THE 2011 PERIASTRON PASSAGE OF THE Be BINARY {delta} Scorpii
- Department of Physics and Astronomy, University of North Carolina at Greensboro, Greensboro, NC 27402-6170 (United States)
- Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-21500 Puekkioe (Finland)
- CFHT Corporation, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743 (United States)
- Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo (Brazil)
- European Organisation for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19 (Chile)
- ESO/ALMA, Alonso de Cordova 3107, Vitacura, Santiago (Chile)
- Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetskij Pr. 13, Moscow 119992 (Russian Federation)
- Observatorio do Instituto Geografico do Exercito, Lisboa (Portugal)
- ATALAIA.org Group, Lisboa (Portugal)
- Observatoire de Juvignac, 19 avenue de Hameau du Golf F-34990, Juvignac (France)
- Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)
- Castanet Tolosan Observatory, 6 place Clemence Isaure F-31320 Castanet Tolosan (France)
- Barfold Observatory, Glenhope, Victoria 3444 (Australia)
- Emil-Nolde-Str. 12, D-51375, Leverkusen (Germany)
- Observatoire du Val d'Arc, route de Peynier F-13530, Trets (France)
- Shelyak Instruments, 1116 route de Chambery, F-38330, Saint-Ismier (France)
- Barber Research Observatory, Department of Physics and Astronomy, University of Illinois-Springfield, IL 62703 (United States)
- Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. Postal 877, Ensenada, 22800, Baja California (Mexico)
- Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605 (Japan)
We describe the results of the world-wide observing campaign of the highly eccentric Be binary system {delta} Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092 {+-} 0.0005 yr. Fitting of the He II 4686 A line radial velocity curve determined the periastron passage time on 2011 July 3, UT 9:20 with a 0.9-day uncertainty. Both these results are in a very good agreement with recent findings from interferometry. We also derived new evolutionary masses of the binary components (13 and 8.2 M{sub Sun }) and a new distance of 136 pc from the Sun, consistent with the HIPPARCOS parallax. The radial velocity and profile variations observed in the H{alpha} line near the 2011 periastron reflected the interaction of the secondary component and the circumstellar disk around the primary component. Using these data, we estimated a disk radius of 150 R{sub Sun }. Our analysis of the radial velocity variations measured during the periastron passage time in 2000 and 2011 along with those measured during the 20th century, the high eccentricity of the system, and the presence of a bow shock-like structure around it suggest that {delta} Sco might be a runaway triple system. The third component should be external to the known binary and move on an elliptical orbit that is tilted by at least 40 Degree-Sign with respect to the binary orbital plane for such a system to be stable and responsible for the observed long-term radial velocity variations.
- OSTI ID:
- 22167477
- Journal Information:
- Astrophysical Journal, Vol. 766, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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