COMPARATIVE SPECTRA OF OXYGEN-RICH VERSUS CARBON-RICH CIRCUMSTELLAR SHELLS: VY CANIS MAJORIS AND IRC +10216 AT 215-285 GHz

Journal Article · Wed Sep 01 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/720/1/L102· OSTI ID:21452832

Tenenbaum, E D; Dodd, J L; Woolf, N J; Ziurys, L M ^[1]

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1. Department of Astronomy and Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

A sensitive (1{sigma} rms at 1 MHz resolution {approx}3 mK) 1 mm spectral line survey (214.5-285.5 GHz) of VY Canis Majoris (VY CMa) and IRC +10216 has been conducted to compare the chemistries of oxygen- and carbon-rich circumstellar envelopes. This study was carried out using the Submillimeter Telescope of the Arizona Radio Observatory with a new Atacama Large Millimeter Array type receiver. This survey is the first to chemically characterize an O-rich circumstellar shell at millimeter wavelengths. In VY CMa, 128 emission features were detected arising from 18 different molecules; and in IRC +10216, 720 lines were observed, assigned to 32 different species. The 1 mm spectrum of VY CMa is dominated by SO{sub 2} and SiS; in IRC +10216, C{sub 4}H and SiC{sub 2} are the most recurrent species. Ten molecules were common to both sources: CO, SiS, SiO, CS, CN, HCN, HNC, NaCl, PN, and HCO{sup +}. Sulfur plays an important role in VY CMa, but saturated/unsaturated carbon dominates the molecular content of IRC +10216, producing CH{sub 2}NH, for example. Although the molecular complexity of IRC +10216 is greater, VY CMa supports a unique 'inorganic' chemistry leading to the oxides PO, AlO, and AlOH. Only diatomic and triatomic compounds were observed in VY CMa, while species with four or more atoms are common in IRC +10216, reflecting carbon's ability to form multiple strong bonds, unlike oxygen. In VY CMa, a new water maser (v {sub 2} = 2) has been found, as well as vibrationally excited NaCl. Toward IRC +10216, vibrationally excited CCH was detected for the first time.

• OSTI ID: 21452832
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 720; ISSN 2041-8205
• Country of Publication: United States
• Language: English

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79 ASTRONOMY AND ASTROPHYSICS
ALKALI METAL COMPOUNDS
AMPLIFIERS
CARBON
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON NITRIDES
CARBON OXIDES
CHALCOGENIDES
CHLORIDES
CHLORINE COMPOUNDS
ELECTRONIC EQUIPMENT
ELEMENTS
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GHZ RANGE
GHZ RANGE 100-1000
GIANT STARS
HALIDES
HALOGEN COMPOUNDS
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC COMPOUNDS
INTERSTELLAR GRAINS
INTERSTELLAR SPACE
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PARTICLES
PNICTIDES
SILICON COMPOUNDS
SILICON OXIDES
SODIUM CHLORIDES
SODIUM COMPOUNDS
SPACE
STARS
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
TELESCOPES