Kotomi Taniguchi (SOKENDAI / NRO) Hiroyuki Ozeki (Toho Univ.), Masao Saito (NRO/SOKENDAI) Fumitaka Nakamura (NAOJ/SOKENDAI), Seiji Kameno (JAO) Masatoshi Ohishi (NAOJ/SOKENDAI), Tomoya Hirota (NAOJ/SOKENDAI) Nami Sakai (The Univ. of Tokyo), Satoshi Yamamoto ( The Univ. of Tokyo), Shuro Takano (Nihon Univ.)

 Introduction  Observations  Results & Discussion  Summary  Future Works

 Introduction  Observations  Results & Discussion  Summary  Future Works

 One of the representative carbon-chain molecules  They have been detected in the interstellar medium since 1970s CH CCC C N

(Winstanley & Nejad, 1996) Ion-Molecule Reactions ( t < 10 4 yrs) Neutral-neutral Reactions (t > 10 4 yrs) C n H + → C n N + → HC n N + → H 2 C n N + → HC n N N H2H2 e-e- H2H2 HCN → HC 3 N → HC 5 N → HC 7 N → HC 9 N C2HC2H C n H 2 + CN → HC 2n+1 N + H (n = 4,6, and 8) C2HC2H C2HC2H C2HC2H

Toward the Cyanopolyyne Peak (CP) in TMC-1  HC 3 N ( Takano et al., 1998 )  CCS ( Sakai et al., 2007 )  CCH ( Sakai et al., 2010 )  C 3 S & C 4 H ( Sakai et al., 2013 )

Ex. HC 3 N [H 13 CCCN] : [HC 13 CCN] : [HCC 13 CN ] = 1.0 : 1.0 : 1.4 Molecules with two equivalent carbon atoms 13 C-enriched Main formation pathway C 2 H 2 + CN → HC 3 N + H Main formation pathway C 2 H 2 + CN → HC 3 N + H

HC 4 H + CN → HC 5 N + H Exothermic Reaction (Fukuzawa et al. (1998)) Rapid Reaction k = (4.2 ± 0.2) × 10 − 10 cm 3 mol − 1 s − 1 (Seki et al. (1996))

 Reveal the main formation pathway of HC 5 N in TMC-1  Obtain perception of the formation mechanism of the longer cyanopolyynes

 Introduction  Observations  Results & Discussion  Summary  Future Works

(Hirahara et al. (1992)) Cyanopolyyne Peak in TMC-1 ( R.A. = 04h 41m 42s.29, Decl. = 25°41’ 27”, J2000) *Distance from the Earth ≈ 140 pc *One of the most studied dark clouds *Carbon-chain molecules are abundant Cyanopolyyne Peak in TMC-1 ( R.A. = 04h 41m 42s.29, Decl. = 25°41’ 27”, J2000) *Distance from the Earth ≈ 140 pc *One of the most studied dark clouds *Carbon-chain molecules are abundant

SEASON SEASON  Receiver : Z45  Spectrometer : SAM45  J = (42 GHz region)  Integration time (ON) = 27.5 hr  Receiver : H20  Spectrometer : SAM45  J = 9-8 (23 GHz region)  Integration time (ON) = 42.1 hr Normal species and five 13 C isotopologues of HC 5 N

(Yamaki et al. (2002)) On : Off = 20 : 5 [sec]  60-ch smoothing for the 23 GHz region  32-ch smoothing for the 42 GHz region Applied smoothing for the off-source spectra

 Introduction  Observations  Results & Discussion  Summary  Future Works

(1 σ ) H 13 CCCCCN HC 13 CCCCN HCC 13 CCCN HCCC 13 CCN HCCCC 13 CN

[H 13 CCCCCN] : [HC 13 CCCCN] : [HCC 13 CCCN] : [HCCC 13 CCN] : [HCCCC 13 CN] = 1.00 : 0.97 : 1.03 : 1.05 : 1.16 (± 0.19) ( 1σ ) [H 13 CCCCCN] : [HC 13 CCCCN] : [HCC 13 CCCN] : [HCCC 13 CCN] : [HCCCC 13 CN] = 1.00 : 0.97 : 1.03 : 1.05 : 1.16 (± 0.19) ( 1σ ) No significant differences in abundances among the five 13 C isotopologues

If HC 5 N is formed by the reactions involving CN HCCCC 13 CN is more abundant than the other 13 C isotopologues by 1.4 [H 13 CCCN] : [HC 13 CCN] : [HCC 13 CN] = 1.0 : 1.0 : 1.4 (Takano et al. (1998))

Pathways involving CN HC 4 H + CN → HC 5 N + H Growth of the carbon chain of HC 3 N Ex. HC 3 N + C 2 H →HC 5 N + H HC 3 N + C 2 H m + → HC 5 N + mH e-e-

There is no mechanisms for 13 C concentration of specific carbon atom All carbon atoms in HC 5 N are originated from C 5 H m + All 13 C isotopologues of HC 5 N have almost same abundances

Double Isotope Method m, n = 0 - 4

The 14 N/ 15 N of HC 3 N is considered to reflect that of CN HC 5 N 363 (31) HC 5 N 363 (31) 15 N is concentrated in CN

Assumptions : 14 N/ 15 N elemental ratio = 440 (Solar wind) C 14 N/C 15 N = 195 (HC 3 N) HC 5 N N N CN 31% 59% (16%)

Assumptions : 12 C/ 13 C Hydrocarbon ions : CN = 1.0 : 1.4 HC 5 N N N CN 40% 60% (18%) (Takano et al. (1998))

HC 5 N N N CN 40% 60% (18%) HC 5 N N N CN 31% 59% (16%) 15 N Isotopic Fractionation 13 C Isotopic Fractionation Consistent!

 Introduction  Observations  Results & Discussion  Summary  Future Works

 We carried out observations of the normal species and the five 13 C isotopologues in TMC-1  We conclude that the main formation pathways leading to HC 5 N are the reactions of C 5 H m + + N  We have succeeded in the detection of HC 5 15 N in the interstellar medium for the first time  We evaluated the contributions of CN and N in the formation of HC 5 N, and found out that ~ 40% of HC 5 N is formed by the reactions involving CN

 Introduction  Observations  Results & Discussion  Summary  Future Works

 Green et al. (2014) have been detected HC 5 N towards 35 hot cores  We have carried out observations of HC 5 N, HC 7 N, and other carbon-chain molecules toward G

Solar wind 440 Solar wind 440 Earth 272 Earth 272 Meteorites, Comets When and How 15 N isotopic fractionation does occur? Our results suggest that concentration of 15 N in CN occur in the dark cloud stage How is inherited? Taniguchi et al. (ALMA Proposal)

We aim to establish new carbon-chain chemistry in hot cores (My Doctor’s thesis) Submitted proposals for GBT and ALMA Through these studies, I would like to reveal the formation mechanisms of complex organic molecules Work with Saito-san, Ohishi-san, Hirota-san, Ozeki-san

I thank Prof. Dobashi and Dr. Shimoikura for discussing calibration of the data of the Z45 receiver. I’m grateful for all NRO Staff and members of Z45 Receiver Group.