On UT 2013 November 15.6, we performed high-dispersion spectroscopic observation of comet C/2012 S1 (ISON), using the High-Dispersion Spectrograph (HDS) mounted on the Subaru Telescope in Hawaii. We successfully observed comet ISON during an outburst starting at around UT November 14. The obtained spectrum showed many emission lines from gaseous molecules and atoms (C2, NH2, H2O+, CN, O, Na, and unidentified species). Our observation will play an important role in shedding light on the mechanisms of the outburst and the origin of comet ISON.�

2. Observations with Subaru / HDS�

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Optical Spectrum of Comet C/2012 S1 (ISON) with Subaru/HDS on 2013 November 15.6

Comet �  Most pristine icy bodies in the Solar system. �  The remnants of planetesimals formed in the solar nebula 4.6 Gyrs ago. �  When a cometary nucleus approaches the sun, coma and tail appear.

�  Date: UT 2013 Nov. 15.6 (El.~20.6 deg) �  Heliocentric distance: 0.601 AU �  Geocentric distances: 0.898 AU �  Exposure time: 1200 s (R=72000) �  The outburst: UT Nov. 14.0±0.2 (10 times by 48 hrs) �

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3. Preliminary Results�

NH2 Bands� NH3 OPR� NH3 Tspin (K)�(0,9,0)� 1.09 ± 0.09� 33 +17/–6 (0,8,0)� 1.14 ± 0.04� 29 +3/–2�(0,7,0)� 1.15 ± 0.03� 29 ± 2

Weighted mean� 1.14 ± 0.02� 29 ± 1�

Table: OPRs and Tspin of NH3 of Comet ISON.�

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4. Future Works�Plan to pursue the researches �  The origin of Comet ISON. �  The mechanisms of the outburst. �  The formation history of the Solar system. Concrete examples of studies �  Emission line atlas for comet ISON. �  Isotopic ratios of Carbon and Nitrogen. �  Molecular abundance ratios relative to water. �  Origin of forbidden lines of [OI]. �  Ortho-to-para abundance ratios of NH3 & H2O.

Subaru Users’ Meeting 2013, Jan. 21–23, 2014, Mitaka, Japan

�  Estimated a OPRs of ammonia from three NH2 bands (NH2 is a photo dissociation product of NH3 in the coma, B.R~95 %). �  Our results are consistent with each other and similar to the value ever observed (~30K for formation temperature).�

1. Introduction�Ortho/Para abundance Ratio of NH3 in Comets �  There is a relationship between OPRs and formation temperatures of the molecule. �  Obtained OPRs clustered at around 1.15 (30K).

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Observed spectrum of C/2001 Q4 (NEAT)

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Residual spectrum

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Comet C/2012 S1 (ISON) �  Discovered on 2012 Sep. 21, by the ISON group. �  A sungrazing comet from the Oort cloud. �  Disintegrated by approaching the sun (Perihelion: 2013 Nov. 28, q=0.012 AU).

Please contact us, if you would like to collaborate with us to cometary study. �

Comet C/2012 S1 (ISON) Observed with HDS during an Outburst in the middle of November 2013�

Yoshiharu Shinnaka (yoshiharu.shinnaka@gmail.com) Hideyo Kawakita, Masayoshi Nagashima, Hitomi Kobayashi

Koyama Astronomical Observatory of Kyoto Sangyo University�

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✢  Yoshiharu  Shinnaka(3rd  grade  PhD.  course  of  Kyoto  Sangyo  Univ.)

✢  ID:S13B-‐‑‒08  (PI:  Shinnaka)  ✢  Instruments:  HDS  ✢  Target:  Comet  ISON  ✢  Date:  2013  Nov.  15(during  its  outburst)  

✢  First  detection  of  15NH2  from  a  single  comet  &  inferred  14N/15N  ratio  in  cometary  Ammonia.→  Now  printing  to  ApJL