J/ApJ/800/85 Teff, radii and luminosities of cool dwarfs (Newton+, 2015)
An empirical calibration to estimate cool dwarf fundamental parameters from
H-band spectra.
Newton E.R., Charbonneau D., Irwin J., Mann A.W.
<Astrophys. J., 800, 85 (2015)>
=2015ApJ...800...85N 2015ApJ...800...85N
ADC_Keywords: Stars, double and multiple ; Equivalent widths ; Planets ;
Stars, diameters ; Effective temperatures
Keywords: stars: atmospheres; binaries: general; stars: fundamental parameters;
stars: low-mass
Abstract:
Interferometric radius measurements provide a direct probe of the
fundamental parameters of M dwarfs. However, interferometry is within
reach for only a limited sample of nearby, bright stars. We use
interferometrically measured radii, bolometric luminosities, and
effective temperatures to develop new empirical calibrations based on
low-resolution, near-infrared spectra. We find that H-band Mg and Al
spectral features are good tracers of stellar properties, and derive
functions that relate effective temperature, radius, and log
luminosity to these features. The standard deviations in the residuals
of our best fits are, respectively, 73K, 0.027R☉, and 0.049dex
(an 11% error on luminosity). Our calibrations are valid from mid K to
mid M dwarf stars, roughly corresponding to temperatures between 3100
and 4800K. We apply our H-band relationships to M dwarfs targeted by
the MEarth transiting planet survey and to the cool Kepler Objects of
Interest (KOIs). We present spectral measurements and estimated
stellar parameters for these stars. Parallaxes are also available for
many of the MEarth targets, allowing us to independently validate our
calibrations by demonstrating a clear relationship between our
inferred parameters and the stars' absolute K magnitudes. We identify
objects with magnitudes that are too bright for their inferred
luminosities as candidate multiple systems. We also use our estimated
luminosities to address the applicability of near-infrared metallicity
calibrations to mid and late M dwarfs. The temperatures we infer for
the KOIs agree remarkably well with those from the literature;
however, our stellar radii are systematically larger than those
presented in previous works that derive radii from model isochrones.
This results in a mean planet radius that is 15% larger than one would
infer using the stellar properties from recent catalogs. Our results
confirm the derived parameters from previous in-depth studies of KOIs
961 (Kepler-42), 254 (Kepler-45), and 571 (Kepler-186), the latter of
which hosts a rocky planet orbiting in its star's habitable zone.
Description:
Our observations and data reduction were carried out as discussed in
Newton et al. (2014, J/AJ/147/20), which we summarize briefly here. We
used the SpeX instrument on IRTF on 2011 May-2012 Aug (spectra from
0.8-2.4um with R=2000). Four observations were acquired for each
object, with two observations at each of the two nod positions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 80 25 Inferred parameters for the interferometric sample
table5.dat 157 447 Measured quantities and inferred stellar parameters
for M dwarfs in the MEarth sample
table7.dat 86 92 Stellar parameters of cool Kepler Objects of Interest
with high-fidelity spectra
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/298 : LSPM-North Catalog (Lepine+ 2005)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/799/4 : Robo-AO obs. of binary stars (Riddle+, 2015)
J/ApJS/213/5 : Cool KOIs. VI. H- and K- band spectra (Muirhead+, 2014)
J/ApJS/211/2 : Revised properties of Q1-16 Kepler targets (Huber+, 2014)
J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)
J/ApJ/779/188 : Spectra of nearby late K and M Kepler stars (Mann+, 2013)
J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)
J/A+A/556/A15 : Effective temperature scale of M dwarfs (Rajpurohit+, 2013)
J/ApJ/770/90 : Candidate planets in the habitable zones (Gaidos, 2013)
J/ApJ/767/95 : Improved stellar param. of smallest KIC stars (Dressing+, 2013)
J/AJ/145/52 : Abundances of late K & M dwarfs in binary systems (Mann+, 2013)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/ApJ/753/90 : Stellar param. of K5 & later type Kepler stars (Mann+, 2012)
