J/AJ/157/211 Unresolved binaries in TESS with speckle imaging (Matson+, 2019)
Detecting unresolved binaries in TESS data with speckle imaging.
Matson R.A., Howell S.B., Ciardi D.R.
<Astron. J., 157, 211 (2019)>
=2019AJ....157..211M 2019AJ....157..211M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, bright ; Stars, double and multiple ;
Stars, masses ; Stars, diameters ; Effective temperatures ;
Magnitudes ; Stars, distances ; Spectral types
Keywords: binaries: general - binaries: visual - planetary systems -
techniques: high angular resolution
Abstract:
The Transiting Exoplanet Survey Satellite (TESS) is conducting a two-year
wide-field survey searching for transiting exoplanets around nearby bright
stars that will be ideal for follow-up characterization. To facilitate
studies of planet compositions and atmospheric properties, accurate and
precise planetary radii need to be derived from the transit light curves.
Since 40%-50% of exoplanet host stars are in multiple star systems,
however, the observed transit depth may be diluted by the flux of a
companion star, causing the radius of the planet to be underestimated.
High angular resolution imaging can detect companion stars that are not
resolved in the TESS Input Catalog, or by seeing-limited photometry,
to validate exoplanet candidates and derive accurate planetary radii.
We examine the population of stellar companions that will be detectable
around TESS planet candidate host stars, and those that will remain
undetected, by applying the detection limits of speckle imaging to the
simulated host star populations of Sullivan et al. (2015, J/ApJ/809/77)
and Barclay et al. (2018, J/ApJS/239/2). By detecting companions with
contrasts of Δm~<7-9 and separations of ∼0.02"-1.2", speckle imaging
can detect companion stars as faint as early M stars around A-F stars and
stars as faint as mid-M around G-M stars, as well as up to 99% of the
expected binary star distribution for systems located within a few hundred
parsecs.
Description:
Since 2010, the Differential Speckle Survey Instrument (DSSI;
Horch et al. 2009AJ....137.5057H 2009AJ....137.5057H) has been used to provide
diffraction-limited imaging of targets of interest from the Kepler/K2
mission at the 3.5 m WIYN telescope at Kitt Peak National Observatory,
the 8 m Frederick C. Gillett Gemini North telescope on the summit of
Maunakea in Hawaii, and the 8 m Gemini South telescope on the summit
of Cerro Pachon in Chile. Based on the success of DSSI, two new speckle
instruments were designed and built at NASA's Ames Research Center to
enable validation and characterization of exoplanet candidates discovered
by Kepler, K2, and future missions. The NASA-NSF Exoplanet Observational
Research (NN-EXPLORE) Exoplanet Stellar Imager (NESSI) is available at
WIYN (Scott et al. 2018PASP..130e4502S 2018PASP..130e4502S), while the second speckle
instrument, 'Alopeke, resides at Gemini North (N. J. Scott et al. 2019,
in preparation). DSSI is still used as a visiting instrument at Gemini
South, but a third dedicated speckle instrument, Zorro, will be
commissioned there in summer 2019.
In this work we use the TESS predictions of Sullivan et al. (2015,
J/ApJ/809/77) and Barclay et al. (2018, J/ApJS/239/2) to examine the
expected host star properties and determine the types of bound stellar
companions that will be unresolved in TESS data and their impact on
planetary properties. Since we anticipate Zorro, which will be identical
to 'Alopeke, to be available in early 2019 we focus on the observing
capabilities of 'Alopeke/Zorro and NESSI; however, DSSI will make
similar contributions at Gemini South in the meantime.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 97 787 Stellar parameters and companion space observable
with speckle imaging for stars in Barclay et al.
(2018, J/ApJS/239/2)
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See also:
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/AJ/156/102 : The TESS Input Catalog and Candidate Target List
(Stassun+, 2018)
J/ApJS/239/2 : Simulated exoplanets from TESS list of targets (Barclay+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- TIC [593228/470971145] TESS Input Catalog identifier
11- 15 F5.3 Msun M* [0.068/2.437] Stellar mass
17- 22 F6.3 Rsun R* [0.088/35.912] Stellar radius
24- 27 I4 K Teff [2560/9571] Effective temperature
29- 33 F5.2 mag Vmag [4.33/12.05] Apparent V band magnitude
35- 39 F5.2 mag Tmag [3.32/11.52] Apparent TESS band magnitude
41- 47 F7.2 pc Dist [1.18/1072.76]? Distance
49- 53 A5 --- SpType Stellar MK spectral type
55- 59 A5 --- SpT-6 Companion MK spectral type at Δmv=6
61- 65 A5 --- SpT-8 Companion MK spectral type at Δmv=8
67- 71 F5.3 --- Comp [0/1]? Fraction of companions with Δmv=<8
73- 77 F5.2 AU b_Sep [0.02/18.73]? Minimum companion separation (1)
79- 85 F7.2 AU B_Sep [1.42/1287.31]? Maximum companion separation (1)
87- 91 F5.3 --- Dis [0/1]? Fraction of companion orbital period
distribution (1)
93- 97 F5.3 --- Spec [0/1]? Fraction of companions detectable with
speckle imaging
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Note (1): Observable with speckle imaging.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 08-Aug-2019