Abstract
The highly eccentric Be binary system ¿ Sco reached periastron
during early 2011 July, when the distance between the primary and
secondary was a few times the size of the primary disk in the H band.
This opened a window of opportunity to study how the gaseous disks
around Be stars respond to gravitational disturbance. We first refine
the binary parameters with the best orbital phase coverage data from the
Navy Precision Optical Interferometer. Then we present the first imaging
results of the disk after the periastron, based on seven nights of five
telescope observations with the MIRC combiner at the CHARA array. We
found that the disk was inclined 27fdg6 ± 6fdg0 from the plane of
the sky, had a half-light radius of 0.49 mas (2.2 stellar radii), and
consistently contributed 71.4% ± 2.7% of the total flux in the H
band from night to night, suggesting no ongoing transfer of material
into the disk during the periastron. The new estimation of the
periastron passage is UT 2011 July 3 07:00 ± 4:30. Re-analysis of
archival VLTI-AMBER interferometry data allowed us to determine the
rotation direction of the primary disk, constraining it to be inclined
either ~119° or ~171° relative to the orbital plane of the
binary system. We also detect inner disk asymmetries that could be
explained by spot-like emission with a few percent of the disk total
flux moving in Keplerian orbits, although we lack sufficient angular
resolution to be sure of this interpretation and cannot yet rule out
spiral density waves or other more complicated geometries.
Original language | English |
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Pages (from-to) | 29 |
Journal | The Astrophysical Journal |
Volume | 757 |
Issue number | 1 |
Publication status | Published - 1 Sept 2012 |