J/AJ/158/87 86 cool dwarfs observed during K2 Campaigns 1-17 (Dressing+, 2019)
Characterizing K2 candidate planetary systems orbiting low-mass stars.
IV. Updated properties for 86 cool dwarfs observed during Campaigns 1-17.
Dressing C.D., Hardegree-Ullman K., Schlieder J.E., Newton E.R.,
Vanderburg A., Feinstein A.D., Duvvuri G.M., Arnold L., Bristow M.,
Thackeray B., Abrahams E.S., Ciardi D.R., Crossfield I.J.M., Yu L.,
Martinez A.O., Christiansen J.L., Crepp J.R., Isaacson H.
<Astron. J., 158, 87 (2019)>
=2019AJ....158...87D 2019AJ....158...87D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, double and multiple ; Spectral types ;
Photometry ; Spectroscopy ; Stars, distances ; Proper motions ;
Stars, masses ; Equivalent widths ; Abundances ; Exoplanets
Keywords: planetary systems - stars: fundamental parameters - stars: late-type -
stars : low-mass - techniques: photometric - techniques: spectroscopic
Abstract:
We present revised stellar properties for 172 K2 target stars that were
identified as possible hosts of transiting planets during Campaigns 1-17.
Using medium-resolution near-infrared spectra acquired with the NASA
Infrared Telescope Facility/SpeX and Palomar/TripleSpec, we found that
86 of our targets were bona fide cool dwarfs, 74 were hotter dwarfs, and
12 were giants. Combining our spectroscopic metallicities with Gaia
parallaxes and archival photometry, we derived photometric stellar
parameters and compared them to our spectroscopic estimates. Although
our spectroscopic and photometric radius and temperature estimates are
consistent, our photometric mass estimates are systematically
ΔM*=0.11 M☉ (34%) higher than our spectroscopic mass
estimates for the least massive stars (M*,phot<0.4 M☉). Adopting
the photometric parameters and comparing our results to parameters
reported in the Ecliptic Plane Input Catalog, our revised stellar radii
are ΔR*=0.15 R☉ (40%) larger, and our revised stellar
effective temperatures are roughly ΔTeff=65 K cooler. Correctly
determining the properties of K2 target stars is essential for
characterizing any associated planet candidates, estimating the planet
search sensitivity, and calculating planet occurrence rates. Even though
Gaia parallaxes have increased the power of photometric surveys,
spectroscopic characterization remains essential for determining stellar
metallicities and investigating correlations between stellar metallicity
and planetary properties.
Description:
The overarching goal of our project is to characterize planetary systems
orbiting cool dwarfs observed by K2. Accordingly, we selected our targets
from the set of planet candidate host stars. The majority of our targets
were the putative hosts of candidate planets discovered by A. Vanderburg
and the K2 California Consortium (K2C2), but we also consulted the public
repository of K2 candidates provided by the NASA Exoplanet Archive
(Akeson et al. 2013PASP..125..989A 2013PASP..125..989A). We aimed to characterize all stars
with proper motions and colors consistent with those of cool dwarfs (see
Section 4), as well as those for which the planet candidate discoverers
estimated host star properties of Teff=<5000 K and logg≥4.0.
As in Dressing et al. (2017, J/ApJ/836/167), we conducted our observations
using two medium-resolution spectrographs: SpeX on the NASA Infrared
Telescope Facility (IRTF) and TripleSpec (TSPEC) on the Palomar 200 inch.
Our SpeX observations were acquired during the 2016B-2018A semesters as
part of programs 2016B057, 2017A019, 2017B064, and 2018A073 (PI: Dressing).
