J/AJ/147/36 Photometry and spectroscopy of AQ Ser (Torres+, 2014)
Absolute properties of the eclipsing binary system AQ Serpentis: a stringent
test of convective core overshooting in stellar evolution models.
Torres G., Vaz L.P.R., Lacy C.H.S., Claret A.
<Astron. J., 147, 36 (2014)>
=2014AJ....147...36T 2014AJ....147...36T
ADC_Keywords: Binaries, eclipsing ; Radial velocities ; Photometry, UBV
Keywords: binaries: eclipsing - stars: evolution - stars: fundamental parameters
Abstract:
We report differential photometric observations and radial-velocity
measurements of the detached, 1.69 day period, double-lined eclipsing
binary AQ Ser. Accurate masses and radii for the components are
determined to better than 1.8% and 1.1%, respectively, and are
M1=1.417±0.021M☉, M2=1.346±0.024M☉,
R1=2.451±0.027R☉, and R2=2.281±0.014R☉. The
temperatures are 6340±100K (spectral type F6) and 6430±100K (F5),
respectively. Both stars are considerably evolved, such that
predictions from stellar evolution theory are particularly sensitive
to the degree of extra mixing above the convective core (overshoot).
The component masses are different enough to exclude a location in the
H-R diagram past the point of central hydrogen exhaustion, which
implies the need for extra mixing. Moreover, we find that current
main-sequence models are unable to match the observed properties at a
single age even when allowing the unknown metallicity, mixing length
parameter, and convective overshooting parameter to vary freely and
independently for the two components. The age of the more massive star
appears systematically younger. AQ Ser and other similarly evolved
eclipsing binaries showing the same discrepancy highlight an
outstanding and largely overlooked problem with the description of
overshooting in current stellar theory.
Description:
Photometric measurements of AQ Ser were determined by two different
and independent robotic observatories: the Undergraduate Research
Studies in Astronomy (URSA) WebScope, and the Neely and Farley
Observatory (NFO) WebScope.
The URSA WebScope uses a 10inch Meade LX200 Schmidt-Cassegrain
telescope with an SBIG ST8 CCD camera, housed in a Technical
Innovations RoboDome on the roof of the Kimpel Hall on the University
of Arkansas campus at Fayetteville. Observations with a Bessel V
filter were carried out from 2003 June to 2011 July, producing a total
of 8642 science frames from 80s exposures.
The NFO WebScope is located near Silver City (New Mexico) in a
roll-off roof structure, and consists of a 24 inch Cassegrain
reflector. At the focus is a camera based on the Kodak KAF-4301E CCD
chip. AQ Ser was observed at the NFO between 2005 January and 2007
June, producing a total of 6694 observations from 80 s exposures with
a Bessel V filter.
Spectroscopic observations of AQ Ser were carried out at the
Harvard-Smithsonian Center for Astrophysics using an echelle
spectrograph on the 1.5m Tillinghast reflector at the F. L. Whipple
Observatory (Mount Hopkins, Arizona). The resolving power of these
observations is λ/Δλ~35000. We gathered 39
spectra between 2004 March and 2008 June.
Objects:
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RA (ICRS) DE Designation(s) (Period)
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15 22 15.18 +02 30 11.1 AQ Serpentis = BD+03 3015 (P=1.68743059)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 25 8642 Differential V-band measurements of AQ Ser from the
the URSA WebScope (at Kimpel Observatory, Arkansas)
table2.dat 25 6694 Differential V-band measurements of AQ Ser from
the NFO WebScope (near Silver City, New Mexico)
table3.dat 50 39 Heliocentric radial velocities for AQ Ser
table5.dat 31 215 Eclipse timing measurements for AQ Ser
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See also:
V/128 : Chromospherically Active Binaries. Third version (Eker+, 2008)
B/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2013)
J/AJ/147/1 : Spectroscopy and photometry of HP Aur (Lacy+, 2014)
J/AJ/143/129 : BF Dra photometric & spectroscopic observations (Lacy+, 2012)
J/AJ/139/2347 : CO And Vr light curves and RV curve (Lacy+, 2010)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 11 F11.5 d HJD Heliocentric Julian Date (HJD-2400000)
13- 18 F6.4 --- Phase [0/1] Orbital phase (G1)
20- 25 F6.3 mag DVmag Differential V band magnitude
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 d HJD Heliocentric Julian Date (HJD-2400000)
12- 17 F6.4 --- Phase [0/1] Orbital phase (G1)
19- 24 F6.1 km/s RV1 Primary radial velocity
26- 28 F3.1 km/s e_RV1 Error in RA1
30- 35 F6.1 km/s RV2 Secondary radial velocity
37- 39 F3.1 km/s e_RV2 Error in RA2
41- 44 F4.1 km/s O-C1 Primary (O-C) residual
46- 50 F5.1 km/s O-C2 Secondary (O-C) residual
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 11 F11.5 d HJD Heliocentric Julian Date (HJD-2400000)
13- 19 F7.5 d e_HJD Uncertainty in HJD (1)
21 A1 --- Type Eclipse type (primary or secondary) (2)
23 A1 --- Src Source of the measurement (3)
25- 31 F7.4 d O-C Residual (4)
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Note (1): Uncertainties include the scaling described in Section 3.
Note (2): Type of eclipse are defined as below:
p = primary (hotter and less massive star, behind during the deeper minimum);
s = secondary.
Note (3): Source of measurement as follows:
P = Photographic (from the literature);
V = Visual (from the literature);
C = CCD or photoelectric (from the literature);
U = New measurement from incompletely covered minima gathered with URSA
(Undergraduate Research Studies in Astronomy WebScope) and fit using a
Wilson-Devinney (WD) model (see Section 4);
N = New measurement from incompletely covered minima gathered with NFO (Neely
and Farley Observatory WebScope) and fit using a WD model (see Section 4);
u = Weighted mean of new determinations made with the Kwee & van Woerden
(1956BAN....12..327K 1956BAN....12..327K), a parabolic fit, and the WD procedure, for minima
with observations on both the descending and ascending branches.
n = Weighted mean of new determinations made with the Kwee & van Woerden
(1956BAN....12..327K 1956BAN....12..327K), a parabolic fit, and the WD procedure, for minima
with observations on both the descending and ascending branches.
Note (4): Residuals are based on the following ephemeris:
MinI=2453399.982270(47)+1.68743059(17)E.
The standard deviation of the (weighted) residuals is 0.0042 days for the
all residuals combined.
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Global notes:
Note (G1): Computed with the following ephemeris:
MinI=2453399.982270(47)+1.68743059(17)E.
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 05-Sep-2014