LOCATING THE ACCRETION FOOTPRINT ON A HERBIG Ae STAR: MWC 480

Journal Article · Fri Aug 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/719/2/1565· OSTI ID:21457066

Grady, C A ^[1]; Hamaguchi, K ^[2]; Schneider, G ^[3]; Stecklum, B ^[4]; Woodgate, B E ^[5]; McCleary, J E ^[6]; Williger, G M ^[7]; Sitko, M L; Hines, D ^[8]; Menard, F ^[9]; Henning, Th ^[10]; Brittain, S; Troutmann, M; Donehew, B ^[11]; Wisniewski, J P ^[12]; Lynch, D K; Russell, R W; Rudy, R J ^[13]; Day, A N ^[14]; Shenoy, A ^[15]

---

1. Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002 (United States)
2. CRESST and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)
3. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
4. Thueringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany)
5. ExoPlanets and Stellar Astrophysics Laboratory, NASA's Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
6. Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)
7. Department of Physics, University of Louisville, Louisville, KY 40292 (United States)
8. Space Science Institute, 4750 Walnut St., Suite 205, Boulder, CO 80301 (United States)
9. Laboratoire d'Astrophysique de Grenoble, CNRS/UJF UMR 5571 (France)
10. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
11. Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States)
12. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
13. Aerospace Corporation, Los Angeles, CA 90009 (United States)
14. Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 (United States)
15. NASA Goddard Space Flight Center, Summer High School Intern and Thomas Wootton High School, Rockville, MD 20850-3099 (United States)

Accretion is a fundamental process which establishes the dynamics of the protoplanetary disk and the final properties of the forming star. In solar-type stars, the star-disk coupling is determined by the magnetic field structure, which is responsible for funneling material from the disk midplane to higher latitudes on the star. Here, we use pan-chromatic data for the Herbig Ae star MWC 480 to address whether similar processes occur in intermediate-mass stars. MWC 480 has X-ray emission typical of actively accreting Herbig Ae stars, but with {approx}10x more photoelectric absorption than expected from optical and FUV data. We consider three sources for the absorption: the disk, absorption in a wind or jet, and accretion. While we detect the disk in scattered light in a re-analysis of archival Hubble Space Telescope data, the data are consistent with grazing illumination of the dust disk. We find that MWC 480's disk is stratified, geometrically thin, and is not responsible for the observed photoelectric absorption. MWC 480 drives a bipolar jet, but with a mass-loss rate that is low compared to other Herbig Ae stars, where the outflow is more favorably oriented and enhanced photoelectric absorption is not seen. This excludes a jet or wind origin for the enhanced photoelectric absorption. We compare MWC 480's O VI emission with other Herbig Ae stars. The distribution of the emission in inclination, and lack of a correlation of profile shape and system inclination excludes equatorially confined accretion for the FUSE Herbig Ae stars. The photoelectric absorption data further suggest that the accretion footprint on MWC 480 and other Herbig Ae stars is located at high-temperate, rather than polar, latitudes. These findings support the presence of funneled accretion in MWC 480 and Herbig Ae stars, strengthening the parallel to T Tauri stars.

• OSTI ID: 21457066
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 719; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
BINARY STARS
DUSTS
ELECTROMAGNETIC RADIATION
EMISSION
ERUPTIVE VARIABLE STARS
INCLINATION
IONIZING RADIATIONS
MAGNETIC FIELDS
PHOTON EMISSION
PROTOPLANETS
RADIATIONS
SORPTION
STARS
T TAURI STARS
TELESCOPES
ULTRAVIOLET RADIATION
VARIABLE STARS
X RADIATION