telescopes, capable of magnifying cosmologically distant sources. In this Letter we present new, 0"9 resolution CO (7– 6) observations of the z 5 2.56 Cloverleaf quasar (H14131117) and spatially resolved images. By modeling the gravitational lens, we infer a size scale of 0"3 (11 kpc) for the molecular gas structure surrounding the quasar, and the gas has a kinematic structure roughly consistent with a rotating disk. The observed properties of the CO-emitting gas are similar to the nuclear starburst complexes found in the infrared luminous galaxies in the local universe, and metal …

Extended Molecular Gas In Fsc 10214+4724, N Z. Scoville, Min S. Yun, R L. Brown, P A. Vanden Bout

Min S. Yun

e report high resolution imaging of the CO (3-2) emission in the luminous infrared source FSC 10214+4724 at z = 2.2853. Maps at resolutions of 2farcs3 × 3farcs0 and 45-90 km s-1 show the CO emission peak coinciding with those of Hα and radio continuum. Two components are identified in the CO emission: an unresolved core and an extended source (~1farcs9 × 4farcs4)—elongated southeast-northwest. The implied size is 9 × 24 kpc for H0 = 75 km s-1 Mpc-1 and q0 = 0.5. The extent of the CO emission is significantly greater than that of either the optical or the …