Gone in a Blaze of Glory: the Demise of Comet C/2015 D1 (SOHO)

Status Report From: e-Print archive
Posted: Tuesday, July 26, 2016

Man-To Hui, Quan-Zhi Ye, Matthew Knight, Karl Battams, David Clark
(Submitted on 25 Sep 2015)

We present studies of C/2015 D1 (SOHO), the first sunskirting comet ever seen from ground stations over the past half century. The Solar and Heliospheric Observatory (SOHO) witnessed its peculiar light curve with a huge dip followed by a flareup around perihelion: the dip was likely caused by sublimation of olivines, directly evidenced by a coincident temporary disappearance of the tail. The flareup likely reflects a disintegration event, which we suggest was triggered by intense thermal stress established within the nucleus interior. Photometric data reveal an increasingly dusty coma, indicative of volatile depletion. A catastrophic mass loss rate of 105 kg s1 around perihelion was seen. Ground-based Xingming Observatory spotted the post-perihelion debris cloud. Our morphological simulations of post-perihelion images find newly released dust grains of size a10 m in radius, however, a temporal increase in amin was also witnessed, possibly due to swift dispersions of smaller grains swept away by radiation forces without replenishment. Together with the fading profile of the light curve, a power law dust size distribution with index =3.20.1 is derived. We detected no active remaining cometary nuclei over 0.1 km in radius in post-perihelion images acquired at Lowell Observatory. Applying radial non-gravitational parameter, A1=(1.2090.118)106 AU day2, from an isothermal water-ice sublimation model to the SOHO astrometry significantly reduces residuals and sinusoidal trends in the orbit determination. The nucleus mass 108--109 kg, and the radius 50--150 m (bulk density d=0.4 g cm3 assumed) before the disintegration are deduced from the photometric data; consistent results were determined from the non-gravitational effects.

Comments: Accepted by ApJ; 13 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1509.07606 [astro-ph.EP] (or arXiv:1509.07606v1 [astro-ph.EP] for this version)
Submission history
From: Man-To Hui
[v1] Fri, 25 Sep 2015 07:32:37 GMT (1608kb)



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