Where are the Mini Kreutz-family Comets?
Abstract
The Kreutz family of sungrazing comets contains over 2000 known members, many of which are believed to be under ~100 m sizes (mini comets) and have only been studied at small heliocentric distances (r H) with space-based SOHO/STEREO spacecraft. To understand the brightening process of mini Kreutz comets, we conducted a survey using CFHT/MegaCam at moderate r H guided by SOHO/STEREO observations. We identify two comets that should be in our search area but are not detected, indicating that the comets have either followed a steeper brightening rate within the previously reported rapid brightening stage (the brightening burst), or the brightening burst starts earlier than expected. We present a composite analysis of the pre-perihelion light curves of five Kreutz comets that cover to ~1 AU. We observe significant diversity in the light curves that can be used to grossly classify them into two types: C/Ikeya-Seki and C/SWAN follow the canonical rH-4 while the others follow rH-7. In particular, C/SWAN seems to have undergone an outburst (Δm > 5 mag) or a rapid brightening (n >~ 11) between r H = 1.06 AU and 0.52 AU, and shows hints of structural/compositional differences compared to other bright Kreutz comets. We also find evidence that the Kreutz comets as a population lose their mass less efficiently than the dynamically new comet, C/ISON, and are relatively devoid of species that drive C/ISON's activity at large r H. Concurrent observations of C/STEREO in different wavelengths also suggest that a blueward species such as CN may be the main driver for brightening bursts, instead of sodium as previously thought.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2014
- DOI:
- 10.1088/0004-637X/796/2/83
- arXiv:
- arXiv:1409.8657
- Bibcode:
- 2014ApJ...796...83Y
- Keywords:
-
- comets: general;
- comets: individual: C/1965 S1 (Ikeya-Seki) C/2011 W3 (Lovejoy) C/2012 E2 (SWAN) C/2012 S1 (ISON) C/2012 U3 (STEREO) SOHO-2388;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- ApJ in press