Evidence for Dust Related X-ray Emission from Comet C/1995 O1 (Hale-Bopp)
Abstract
We report the discovery of X-ray emission from comet C/1995 O1 (Hale-Bopp) by the LECS instrument on-board BeppoSAX on 1996 September 10--11. The 0.1--2.0 keV luminosity decayed by a factor of 2 on a timescale of ~10 hr with a mean value of 5.10E16 erg s-1. The spectrum is well fit by a thermal bremsstrahlung model with a temperature of 0.29 +/- 0.06 keV, or a power-law with a photon index of 3.1 +{0.6} -{0.2}. The lack of detected C and O line emission places severe constraints on many models for cometary X-ray emission, especially those which involve X-ray production in cometary gas. The luminosity is a factor of at least 3.4 greater than measured by Extreme Ultraviolet Explorer (EUVE) 4 days later. This difference may be related to the emergence from the nucleus on 1996 September 9 of a dust-rich cloud. Over the next few days the cloud continued to expand becoming increasingly tenuous, until it had reached an extent of ~3.10E5 km (or ~2 arcmin) by the start of EUVE observation. We speculate that the observed reduction in X-ray intensity is evidence for dust fragmentation. These results support the view that cometary X-ray emission arises from the interaction between solar X-rays and cometary dust.
Keywords
Cite
@article{arxiv.astro-ph/9710363,
title = {Evidence for Dust Related X-ray Emission from Comet C/1995 O1 (Hale-Bopp)},
author = {Alan Owens and A. N. Parmar and T. Oosterbroek and A. Orr and L. A. Antonelli and F. Fiore and R. Schulz and G. P. Tozzi and M. C. Maccarone and L. Piro},
journal= {arXiv preprint arXiv:astro-ph/9710363},
year = {2009}
}
Comments
17 pages. 4 postscript figs (2 in color). Accepted for publication in ApJ (Letters)