J/ApJ/809/25 Stellar and planet properties for K2 candidates (Montet+, 2015)
Stellar and planetary properties of K2 campaign 1 candidates and validation
of 17 planets, including a planet receiving earth-like insolation.
Montet B.T., Morton T.D., Foreman-Mackey D., Johnson J.A., Hogg D.W.,
Bowler B.P., Latham D.W., Bieryla A., Mann A.W.
<Astrophys. J., 809, 25 (2015)>
=2015ApJ...809...25M 2015ApJ...809...25M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry, UBVRIJKLMNH ;
Stars, masses ; Stars, diameters ; Abundances, [Fe/H]
Keywords: catalogs - planetary systems - planets and satellites: detection -
stars: fundamental parameters
Abstract:
The extended Kepler mission, K2, is now providing photometry of new
fields every three months in a search for transiting planets. In a
recent study, Foreman-Mackey and collaborators presented a list of 36
planet candidates orbiting 31 stars in K2 Campaign 1. In this
contribution, we present stellar and planetary properties for all
systems. We combine ground-based seeing-limited survey data and
adaptive optics imaging with an automated transit analysis scheme to
validate 21 candidates as planets, 17 for the first time, and identify
6 candidates as likely false positives. Of particular interest is
K2-18 (EPIC 201912552), a bright (K=8.9) M2.8 dwarf hosting a
2.23±0.25 R{earth} planet with Teq=272±15 K and an orbital
period of 33 days. We also present two new open-source software
packages which enable this analysis. The first, isochrones, is a
flexible tool for fitting theoretical stellar models to observational
data to determine stellar properties using a nested sampling scheme to
capture the multimodal nature of the posterior distributions of the
physical parameters of stars that may plausibly be evolved. The second
is vespa, a new general-purpose procedure to calculate false positive
probabilities and statistically validate transiting exoplanets.
Description:
In this paper, we present stellar and planetary parameters for each
system. We also analyze the false positive probability (FPP) of each
system using vespa, a new publicly available, general-purpose
implementation of the Morton (2012ApJ...761....6M 2012ApJ...761....6M) procedure to
calculate FPPs for transiting planets. Through this analysis, as well
as archival imaging, ground-based seeing-limited survey data, and
adaptive optics imaging, we are able to confirm 21 of these systems as
transiting planets at the 99% confidence level. Additionally, we
identify six systems as false positives.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 130 31 *Photometry for All Objects of Interest
table2.dat 118 31 *Stellar Properties for All Objects of Interest
table3.dat 112 36 *Planet Properties for All Objects of Interest
table4.dat 79 31 Detected Companions to Candidate Host Stars
table5.dat 75 36 False Positive Probability Calculation Results
--------------------------------------------------------------------------------
Note on table1.dat:
These data are available in interactive form at
https://filtergraph.com/k2_planets_montet.
Note on table2.dat:
The values and their uncertainties are derived from MULTINEST analysis and the
numbers are computed as the 0.158, 0.500, and 0.842 posterior sample quantiles.
Note on table3.dat:
These values and uncertainties are given by the mean and standard deviation of
MCMC posterior samplings.
--------------------------------------------------------------------------------
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/ApJ/738/170 : False positive Kepler planet candidates (Morton+, 2011)
J/ApJS/197/8 : Kepler's candidate multiple transiting planets
(Lissauer+, 2011)
J/ApJ/783/4 : Properties of Kepler multi-planet candidate systems
(Wang+, 2014)
J/A+A/582/A33 : K2-19b light curve (Armstrong+, 2015)
J/A+A/594/A100 : K2 new planetary and EB candidates (Barros+, 2016)
J/AJ/152/18 : Robo-AO Kepler planetary candidate survey. II.