Our TSPEC observations were obtained during 2016A-2017B through programs
P08, P03, P11, and P08 (PI: Dressing).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 95 196 Stellar classifications
table3.dat 125 20 Spectral indices and Gaia crossmatches for targets
classified as evolved stars
table4.dat 168 24 Candidate stellar companions identified
in Gaia DR2 (Cat. I/345)
table5.dat 113 75 Spectroscopic parameters for cool dwarfs
table6.dat 85 75 Photometric parameters for cool dwarfs
table7.dat 351 75 Derived and adopted parameters for cool dwarfs
--------------------------------------------------------------------------------
See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
J/ApJ/800/85 : Teff, radii and luminosities of cool dwarfs (Newton+, 2015)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/ApJS/216/7 : Planets Around Low-Mass Stars (PALMS). IV. (Bowler+, 2015)
J/ApJS/218/26 : Parameters of planets orbiting coolest dwarfs (Swift+, 2015)
J/ApJS/222/14 : Planetary candidates from 1st yr K2 mission (Vanderburg+, 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/AJ/154/207 : K2 planetary systems orbiting low-mass stars (Dressing+, 2017)
J/ApJ/836/167 : K2 planetary syst. around low-mass stars. I. (Dressing+, 2017)
J/AJ/155/21 : Planet candidates from K2 campaigns 5-8 (Petigura+, 2018)
J/AJ/155/136 : Planets orbiting bright stars in K2 campaigns 0-10
(Mayo+, 2018)
J/AJ/156/22 : Planetary candidates from K2 Campaign 16 (Yu+, 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Star name in the Ecliptic Plane Input Catalog
(Cat. IV/34)
11 A1 --- f_EPIC [fgh] Object flag (1)
13- 18 A6 --- K2 K2 name (K2-NNN)
20- 24 A5 --- SpType Spectral type
26- 27 I2 --- Camp [0/16]? Campaign
29- 34 F6.3 mag Kpmag [9.087/16.733] Apparent magnitude in the Kepler
bandpass
36- 41 F6.3 mag Ksmag [5.883/13.598]? Apparent 2MASS Ks magnitude
43 A1 --- Speckle [y] ExoFOP reports that star has been observed
using speckle imaging
45 A1 --- AO [y] ExoFOP reports that star has been observed
using adaptive optics imaging
47 A1 --- EB [y] ExoFOP reports that the candidate is
a likely eclipsing binary
49 A1 --- Nearby [y] ExoFOP reports that there is another star
near the target star
51- 55 A5 --- Gaia [y close] Assessment about whether the target
has a match in Gaia DR2 (Cat. I/345)
57- 75 I19 --- Source ? Designation of crossmatched star in Gaia DR2
77- 81 F5.2 mas plx [-1.15/35.78]? Gaia DR2 parallax
83- 86 I4 pc Dist [28/8546]? Stellar distance calculated by
Bailer-Jones et al. (2018, Cat. I/347) based
on the Gaia DR2 parallax
88 A1 --- AF [y] Astrometric flag (G1)
90 A1 --- EF [y] Excess flag (G2)
92 A1 --- VF [y] Visibility flag (G3)
94- 95 I2 --- VP [4/14]? Number of visibility periods used
in Gaia DR2
--------------------------------------------------------------------------------
Note (1): Note on individual object as follows:
f = Classified as a dwarf star with a spectral type of K5 but excluded from
further analyses because the estimated properties were outside the
validity range for the spectroscopic relations established by
Newton et al. (2015, J/ApJ/800/85);
g = Validated by Mayo et al. (2018, J/AJ/155/136) assuming Teff=4972±50 K
and R*=2.57+0.31-0.25 R☉;
h = Announced by Vanderburg et al. (2016, J/ApJS/222/14) and validated by
Crossfield et al. (2016, J/ApJS/226/7). Vanderburg et al. (2016,
