J/A+A/580/A21 BEER analysis of CoRoT light curves (Tal-Or+, 2015)
BEER analysis of Kepler and CoRoT light curves.
III. Spectroscopic confirmation of seventy new beaming binaries discovered in
CoRoT lightcurves.
Tal-Or L., Faigler S., Mazeh T.
<Astron. Astrophys. 580, A21 (2015)>
=2015A&A...580A..21T 2015A&A...580A..21T
ADC_Keywords: Binaries, spectroscopic ; Binaries, eclipsing
Keywords: binaries: spectroscopic - binaries: eclipsing - brown dwarfs -
techniques: photometric - techniques: spectroscopic -
techniques: radial velocities
Abstract:
The BEER algorithm, introduced by Faigler & Mazeh
(2011MNRAS.415.3921F 2011MNRAS.415.3921F), searches stellar lightcurves for the BEaming,
Ellipsoidal, and Reflection (BEER) photometric modulations that are
caused by a short-period companion. These three effects are typically
of very low amplitude, and can mainly be detected in lightcurves from
space-based photometers. Unlike eclipsing binaries, these effects are
not limited to edge-on inclinations.
Applying the algorithm to wide-field photometric surveys such as CoRoT
and Kepler offers an opportunity to better understand the statistical
properties of short-period binaries. It also widens the window for
detecting intrinsically rare systems, like short-period brown-dwarf
and massive- planetary companions to main-sequence stars.
Applying the search to the first five long-run center CoRoT fields, we
identified 481 non-eclipsing candidates with periodic flux amplitudes
of 0.5-87mmag. Optimizing the Anglo-Australian-Telescope pointing
coordinates and the AAOmega fiber-allocations with dedicated
softwares, we acquired 6-7 medium-resolution spectra of 281 candidates
in a seven-night campaign. Analysis of the red-arm AAOmega spectra,
which covered the range of 8342-8842Å, yielded a radial-velocity
precision of ∼1 km/s. Spectra containing lines of more than one star
were analyzed with the two- dimensional correlation algorithm TODCOR.
The measured radial velocities confirmed the binarity of seventy of
the BEER candidates, 45 single-line binaries, 18 double-line binaries,
and 7 diluted binaries. We show that red giants introduce a major
source of false candidates and demonstrate a way to improve BEER's
performance in extracting higher fidelity samples from future searches
of CoRoT lightcurves. The periods of the confirmed binaries span a
range of 0.3-10days and show a rise in the number of binaries per
logP bin toward longer periods. The estimated mass ratios of the
double-line binaries and the mass ratios assigned to the single-line
binaries, assuming an isotropic inclination distribution, span a range
of 0.03-1. On the low-mass end we have detected two brown-dwarf
candidates on a ∼1day period orbit. This is the first time
non-eclipsing beaming binaries are detected in CoRoT data, and we
estimate that ∼300 such binaries can be detected in the CoRoT long-run
lightcurves.
Description:
We performed RV follow-up observations with the AAOmega multi-object
spectrograph at the Anglo-Australian Telescope (AAT). In total, we
observed 281 out of the 481 selected BEER candidates.
Table 2 lists the coordinates, magnitudes, photometric ephemeris, and
amplitudes of the three BEER effects for the candidates observed with
AAOmega. For convenience, the confirmed binaries are indicated in the
rightmost column of Table 2.
Table 4 lists the 255 non-composite spectrum candidates observed, and
the synthetic-spectrum parameters used to derive their RVs. For
convenience, the rightmost column identifies the confirmed BEER
single-line binaries (SB1s), 45 of which were identified in that list.
Table 5 lists the 26 composite-spectrum BEER candidates detected, the
primary and secondary synthetic-spectrum parameters used by TODCOR to
derive the primary and secondary RVs, and the estimated flux ratio
between the primary and the secondary components (TODCOR's alpha
parameter).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 124 281 Coordinates and photometric parameters of the
BEER candidates observed at AAOmega
table4.dat 30 255 Template parameters of the non-composite
spectrum candidates
table5.dat 50 26 Template parameters of the composite spectrum
candidates
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See also:
B/corot : CoRoT observation log Release 13 (CoRoT, 2009-2014)
J/A+A/479/865 : CoRoT exoplanet candidates (Loeillet+, 2008)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- CoRoT CoRoT ID
11- 18 F8.4 deg RAdeg Right ascension (J2000)
20- 26 F7.4 deg DEdeg Declination (J2000)
28- 31 F4.1 mag Vmag [12.4/17.1] Magnitude in V filter
33- 42 F10.7 d P [0.07/17] Orbital period
44- 52 F9.7 d e_P Orbital period uncertainty
54- 65 F12.4 d T0 Orbital phase (HJD)
66- 72 F7.4 d e_T0 Orbital phase uncertainty
75- 82 F8.1 ppm Aell [-86963/-94] Ellipsoidal amplitude (in 10-6)
85- 90 F6.1 ppm e_Aell [3/2024] Ellipsoidal amplitude uncertainty
92- 98 F7.1 ppm Abeam [-16/11552] Beaming amplitude (in 10-6)
101-106 F6.1 ppm e_Abeam [5/4728] Beaming amplitude uncertainty
107-114 F8.1 ppm Aref [-18809/9718] Reflection amplitude (in 10-6)
117-122 F6.1 ppm e_Aref [7/3692] Reflection amplitude uncertainty
124 I1 --- Conf [0/1] Confirmation flag: 0=false alarm,
1=confirmed BEER binary
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- CoRoT CoRoT ID
11- 14 I4 K Teff [4800/9200] Effective temperature
16- 18 F3.1 [cm/s] logg [2.5/5.5] Surface gravity
20- 23 F4.1 [Sun] [m/H] [-1.5/0.5] Metallicity
25- 27 I3 km/s rot [1/188] Projected rotational broadening
of the lines
30 I1 --- Conf [0/1] Confirmation flag: 0=false alarm,
1=confirmed BEER binary
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- CoRoT CoRoT ID
11- 14 I4 K Teff1 [5000/8200] Primary effective temperature
16- 18 F3.1 [cm/s2] logg1 [3/5] Primary surface gravity
20- 23 F4.1 [Sun] [m/H]1 [0/0.5] Primary metallicity
25- 27 I3 km/s rot1 [1/151] Primary projected rotational
broadening of the lines
29- 32 I4 K Teff2 [4700/6600] Secondary effective temperature
34- 36 F3.1 [cm/s2] logg2 [4/4.5] Secondary surface gravity
38- 41 F4.1 [Sun] [m/H]2 [0/0.5] Secondary metallicity
43- 45 I3 km/s rot2 [5/131] Secondary projected rotational
broadening of the lines
47- 50 F4.2 --- alpha [0/1] Flux ratio (B/A) in AAOmega
red-arm spectra
--------------------------------------------------------------------------------
Acknowledgements:
Lev Tal-Or, levtalo(at)post.tau.ac.il
References:
Faigler et al., Paper I 2013ApJ...771...26F 2013ApJ...771...26F
Faigler & Mazeh, Paper II 2015ApJ...800...73F 2015ApJ...800...73F
(End) Lev Tal-Or [Tel Aviv Univ., Israel], Patricia Vannier [CDS] 28-May-2015