2007/09/26 by A. Gáspár, Andras Gáspár, K. Y. L. Su +7 · 4 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/523299
11 pages, 1 table and 13 figures, emulateapj; Accepted for publication in The Astrophysical Journal
arxiv created 2007/09/26 · openalex publication_date 2008/01/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We have discovered a bow shock shaped mid-infrared excess region in front of δ Velorum using 24 μm observations obtained with the Multiband Imaging Photometer for Spitzer (MIPS). Although the bow shock morphology was only detected in the 24 μm observations, its excess was also resolved at 70 μm. We show that the stellar heating of an ambient interstellar medium (ISM) cloud can produce the measured flux. Since δ Velorum was classified as a debris disk star previously, our discovery may call into question the same classification of other stars. We model the interaction of the star and ISM, producing images that show the same geometry and surface brightness as is observed. The modeled ISM is ~15 times overdense relative to the average Local Bubble value, which is surprising considering the close proximity (24 pc) of δ Velorum. The abundance anomalies of λ Boötis stars have been previously explained as arising from the same type of interaction of stars with the ISM. Low-resolution optical spectra of δ Velorum show that it does not belong to this stellar class. The star therefore is an interesting testbed for the ISM accretion theory of the λ Boötis phenomenon.