J/AJ/156/259 Robo-AO detected close binaries in Gaia DR2 (Ziegler+, 2018)
Measuring the recoverability of close binaries in Gaia DR2 with the Robo-AO
Kepler survey.
Ziegler C., Law N.M., Baranec C., Morton T., Riddle R., De Lee N., Huber D.,
Mahadevan S., Pepper J.
<Astron. J., 156, 259 (2018)>
=2018AJ....156..259Z 2018AJ....156..259Z (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry
Keywords: binaries: close - instrumentation: adaptive optics -
methods: data analysis - methods: observational -
techniques: high angular resolution
Abstract:
We use the Robo-AO survey of Kepler planetary candidate host stars,
the largest adaptive optics survey yet performed, to measure the recovery
rate of close stellar binaries in Gaia DR2 (Cat. I/345). We find that Gaia
recovers binaries down to 1" at magnitude contrasts as large as six; closer
systems are not resolved, regardless of secondary brightness. Gaia DR2
binary detection does not have a strong dependence on the orientation of
the stellar pairs. We find 177 nearby stars to Kepler planetary candidate
host stars in Gaia DR2 that were not detected in the Robo-AO survey, almost
all of which are faint (G>20); the remainder were largely targets observed
by Robo-AO in poor conditions. If the primary star is the host, the impact
on the radii estimates of planet candidates in these systems is likely
minimal; many of these faint stars, however, could be faint eclipsing
binaries that are the source of a false positive planetary transit signal.
With Robo-AO and Gaia combined, we find that 18.7±0.7% of Kepler planet
candidate hosts have nearby stars within 4". We also find 36 nearby stars
in Gaia DR2 around 35 planetary candidate host stars detected with K2.
The nearby star fraction rate for K2 planetary candidates is significantly
lower than that for the primary Kepler mission. The binary recovery rate
of Gaia will improve initial radius estimates of future Transiting
Exoplanet Survey Satellite planet candidates significantly; however,
ground-based high-resolution follow-up observations are still needed for
precise characterization and confirmation. The sensitivity of Gaia to
closely separated binaries is expected to improve in later data releases.
Description:
Observations in the survey were performed using the Robo-AO automated
laser adaptive optics system at Palomar and Kitt Peak (Baranec et al.
2014ApJ...790L...8B 2014ApJ...790L...8B, 2017arXiv170907103B 2017arXiv170907103B; Jensen-Clem et al.
2018AJ....155...32J 2018AJ....155...32J) that can efficiently perform large, high angular
resolution surveys. The adaptive optics system runs at a loop rate of
1.2 kHz to correct high-order wavefront aberrations, delivering median
Strehl ratios of 9% and 4% in the i'-band at Palomar and Kitt Peak,
respectively. Observations were between 90 and 120 s, and taken in a
long-pass filter cutting on at 600 nm. We obtained high-angular-resolution
images of 3313 KOIs with Robo-AO between 2012 July 16 and 2015 June 12 (UT)
at the Palomar 1.5 m telescope. We observed 532 additional KOIs with
Robo-AO between 2016 June 8 and July 15 (UT) at the Kitt Peak 2.1 m
telescope.
A list of sources from DR2 (Cat. I/345) within 5" of the positions of
the candidates was generated, and the host star was identified with
magnitude cuts using the Kepler magnitude and Gaia G-magnitude. Detections
of sources nearby K2 planet candidate host stars are listed in Table 1.
We find that, of the 620 stars detected with Robo-AO within 4" of 3857
Kepler planetary candidates, 484, or 78%, appear in Gaia DR2. The recovery
classifications for each star is listed in Table 2, along with the Robo-AO
measured binary properties and Gaia DR2 source IDs for the primary and
recovered secondary stars. Within 4" of the 3857 Kepler planetary candidate
host stars observed by Robo-AO, Gaia DR2 catalogs 177 nearby stars around
163 host stars that were not detected in the Robo-AO survey. The properties
of these nearby stars, calculated from the Gaia astrometry and photometry,
are listed in Table 3.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 92 36 Nearby stars to K2 planetary candidates in Gaia DR2
(Cat. I/345)
table2.dat 92 601 Robo-AO detected nearby stars to Kepler planetary
candidates in Gaia DR2
table3.dat 92 172 New nearby stars to Kepler planetary candidates
in Gaia DR2
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/791/35 : Detection of 715 Kepler planet candidates host stars
(Law+, 2014)
J/AJ/152/18 : Robo-AO Kepler planetary candidate survey. II. (Baranec+, 2016)
J/AJ/153/66 : Robo-AO Kepler Planetary Candidate Survey. III.
(Ziegler+, 2017)
J/ApJS/229/30 : Revised stellar properties of Q1-17 Kepler targets
(Mathur+, 2017)
J/AJ/155/161 : Stars nearby Robo-AO Kepler planetary candidates
(Ziegler+, 2018)
J/ApJS/235/38 : Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018)
Byte-by-byte Description of file: table1.dat table2.dat table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.2 --- Planet ? K2 planet candidate (only in Table 1)
14- 17 I4 --- KOI [1/7596]? Kepler Object of Interest (not in
Table 1)
19- 22 F4.2 arcsec Sep [0.21/4.54] Separation
24- 26 I3 deg PA [0/358] Position angle (degrees east of north)
28- 32 F5.2 mag Dgmag [-0.67/8.16] Gaia g-band magnitude difference
34 I1 --- K2C [0/8]? K2 campaign (only in Table 1)
36- 38 A3 --- Ref Detection reference (only in Table 2) (1)
40- 58 I19 --- PriDR2 ? Primary Gaia DR2 identifier (2)
60- 78 I19 --- SecDR2 ? Secondary Gaia DR2 identifier (2)
80- 92 A13 --- Recov Recovery status (only in Table 2) (3)
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Note (1): Provenance of reported companion properties is the detection reference
publication:
L14 = Law et al. (2014, J/ApJ/791/35);
B16 = Baranec et al. (2016, J/AJ/152/18);
Z17 = Ziegler et al. (2017, J/AJ/153/66);
Z18 = Ziegler et al. (2018, J/AJ/155/161).
Note (2): In Table 3, provenance of reported companion properties is from Gaia
DR2 (Gaia Collaboration et al. 2018, Cat. I/345).
Note (3): Recovery status as follows:
recovered = Nearby stars in Gaia DR2 (Cat. I/345) with similar contrasts
and separations (G-magnitude within 1 magnitude and
separations within 0.20") to the nearby stars detected using
Robo-AO;
not-recovered = Nearby stars detected with Robo-AO that are not in Gaia DR2.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 16-Apr-2019