TA06 International Symposium on Molecular Spectroscopy TA. Astronomy Tuesday, 2017-06-20 Detections of Long Carbon Chains CH3CCCCH, C6H, l-C6H2 and C7H in the Low-Mass Star-Forming Region L1527 M. Araki1, S. Takano2, N. Sakai3, S. Yamamoto4, T. Oyama1, N. Kuze5, and K. Tsukiyama1 1 Tokyo University of Science, 2 Nihon University, 3 RIKEN, 4 The University of Tokyo, 5 Sophia University

Material Cycle in Space 2018/11/15 Material Cycle in Space IRC+10216 Circumstellar Envelop Cn Long n ≥ 5 Warm n/i Late Type Star Diffuse Cloud Atomic Gas Carbon Chain Long / Short Short TMC-1 Dark Cloud Star Main Sequence 10 K Planet Comet Long Carbon Chain ? Low-Mass Star-Forming Region L1527 This is a material cycle in space. Translucent. Diffuse cloud grows to dark cloud. This cycle suggests origin of material on planet came from diffuse cloud. Thus identification of DIBs give us the discovery of origin of planet material. Star IR star 25 K Class II/III Class 0 Warm Carbon Chain Chemistry (WCCC) Sakai et al. 2008 ApJ, 672, 371, & 2009 ApJ, 697, 769 Class I

Observed Molecules in L1527 Number 2 3 4 5 6 7 8~ CS HNC l-C3H l-C3H2 C4H2 HC5N l-C6H2 CO HCO+ HCO2+ c-C3H2 C5H CH3C2H HC7N HCN HCNO HC3N CH3OH C6H HC9N CCH H2CO H2CCC HCCCHO C6H- CCS HNCO C4H HCS+ C4H- H2CCO 現在140種類発見。 赤：直線炭素鎖分子　青：酸素含有分子 Carbon Chain

Trend of Column Densities of Carbon Chains Circumstellar Envelop Column Density N (cm-2) Dark cloud Low-Mass Star-Forming Region

Trend of Column Density Ratios of Carbon Chains Long Carbon Chains: L1527 < TMC-1 … … Are there Long Carbon Chains in L1527? How about trend of Long Carbon Chains in L1527?

L1527: Low-mass star-forming region Taurus Galactic Plane Orion The equinoctial Outdoor sky map 2000 L1527 4h 39m 53.89s 26d 03' 11".0 (J2000)

Taurus Dark-Clouds Region L1527: Low-mass star-forming region Galactic Longitude [degree] Galactic Latitude [degree] TMC-1 L1527 Taurus Dark-Clouds Region Light Extinction Tokyo Gakugei University, http://darkclouds.u-gakugei.ac.jp/

Observations 42.0‒44.8 GHz region Low-mass star-forming region L1527 on site remote Low-mass star-forming region L1527 Green Bank 100 m telescope March-October 2015（on site and remote） 42.0‒44.8 GHz region 43 hours of Observation Time Noise level: 2-4 mK

c-C3H & c-C3H2O Results First detection in L1527 Column Density 5.65(9) × 1012 cm−2 at 12 K (μa = 2.4 D) 8.2(2) × 1010 cm−2 Intensity TMB [K] 3.07(6) × 1011 at 12 K (μa = 4.39 D) Doppler Velocity VLSR km/s

CH3C4H Results Intensity TMB [K] K Doppler Velocity VLSR km/s Gas kinetic temperature: 20 ± 2 K Column density: 5.61(16) × 1012 cm−2

C6H Results 2П3/2 Intensity TMB [K] 2П3/2 2П1/2 = 15.04 cm-1 Doppler Velocity VLSR km/s Column density: 2Π3/2 1.08(2) × 1012 cm−2 2Π1/2 1.58(4) × 1011 cm−2 dipole moment of μ = 5.536 D the excitation temperature of 12 K 2П3/2 2П1/2 IRC+10216 yes TMC-1 No L1527

C6H2 Results Intensity TMB [K] Doppler Velocity VLSR km/s ortho para Ka 1 IRC+10216 yes TMC-1 No L1527 Column density: ortho 1.31(4) × 1011 cm−2 para 5.5(3) × 1010 cm−2 dipole moment of μ = 6.2 D the excitation temperature of 12 K

C7H Results Intensity TMB [K] Column density: 6(1) × 1010 cm−2 dipole moment of μ = 5.945 D the excitation temperature of 12 K Doppler Velocity VLSR km/s

Trend of Column Density Ratios of Carbon Chains

UMIST Database for Astrochemistry 2012 (McElroy et al. 2013) the reaction scheme producing C7H via shorter carbon chain e− + C7H2+ → C7H + H C + HC6H → C7H + H C + C6H− → C7H + e− Walsh et al. 2009, ApJ, 700, 752, Smith et al. 2004, MNRAS, 350, 323

Trend of Column Density Ratios of Carbon Chains L1527: Sakai et al. 2007, ApJ, 667 L65 TMC-1: McCarthy et al. 2006, ApJS, 113, 105

Hassel et al. 2008, ApJ, 681,1385

L1527 can be in the translational phase cold remnant warm WCCC product NL1527/NTMC-1 WCCC product remnant C6H− L1527 can be in the translational phase from a dark cloud to a WCCC source. Spatial distributions may not be the same.

If they are in the same region, NL1527/NTMC-1 C6H− If they are in the same region, Model for larger molecules should be revised.

Summary We carried out the deep survey in L1527 with GBT 100 m. Long carbon chains were detected. CH3C4H, C6H, l-C6H2, and C7H The 2П1/2 state of C6H, para species of C6H2, and C7H were firstly detected in molecular clouds. C7H and C6H2 are remarkably abundant. L1527 can be in the translational phase from a dark cloud to a WCCC source. We thank the staff at the National Radio Astronomy Observatory. M.A. thanks Grant-in-Aid for Scientific Research on Innovative Areas (Grant No. 25108002), Grant-in-Aid for Scientific Research (C) (Grant No. 15K05395), and Institute for Quantum Chemical Exploration.

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