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

Autor(es)

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

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Strasbourg, CNRS, UMR 7550, Astron Observ, F-67000 Strasbourg - France

• Tipo de documento: Artigo Científico
• Fonte: Astrophysical Journal Letters; v. 731, n. 1 APR 10 2011.
• Citações Web of Science: 6

Resumo

We report the discovery with XMM-Newton of a hard-thermal (T similar to 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 similar to 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. (AU)

• Processo FAPESP: 09/06295-7 - Astrofísica de altas energias
• Beneficiário: Raimundo Lopes de Oliveira Filho
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 10/08341-3 - Astrofísica de altas energias
• Beneficiário: Raimundo Lopes de Oliveira Filho
• Modalidade de apoio: Bolsas no Brasil - Jovens Pesquisadores