J/ApJ/750/L37 : Stellar parameters of low-mass KOIs (Muirhead+, 2012)
J/ApJ/748/93 : K-band spectra for 133 nearby M dwarfs (Rojas-Ayala+, 2012)
J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)
J/ApJ/718/1353 : Light curve of the triple system NLTT 41135 (Irwin+, 2010)
J/MNRAS/389/585 : Fundamental parameters of M dwarfs (Casagrande+, 2008)
J/ApJ/683/424 : CHARA observations of 3 late-type stars (Boyajian+, 2008)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/AJ/123/3356 : Palomar/MSU nearby star spectrosc. survey III. (Gizis+, 2002)
http://exoplanetarchive.ipac.caltech.edu/ : NASA exoplanet archive
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Star name
9 A1 --- f_Name [fg] f=star excluded; g=peculiar origin of
interferometry (1)
11- 14 I4 K Teff [3142/4773] Measured effective temperature (2)
16- 17 I2 K e_Teff [11/90] Teff uncertainty
19- 24 F6.4 Rsun R [0.18/0.8] Measured radius (3)
26- 31 F6.4 Rsun e_R [0.001/0.03] Rad uncertainty
33- 39 F7.4 [Lsun] logL [-2.5/-0.5] Bolometric luminosity (2)
41- 46 F6.4 [Lsun] e_logL [0.002/0.02] logLbol uncertainty
48- 51 I4 K Te.i [3248/4825] Inferred effective temperature (4)
53- 55 I3 K e_Te.i [74/227] Te.i uncertainty
56 A1 --- f_Te.i [f] point excluded from logL calibration (1)
58- 62 F5.3 Rsun R.i [0.18/0.9] Inferred radius (4)
64- 68 F5.3 Rsun e_R.i [0.02/0.07] R.i uncertainty
70- 74 F5.2 [Lsun] logL.i [-2.5/-0.5] Inferred bolometric luminosity (4)
76- 79 F4.2 [Lsun] e_logL.i [0.05/0.2] logL.i uncertainty
80 A1 --- f_logL.i [f] point excluded from logL calibration (1)
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Note (1): Flag as follows:
f = Gl 725B was excluded from our Teff and Lbol calibrations, as
discussed in Section 2.1. The Teff and Lbol we infer from Equations
(1) and (3) for this star are nevertheless included in this table.
g = Values for interferometric radii are from von Braun et al.
(2014MNRAS.438.2413V 2014MNRAS.438.2413V); updated Teff and Lbol from this work.
Note (2): Calculated from the interferometric radius and bolometric flux as
described in Section 2.1. Values are from Mann et al. (2013,
J/ApJ/779/188) Table 1 unless otherwise noted (g)
Note (3): Measured from interferometry; see Boyajian et al. (2012,
J/ApJ/757/112) Table 6 for references unless otherwise noted (g)
Note (4): Inferred from equivalent widths of Al at 1.67um (blue component)
and MgI at 1.50um with equations 1 (Teff), 2 (R) and 3 (logL).
The fits are shown in Fig.4 for Teff (top left), R (top right) and
logL (bottom left)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 24 A24 --- Name Star identification (1)
26- 27 A2 --- m_Name [EWNS ] Component identifier (1)
29- 33 F5.2 0.1nm Mg1.48 Equivalent width of MgI 1.48um line (Å)
35- 38 F4.2 0.1nm e_Mg1.48 Uncertainty in Mg1.48 (Å)
40- 44 F5.2 0.1nm Mg1.50 Equivalent width of MgI 1.50um line (Å)
46- 49 F4.2 0.1nm e_Mg1.50 Uncertainty in Mg1.50 (Å)
51- 55 F5.2 0.1nm Mg1.58 Equivalent width of MgI 1.58um line (Å)
57- 60 F4.2 0.1nm e_Mg1.58 Uncertainty in Mg1.58 (Å)
62- 66 F5.2 0.1nm Al-a Equivalent width of Al 1.67um-blue line (Å)
68- 71 F4.2 0.1nm e_Al-a Uncertainty in Al-a (Å)
73- 76 F4.2 0.1nm Al-b Equivalent width of Al 1.67um-red line (Å)
78- 81 F4.2 0.1nm e_Al-b Uncertainty in Al-b (Å)
83- 87 F5.2 0.1nm Mg1.71 Equivalent width of MgI 1.71um line (Å)
89- 92 F4.2 0.1nm e_Mg1.71 Uncertainty in Mg1.71 (Å)
94- 97 F4.2 --- K [0.7/1.3] K-band index from Mann et al. 2013
(J/ApJ/779/188)
99-102 I4 K Teff [2644/4093]? Inferred effective temperature (2)
104-106 I3 K e_Teff [75/123]? Uncertainty in Teff
108-113 F6.3 Rsun R [-1.1/1.9] Inferred radius (3)
115-119 F5.3 Rsun e_R [0.02/4] Uncertainty in R
121-125 F5.2 [Lsun] logL [-4/-0.9] Inferred log(luminosity) (4)
127-130 F4.2 [Lsun] e_logL [0.05/0.2] Uncertainty in logL
132-136 F5.1 mas plx [15/395]? Parallax
138-141 F4.1 mas e_plx [0/25]? Uncertainty in plx
143-145 A3 --- r_plx Reference for plx (5)
147-151 F5.2 [Sun] [Fe/H]1 [-1/0.8] Metallicity from 2013 calibration (6)
153-157 F5.2 [Sun] [Fe/H]2 [-1.3/0.9] Metallicity from 2014 calibration (7)
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Note (1): For most stars we use the LSPM name (Lepine & Shara 2005, I/298).