J/ApJS/222/14) classified the star as an M dwarf with Teff=3260 K and
R*= 0.23 R☉ but Crossfield et al. (2016, J/ApJS/226/7) revised
the stellar properties to Teff=6133 K and R*=1.49±0.52 R☉.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Star name in the Ecliptic Plane Input Catalog
11 A1 --- f_EPIC [ab] Object flag (1)
13- 18 F6.3 mag Kpmag [9.178/15.605] Apparent magnitude in the Kepler
bandpass
20- 25 F6.3 mag Ksmag [5.883/12.612] Apparent 2MASS Ks magnitude
27- 45 I19 --- Source Gaia DR2 designation
47- 56 F10.6 mas/yr pmRA [-14.137402/7.634639]? Gaia DR2 proper motion
in Right Ascension (pmRA*cosDE)
58- 67 F10.6 mas/yr pmDE [-37.565546/3.770199]? Gaia DR2 proper motion
in Declination
69- 77 F9.6 mas plx [-0.965834/2.928539]? Gaia DR2 parallax
79- 89 F11.6 pc Dist [338.334113/7127.918387]? Gaia DR2 distance
91- 95 A5 --- Inst Instrument used in this work (SpeX or TSPEC)
97-105 F9.6 0.1nm EW-KI [-0.43472/2.295561]? KI equivalent width
from this work (Å)
107-115 F9.6 0.1nm EW-NaI [-0.755824/1.497482]? NaI equivalent width
from this work (Å)
117-125 F9.6 0.1nm EW-CaII [5.11754/13.595743]? CaII equivalent width
from this work (Å)
--------------------------------------------------------------------------------
Note (1): Note on individual source as follows:
a = Brahm et al. (2019MNRAS.483.1970B 2019MNRAS.483.1970B) classified EPIC 201231064 (K2-161) as
a "slightly evolved G star" with R*=1.669±0.022 R☉ and
M*=1.105±0.019 M☉;
b = Our SpeX observation of EPIC 224685166 had insufficient S/N at blue
wavelengths to compute these spectral indices.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Star name in the Ecliptic Plane Input Catalog
11- 29 I19 --- Source1 Gaia DR2 designation of the primary
31- 40 F10.6 deg RAdeg1 Primary Right Ascension in decimal degrees (ICRS)
42- 51 F10.6 deg DEdeg1 Primary Declination in decimal degrees (ICRS)
53- 59 F7.2 mas/yr pmRA1 [-106.0/187.1]? Primary proper motion
in Right Ascension (pmRA*cosDE)
61- 67 F7.2 mas/yr pmDE1 [-237.8/-1.49]? Primary proper motion
in Declination
69- 73 F5.2 mas plx1 [0.07/15.45]? Primary Gaia DR2 parallax
75- 93 I19 --- Source2 Gaia DR2 designation of the secondary
95-104 F10.6 deg RAdeg2 Secondary Right Ascension in decimal degrees
(ICRS)
106-115 F10.6 deg DEdeg2 Secondary Declination in decimal degrees (ICRS)
117-122 F6.2 mas/yr pmRA2 [-27.6/185.5]? Secondary proper motion
in Right Ascension (pmRA*cosDE)
124-131 F8.3 mas/yr pmDE2 [-208.9/0.62]? Secondary proper motion
in Declination
133-137 F5.2 mas plx2 [-1.15/19.98]? Secondary Gaia DR2 parallax
139-142 F4.2 arcsec Sep [0.46/6.22] Measured separation
144-149 F6.2 mas/yr dpm [0.38/272.96]? Separation in proper motion
151-160 F10.5 mas/yr Cut [1e-05/3169]? Proper motion cut limit
162-168 A7 --- Bound Bound pair inference
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Star name in the Ecliptic Plane Input Catalog
11- 16 A6 --- K2 Name of confirmed K2 planet host star (K2-NNN)
18- 20 A3 --- SpType Spectral type
22- 25 I4 K Teffsp [3229/4712] Spectroscopic stellar effective
temperature
27- 29 I3 K e_Teffsp [73/229] Lower error on Teffsp
31- 33 I3 K E_Teffsp [73/304] Upper error on Teffsp
35- 39 F5.3 Rsun R*sp [0.193/0.763] Spectroscopic stellar radius
41- 45 F5.3 Rsun e_R*sp [0.027/0.123] Lower error on R*sp
