2002/09/04 by C. H. Chen, Christine Chen, M. Jura · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/344589
published as Astrophys.J. 582 (2003) 443-448 · 6 pages, 3 figures, ApJ in press
arxiv created 2002/09/04 · openalex publication_date 2003/01/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We have obtained Far Ultraviolet Spectroscopic Explorer spectra of σ Her, a nearby binary system with a main-sequence primary that has a Vega-like infrared excess. We observe absorption in the excited fine structure lines C II* at 1037 Å, N II* at 1085 Å, and N II** at 1086 Å that are blueshifted by as much as ~30 km s -1 with respect to the star. Since these features are considerably narrower than the stellar lines and broader than interstellar features, the C II and N II are circumstellar. We suggest that there is a radiatively driven wind arising from the circumstellar matter rather than accretion as occurs around β Pic because of σ Her's high luminosity. Assuming that the gas is liberated by collisions between parent bodies at 20 AU, the approximate distance at which blackbody grains are in radiative equilibrium with the star and at which three-body orbits become unstable, we infer dM / dt ~ 6 × 10 -12 M ☉ yr -1 . This wind depletes the minimum mass of parent bodies in less than the estimated age of the system.