J/ApJ/809/159 Variations of RS CVn primaries. II. o Dra (Roettenbacher+, 2015)
Detecting the companions and ellipsoidal variations of RS CVn primaries.
II. ο Draconis, a candidate for recent low-mass companion ingestion.
Roettenbacher R.M., Monnier J.D., Fekel F.C., Henry G.W., Korhonen H.,
Latham D.W., Muterspaugh M.W., Williamson M.H., Baron F.,
ten Brummelaar T.A., Che X., Harmon R.O., Schaefer G.H., Scott N.J.,
Sturmann J., Sturmann L., Turner N.H.
<Astrophys. J., 809, 159 (2015)>
=2015ApJ...809..159R 2015ApJ...809..159R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Radial velocities ; Interferometry ;
Photometry, UBV
Keywords: binaries: close; stars: activity; stars: imaging;
stars: individual: Dra; stars: variables: general
Abstract:
To measure the stellar and orbital properties of the metal-poor RS CVn
binary o Draconis (o Dra), we directly detect the companion using
interferometric observations obtained with the Michigan InfraRed
Combiner at Georgia State University's Center for High Angular
Resolution Astronomy (CHARA) Array. The H-band flux ratio between the
primary and secondary stars is the highest confirmed flux ratio
(370±40) observed with long-baseline optical interferometry. These
detections are combined with radial velocity data of both the primary
and secondary stars, including new data obtained with the Tillinghast
Reflector Echelle Spectrograph on the Tillinghast Reflector at the
Fred Lawrence Whipple Observatory and the 2m Tennessee State
University Automated Spectroscopic Telescope at Fairborn Observatory.
We determine an orbit from which we find model-independent masses and
ages of the components (MA=1.35±0.05M☉,
MB=0.99±0.02M☉, system age =3.0±0.5Gyr). An average of a
23-year light curve of o Dra from the Tennessee State University
Automated Photometric Telescope folded over the orbital period newly
reveals eclipses and the quasi-sinusoidal signature of ellipsoidal
variations. The modeled light curve for our system's stellar and
orbital parameters confirm these ellipsoidal variations due to the
primary star partially filling its Roche lobe potential, suggesting
most of the photometric variations are not due to stellar activity
(starspots). Measuring gravity darkening from the average light curve
gives a best-fit of β=0.07±0.03, a value consistent with
conventional theory for convective envelope stars. The primary star
also exhibits an anomalously short rotation period, which, when taken
with other system parameters, suggests the star likely engulfed a
low-mass companion that had recently spun-up the star.
Description:
We obtained interferometric data at Georgia State University's Center
for High-Angular Resolution Astronomy (CHARA) Array. Using all six
telescopes and the Michigan InfraRed Combiner (MIRC), we obtained
H-band (1.5-1.8um) data on UT 2012 May 9, 11, 12 and June 6, 8, 17,
18; 2014 May 25, 26, 27, June 29, 30, and July 1.
We detected the faint companion in the data from UT 2012 May 9, 12;
2012 June 17, 18; and 2014 May 26, 27.
Three radial velocities published in Massarotti et al. (M08; 2008,
J/AJ/135/209) were obtained with the CfA Digital Speedometer on the
Wyeth Reflector at the Oak Ridge Observatory (Harvard, MA; 2004
September 1-2005 April 14). Two radial velocities also published in
M08 were obtained with the CfA Digital Speedometer on the Tillinghast
Reflector at the Fred L.Whipple Observatory (Mount Hopkins, AZ; 2006
June 14-2007 September 21). Six additional radial velocities (2012 May
9-October 10) for the primary star were taken with the Tillinghast
Reflector Echelle Spectrograph (TRES) at the Tillinghast Reflector
(see Table 2).
With the Tennessee State University (TSU) 2m automatic spectroscopic
telescope (AST) at Fairborn Observatory, AZ, we have determined radial
velocities from 86 spectrograms of the primary of o Dra taken between
2007 October 11 and 2014 October 28 and 19 measurements of the
companion radial velocity (2012 October 10-2014 October 28; see
Table 3).
o Dra has been monitored since 1992 with Tennessee State University's
T3 0.4m Automatic Photometric Telescope (APT) at Fairborn Observatory.
