High-resolution X-Ray Spectroscopy of the Magnetic Of?p Star HD 148937
Abstract
High-resolution data of the peculiar magnetic massive star HD 148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the high-Z elements (Mg, Si, S) were found to be unshifted and relatively narrow (FWHM of about 800 km s-1), i.e., narrower than the O line recorded by RGS, which possibly indicates that the hot plasma is multi-thermal and has several origins. These data further indicate a main plasma temperature of about 0.6 keV and a formation of the X-ray emission at about one stellar radius above the photosphere. From the spectral fits and the H-to-He line ratios, the presence of very hot plasma is, however, confirmed, though with a smaller relative strength than for the prototype magnetic oblique rotator θ1 Ori C. Both stars thus share many similarities, but HD 148937 appears less extreme than θ1 Ori C despite also having a large magnetic confinement parameter.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2012
- DOI:
- 10.1088/0004-637X/746/2/142
- arXiv:
- arXiv:1111.7186
- Bibcode:
- 2012ApJ...746..142N
- Keywords:
-
- stars: early-type;
- stars: individual: HD148937;
- stars: massive;
- X-rays: stars;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 13 pages, accepted for publication by ApJ