For binaries that were not resolved in the LSPM catalogs but which
we resolve, we use the appropriate LSPM name in the first column and
identify the components in the second column (m_Name)
Note (2): Inferred from EWs using Equation 1; fit shown in Figure 4, top left.
We do not report estimated temperatures for stars for which the
contribution from EW uncertainties to the total error exceeds 100K
because we find that the temperatures are systematically effected.
Our temperatures are calibrated between 3200 and 4800K.
Note (3): Inferred from EWs using Equation 2; fit shown in Figure 4, top right.
Our radius calibration is valid only for stars with radii between
0.2 and 0.8R☉. We report radii for stars outside of this range,
but caution that the extrapolated radii can only be used as a
relative indicator. Some extrapolated radii may be negative.
Note (4): Inferred from EWs using Equation 3; fit shown in Figure 4, bottom
left. Our luminosity calibration is valid only for stars with
log L/L☉ between -2.5 and -0.5. We report luminosities for stars
outside of this range, but caution that the extrapolated luminosities
can only be used as a relative indicator.
Note (5): For parallaxes compiled from the literature, we refer the reader to
Newton et al. (2014, J/AJ/147/20) for the reference.
D14 = parallax from Dittmann et al. (2014ApJ...784..156D 2014ApJ...784..156D);
N14 = parallax compiled from the literature by Newton et al. (2014,
J/AJ/147/20).
Note (6): Using the Mann et al. (2013, J/AJ/145/52) calibration, appropriate
for early M dwarfs (log L/L☉> -2.25).
Note (7): Using the Mann et al. (2014AJ....147..160M 2014AJ....147..160M) calibration, appropriate
for early M dwarfs (log L/L☉< -2.25).
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 --- KOI [247.01/4427.01] KOI number
(<KOI-NNNN.NN> in Simbad)
9- 16 I8 --- KIC Kepler Input Catalog (V/133) identifier
18- 21 I4 K Te.H [3068/4385] Huber et al. 2014, J/ApJS/211/2,
stellar effective temperature
23- 26 F4.2 Rsun R.H [0.17/0.8] Huber et al. 2014, J/ApJS/211/2,
stellar radius
28- 32 A5 --- r_R.H Huber et al. 2014, J/ApJS/211/2, data
reference (1)
34- 37 I4 K Teff [3134/4251] This work's stellar effective
temperature
39- 41 I3 K e_Teff [73/159] Uncertainty in Teff
43- 47 F5.3 Rsun R [0.18/0.7] This work's stellar radius
49- 53 F5.3 Rsun e_R [0.02/0.05] Uncertainty in R
55- 59 F5.2 [Lsun] logL [-2.8/-0.7] This work's log luminosity
61- 64 F4.2 [Lsun] e_logL [0.05/0.3] Uncertainty in logL
66- 70 F5.2 Rgeo Rp.l [0.6/18.5] Literature planetary radius (2)
72- 75 I4 K Tp.l [172/1637] Literature planetary equilibrium
temperature (2)
77- 81 F5.2 Rgeo Rp [0.6/19.8] This work's planetary radius
83- 86 I4 K Tp [171/1684] This work's planetary equilibrium
temperature
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Note (1): Reference as follows:
SPE5 = Muirhead et al. (2014, J/ApJS/213/5);
PHO2 = Dressing & Charbonneau (2013, J/ApJ/767/95);
SPE41 = Muirhead et al. (2012ApJ...747..144M 2012ApJ...747..144M);
SPE43 = Johnson et al. (2012AJ....143..111J 2012AJ....143..111J);
PHO16 = Gaidos (2013, J/ApJ/770/90);
PHO54 = Huber et al. (2014, J/ApJS/211/2);
KIC0 = Brown et al. (2011, J/AJ/142/112).
Note (2): Planet properties one infers using the stellar parameters from
Huber et al. (2014, J/ApJS/211/2) and the planet parameters from the
NASA Exoplanet Archive.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 30-Jun-2015