J/A+A/618/A112 β Lyr light curves (Mourard+, 2018)
Physical properties of β Lyrae A and its opaque accretion disk.
Mourard D., Broz M., Nemravova J.A., Harmanec P., Budaj J., Baron F.,
Monnier J.D., Schaefer G.H., Schmitt H., Tallon-Bosc I., Armstrong J.T.,
Baines E.K., Bonneau D., Bozic H., Clausse J.M., Farrington C., Gies D.,
Jurysek J., Korcakova D., McAlister H., Meilland A., Nardetto N.,
Svoboda P., Slechta M., Wolf M., Zasche P.
<Astron. Astrophys. 618, A112 (2018)>
=2018A&A...618A.112M 2018A&A...618A.112M (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Photometry
Keywords: stars: close - binaries: spectroscopic - binaries: eclipsing -
stars: emission-line - stars: individual: beta Lyr A -
stars: individual: beta Lyr B
Abstract:
Mass exchange and mass loss in close binaries can significantly affect
their evolution, but a complete self-consistent theory of these
processes is still to be developed. Processes such as radiative
shielding due to a hot-spot region, or a hydrodynamical interaction of
different parts of the gas stream have been studied previously. In
order to test the respective predictions, it is necessary to carry out
detailed observations of binaries undergoing the largescale mass
exchange, especially for those that are in the rapid transfer phase.
β Lyr A is an archetype of such a system, having a long and rich
observational history. Our goal for this first study is to
quantitatively estimate the geometry and physical properties of the
optically thick components, namely the Roche-lobe filling mass-losing
star, and the accretion disk surrounding the mass-gaining star of
β Lyr A. A series of continuum visible and NIR
spectro-interferometric observations by the NPOI, CHARA/MIRC and VEGA
instruments covering the whole orbit of β Lyr A acquired during a
two-week campaign in 2013 were complemented with UBVR photometric
observations acquired during a three-year monitoring of the system. We
included NUV and FUV observations from OAO A-2, IUE, and Voyager
satellites.
All these observations were compared to a complex model of the system.
It is based on the simple LTE radiative transfer code SHELLSPEC, which
was substantially extended to compute all interferometric observables
and to perform both global and local optimization of system
parameters. Several shapes of the accretion disk were successfully
tested - slab, wedge, and a disk with an exponential vertical
profile - and the following properties were consistently found: the
radius of the outer rim is 30.0±1.0R☉, the semithickness of
the disk 6.5±1.0R☉, and the binary orbital inclination
i=93.5±1.0deg. The temperature profile is a power-law or a
steady-disk in case of the wedge geometry. The properties of the
accretion disk indicate that it cannot be in a vertical hydrostatic
equilibrium, which is in accord with the ongoing mass transfer. The
hot spot was also detected in the continuum but is interpreted as a
hotter part of the accretion disk illuminated by the donor. As a
by-product, accurate kinematic and radiative properties of Lyr B were
determined.
Description:
Our study is based on the following sets of dedicated
spectrointerferometric observations and multicolor photometric
observations.
Three spectro-interferometric instruments took part in a twelve nights
long observational campaign aimed at β Lyr in 2013. We also have
at our disposal all previous interferometric observations as detailed
below.
Navy Precision Optical Interferometer (NPOI) (Armstrong et al.,
1998ApJ...496..550A 1998ApJ...496..550A): These observations were carried out in 16
spectral channels spread over wavelength region
Δλ=562-861nm with two triplets of telescopes.
Michigan InfraRed Combiner (MIRC) (Monnier et al. 2004, New Frontiers
in Stellar Interferometry, ed. W. A. Traub, Vol. 5491, 1370, 2006, in
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference
Series, Vol. 6268, Society of Photo-Optical Instrumentation Engineers
(SPIE) Conference Series, 1): These observations were acquired with
six telescopes in H-band split into eight channels. Earlier
observations in four-telescope mode have already been analyzed by Zhao
et al. (2008ApJ...684L..95Z 2008ApJ...684L..95Z) and qualitatively compared to a working
model. We note also that these observations were acquired before the
instrument was equipped with photometric channels (Che et al., 2010,
in Proc. SPIE, Vol. 7734, Optical and Infrared Interferometry II,
77342V).
