Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-08-15
Astronomy and Astrophysics
Astrophysics
submitted to ApJ. 35 pages, 16 figures, Latex revised version uses improved estimates of point source count rate, and improved
Scientific paper
10.1086/376855
We use published ROSAT observations of the X-ray Nova V1974 Cygni 1992 to test a model for interstellar dust, consisting of a mixture of carbonaceous grains and silicate grains. The time-dependent X-ray emission from the nova is modelled, and X-ray scattering is calculated for a dust mixture with a realistic size distribution. Model results are compared with the scattered X-ray halos measured by ROSAT at 9 epochs. The observed X-ray halos are consistent with the halos calculated for the size distribution of Weingartner & Draine which reproduces the Milky Way extinction with R_V=3.1, provided that the reddening E(B-V) approx 0.20, consistent with E(B-V) = 0.19 inferred from the late-time Balmer decrement. The time delay of the scattered halo relative to the direct flux from the nova is clearly detected. Models with smoothly-distributed dust give good overall agreement with the observed scattering halo, but tend to produce somewhat more scattering than observed at 200-300", and insufficient scattering at 50-100". While an additional population of large grains can increase the scattered intensity at 50-100", this could also be achieved by having ~30% of the dust in a cloud at a distance from us equal to ~95% of the distance to the nova. Such a model also improves agreement with the data at larger angles, and illustrates the sensitivity of X-ray scattering halos to the location of the dust. The observations therefore do not require a population of micron-sized dust grains.
Draine Bruce T.
Tan Jonathan C.
No associations
LandOfFree
The X-Ray Scattering Halo Around Nova Cygni 1992: Testing a Model for Interstellar Dust 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 The X-Ray Scattering Halo Around Nova Cygni 1992: Testing a Model for Interstellar Dust, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The X-Ray Scattering Halo Around Nova Cygni 1992: Testing a Model for Interstellar Dust will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-514801