π Aquarii is another γ Cassiopeiae object
Abstract
The γ Cas category is a subgroup of Be stars displaying a strong, hard, and variable thermal X-ray emission. An XMM-Newton observation of π Aqr reveals spectral and temporal characteristics that clearly make this Be star another member of the γ Cas category. Furthermore, π Aqr is a binary but, contrary to γ Cas, the nature of the companion to the Be star is known; it is a non-degenerate (stellar) object and its small separation from the Be star does not leave much room for a putative compact object close to the Be disk. This renders the accretion scenario difficult to apply in this system, and, hence, this discovery favors a disk-related origin for the γ Cas phenomenon.
Based on observations collected with the ESA science mission XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).- Publication:
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Astronomy and Astrophysics
- Pub Date:
- June 2017
- DOI:
- 10.1051/0004-6361/201731135
- arXiv:
- arXiv:1706.05195
- Bibcode:
- 2017A&A...602L...5N
- Keywords:
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- stars: early-type;
- stars: emission-line;
- Be;
- X-rays: stars;
- stars: individual:πAqr;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, letter accepted by A&