J/AJ/155/21 Planet candidates from K2 campaigns 5-8 (Petigura+, 2018)
Planet candidates from K2 campaigns 5-8 and follow-up optical spectroscopy.
Petigura E.A., Crossfield I.J.M., Isaacson H., Beichman C.A.,
Christiansen J.L., Dressing C.D., Fulton B.J., Howard A.W., Kosiarek M.R.,
Lepine S., Schlieder J.E., Sinukoff E., Yee S.W.
<Astron. J., 155, 21 (2018)>
=2018AJ....155...21P 2018AJ....155...21P (SIMBAD/NED BibCode)
ADC_Keywords: Exoplanets ; Stars, double and multiple ; Stars, diameters ;
Effective temperatures ; Abundances, [Fe/H] ; Stars, masses ;
Spectroscopy
Keywords: planetary systems - planets and satellites: detection -
planets and satellites: fundamental parameters - stars: abundances -
stars: fundamental parameters - techniques: spectroscopic
Abstract:
We present 151 planet candidates orbiting 141 stars from K2 campaigns 5-8
(C5-C8), identified through a systematic search of K2 photometry. In
addition, we identify 16 targets as likely eclipsing binaries, based
on their light curve morphology. We obtained follow-up optical spectra
of 105/141 candidate host stars and 8/16 eclipsing binaries to improve
stellar properties and to identify spectroscopic binaries. Importantly,
spectroscopy enables measurements of host star radii with ∼10% precision,
compared to ∼40% precision when only broadband photometry is available.
The improved stellar radii enable improved planet radii. Our curated
catalog of planet candidates provides a starting point for future
efforts to confirm and characterize K2 discoveries.
Description:
In this paper, we provide a catalog of planet candidates and eclipsing
binaries from the second year of K2 operations, corresponding to
campaigns 5-8 (C5-C8). We generated light curves for 87913 stars
observed by K2 during C5-C8 using the publicly available k2phot Python
package (https://github.com/petigura/k2phot). The general methodology
is described in previous works (Crossfield et al. 2015ApJ...804...10C 2015ApJ...804...10C,
2016, J/ApJS/226/7; Petigura et al. 2015ApJ...811..102P 2015ApJ...811..102P).
As a part of our team's standard follow-up efforts, we obtained optical
spectra of 143 C5-C8 target stars using the HIgh Resolution Echelle
Spectrometer (HIRES; Vogt et al. 1994SPIE.2198..362V 1994SPIE.2198..362V) on the Keck I 10 m
telescope. We gathered spectra for the purpose of improving host star
parameters and to place limits on the presence of companion stars with
small separations through searches for spectroscopic binaries (SB2s).
We aimed to obtain a spectrum of every K2OI brighter than V=14.0 mag.
For G stars, this limit corresponds roughly to Kp=13.6 mag.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 220 167 Planet Candidates
table2.dat 80 143 Stars with HIRES Spectra and Derived Parameters
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See also:
J/ApJ/809/25 : Stellar and planet properties for K2 candidates
(Montet+, 2015)
J/A+A/594/A100 : K2 new planetary and EB candidates (Barros+, 2016)
J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)
J/ApJS/226/7 : Planet candidates discovered using K2's 1st yr
(Crossfield+, 2016)
J/ApJ/836/77 : A library of high-S/N optical spectra of FGKM stars
(Yee+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Camp K2 campaign identifier
4- 15 F12.2 --- K2OI K2 Object of Interest identifier
17- 20 F4.1 mag Kpmag [8.8/17.5] Kepler apparent magnitude
22- 26 F5.2 Rsun R* [0.23/11.57] Highest quality stellar radius
28 A1 --- n_R* [SP] Note on R* (1)
30- 38 F9.6 d Per [0.515013/30.952606] Planet orbital period
40- 47 F8.6 d E_Per [2e-06/0.006202] Upper uncertainty in Per
49- 56 F8.6 d e_Per [2e-06/0.005718] Lower uncertainty in Per
58- 68 F11.6 d T0 Modified Julian Date of first transit time
70- 77 F8.6 d E_T0 Upper uncertainty in T0
79- 86 F8.6 d e_T0 Lower uncertainty in T0
88- 92 F5.2 % Rp/R* [0.97/60.7] Planet to star radius ratio
94- 98 F5.2 % E_Rp/R* [0.01/46.48] Upper uncertainty in Rp/R*
100-104 F5.2 % e_Rp/R* [0.01/28.86] Lower uncertainty in Rp/R*
106-110 F5.2 h T14 [0/11.05] Time between first and last contact
112-115 F4.2 h E_T14 [0/1.21] Upper uncertainty in T14
117-120 F4.2 h e_T14 [0/3.9] Lower uncertainty in T14
122-125 F4.2 --- b [0.03/1.69] Impact parameter
127-130 F4.2 --- E_b [0.01/0.66] Upper uncertainty in b
132-135 F4.2 --- e_b [0.01/0.53] Lower uncertainty in b
137-141 F5.1 Rgeo Rp [1/591.1] Planetary radius
143-147 F5.1 Rgeo E_Rp [0.1/453.8] Upper uncertainty in Rp
149-153 F5.1 Rgeo e_Rp [0.1/367.2] Lower uncertainty in Rp
155 I1 --- EB [0/2]? Eclipsing binary assessment code (2)
157-220 A64 --- Com Additional comment
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Note (1): Note as follows:
S = Computed from spectroscopy;
P = Computed from photometry.