(Baranec+, 2016)
J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)
J/ApJS/224/12 : Kepler planetary candidates. VII. 48-month (Coughlin+, 2016)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- Star Star's name (EPIC NNNNNNNNN in Simbad)
11- 15 F5.2 mag Bmag ? APASS DR6 B-band magnitude (1)
17- 20 F4.2 mag e_Bmag ? Uncertainty in Bmag (1)
22- 26 F5.2 mag Vmag ? APASS DR6 V-band magnitude (1)
28- 31 F4.2 mag e_Vmag ? Uncertainty in Vmag (1)
33- 37 F5.2 mag gmag APASS DR6 g-band magnitude (1)
39- 42 F4.2 mag e_gmag Uncertainty in gmag (1)
44- 48 F5.2 mag rmag APASS DR6 r-band magnitude (1)
50- 53 F4.2 mag e_rmag Uncertainty in rmag (1)
55- 59 F5.2 mag imag APASS DR6 i-band magnitude (1)
61- 64 F4.2 mag e_imag Uncertainty in imag (1)
66- 70 F5.2 mag Jmag 2MASS J-band magnitude (2)
72- 75 F4.2 mag e_Jmag Uncertainty in Jmag (2)
77- 81 F5.2 mag Hmag 2MASS H-band magnitude (2)
83- 86 F4.2 mag e_Hmag Uncertainty in Hmag (2)
88- 92 F5.2 mag Kmag 2MASS K-band magnitude (2)
94- 97 F4.2 mag e_Kmag Uncertainty in Kmag (2)
99-103 F5.2 mag W1mag AllWISE W1-band magnitude (3)
105-108 F4.2 mag e_W1mag Uncertainty in W1mag (3)
110-114 F5.2 mag W2mag AllWISE W2-band magnitude (3)
116-119 F4.2 mag e_W2mag Uncertainty in W2mag (3)
121-125 F5.2 mag W3mag ? AllWISE W3-band magnitude (3)
127-130 F4.2 mag e_W3mag ? Uncertainty in W3mag (3)
--------------------------------------------------------------------------------
Note (1): Magnitude from the AAVSO Photometric All-sky Survey (APASS) DR6
(Henden & Munari 2014CoSka..43..518H 2014CoSka..43..518H) as reported in the UCAC4 Catalog
(Zacharias et al. 2012yCat.1322....0Z 2012yCat.1322....0Z, Cat. I/322).
Note (2): Magnitude from the 2MASS All-sky Catalog of Point Sources
(Cutri et al. 2003, Cat. II/246).
Note (3): Magnitude from the ALLWise Data Release
(Cutri et al. 2013, Cat. II/328).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- Star Star's name (EPIC NNNNNNNNN in Simbad)
11- 15 A5 --- Other Other name (K2-NN)
16 A1 --- n_Other [a] Note on Other (G1)
18- 27 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000) (1)
29- 37 F9.6 deg DEdeg Declination in decimal degrees (J2000) (1)
39- 43 F5.3 Msun Mass Stellar mass
45- 49 F5.3 Msun E_Mass Upper limit uncertainty in Mass
51- 55 F5.3 Msun e_Mass Lower limit uncertainty in Mass
57- 62 F6.3 Rsun Rad Stellar radius
64- 68 F5.3 Rsun E_Rad Upper limit uncertainty in Rad
70- 74 F5.3 Rsun e_Rad Lower limit uncertainty in Rad
76- 79 I4 K Teff Effective temperature
81- 83 I3 K E_Teff Upper limit uncertainty in Teff
85- 87 I3 K e_Teff Lower limit uncertainty in Teff
89- 93 F5.2 [-] [Fe/H] Stellar metallicity (in dex)
95- 98 F4.2 [-] E_[Fe/H] Upper limit uncertainty in [Fe/H]
100-103 F4.2 [-] e_[Fe/H] Lower limit uncertainty in [Fe/H]
105-108 I4 pc Dist Distance
110-113 I4 pc E_Dist Upper limit uncertainty in Dist
115-118 I4 pc e_Dist Lower limit uncertainty in Dist
--------------------------------------------------------------------------------
Note (1): The coordinates are retrieved directly from the EPIC (Huber et al.