Visible spEctroGraph and polArimeter (VEGA) (Mourard et al.
2009A&A...508.1073M 2009A&A...508.1073M, 2011A&A...531A.110M 2011A&A...531A.110M): These observations were
taken in four spectral regions using medium spectral resolution
R=5000. In each of these regions two channels in continuum
∼10-15nm wide were chosen. Either two or three telescopes were
used.
Objects:
------------------------------------------------
RA (2000) DE Designation(s)
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18 50 04.80 +33 21 45.6 beta Lyr = HR 7106
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 59 363 Detailed journal of interferometric observations
tableb1a.dat 80 282 beta Lyr (HD 174638) Hvar 2013-2017
UBVR photometry
tableb1b.dat 26 926 beta Lyr (HD 174638) Svoboda private observatory
Brno, B band
tableb1c.dat 26 916 beta Lyr (HD 174638) Svoboda private observatory
Brno, V band
tableb1d.dat 27 938 beta Lyr (HD 174638) Svoboda private observatory
Brno, Rc band
oifits/* . 3 Individual OIFITS files in MIRC, NPOI and VEGA
instruments
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See also:
J/A+A/312/879 : beta Lyr radial velocities and UBV data (Harmanec+, 1996)
J/A+A/463/233 : UBV and radial velocity light curves of beta Lyr (Ak+, 2007)
J/ApJ/750/59 : BVR polarimetric observations of β Lyr (Lomax+, 2012)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "date" Obs.Date Observation date
12- 21 F10.4 d RJD Mid-exposure epoch (JD-2400000)
23- 30 F8.3 --- Phase Phase (1)
32- 46 A15 --- Tel Configuration of the source instrument
48- 54 A7 --- Dlambda Passband
56- 57 I2 --- Nch Number of channels into which the
passband was sliced
59 I1 --- Src [1/3] Source instrument of the observations (2)
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Note (1): full number of orbital cycles since the reference epoch
by Ak et al. (2007, Cat. J/A+A/463/233)
Note (2): Source instrument of the observations as follows:
1 = CHARA/VEGA
2 = CHARA/MIRC
3 = NPOI
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Byte-by-byte Description of file: tableb1a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 d RJD Reduced Julian date (JD-2400000)
13- 17 F5.3 mag Vmag V magnitude
20- 24 F5.3 mag Bmag B magnitude
27- 31 F5.3 mag Umag U magnitude
34- 38 F5.3 mag Rmag R magnitude
40- 45 F6.3 mag B-V B-V colour index
47- 52 F6.3 mag U-B U-B colour index
54- 59 F6.3 mag V-R V-R colour index
62- 66 F5.3 --- X Air mass of the variable star
68- 73 F6.3 --- dX Difference in the air mass between the
variable star and comparison star
75- 80 I6 --- Comp HD number of comparison star (1)
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Note (1): Comparison stars used:
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HD star V B-V U-B V-R
-----------------------------------------------------
176437 gamma Lyr 3.253 -0.064 -0.038 -0.022
174602 nu2 Lyr 5.243 0.098 0.103 0.111
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Byte-by-byte Description of file: tableb1[bcd].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 d RJD Reduced Julian date (JD-2400000)
12- 17 F6.4 mag mag Magnitude in Band
19- 24 F6.4 mag e_mag rms uncertainty on mag
26- 27 A2 --- Band [BV Rc] Band for magnitude
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Acknowledgements:
Denis Mourard, denis.mourard(at)oca.eu
(End) Patricia Vannier [CDS] 15-Jul-2018