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Locating the Accretion Footprint on a Herbig Ae Star: MWC 480Accretion 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 5-9 x more photoelectric absorption than expected from optical and FUV data. We consider 3 sources for the absorption: the disk absorption in a wind or jet, and accretion. While we detect the disk in scattered light in are-analysis of archival HST 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 which 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 0 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.
Document ID
20110023025
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Grady, C. A. (Eureka Scientific, Inc. Oakland, CA, United States)
Hamaguchi, K. (Maryland Univ. Baltimore County Baltimore, MD, United States)
Schneider, G. (Arizona Univ. Tucson, AZ, United States)
Stecklum, B. (Thueringer Landessternwarte Tautenburg, Germany)
Woodgate, B. E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
McCleary, J. E. (New Mexico State Univ. Las Cruces, NM, United States)
Williger, G. M. (Johns Hopkins Univ. Baltimore, MD, United States)
Sitko, M. L. (Space Science Inst. Boulder, CO, United States)
Menard, F. (Centre National de la Recherche Scientifique Grenoble, France)
Henning, Th. (Max-Planck-Inst. fuer Astronomie Heidelberg, Germany)
Brittain, S. (Clemson Univ. SC, United States)
Troutmann, M. (Clemson Univ. SC, United States)
Donehew, B. (Clemson Univ. SC, United States)
Hines, D. (Space Science Inst. Boulder, CO, United States)
Wisniewski, J. P. (Washington Univ. Seattle, WA, United States)
Lynch, D. K. (Aerospace Corp. Los Angeles, CA, United States)
Russell, R. W. (Aerospace Corp. Los Angeles, CA, United States)
Rudy, R. J. (Aerospace Corp. Los Angeles, CA, United States)
Day, A. M. (Cincinnati Univ. OH, United States)
Shenoy, A. (Thomas Wootton High School Rockville, MD, US)
Wilner, D. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Silverston, M. (Eureka Scientific, Inc. Oakland, CA, United States)
Bouret, J.-C. (Centre National de la Recherche Scientifique Marseilles, France)
Clampin, M. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Petre, R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2011
Subject Category
Astrophysics
Report/Patent Number
GSFC.JA.5192.2011
Funding Number(s)
CONTRACT_GRANT: NAS5-26555
CONTRACT_GRANT: HST-GO-10864
CONTRACT_GRANT: HST-GO-10764
CONTRACT_GRANT: NSF AST-0708899
CONTRACT_GRANT: NAS5-32985
CONTRACT_GRANT: NNH06CC28C
PROJECT: RTOP 399131.02.06.02.32
CONTRACT_GRANT: NAS8-03060
CONTRACT_GRANT: NNG05EA89P
CONTRACT_GRANT: NNX09AC73G
CONTRACT_GRANT: HST-GO-10177
CONTRACT_GRANT: NNX08AH90G
CONTRACT_GRANT: NNG09EP47P
Distribution Limits
Public
Copyright
Public Use Permitted.

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