47- 51 F5.3 Rsun E_R*sp [0.027/0.247] Upper error on R*sp
53- 57 F5.3 Msun M*sp [0.129/0.753] Spectroscopic stellar mass
59- 63 F5.3 Msun e_M*sp [0.072/0.21] Lower error on M*sp
65- 69 F5.3 Msun E_M*sp [0.068/0.197] Upper error on M*sp
71- 75 F5.3 Lsun L*sp [0.005/0.278] Spectroscopic stellar luminosity
77- 81 F5.3 Lsun e_L*sp [0.002/0.11] Lower error on L*sp
83- 87 F5.3 Lsun E_L*sp [0.002/0.17] Upper error on L*sp
89- 94 F6.3 --- [Fe/H] [-0.423/0.496] Iron abundance
96-100 F5.3 --- e_[Fe/H] [0.08/0.144] Error on [Fe/H]
102-107 F6.3 --- [M/H] [-0.334/0.35] Metallicity
109-113 F5.3 --- e_[M/H] [0.08/0.138] Error on [M/H]
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Star name in the Ecliptic Plane Input Catalog
11 A1 --- f_EPIC [b] Object flag (1)
13- 18 A6 --- K2 Name of confirmed K2 planet host star (K2-NNN)
20- 24 F5.3 mag KsMag [3.4/7.562]? Absolute Ks magnitude
26- 31 F6.3 mag E_KsMag [0.003/0.125]? Upper error on KsMag
33- 38 F6.3 mag e_KsMag [0.004/0.132]? Lower error on KsMag
40- 43 I4 K Teffph [3223/4532]? Photometric stellar effective
temperature
45- 47 I3 K e_Teffph [57/159]? Error on Teffph
49- 53 F5.3 Rsun R*ph [0.248/0.723]? Photometric stellar radius
55- 59 F5.3 Rsun e_R*ph [0.007/0.028]? Error on R*ph
61- 65 F5.3 Msun M*ph [0.22/0.752]? Photometric stellar mass
67- 71 F5.3 Msun e_M*ph [0.006/0.03]? Error on M*ph
73- 77 F5.3 Lsun L*ph [0.007/0.275]? Photometric stellar luminosity
79- 83 F5.3 Lsun e_L*ph [0/0.017]? Error on L*ph
85 A1 --- f_R*ph [y] Flag on photometric radius estimate (G4)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
b = We do not report a photometric luminosity or a photometric temperature for
EPIC 220448185 because we did not find a match for this star in the
Carlsberg Meridian Catalogue (Muinos & Evans 2014AN....335..367M 2014AN....335..367M) and were
therefore unable to use the r-J color to compute a bolometric correction.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Star name in the Ecliptic Plane Input Catalog
11- 16 A6 --- K2 Name of confirmed K2 planet host star (K2-NNN)
18- 20 A3 --- SpType Spectral type
22- 26 F5.3 mag KsMag [3.4/7.562]? Absolute Ks magnitude
28- 33 F6.3 mag e_KsMag [-0.125/-0.003]? Lower error on KsMag
35- 40 F6.3 mag E_KsMag [-0.132/-0.004]? Upper error on KsMag
42- 43 I2 --- Camp [0/16]? K2 Campaign in which target was
observed
47- 52 F6.3 mag Kpmag [10.277/16.733] Apparent magnitude in
the Kepler bandpass
54- 59 F6.3 mag Ksmag [7.193/13.598] Apparent Ks magnitude
61 A1 --- Speckle [y] ExoFOP reports that star has been observed
using speckle imaging
63 A1 --- AO [y] ExoFOP reports that star has been observed
using adaptive optics imaging
65 A1 --- EB ExoFOP reports that the candidate is a likely
eclipsing binary
67 A1 --- Nearby [y] ExoFOP reports that there is another star
near the target star
69 A1 --- Gaia [y] Assessment about whether the target has
a match in Gaia DR2
71- 89 I19 --- Source ? Designation of crossmatched star in Gaia DR2
91- 96 F6.3 arcsec plx [1.788/35.778]? Parallax reported in Gaia DR2
98-104 F7.3 pc Dist [27.928/550.553]? Stellar distance calculated
by Bailer-Jones et al. (2018, Cat. I/347)
based on the Gaia DR2 parallax
106 A1 --- AF Astrometric flag (G1)
108 A1 --- EF Excess noise flag (G2)
110 A1 --- VF [y] Visibility flag (G3)
112-113 I2 --- VP [4/14]? Number of visibility periods used
