Large-scale CO J=4–3 mapping toward the Orion-A giant molecular cloudReportar como inadecuado

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We have mapped the Orion-A giant molecular cloud in the COJ=4–3 line with theTsukuba 30cm submillimeter telescope. The map covered a 7.125 deg2 area with a 9 resolution, including main components of the cloud such as the Orion Nebula, OMC-2-3, and L1641-N. The most intense emission was detected toward the Orion KL region.The integrated intensity ratio between COJ=4–3 and COJ=1–0 was derived usingdata from the Columbia–Universidad de Chile CO survey, which was carried out witha comparable angular resolution. The ratio was r4−3-1−0 ∼0.2 in the southern region ofthe cloud and 0.4–0.8 at star forming regions. We found a trend that the ratio showshigher values at the edges of the cloud. In particular, the ratio at the northeastern edgeof the cloud at l, b ≈ 208. ◦ 375, −19. ◦ 0 shows the highest value of 1.1. The physicalcondition of the molecular gas in the cloud was estimated by non-LTE calculation. Theresult indicates that the kinetic temperature has a gradient from north Tkin = 80 K tosouth 20 K. The estimation shows that the gas associated with the edge of the cloud iswarm Tkin ∼60 K, dense nH2∼ 104 cm−3, and optically thin, which may be explained byheating and sweeping of interstellar materials from OB clusters.Indización

Artículo de publicación ISI

Autor: ISHII, Shun; - Seta, Masumichi; - Nagai, Makoto; - Miyamoto, Yusuke; - Nakai, Naomasa; - Nagasaki, Taketo; - Arai, Hitoshi; - Ima



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