2014-2015 MULTIPLE OUTBURSTS OF 15P/FINLAY

• Published in: The Astronomical journal 2016-12, Vol.152 (6), p.169
• Main Authors: Ishiguro, Masateru, Kuroda, Daisuke, Hanayama, Hidekazu, Kwon, Yuna Grace, Kim, Yoonyoung, Lee, Myung Gyoon, Watanabe, Makoto, Akitaya, Hiroshi, Kawabata, Koji, Itoh, Ryosuke, Nakaoka, Tatsuya, Yoshida, Michitoshi, Imai, Masataka, Sarugaku, Yuki, Yanagisawa, Kenshi, Ohta, Kouji, Kawai, Nobuyuki, Miyaji, Takeshi, Fukushima, Hideo, Honda, Satoshi, Takahashi, Jun, Sato, Mikiya, Vaubaillon, Jeremie J., Watanabe, Jun-ichi
• Format: Article
• Language: English
• Subjects: ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON NITRIDES; COMETS; comets: individual (15P/Finlay); COSMIC DUST; GRAVITATION; interplanetary medium; INTERPLANETARY SPACE; INTERSTELLAR SPACE; JUPITER PLANET; KINETIC ENERGY; MASS; METEORITES; meteorites, meteors, meteoroids; METEOROIDS; Physics; POROUS MATERIALS; RADIATION PRESSURE; SILICATES; SOLAR RADIATION
• ISSN: 0004-6256; 1538-3881; 1538-3881
• DOI: 10.3847/0004-6256/152/6/169

ABSTRACT Multiple outbursts of a Jupiter-family comet (JFC), 15P/Finlay, occurred from late 2014 to early 2015. We conducted an observation of the comet after the first outburst and subsequently witnessed another outburst on 2015 January 15.6-15.7. The gas, consisting mostly of C2 and CN, and dust particles expanded at speeds of 1110 180 m s−1 and 570 40 m s−1 at a heliocentric distance of 1.0 au. We estimated the maximum ratio of solar radiation pressure with respect to the solar gravity βmax = 1.6 0.2, which is consistent with porous dust particles composed of silicates and organics. We found that 108-109 kg of dust particles (assumed to be 0.3 m-1 mm) were ejected through each outburst. Although the total mass is three orders of magnitude smaller than that of the 17P/Holmes event observed in 2007, the kinetic energy per unit mass (104 J kg−1) is equivalent to the estimated values of 17P/Holmes and 332P/2010 V1 (Ikeya-Murakami), suggesting that the outbursts were caused by a similar physical mechanism. From a survey of cometary outbursts on the basis of voluntary reports, we conjecture that 15P/Finlay-class outbursts occur >1.5 times annually and inject dust particles from JFCs and Encke-type comets into interplanetary space at a rate of ∼10 kg s−1 or more.