J/ApJ/814/159 Hα interferometric visibilities of o Aqr (Sigut+, 2015)
The circumstellar disk of the Be star o Aquarii as constrained by simultaneous
spectroscopy and optical interferometry.
Sigut T.A.A., Tycner C., Jansen B., Zavala R.T.
<Astrophys. J., 814, 159 (2015)>
=2015ApJ...814..159S 2015ApJ...814..159S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Interferometry
Keywords: circumstellar matter; stars: emission-line, Be;
stars: individual: Aqr; techniques: interferometric
Abstract:
Omicron Aquarii is a late-type, Be shell star with a stable and nearly
symmetric Hα emission line. We combine Hα interferometric
observations obtained with the Navy Precision Optical Interferometer
covering 2007 through 2014 with Hα spectroscopic observations
over the same period and a 2008 observation of the system's
near-infrared spectral energy distribution to constrain the properties
of o Aqr's circumstellar disk. All observations are consistent with a
circumstellar disk seen at an inclination of 75°±3° with a
position angle on the sky of 110°±8° measured East from
North. From the best-fit disk density model, we find that 90% of the
Hα emission arises from within 9.5 stellar radii, and the mass
associated with this Hα disk is ∼1.8x10-10 of the stellar
mass, and that the associated angular momentum, assuming Keplerian
rotation for the disk, is ∼1.6x10-8 of the total stellar angular
momentum. The occurrence of a central quasi-emission feature in Mg II
λ4481 is also predicted by this best-fit disk model and the
computed profile compares successfully with observations from 1999. To
obtain consistency between the Hα line profile modeling and the
other constraints, it was necessary in the profile fitting to weight
the line core (emission peaks and central depression) more heavily
than the line wings, which were not well reproduced by our models.
This may reflect the limitation of assuming a single power law for the
disk's variation in equatorial density. The best-fit disk density
model for o Aqr predicts that Hα is near its maximum strength as
a function of disk density, and hence the Hα equivalent width
and line profile change only weakly in response to large (factor of
∼5) changes in the disk density. This may in part explain the
remarkable observed stability of o Aqr's Hα emission line
profile.
Description:
Spectroscopic observations in the Hα region have been obtained
using the Solar Stellar Spectrograph on the John S. Hall telescope at
Lowell Observatory. Thirty individual spectra are available for
observing seasons from 2005 through 2014.
We have analyzed a large set (N=994) of Hα interferometric
visibilities obtained from the Navy Precision Optical Interferometer
(NPOI) for the Be shell star o Aqr, covering the period 2007 through
2014.
Objects:
---------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------
22 03 18.84 -02 09 19.3 omicron Aquarii = HD 209409
---------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 44 994 The Navy Precision Optical Interferometer (NPOI)
Hα interferometric visibilities
of ο Aquarii
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See also:
J/A+A/585/A12 : Nearby early-type stars spectroscopic survey (Bailey+, 2016)
J/ApJ/768/128 : K-band calibrated visibilities of 24 Be stars (Touhami+, 2013)
J/A+A/550/A79 : Hα & Hβ lines of northern Be stars (Catanzaro, 2013)
J/ApJS/199/8 : Interstellar column densities compilation (Gudennavar+, 2012)
J/MNRAS/424/1925 : Spectrocopic Binarity of O and B type stars (Chini+, 2012)
J/other/A+ARV/20.51 : Rapidly rotating stars (Van Belle, 2012)
J/ApJS/187/228 : Hα profiles of Be stars (Silaj+, 2010)
J/A+A/510/A54 : NaI and CaII interstellar absorption (Welsh+, 2010)
J/ApJ/689/461 : Circumstellar disk of χ Oph (Tycner+, 2008)
J/ApJ/654/527 : Interferometric observations of northern Be stars (Gies+, 2007)
J/A+A/440/305 : Fundamental parameters of fast-rotating B stars (Fremat+, 2005)
J/ApJS/152/251 : Indo-US library of coude feed stellar spectra (Valdes+, 2004)
J/ApJS/147/61 : Interstellar Ca I absorption (Welty+, 2003)
J/ApJ/573/359 : Rotational velocities of B stars from BSC (Abt+, 2002)
J/A+A/390/1033 : The ISO-SWS post-helium atlas (Vandenbussche+, 2002)
J/A+A/384/473 : O, B and Be stars equivalent widths (Lenorzer+, 2002)
J/A+A/378/861 : Spectroscopy of Be stars (Chauville+, 2001)
J/A+A/368/912 : Polarization & rotational velocities of Be stars (Yudin, 2001)
J/ApJS/94/127 : Distribution of H I in the ISM. I. (Fruscione+, 1994)
J/A+AS/105/305 : OB stars observed with high dispersion by IUE (Bohlin+ 1994)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 d JD Julian Date (JD-2450000.0)
10- 17 F8.3 10+6/rad u [-81/118.5] Spatial frequency u
in 10+6cycles/radian
19- 26 F8.3 10+6/rad v [-33/62] Spatial frequency v
in 10+6cycles/radian
28- 32 F5.3 --- VHa2 [0.3/1.5] Hα squared visibility
34- 38 F5.3 --- e_VHa2 [0.01/0.6] Uncertainty in VHa2
40- 44 A5 --- Base Baseline (1)
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Note (1): The baseline entries for the NPOI instrument are explained in
Armstrong et al. (1998ApJ...496..550A 1998ApJ...496..550A).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Mar-2016