Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-02-14
Astrophys.J.658:525-533,2007
Astronomy and Astrophysics
Astrophysics
6 figures, AASTEX style, accepted for publication in ApJ
Scientific paper
10.1086/510894
We present the results of high resolution spectroscopy of the prototype polar AM Herculis observed with Chandra High Energy Transmission Grating. The X-ray spectrum contains hydrogen-like and helium-like lines of Fe, S, Si, Mg, Ne and O with several Fe L-shell emission lines. The forbidden lines in the spectrum are generally weak whereas the hydrogen-like lines are stronger suggesting that emission from a multi-temperature, collisionally ionized plasma dominates. The helium-like line flux ratios yield a plasma temperature of 2 MK and a plasma density 1 - 9 x10^12 cm^-3, whereas the line flux ratio of Fe XXVI to Fe XXV gives an ionization temperature of 12.4 +1.1 -1.4 keV. We present the differential emission measure distribution of AM Her whose shape is consistent with the volume emission measure obtained by multi-temperature APEC model. The multi-temperature plasma model fit to the average X-ray spectrum indicates the mass of the white dwarf to be ~1.15 M_sun. From phase resolved spectroscopy, we find the line centers of Mg XII, S XVI, resonance line of Fe XXV, and Fe XXVI emission modulated by a few hundred to 1000 km/s from the theoretically expected values indicating bulk motion of ionized matter in the accretion column of AM Her. The observed velocities of Fe XXVI ions are close to the expected shock velocity for a 0.6 M_sun white dwarf. The observed velocity modulation is consistent with that expected from a single pole accreting binary system.
Girish V.
Rana Vikram R.
Singh Kamal P.
No associations
LandOfFree
Chandra High Resolution X-ray Spectroscopy of AM Her 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 Chandra High Resolution X-ray Spectroscopy of AM Her, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chandra High Resolution X-ray Spectroscopy of AM Her will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-209100