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Title: X-RAY EMISSION FROM MAGNETIC MASSIVE STARS

Magnetically confined winds of early-type stars are expected to be sources of bright and hard X-rays. To clarify the systematics of the observed X-ray properties, we have analyzed a large series of Chandra and XMM-Newton observations, corresponding to all available exposures of known massive magnetic stars (over 100 exposures covering ∼60% of stars compiled in the catalog of Petit et al.). We show that the X-ray luminosity is strongly correlated with the stellar wind mass-loss rate, with a power-law form that is slightly steeper than linear for the majority of the less luminous, lower- M-dot B stars and flattens for the more luminous, higher- M-dot O stars. As the winds are radiatively driven, these scalings can be equivalently written as relations with the bolometric luminosity. The observed X-ray luminosities, and their trend with mass-loss rates, are well reproduced by new MHD models, although a few overluminous stars (mostly rapidly rotating objects) exist. No relation is found between other X-ray properties (plasma temperature, absorption) and stellar or magnetic parameters, contrary to expectations (e.g., higher temperature for stronger mass-loss rate). This suggests that the main driver for the plasma properties is different from the main determinant of the X-ray luminosity. Finally, variationsmore » of the X-ray hardnesses and luminosities, in phase with the stellar rotation period, are detected for some objects and they suggest that some temperature stratification exists in massive stars' magnetospheres.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [6]
  1. GAPHE, Département AGO, Université de Liège, Allée du 6 Août 17, Bat. B5C, B-4000 Liège (Belgium)
  2. Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)
  3. Department of Physics and Astronomy, University of Delaware, Bartol Research Institute, Newark, DE 19716 (United States)
  4. Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081 (United States)
  5. Penn State Worthington Scranton, Dunmore, PA 18512 (United States)
  6. Department of Physics, Royal Military College of Canada, PO Box 17000, Station Forces, Kingston, ON K7K 4B4 (Canada)
Publication Date:
OSTI Identifier:
22340139
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 215; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOLOMETERS; ELECTRON TEMPERATURE; HARD X RADIATION; ION TEMPERATURE; LUMINOSITY; MAGNETIC FIELDS; MAGNETIC STARS; MAGNETOHYDRODYNAMICS; MASS TRANSFER; STELLAR WINDS; TEMPERATURE RANGE 0400-1000 K