A HARD AND VARIABLE X-RAY EMISSION FROM THE MASSIVE EMISSION-LINE STAR HD 157832

Journal Article · Sun Apr 10 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/731/1/L6· OSTI ID:21562751

Lopes de Oliveira, R ^[1]; Motch, C ^[2]

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1. Universidade de Sao Paulo, Instituto de Fisica de Sao Carlos, Caixa Postal 369, 13560-970, Sao Carlos, SP (Brazil)
2. Universite de Strasbourg, CNRS UMR 7550, Observatoire Astronomique, 11 rue de l'Universite, F67000 Strasbourg (France)

We report the discovery with XMM-Newton of a hard-thermal (T {approx} 130 MK) and variable X-ray emission from the Be star HD 157832, a new member of the puzzling class of {gamma}-Cas-like Be/X-ray systems. Recent optical spectroscopy reveals the presence of a large/dense circumstellar disk seen at intermediate/high inclination. With a B1.5V spectral type, HD 157832 is the coolest {gamma}-Cas analog known. In addition, its non-detection in the ROSAT all-sky survey shows that its average soft X-ray luminosity varied by a factor larger than {approx}3 over a time interval of 14 yr. These two remarkable features, 'low' effective temperature, and likely high X-ray variability turn HD 157832 into a promising object for understanding the origin of the unusually high-temperature X-ray emission in these systems.

• OSTI ID: 21562751
• Journal Information: Astrophysical Journal Letters, Vol. 731, Issue 1; Other Information: DOI: 10.1088/2041-8205/731/1/L6; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
EMISSION
LUMINOSITY
SOFT X RADIATION
SPECTROSCOPY
STARS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
X RADIATION