ON THE NATURE OF THE HERBIG B[e] STAR BINARY SYSTEM V921 SCORPII: DISCOVERY OF A CLOSE COMPANION AND RELATION TO THE LARGE-SCALE BIPOLAR NEBULA
- Department of Astronomy, University of Michigan, 918 Dennison Building, Ann Arbor, MI 48109-1090 (United States)
- Max Planck Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany)
Belonging to the group of B[e] stars, V921 Scorpii is associated with a strong infrared excess and permitted and forbidden line emission, indicating the presence of low- and high-density circumstellar gas and dust. Many aspects of V921 Sco and other B[e] stars still remain mysterious, including their evolutionary state and the physical conditions resulting in the class-defining characteristics. In this Letter, we employ Very Large Telescope Interferometer/AMBER spectro-interferometry in order to reconstruct high-resolution ({lambda}/2B = 0.''0013) model-independent interferometric images for three wavelength bands around 1.65, 2.0, and 2.3 {mu}m. In our images, we discover a close (25.0 {+-} 0.8 mas, corresponding to {approx}29 {+-} 0.9 AU at 1.15 kpc) companion around V921 Sco. Between two epochs in 2008 and 2009, we measure orbital motion of {approx}7 Degree-Sign , implying an orbital period of {approx}35 years (for a circular orbit). Around the primary star, we detect a disk-like structure with indications for a radial temperature gradient. The polar axis of this AU-scale disk is aligned with the arcminute-scale bipolar nebula in which V921 Sco is embedded. Using Magellan/IMACS imaging, we detect multi-layered arc-shaped substructure in the nebula, suggesting episodic outflow activity from the system with a period of {approx}25 years, roughly matching the estimated orbital period of the companion. Our study supports the hypothesis that the B[e] phenomenon is related to dynamical interaction in a close binary system.
- OSTI ID:
- 22048062
- Journal Information:
- Astrophysical Journal Letters, Vol. 746, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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