2016, J/ApJS/224/2).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.2 --- Planet Planet candidate name (EPIC NNNNNNNNN.NN in
Simbad)
14- 19 A6 --- Other Other name (K2-NNa)
21 A1 --- n_Other [a] Note on Other (G1)
23- 30 F8.5 d Per ? Period
32- 38 F7.5 d e_Per ? Uncertainty in Per
40- 46 F7.4 d Epoch ? Epoch (BJD-2456808)
48- 53 F6.4 d e_Epoch ? Uncertainty in Epoch
55- 60 F6.2 Rgeo Rad ? Planet radius
62- 66 F5.2 Rgeo e_Rad ? Uncertainty in Rad
68- 72 F5.2 --- a/R* ? Semi-major axis to stellar radius ratio
74- 78 F5.2 --- e_a/R* ? Uncertainty in a/R*
80- 85 F6.4 AU a ? Semi-major axis in AU
87- 92 F6.4 AU e_a ? Uncertainty in a
94- 97 I4 K Teq ? Equilibrium temperature
99-101 I3 K e_Teq ? Uncertainty in Teq
103-111 A9 --- Disp Disposition (Planet,Candidate,FP=False Positive)
112 A1 --- n_Disp [b] Note on Disp (1)
--------------------------------------------------------------------------------
Note (1): Note as follows:
b = Declared a false positive due to noise modeling systematics
(see Section 5.2).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- Star Primary star name (EPIC NNNNNNNNN in Simbad)
11- 14 F4.1 arcsec Aper Aperture used to create the K2 stellar light
curve
16- 25 F10.6 deg RAdeg ? Right Ascension in decimal degrees (J2000) (1)
27- 35 F9.6 deg DEdeg ? Declination in decimal degrees (J2000) (1)
37- 43 A7 --- Detec Dataset used to detect the imaged companion
45- 49 F5.2 arcsec Sep ? Separation (2)
51- 54 F4.2 arcsec e_Sep ? Uncertainty in Sep
55 A1 --- n_Sep [hi] Note on Sep (3)
57- 60 F4.2 mag drmag ? Difference in r-band magnitude between the
primary K2 target star and the companion
62- 65 F4.2 mag e_drmag ? Uncertainty in drmag
66 A1 --- n_drmag [j] Note on drmag (4)
68- 72 F5.1 10-3 Depth1 ? Observed "transit" depth (in parts per
thousand, ppt) (5)
74- 79 F6.2 10-3 Depth Observed transit depth in the K2 dataset (in
parts per thousand, ppt) (6)
--------------------------------------------------------------------------------
Note (1): Position of imaged companion.
Note (2): Distance between the primary K2 target star and companion, in the
dataset in which the companion is detected.
Note (3): Note as follows:
h = Separation from AO imaging;
i = Separation from SDSS photometry.
Note (4): Note as follows:
j = Δr inferred from JHK relative photometry.
Note (5): If the imaged companion's flux were fully contained in the aperture
and if it were an equal-mass eclipsing binary, leading to an eclipse
depth of 50%. This is the maximum possible false positive eclipse
depth, as described in Section 4.3.
Note (6): If larger than the "max depth", this transit event cannot be caused by
eclipses of the background star.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.2 --- Planet Planet candidate name (EPIC NNNNNNNNN.NN in
Simbad)
14- 19 A6 --- Other Other name (K2-NNa)
21- 24 F4.2 10-3 delta Maximum depth of potential secondary eclipse
signal (in parts per thousand, ppt)
26 A1 --- AO [Y-] Adaptive optics observation presented in
this paper ?
28 A1 --- l_PrEB [<] Limit flag on PrEB
29- 34 E6.2 --- PrEB ? Relative probability for this false positive
scenario : undiluted eclipsing binary
36 A1 --- l_PrBEB [<] Limit flag on PrBEB
37- 42 E6.2 --- PrBEB ? Relative probability for this false positive
scenario : chance-aligned background
(/foreground) eclipsing binary
44 A1 --- l_PrHEB [<] Limit flag on PrHEB
45- 50 E6.2 --- PrHEB ? Relative probability for this false positive
scenario : hierarchical triple eclipsing binary
52- 55 F4.2 --- fp ? Integrated planet occurrence rate (1)
57 A1 --- l_FPP [<] Limit flag on FPP
58- 63 E6.2 --- FPP ? False positive probability (2)
65- 73 A9 --- Disp Disposition (Planet,Candidate,FP=False Positive)
75 A1 --- n_Disp [defg] Note on Disp (3)
--------------------------------------------------------------------------------
Note (1): Assumed between 0.7x and 1.3x the candidate radius.
Note (2): Candidates are declared to be validated planets if FPP<0.01.
Note (3): Note as follows:
d = Despite low FPP, returned to candidate status out of abundance of caution
due to secondary star detection within or near photometric aperture.
e = Declared a false positive due to noise modeling systematics
(see Section 5.2).
f = Identified as planets by Crossfield et al. (2015ApJ...804...10C 2015ApJ...804...10C).
g = Identified as planets by Armstrong et al. (2015, J/A+A/582/A33).
--------------------------------------------------------------------------------
Global notes:
Note (G1): Note as follows:
a = Parameters inferred from spectroscopic observations.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 21-Sep-2017