The 2014 X-Ray Minimum of η Carinae as Seen by Swift
- CRESST and X-Ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- University of the Virgin Islands, College of Science and Mathematics, John Brewers Bay, St. Thomas, USVI 00802-9990 (United States)
- NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)
- NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States)
- Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192 (United States)
- Universities Space Research Association, 7178 Columbia Gateway Drive, Columbia, MD 21044 (United States)
- Département de physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7 (Canada)
- Ritter Observatory, Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606 (United States)
- Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States)
- Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão 1226, Cidade Universitária, São Paulo, 05508-900 (Brazil)
- School of Physics, Trinity College Dublin, Dublin 2 (Ireland)
We report on Swift X-ray Telescope observations of Eta Carinae ( η Car), an extremely massive, long-period, highly eccentric binary obtained during the 2014.6 X-ray minimum/periastron passage. These observations show that η Car may have been particularly bright in X-rays going into the X-ray minimum state, while the duration of the 2014 X-ray minimum was intermediate between the extended minima seen in 1998.0 and 2003.5 by Rossi X-Ray Timing Explorer ( RXTE ), and the shorter minimum in 2009.0. The hardness ratios derived from the Swift observations showed a relatively smooth increase to a peak value occurring 40.5 days after the start of the X-ray minimum, though these observations cannot reliably measure the X-ray hardness during the deepest part of the X-ray minimum when contamination by the “central constant emission” component is significant. By comparing the timings of the RXTE and Swift observations near the X-ray minima, we derive an updated X-ray period of P {sub X} = 2023.7 ± 0.7 days, in good agreement with periods derived from observations at other wavelengths, and we compare the X-ray changes with variations in the He ii 4686 emission. The middle of the “Deep Minimum” interval, as defined by the Swift column density variations, is in good agreement with the time of periastron passage derived from the He ii λ 4686 line variations.
- OSTI ID:
- 22661247
- Journal Information:
- Astrophysical Journal, Vol. 838, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE OPTICAL WIND LINE VARIABILITY OF η CARINAE DURING THE 2009.0 EVENT
He II {lambda}4686 IN {eta} CARINAE: COLLAPSE OF THE WIND-WIND COLLISION REGION DURING PERIASTRON PASSAGE