Note (2): Eclipsing binary assessment code as follows:
0 = No obvious indication of EB;
1 = Secondary eclipse visible;
2 = Photometric variability that is phase-locked to the eclipse.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Camp K2 campaign identifier
4- 12 I9 --- EPIC [211311380/220725183] EPIC identifier
14- 17 F4.1 mag Kpmag [6.5/15.5] Kepler apparent magnitude
19- 22 I4 K Teff [3633/7030]? Effective temperature (1)
24- 27 F4.2 [cm/s2] log(g) [2.12/4.81]? Log surface gravity (1)
29- 33 F5.2 [Sun] [Fe/H] [-1.54/0.45]? Metallicity (1)
35- 39 F5.1 km/s vsin(i) [0/252.7]? Projected rotational velocity (1)
41- 44 F4.2 Msun M* [0.69/2.09]? Stellar mass (1)
46- 49 F4.2 Msun E_M* [0.03/0.58]? Upper uncertainty in M*
51- 54 F4.2 Msun e_M* [0.03/0.56]? Lower uncertainty in M*
56- 60 F5.2 Rsun R* [0.45/13.91]? Stellar radius (1)
62- 65 F4.2 Rsun E_R* [0.02/2.96]? Upper uncertainty in R*
67- 70 F4.2 Rsun e_R* [0.02/2.32]? Lower uncertainty in R*
72 I1 --- Src [0/2]? Source of spectroscopic properties (2)
74 I1 --- SB2 [1/5] ReaMatch classification code (3)
76- 80 A5 --- Type Type flag (4)
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Note (1): We derived stellar properties using two complimentary techniques:
SpecMatch-Syn (Petigura 2015PhDT........82P 2015PhDT........82P) and SpecMatch-Emp (Yee et al.
2017, J/ApJ/836/77). For stars cooler than 4700 K, we used SpecMatch-Syn to
compute Teff, logg, and [Fe/H], which were converted into R* and M* using
the isochrones package (Morton 2015ascl.soft03010M). For stars cooler than
4700 K, we used SpecMatch-Emp to compute Teff, R*, M*, and [Fe/H].
We also searched for SB2s using the methodology of Kolbl et al.
(2015AJ....149...18K 2015AJ....149...18K).
Note (2): Source of spectroscopic properties as follows:
0 = Spectroscopic properties are not reliable (13 stars);
1 = Parameters from SpecMatch-Syn (116 stars);
2 = Parameters from SpecMatch-Emp (14 stars). The spectroscopic parameters
are not reliable if Teff>6500 K or vsin(i)>20 km/s. SpecMatch-Syn achieves
precisions of 60 K, 0.10 dex, 0.04 dex, and 1 km/s in Teff, log(g), [Fe/H],
and vsin(i). SpecMatch-Emp achieves precisions of 70 K in Teff, 10%
in R*, and 0.12 dex in [Fe/H].
Note (3): ReaMatch (Kolbl et al. 2015AJ....149...18K 2015AJ....149...18K) classification code as
follows:
1 = No detection;
2 = Star is unfit for ReaMatch: Teff below 3500 K or above 6500 K;
3 = Star is unfit for ReaMatch: vsin(i) above 10 km/s;
4 = Ambiguous detection;
5 = Obvious detection.
Note (4): Type flag as follows:
PC = Planet candidate;
EB = Eclipsing binary;
Other = Not included in our candidate list.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 13-Sep-2018