Japan Geoscience Union Meeting 2019

Presentation information

[J] Poster

P (Space and Planetary Sciences ) » P-CG Complex & General

[P-CG23] Origin and evolution of materials in space

Sun. May 26, 2019 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Hitoshi Miura(Graduate School of Natural Sciences, Department of Information and Basic Science, Nagoya City University), Hideko Nomura(Department of Earth and Planetary Sciences, Tokyo Institute of Technology), Takafumi Ootsubo(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Aki Takigawa(Division of Earth and Planetary Science, Kyoto University)

[PCG23-P07] Detection of CH3CN in Envelope around Sagittarius B2(N)

*Mitsunori Araki1, Shuro Takano2, Takahiro Oyama1, Nobuhiko Kuze3, Kazuhisa Kamegai4, Koichi Tsukiyama1 (1.Tokyo University of Science, 2.Nihon University, 3.Sophia University, 4.National Astronomical Observatory of Japan)

Keywords:Sagittarius B2, CH3CN, molecular cloud, Hot Axis Effect

Traditionally used model of evolution of molecular clouds in interstellar space is described as increasing of cloud gas density from diffuse to dense conditions, i.e., from an atomic-gas cloud to a star-forming region via a diffuse cloud and a dense cloud. However, recently “reverse evolution” of molecular clouds is suggested by Price et al. [1]. For example, outflow from a star-forming region makes a relatively-low-density cloud. To find a clue of reverse evolution, investigation of chemical composition of relatively-low-density clouds is necessary. Absorption of CH3CN can be observed by the hot axis effect, which shows special rotational distributions of CH3CN in a relatively-low-density cloud [2]. In our previous work, CH3CN was detected via absorption of the J = 4–3 rotational transition in the envelope of Sagittarius B2(M) core in the Galactic Center region by using Nobeyama 45-m telescope [3]. In this work, using ALMA data archive [4], we investigated absorption of the J = 5–4 and 6–5 rotational transitions of CH3CN in the envelope of Sagittarius B2(N) core, which is an adjacent core of the (M) core. The column density of CH3CN in the envelope of the (N) core is derived to be (1.0 ± 0.2) × 1015 cm−2, which is 7 times larger than that in the envelope of the (M) core, while the (N) core has an 11-times larger column density than the (M) core [5]. Similar abundance relation was found in a case of HC3N. Thus, as chemical compositions of relatively-low-density clouds, it was found that an abundant core has an abundant envelope and vice versa.

[1] Price et al., 2003, MNRAS, 343, 1257. [2] Araki et al., Astronomical Journal, 148, 87 (2014). [3] Araki et al., JpGU 2018, PPS09-01. [4] Project Code: 2016.1.00074.S. [5] Belloche et al., 2013, A&A, 559, 47