Properties of the H -emitting
Circumstellar Regions of Be Stars
Christopher Tycner,1,2,3
John B. Lester,4
Arsen R. Hajian,5
J.T. Armstrong,6
J.A. Benson,1
G.C. Gilbreath,6
D.J. Hutter,1
T.A. Pauls,6 and
N.M. White7
1
U.S. Naval Observatory, Flagstaff Station, P.O. Box 1149,
Flagstaff, AZ 86002-1149
2
NVI, Inc., 7257 Hanover Parkway, Suite D, Greenbelt, MD 2077011
3
Also Department of Astronomy and Astrophysics,
University of Toronto, Toronto, ON, Canada
4
Department of Astronomy and Astrophysics, Erindale Campus,
University of Toronto, 3359 Mississauga Road North, Mississauga, ON
L5L 1C6, Canada
5
United States Naval Observatory, 3450 Massachusetts
Avenue NW, Washington, DC 20392-5420
6
Remote Sensing Division, Code 7210, Naval Research Laboratory,
4555 Overlook Avenue, SW, Washington, DC 20375
7
Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ
86001
Long-baseline interferometric observations obtained with the Navy
Prototype Optical Interferometer of the H -emitting envelopes
of the Be stars  Tauri and
 Canis Minoris are presented.
For compatibility with the previously published interferometric
results in the literature of other Be stars, circularly symmetric and
elliptical Gaussian models were fitted to the calibrated H
observations. The models are sufficient in characterizing the angular
distribution of the H-emitting circumstellar material
associated with these Be stars. To study the correlations between the
various model parameters and the stellar properties, the model
parameters for Tau
and CMi were combined with data for
other Be stars from the literature. After accounting for the
different distances to the sources and stellar continuum flux levels,
it was possible to study the relationship between the net H
emission and the physical extent of the H-emitting
circumstellar region. A clear dependence of the net H
emission on the linear size of the emitting region is demonstrated and
these results are consistent with an optically thick line emission
that is directly proportional to the effective area of the emitting
disk. Within the small sample of stars considered in this analysis,
no clear dependence on the spectral type or stellar rotation is found,
although the results do suggest that hotter stars might have more
extended H-emitting regions.
Accepted by ApJ
Preprints available at
http://xxx.arxiv.cornell.edu/abs/astro-ph/0501552
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