Why Chemistry? Satoshi Yamamoto Nami Sakai, Yoshimasa Watanabe, Department of Physics, The Univ. of Tokyo

初期宇宙における揺らぎ 銀河形成 星形成 惑星系形成 物質の進化 原子 分子 原始太陽系の 環境はどうやって できあがったの？ 宇宙における構造形成

Line Survey of TMC-1 with NRO 45 m Kaifu et al. (2004) HC 3 N HC 5 N HC 7 N CCS, CCCS, c-C 3 H, CCO, CCCO, C 4 H 2, etc

Interstellar Molecules H 2 CO HCN, HNC, H 2 CO, NH 3, CS, SiO, CN, SO, SO 2 H 3 +, HCO +, HN 2 +, HCS +, C 6 H - HC 3 N, HC 5 N, HC 7 N, HC 9 N, HC 11 N C 2 H, C 3 H, C 4 H, C 5 H, C 6 H, C 8 H, CCS, C 3 S CH 3 OH, HCOOCH 3, (CH 3 ) 2 O, C 2 H 5 CN, CH 3 CHO, HCOOH, C 2 H 5 OH, ～ 160 Species

Tycho’s SNR Hayato et al. 2010

Physical Condition T, n etc. Observed Spectrum シミュレーション 多くの場合 Physical Condition T(t), n(t) etc. Observed Spectrum 複雑な構造、複雑な化学過程 複雑な励起機構、非平衡 電波による化学組成研究 事実上無理

Time Scale for Chemical Equilibrium 1/τ ＝ 1/t f + 1/t d t f : Time Scale for Formation of Molecules H X → HX + + H 2 a few 10 5 yr t d : Time Scale for Destruction of Molecules Av > 5 Ionic Destruction slow > 10 6 yr c.f. Reactions with He +, H +, etc. Av < 3 Photodissociation fast 10 2 yr In Actual Cloud Cores τ ～ t dyn ～ t dep t dyn : Dynamical Time Scale for Molecular Clouds t dep : Time Scale for Depletion of Molecules

Observed Spectrum Physical Condition T(t), n(t) etc. Astrochemical Concept 分子の示す意味と その背景を明らかにする Basic Physics & Chemistry

昔むかし。。。 用いるスペクトル線による見え方の違い Zhou et al. 1989

分子ごとの分布の違いを目の前にして。。 。 ひとつの意見 - いったい何を信じればいいのか？ - ＣＯ以外は信用できない。 - 質量（柱密度）を最もよく表すものは何か？ - 化学組成は役に立たない。研究の障害！ もう一つの意見 - 分布の違いの原因は何だろう？ - 原因究明から新しいことがわかるのでは？

化学組成の違いの探求 CCS vs NH 3 CCS NH 3 CCS NH 3 Suzuki et al. 1992

Carbon Chains HN 2 +, NH 3 Deuterated Species DCO +, H 2 D + Complex Organic Molecules C → CO ConversionCO Depletion Mantle Evaporation Chemical Evolution of Molecular Clouds

Detection of Complex Organic Molecules in the low-mass protostar IRAS Cazaux et al ； Bottinelli et al. 2004; Kuan et al Detection of Complex Organic Molecules in the low-mass protostar IRAS Cazaux et al ； Bottinelli et al. 2004; Kuan et al HCOOCH 3 C 2 H 5 CN HCOOCH 3 Compact Distribution Hot Corino Evaporation from Grain Mantles See Poster 23 by Pineda et al.

IRAS with ALMA SV Pineda et al. (2012) Another NEWS: Detection of Glycolaldehyde HCOCH 2 OH Jorgensen et al. (2012 ）

60” L1527 (Tobin et al. 2008) Existence of Various Carbon Chains Eu = 21 K N=9-8, F 2 C6H－C6H－ C4HC4H C 5 H, C 6 H, C 4 H 2, HC 5 N, HC 7 N, HC 9 N, C 4 H - etc. Efficient Production of Various Carbon-Chain Molecules around the Protostar Triggered by Evaporation of Methane from Grain Mantles (Warm Carbon Chain Chemistry)(Sakai et al. 2008; 2009; 2010) Discovery of Carbon-Chain Rich Protostar Sakai et al. (2008, 2009) e.g.) CH 4 + C +  C 2 H H C 2 H e  C 2 H + H + H 

Hot Corino (TIMASS: Caux et al. 2011) WCCC source HC 3 N C4HC4H CCH

CO H H H H H CH 3 OH CO CH 3 OH C C C C CO H C H H H H CH 4 depleted as CO depleted as C Slow contraction Fast contraction （ ~ free fall timescale ） Scenario Abundant COMs (HCOOCH 3, (CH 3 ) 2 O, etc.) Abundant Carbon-Chains (ex. IRAS and NGC1333IRAS4A/4B) (ex. L1527 and IRAS ) CH 4 C C C Hot Corino Chemistry Warm Carbon Chain Chemistry Sakai et al. (2009)

Tentative Detection of Deuterated Methane 2012 Sakai et al. ApJL in press.

Line Survey of Low-mass Protostars with ASTE (Watanabe et al.)

Hot Corino WCCC Chemical Diversity ？ ？ ？ ？ Chemical Evolution toward Protostellar Disks Star Formation Process

Requirements for Unbiased Spectral Line Survey toward Many Sources (1) High Sensitivity  Large Aperture (2) Wide Frequency Coverage  Mm to Submm (THz), Good Atmospheric Transmision (3) Large Instantaneous Bandwidth  Large Correlator System & Multi-Band Obs. (4) Reliable Observations  Stable Pointing, Good Calibration Accuracy

Observing Frequency (1) 70 – 400 GHz: Basic Band Various Organic Molecules (COMs, CCs, etc. ) Full Aperture (50 m) (2) 400 – 900 GHz: High Band High Excitation Lines of Fundamental Molecules Medium Aperture (30 m) (3) 900 – 1500 GHz: THz Band Fundamental Species (H 2 D +, HD 2 +, NH, NH 2 etc.) Small Aperture (15 m)

Example of Observing Mode (1) GHz GHz GHz GHz Total 32 GHz (dual pol.) 5-6 sets are necessary to cover the whole band. (2) GHz GHz GHz GHz Total 32 GHz (dual pol.) 2-3 sets are necessary to cover the two bands.

Roles of Large Single Dish Finding ‘New’ Sources rather than Ordinary Sources Obtaining Large/Complete Statistical Data Studying Large Scale Phenomena Unbiased Survey both in Spatial and Frequency Domains Frequency Domain Survey → Chemical Diagnosis Complimentary to ALMA → Detailed Characterization of Each Source

Why Chemistry? Because it is crucial to understand evolution of matter in space. It also provides us with novel views on physical processes of star and planet formation.