Our observations span over 23 years from 1992 March 24 to 2015 May 13,
but with a gap during 2005-2011 (see Table 4 and Figure 1).
Objects:
-----------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
-----------------------------------------------------------------
18 51 12.10 +59 23 18.1 o Draconis = HD 175306 (P=138.444)
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 17 11 Radial velocity data of o Draconis
(Wyeth & Tillinghast/CfA)
table3.dat 21 86 Radial velocity data of o Draconis (AST/TSU)
table4.dat 38 1745 Johnson B and V differential magnitudes
of o Draconis (APT/TSU)
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See also:
B/pastel : The PASTEL catalogue (Soubiran+, 2010-)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
J/ApJ/807/23 : RS CVn primaries. I. sig Gem (Roettenbacher+, 2015)
J/A+A/579/A68 : CANDID code for interferometric obs. (Gallenne+, 2015)
J/AJ/149/63 : Radial velocities of HD54371, HR 2692 & 16 UMa (Fekel+, 2015)
J/A+A/553/A95 : PCA approach to effective temperatures (Bermejo+, 2013)
J/A+A/547/A91 : Spectroscopic analysis of 348 red giants (Zielinski+, 2012)
J/MNRAS/427/343 : Infrared excesses of Hipparcos stars (McDonald+, 2012)
J/ApJ/746/101 : Diameters and temperatures of AFG stars (Boyajian+, 2012)
J/ApJS/190/203 : 3.6 years of DIRBE NIR stellar light curves (Price+, 2010)
J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)
J/AJ/135/209 : Rotational & radial vel. of HIP giants (Massarotti+, 2008)
J/AJ/130/794 : Radial velocities & BV photometry of HD 144110 (Fekel+, 2005)
J/A+A/430/165 : Radial velocities for 6691 K and M giants (Famaey+, 2005)
J/AJ/128/3012 : Speckle interferometry at USNO. X. (Mason+, 2004)
J/ApJ/578/943 : vsini of binaries with evolved component (de Medeiros+, 2002)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 --- HJD [53249.7/56210.6] Heliocentric Julian Date;
HJD-2400000
12- 17 F6.2 km/s RV1 [-42.7/4.1] Primary star radial velocity (1)
--------------------------------------------------------------------------------
Note (1): Residuals on the primary radial velocities are 0.39km/s.
The first five velocities are published in Massarotti+, 2008,
J/AJ/135/209.
These radial velocities are on the CfA native system; in our analysis,
we add 0.14km/s (Stefanik et al. 1999ASPC..185..354S 1999ASPC..185..354S).
--------------------------------------------------------------------------------
Byte-by-byte Description of file:table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.3 --- HJD [54384.7/57134] Heliocentric Julian Date;
HJD-2400000
11- 15 F5.1 km/s RV1 [-43.1/3.8] Primary star radial velocity (1)
17- 21 F5.1 km/s RV2 [-54/10.9]? Secondary star radial velocity (1)
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Note (1): Errors on the primary radial velocities are 0.84km/s. Errors
on the secondary radial velocities are 3.8km/s. These were then
scaled for our orbit fit to have a total χ^2=1.00. Note these
radial velocities are on the native CfA system. We added 0.14km/s
for use in our analysis (Stefanik+, 1999ASPC..185..354S 1999ASPC..185..354S).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 --- HJD [48705.9/57156] Heliocentric Julian Date;
HJD-2400000
12- 17 F6.3 mag VarB [-1.2/-1]? B mag diff: o Dra - HD175511 (1)
19- 24 F6.3 mag VarV [-2.4/-2.2]? V mag diff: o Dra - HD175511 (1)
26- 31 F6.3 mag ChkB [-0.2/0]? B mag diff: 48 Dra - HD175511 (1)
33- 38 F6.3 mag ChkV [-1.4/-1.2]? V mag diff: 48 Dra - HD175511 (1)
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Note (1): Data null values signify differential magnitudes discarded because
internal standard deviation exceeded 0.01mag.
HD175511 (HIP92594), V=6.94, B-V=-0.04
48 Dra (HD176408, HIP92997), V=5.68, B-V=1.16
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History:
From electronic version of the journal
References:
Roettenbacher et al. I. sig Geminorum 2015ApJ...807...23R 2015ApJ...807...23R J/ApJ/807/23
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Dec-2015