National Astronomical Observatory of Japan

Spectrum of Outburst from Comet ISON Obtained by Subaru Telescope’s High-Dispersion Spectrograph

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During the early morning of November 15, 2013 (HST), a team of astronomers used the High-Dispersion Spectrograph (HDS) mounted on the Subaru Telescope in Hawaii to successfully observe Comet ISON (C/2012 S1) immediately after the beginning of an outburst, when its brightness increased rapidly. The spectrum showed a lot of gas emission lines from molecules and atoms, e.g., C2, NH2, H2O+, O, Na. These data play an important role in shedding light on the mechanisms that triggered Comet ISON’s outburst.

Raw data of the high-dispersion optical spectrum (called an “Echelle format”) of Comet ISON, obtained by HDS mounted on the Subaru Telescope with an exposure time of 20 minutes. A lot of gas emissions e.g., C2, NH2, H2O+, O, Na, were detected in this spectrum. (Credit: NAOJ)