DISCOVERY OF THE SECOND WARM CARBON-CHAIN-CHEMISTRY SOURCE, IRAS15398 - 3359 IN LUPUS
- Department of Physics and Research Center for the Early Universe, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
- Nobeyama Radio Observatory, Minamimaki, Minamisaku, Nagano 384-1305 (Japan)
- National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)
- School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia)
We have conducted a search for carbon-chain molecules toward 16 protostars with the Mopra 22 m and Nobeyama 45 m telescopes, and have detected high excitation lines from several species, such as C{sub 4}H (N = 9-8), C{sub 4}H{sub 2}(J = 10{sub 0,10}-9{sub 0,9}), CH{sub 3}CCH(J = 5-4, K = 2), and HC{sub 5}N(J = 32-31), toward the low-mass protostar, IRAS15398 - 3359 in Lupus. The C{sub 4}H line is as bright as 2.4 K measured with the Nobeyama 45 m telescope. The kinetic temperature is derived to be 12.6 {+-} 1.5 K from the K = 1 and K = 2 lines of CH{sub 3}CCH. These results indicate that the carbon-chain molecules exist in a region of warm and dense gas near the protostar. The observed features are similar to those found toward IRAS04368+2557 in L1527, which shows warm carbon-chain chemistry (WCCC). In WCCC, carbon-chain molecules are produced efficiently by the evaporation of CH{sub 4} from the grain mantles in a lukewarm region near the protostar. Our data clearly indicate that WCCC is no longer specific to L1527, but occurs in IRAS15398 - 3359. In addition, we draw attention to a remarkable contrast between WCCC and hot corino chemistry in low-mass star-forming regions. Carbon-chain molecules are deficient in hot corino sources like NGC1333 IRAS4B, whereas complex organic molecules seem to be less abundant in the WCCC sources. A possible origin for such source-to-source chemical variations is suggested to arise from the timescale of the starless-core phase in each source. If this is the case, the chemical composition provides an important clue to explore the variation of star formation processes between sources and/or molecular clouds.
- OSTI ID:
- 21300529
- Journal Information:
- Astrophysical Journal, Vol. 697, Issue 1; Other Information: DOI: 10.1088/0004-637X/697/1/769; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
AN UNBIASED SPECTRAL LINE SURVEY TOWARD R CrA IRS7B IN THE 345 GHz WINDOW WITH ASTE
DEUTERATED MOLECULES IN WARM CARBON CHAIN CHEMISTRY: THE L1527 CASE