Astronomy and Astrophysics – Astronomy
Scientific paper
Mar 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008head...10.1002n&link_type=abstract
American Astronomical Society, HEAD meeting #10, #10.02
Astronomy and Astrophysics
Astronomy
Scientific paper
Classical Novae are members of the class of Cataclysmic Variables in which an explosion is caused by a thermonuclear runaway (TNR) in accreted material on a white dwarf (WD). When sufficient material has been accreted by the white dwarf an observable outburst occurs. The emitted radiation comes from the optically thick, expanding, shell of gas. It is initially hot and dense but as it expands it cools and the density drops. As long as the gases are optically thick they can be modeled as an expanding stellar atmosphere. However, as the expansion continues, the outer layers go optically thin and the photosphere moves inward. The effective radius of the photosphere shrinks with time but the source remains at constant bolometric luminosity so that the effective temperature gradually increases until the peak of the spectral energy distribution moves into the X-ray regime. Spectra taken at this time are classified as those of a Super Soft Source (SSS) since they resemble those of systems such as CAL 83.
In addition to the SSS phase, there is hard emission seen early in the outburst. The hard emission is typically fainter than the SSS emission and is seen in some cases to fade with time. There is no general agreement on the source of the hard X-ray emission and we discuss several possible explanations including the possibility of magnetically induced coronal emission powered by a dynamo located in the shear layers between the WD and the surrounding shell. We point out that only future X-ray missions will provide the required sensitivity to determine the source. We gratefully acknowledge a Chandra Fellowship at ASU to J-U Ness, and SS acknowledges partial support from NASA and NSF grants to ASU.
Ness Jan-Uwe
Starrfield Summer
No associations
LandOfFree
Soft And Hard: Classical Novae In X-rays 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 Soft And Hard: Classical Novae In X-rays, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Soft And Hard: Classical Novae In X-rays will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-958080