2008ApJ...680L.121T -
Astrophys. J., 680, L121-L124 (2008/June-3)
A search for phosphine in circumstellar envelopes: PH3 in IRC +10216 and CRL 2688?
TENENBAUM E.D. and ZIURYS L.M.
Abstract (from CDS):
We present the results of a search for the JK=10⟶00transition of PH3(phosphine) at 267 GHz toward several circumstellar envelopes using the Arizona Radio Observatory 10 m Submillimeter Telescope (SMT). In the carbon-rich shells of IRC +10216 and CRL 2688, we have detected emission lines exactly at the PH3frequency. Toward the oxygen-rich supergiant VY Canis Majoris, only an upper limit was obtained, while in the evolved carbon-rich proto-planetary nebula CRL 618, the transition is contaminated by vibrationally excited HC3 N (ν7= 4). The line shape in IRC +10216 appears to consist of two distinct components: a flat-topped profile with a width of ∼28 km/s, as is typical for this source, and a narrower feature approximately 4 km/s wide. The narrow component likely arises from the inner envelope (r<8R*) where the gas has not reached the terminal expansion velocity, or it is nonthermal emission. Based on the broader component, the abundance of PH3 with respect to H2is estimated to be 5x10–8 in a region with a radius of r<150R*. If the narrower component is thermal, it implies a phosphine abundance of ∼5x10–7 close to the stellar photosphere (r<8R*). In CRL 2688, the PH3 abundance is less constrained, with plausible values ranging from 3x10^ -8^ to 4x10–7, assuming a spherical distribution. Phosphine appears to be present in large concentrations in the inner envelope of C-rich AGB stars, and thus may function as a parent molecule for other phosphorus species.
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Journal keyword(s):
Astrochemistry - Stars: Circumstellar Matter - ISM: Molecules - Radio Lines: Stars - Stars: Individual: Alphanumeric: CRL 2688 - Stars: Individual: Alphanumeric: IRC +10216
Simbad objects:
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