Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992aas...181.1401g&link_type=abstract
American Astronomical Society, 181st AAS Meeting, #14.01; Bulletin of the American Astronomical Society, Vol. 24, p.1141
Astronomy and Astrophysics
Astronomy
1
Scientific paper
Recent polarimetric studies of young, intermediate mass stars have proven extremely valuable in identifying those stars surrounded by circumstellar dust disks oriented with the circumstellar disk edge-on to our line of sight. We present IUE data for one such system, HD 45677 (B2 [e]psh). Our data, and earlier archival spectra of the star, show high velocity, collisionally ionized accreting gas visible in higher oscillator strength transitions of Fe II, Mg II, Al III, Fe III (34), Si III], C III], Si IV, C IV, and N V. The accreting gas reaches velocities as high as +450 km s(-1) in N V. Broad absorption troughs centered on the systemic velocity, and reminiscent of similar features in FU Orionis-type objects are seen in all of these transitions and show a trend of increasing velocity width with ionization. We do not observe the rotationally broadened absorption features expected for a B2 star with the optical v sin i~ 200 km s(-1) of HD 45677, suggesting that we do not see all the way in to the star in the UV. The IUE data provide convincing evidence for variable UV continuum luminosity. Collectively, these data suggest that much of the UV continuum of HD 45677, and all of the absorption lines originate in a large, viscously heated accretion disk. The presence of accreting gas excludes interpretation of HD 45677 as a proto-planetary nebula (PNe), and instead suggests that this object is a young, massive Herbig Be star. The polarization of the emission lines is consistent with formation in a bipolar flow or disk-wind normal to the circumstellar disk. The available data for HD 45677 are compared with lower mass PMS stars with similar viewing geometry, and with older systems such as beta Pictoris.
Bjorkman Karen S.
de Winter Dolf
Grady Carol A.
Perez Mario R.
Schulte-Ladbeck Regina E.
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