Evidence for dust-related X-ray emission from comet C/1995 O1 (Hale-Bopp)

被引:54
作者
Owens, A [1 ]
Parmar, AN
Oosterbroek, T
Orr, A
Antonelli, LA
Fiore, F
Schulz, R
Tozzi, GP
Maccarone, MC
Piro, L
机构
[1] European Space Agcy, European Space Res & Technol Ctr, Dept Space Sci, Div Astrophys, NL-2200 AG Noordwijk, Netherlands
[2] Nuova Telespazio, BeppoSAX Sci Data Ctr, I-00131 Rome, Italy
[3] European Space Agcy, European Space Res & Technol Ctr, Dept Space Sci, Solar Syst Div, NL-2200 AG Noordwijk, Netherlands
[4] Osservatorio Astrofis Arcetri, I-50125 Florence, Italy
[5] CNR, Ist Fis Cosm & Appl Informat, I-90146 Palermo, Italy
[6] CNR, Ist Astrofis Spaziale, I-00044 Frascati, Italy
[7] Osservatorio Astron Roma, I-00044 Monte Porzio Catone, Italy
关键词
comets; general; individual; (Hale-Bopp; 1995; O1); X-rays;
D O I
10.1086/311119
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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 similar to 10 hr with a mean value of 5 x 10(16) ergs s(-1). The spectrum is well fitted 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(-0.2)(+0.6). The lack of detected C and O line emission places severe constraints on many models for cometary X-ray emission, especially those that involve X-ray production in cometary gas. The luminosity is a factor of at least 3.4 greater than measured by the 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 similar to 3 x 10(5) km (or similar to 2') by the start of the EWE 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.
引用
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页码:L47 / +
页数:7
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