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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 358740.0, MPI für Astronomie / Publikationen_mpia
The disk and environment of a young Vega analog: HD 169142
Authors:Grady, C. A.; Schneider, G.; Hamaguchi, K.; Sitko, M. L.; Carpenter, W. J.; Hines, D.; Collins, K. A.; Williger, G. M.; Woodgate, B. E.; Henning, T.; Ménard, F.; Wilner, D.; Petre, R.; Palunas, P.; Quirrenbach, A.; Nuth, J. A.; Silverstone, M. D.; Kim, J. S.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astrophysical Journal
Start Page:1391
End Page:1406
Audience:Not Specified
Abstract / Description:We trace the disk of HD 169142 (A8 Ve) from 0.57" to 1.4" (~80-200 AU projected distance) in 1.1 mum scattered light with HST NICMOS coronagraphy. The azimuthally symmetric disk has a peak azimuthally medianed surface brightness (SB) of ~5 mJy arcsec-2 at 0.57" from the star, and drops ~r-3. This radial SB profile is consistent with the presence of spatially resolved PAH emission and a Meeus group I IR SED only if the inner disk is either substantially flatter than the outer disk or partially devoid of material. Analysis of new HST ACS FUV imagery in tandem with archival IUE data indicates M˙acc<=10-9 Msolar yr-1. We estimate the age of HD 169142 to be 6+6-3 Myr by identifying 2MASS 18242929-2946559, located 9.3" to the southwest, as a 130 mas separation weak-line T Tauri binary that is comoving with HD 169142 at the 4 sigma confidence level. We find no evidence for any additional stellar companion in either the ACS or Chandra ACIS-S data at r<=1''. HD 169142 has previously been interpreted as a slowly rotating, chemically peculiar star. However, by combining the disk inclination and vsini from the literature, we find that the star has vequatorial~240 km s-1, making it a rapid rotator, similar to Altair or Vega. The UV data for HD 169142 are consistent with gravity darkening, while the X-ray luminosity and spectrum resembles early F stars at the age of the beta Pictoris moving group, rather than mid-A stars. In this context, spectral features previously interpreted as evidence for chemical peculiarity are more likely to reflect the presence of a strong photospheric latitudinal temperature gradient. With such a gradient, HD 169142 should closely resemble Vega at the epoch of central disk clearing.
Free Keywords:Stars: Binaries: Visual; Stars: Planetary Systems: Protoplanetary Disks; stars: individual (2MASS 18242929-2946559); stars: individual (HD 22128); Stars: Individual: Henry Draper Number: HD 36112; stars: individual (HD 142666); stars: individual (HD 169142); stars: individual (HD 220750); Stars: Low-Mass; Brown Dwarfs; Stars: Pre-Main-Sequence
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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