A C - Band Spectral Scan of Irc + 10 216
نویسندگان
چکیده
We report the results of the presently lowest frequency spectral line survey of the asymptotic giant branch carbon star IRC+10 216. The entire Arecibo C band (4–6 GHz) was observed with a noise level of 0.3 mJy (1 ). We report the detection of HC5N (J 1⁄4 2 1), which is the lowest frequency transition of the HC5N molecule found in the envelope of IRC +10 216. The HC5N J 1⁄4 2 column density derived from our observations confirms the presence of two temperature components in the molecular envelope of IRC +10 216. The HC5N J 1⁄4 2 1 transition traces the cold molecular component characterized by an excitation temperature of 13.8 K. We derive upper limits for several transitions of molecules that had previously been detected in IRC +10 216 at higher frequencies. We also report the frequency ranges in the Arecibo C band that were affected by radio frequency interference. Subject headings: circumstellar matter — radio lines: stars — stars: carbon — stars: individual (IRC+10216) — telescopes
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