Thermal starless ammonia core surrounded by CCS in the Orion a cloud

Journal Article · Tue Jul 01 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/789/1/83· OSTI ID:22356445

Tatematsu, Ken'ichi; Hirota, Tomoya; Umemoto, Tomofumi; Kandori, Ryo; Mizuno, Norikazu ^[1]; Ohashi, Satoshi ^[2]; Choi, Minho; Kang, Miju ^[3]; Lee, Jeong-Eun ^[4]; Yamamoto, Satoshi ^[5]

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1. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
2. Department of Astronomy, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
3. Korea Astronomy and Space Science Institute, Daedeokdaero 776, Yuseong, Daejeon 305-348 (Korea, Republic of)
4. School of Space Research, Kyung Hee University, Seocheon-Dong, Giheung-Gu, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of)
5. Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

We imaged two starless molecular cloud cores, TUKH083 and TUKH122, in the Orion A giant molecular cloud in the CCS and NH{sub 3} emission with the Very Large Array. TUKH122 contains one NH{sub 3} core 'TUKH122-n', which is elongated and has a smooth oval boundary. Where observed, the CCS emission surrounds the NH{sub 3} core. This configuration resembles that of the N{sub 2}H{sup +} and CCS distribution in the Taurus starless core L1544, a well-studied example of a dense prestellar core exhibiting infall motions. The linewidth of TUKH122-n is narrow (0.20 km s{sup –1}) in the NH{sub 3} emission line and therefore dominated by thermal motions. The smooth oval shape of the core boundary and narrow linewidth in N{sub 2}H{sup +} seem to imply that TUKH122-n is dynamically relaxed and quiescent. TUKH122-n is similar to L1544 in the kinetic temperature (10 K), linear size (0.03 pc), and virial mass (∼2 M {sub ☉}). Our results strongly suggest that TUKH122-n is on the verge of star formation. TUKH122-n is embedded in the 0.2 pc massive (virial mass ∼30 M {sub ☉}) turbulent parent core, while the L1544 NH{sub 3} core is embedded in the 0.2 pc less-massive (virial mass ∼10 M {sub ☉}) thermal parent core. TUKH083 shows complicated distribution in NH{sub 3}, but was not detected in CCS. The CCS emission toward TUKH083 appears to be extended, and is resolved out in our interferometric observations.

• OSTI ID: 22356445
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 789; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AMMONIA
CONFIGURATION
DISTRIBUTION
EMISSION
MASS
MOLECULES
STARS