in Gaia DR2
115-118 I4 K Teff [3178/4532] Adopted stellar effective
temperature
120-122 I3 K e_Teff [57/191] Lower error on Teff
124-126 I3 K E_Teff [57/265] Upper error on Teff
128-131 A4 --- f_Teff [phot/spec] Provenance of adopted stellar
effective temperature
133-137 F5.3 Rsun R* [0.248/0.743] Adopted stellar radius
139-143 F5.3 Rsun e_R* [0.007/0.092] Lower error on R*
145-149 F5.3 Rsun E_R* [0.007/0.175] Upper error on R*
151-154 A4 --- f_R* [phot/spec] Provenance of adopted radius
156-160 F5.3 Msun M* [0.22/0.752] Adopted stellar mass
162-166 F5.3 Msun e_M* [0.006/0.093] Lower error on M*
168-172 F5.3 Msun E_M* [0.006/0.174] Upper error on M*
174-177 A4 --- f_M* [phot/spec] Provenance of adopted mass
179-183 F5.3 Lsun L* [0.005/0.278] Adopted stellar luminosity
185-189 F5.3 Lsun e_L* [0/0.11] Lower error on L*
191-195 F5.3 Lsun E_L* [0/0.17] Upper error on L*
197-200 A4 --- f_L* [phot/spec] Provenance of adopted luminosity
202-209 F8.3 K Teffph [3222.941/4531.989]? Photometric stellar
effective temperature
211-217 F7.3 K e_Teffph [56.996/158.57]? Error on Teffph
219-223 F5.3 Rsun R*ph [0.248/0.723]? Photometric stellar radius
225-229 F5.3 Rsun e_R*ph [0.007/0.028]? Error on R*ph
231-235 F5.3 Msun M*ph [0.22/0.752]? Photometric stellar mass
237-241 F5.3 Msun e_M*ph [0.006/0.03]? Error on M*ph
243-247 F5.3 Lsun L*ph [0.007/0.275]? Photometric stellar luminosity
249-253 F5.3 Lsun e_L*ph [0/0.017]? Error on L*ph
255 A1 --- f_R*ph [y] Flag on photometric radius estimate (G4)
257-260 I4 K Teffsp [3229/4712] Spectroscopic stellar effective
temperature
262-264 I3 K e_Teffsp [73/229] Lower error on Teffsp
266-268 I3 K E_Teffsp [73/304] Upper error on Teffsp
270-274 F5.3 Rsun R*sp [0.193/0.763] Spectroscopic stellar radius
276-280 F5.3 Rsun e_R*sp [0.027/0.123] Lower error on R*sp
282-286 F5.3 Rsun E_R*sp [0.027/0.247] Upper error on R*sp
288-292 F5.3 Msun M*sp [0.129/0.753] Spectroscopic stellar mass
294-298 F5.3 Msun e_M*sp [0.072/0.21] Lower error on M*sp
300-304 F5.3 Msun E_M*sp [0.068/0.197] Upper error on M*sp
306-310 F5.3 Lsun L*sp [0.005/0.278] Spectroscopic stellar luminosity
312-316 F5.3 Lsun e_L*sp [0.002/0.11] Lower error on L*sp
318-322 F5.3 Lsun E_L*sp [0.002/0.17] Upper error on L*sp
324-329 F6.3 --- [Fe/H] [-0.423/0.496] Iron abundance
331-335 F5.3 --- e_[Fe/H] [0.08/0.144] Error on iron abundance
337-342 F6.3 --- [M/H] [-0.334/0.35] Metallicity
344-351 F8.6 --- e_[M/H] [0.08/0.138] Error on metallicity
--------------------------------------------------------------------------------
Global notes:
Note (G1): Astrometric flag as follows:
y = Star has astrometricsigma5dmax>2 mas in Gaia DR2 (Cat. I/345).
Note (G2): Excess flag as follows:
y = Star has astrometricexcessnoise>2 mas in Gaia DR2.
Note (G3): Visibility flag as follows:
y = Star has visibilityperiodsused<10 in Gaia DR2.
Note (G4): Flag as follows:
y = Photometric radius estimated by extrapolating the relations in Mann et al.
(2015, J/ApJ/804/64).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Dressing et al. Paper I. 2017ApJ...836..167D 2017ApJ...836..167D, Cat. J/ApJ/836/167
Dressing et al. Paper II. 2017AJ....154..207D 2017AJ....154..207D, Cat. J/AJ/154/207
Dressing et al. Paper III. 2018AJ....156...70D 2018AJ....156...70D
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 01-Oct-2019