On the Nature of Soft X-Ray Radiation in Comet Hyakutake 1996 B2

Details On the Nature of Soft X-Ray Radiation in Comet Hyakutake 1996 B2 On the Nature of Soft X-Ray Radiation in Comet Hyakutake 1996 B2

Sep 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996dps....28.0937k&link_type=abstract

American Astronomical Society, DPS meeting #28, #09.37; Bulletin of the American Astronomical Society, Vol. 28, p.1095

Astronomy and Astrophysics

Astrophysics

2

Scientific paper

EUVE and ROSAT observations of comet Hyakutake revealed radiation in the soft X-ray with an intensity in the order of 0.03 ph cm(-2) s(-1) at 0.12 a.u. from the comet. We discuss and develop methods to calculate emission of soft X-ray photons in cometary dust and gas by the following processes: (1) scattering and (2) fluorescence of solar X-rays; (3) K- and L-shell ionization by solar-wind protons and (4) electrons; (5) bremsstrahlung of solar-wind electrons; (6) cometary magnetospheric substorms; (7) collisions with interplanetary dust particles; and (8) the presence of very small particles with mass in the order of 10(-19) g in comets. These particles were detected in comet Halley by Utterback and Kissel (Astron. J. 100, 1315, 1990) using the PUMA and PIA dust analyzers from the Vega and Giotto spacecraft. Of all these processes, only very strong substorms and scattering, to a lesser extent, fluorescence and bremsstrahlung by very small particles are capable to produce the measured intensity of soft X-ray. Appearance of strong substorms during each observation event is not probable. Very small particles are a more plausible explanation of the observed soft X-ray emission. However, the mean particle mass of 4.6x 10(-19) g suggested by Utterback and Kissel implies that the total production of these particles exceeds that of gas by a factor of 3.6 (in mass) and is inconsistent with the polarization and color of comet Halley. Both polarization and color require a reduction of the mean mass to (1-2)x 10(-19) g. This reduction strongly affects the visible brightness of the particles, which is proportional to m(2) , with a relatively weak effect on the soft X-ray. Spatial distribution of soft X-ray in comet Hyakutake is consistent with the sunward ejection of dust (Krasnopolsky et al., Astron. Astrophys. 187, 707, 1987). Soft X-ray observations of comets may be a tool for the study and diagnostics of very small particles. According to current models, solar soft X-ray radiation lambda > 18 Angstroms is rather stable during solar flares, and correlation of cometary X-ray with solar flares should be weak.

Affiliated with

Also associated with

No associations

Rating

On the Nature of Soft X-Ray Radiation in Comet Hyakutake 1996 B2 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On the Nature of Soft X-Ray Radiation in Comet Hyakutake 1996 B2, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the Nature of Soft X-Ray Radiation in Comet Hyakutake 1996 B2 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1461307