Nobeyama 45-m mapping observations toward nearby molecular clouds, Orion A, Aquila Rift, and M17: Project overview
| Autor: | Koji Sugitani, Kazuhito Dobashi, Hideaki Takemura, Quang Nygen-Luong, Asha Hirose, Sachiko K. Okumura, Tomomi Shimoikura, Munetake Momose, Takashi Tsukagoshi, Yumiko Urasawa, Ryoichi Nishi, Yoshito Shimajiri, Shuri Oyamada, Patricio Sanhueza, Shun Ishii, Ryohei Kawabe, Takayoshi Kusune, Fumitaka Nakamura, Yoshihiro Tanabe |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Star formation Molecular cloud Resolution (electron density) FOS: Physical sciences Astronomy and Astrophysics Astrophysics 01 natural sciences Astrophysics - Astrophysics of Galaxies Accretion (astrophysics) Cover (topology) Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Angular resolution Sensitivity (control systems) 010303 astronomy & astrophysics Intensity (heat transfer) Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences |
| Popis: | We carried out mapping observations toward three nearby molecular clouds, Orion A, Aquila Rift, and M17, using a new 100 GHz receiver, FOREST, on the Nobeyama 45-m telescope. In the present paper, we describe the details of the data obtained such as intensity calibration, data sensitivity, angular resolution, and velocity resolution. Each target contains at least one high-mass star-forming region. The target molecular lines were $^{12}$CO ($J = 1 - 0$), $^{13}$CO ($J = 1 - 0$), C$^{18}$O ($J = 1 - 0$), N$_2$H$^+$ ($J=1-0$), and CCS ($J_N=8_7-7_6$), with which we covered the density range of 10$^2$ cm$^{-3}$ to 10$^6$ cm$^{-3}$ with an angular resolution of $\sim 20\arcsec$ and a velocity resolution of $\sim$ 0.1 km s$^{-1}$. Assuming the representative distances of 414 pc, 436 pc, and 2.1 kpc, the maps of Orion A, Aquila Rift, and M17 cover most of the densest parts with areas of about 7 pc $\times$ 15 pc, 7 pc $\times$ 7 pc, and 36 pc $\times$ 18 pc, respectively. On the basis of the $^{13}$CO column density distribution, the total molecular masses are derived to be $3.86 \times 10^4 M_\odot$, $2.67 \times 10^4 M_\odot$, and $8.1\times 10^5 M_\odot$ for Orion A, Aquila Rift, and M17, respectively. For all the clouds, the H$_2$ column density exceeds the theoretical threshold for high-mass star formation of $\gtrsim$ 1 g cm$^{-2}$, only toward the regions which contain current high-mass star-forming sites. For other areas, further mass accretion or dynamical compression would be necessary for future high-mass star formation. This is consistent with the current star formation activity. Using the $^{12}$CO data, we demonstrate that our data have enough capability to identify molecular outflows, and for Aquila Rift, we identify 4 new outflow candidates. The scientific results will be discussed in details in separate papers. 50 pages, 39 figures, accepted by PASJ |
| Databáze: | OpenAIRE |
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