J/A+A/512/A54 Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
An absolutely calibrated Teff scale from the Infrared Flux Method.
Dwarfs and subgiants.
Casagrande L., Ramirez I., Melendez J., Bessell M., Asplund M.
<Astron. Astrophys. 512, A54 (2010)>
=2010A&A...512A..54C 2010A&A...512A..54C
ADC_Keywords: Stars, dwarfs ; Stars, giant; Effective temperatures ;
Photometry, infrared ; Models, atmosphere
Keywords: stars: fundamental parameters - stars: abundances -
stars: atmospheres - infrared: stars - techniques: photometric
Abstract:
Various effective temperature scales have been proposed over the
years. Despite much work and the high internal precision usually
achieved, systematic differences of order 100K (or more) among
various scales are still present. We present an investigation based
on the Infrared Flux Method aimed at assessing the source of such
discrepancies and pin down their origin. We break the impasse among
different scales by using a large set of solar twins, stars which are
spectroscopically and photometrically identical to the Sun, to set the
absolute zero point of the effective temperature scale to within few
degrees. Our newly calibrated, accurate and precise temperature scale
applies to dwarfs and subgiants, from super-solar metallicities to the
most metal-poor stars currently known. At solar metallicities our
results validate spectroscopic effective temperature scales, whereas
for [Fe/H]←2.5 our temperatures are roughly 100 K hotter than those
determined from model fits to the Balmer lines and 200 K hotter than
those obtained from the excitation equilibrium of Fe lines. Empirical
bolometric corrections and useful relations linking photometric
indices to effective temperatures and angular diameters have been
derived. Our results take full advantage of the high accuracy reached
in absolute calibration in recent years and are further validated by
interferometric angular diameters and space based spectrophotometry
over a wide range of effective temperatures and metallicities.
Description:
Sample stars used and fundamental physical parameters (Teff, Fbol,
diam) derived via IRFM. The apparent bolometric magnitudes (mBol) have
been computed according to Casagrande et al. (2006MNRAS.373...13C 2006MNRAS.373...13C),
where the absolute bolometric magnitude of the Sun MBol☉=4.74.
For each star mBol is obtained using its bolometric flux (Fbol) and
effective temperature (Teff) and therefore it is already corrected for
reddening, if present. Notice however that the observed magnitudes
given here are not: before computing bolometric corrections, the
observed magnitudes should be dereddened using the E(B-V) given here.
The correction into dereddened magnitudes as been done iteratively, as
described in Section 2.1 of the paper. However, average relations
between E(B-V) and various photometric bands can be found in
literature e.g. McCall (2004AJ....128.2144M 2004AJ....128.2144M). Bolometric corrections
in each band can be readily obtained using the dereddened magnitudes.
E.g. BCV=mBol-V0, where BCV is the bolometric correction in V
band, mBol is thw apparent bolometric magnitude, V0 is the dereddened
apparent V magnitude (=Vmag if E(B-V)=0). Errors have been computed as
described in the paper, without accounting for the uncertainty in
E(B-V): changing it by ±0.01 would affect Teff by approximately
±50K.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table8.dat 151 423 Photometric data used in the paper and stellar
fundamental parameters determined via
InfraRed Flux Method (IRFM)
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See also:
J/A+A/282/899 : Teff and angular diameters from IRFM (Blackwell+ 1994)
J/A+AS/129/505 : Effective temperatures by IFRM (Blackwell+ 1998)
J/ApJ/626/446 : Effective temperature scale of FGK stars (Ramirez+, 2005)
J/A+A/497/497 : Physical parameters from JHK flux (Gonzalez-Hernandez+, 2009)
Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name
15- 18 F4.2 [cm/s2] logg Surface gravity
21- 25 F5.2 [Sun] [Fe/H] Metallicity
28- 33 F6.3 mag mBol IRFM apparent bolometric magnitude.
(Mbol☉=4.74)
36- 48 E13.7 mW/m2 Fbol IRFM bolometric flux (on the Earth)
51- 61 E11.5 mW/m2 e_Fbol IRFM bolometric flux error
64- 67 I4 K Teff IRFM effective temperature
71- 73 I3 K e_Teff IRFM effective temperature error
76- 80 F5.3 mas Diam IRFM angular diameter
83- 87 F5.3 mas e_Diam IRFM angular diameter error
90- 95 F6.3 mag Bmag Johnson apparent B magnitude
98-103 F6.3 mag Vmag Johnson apparent V magnitude
106-111 F6.3 mag Rmag ?=- Cousins apparent R magnitude
114-119 F6.3 mag Imag ?=- Cousins apparent I magnitude
122-127 F6.3 mag Jmag 2MASS apparent J magnitude
130-135 F6.3 mag Hmag 2MASS apparent H magnitude
138-143 F6.3 mag Kmag 2MASS apparent Ks magnitude
147-151 F5.3 mag E(B-V) Reddening correction
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Acknowledgements:
Luca Casagrande, luca(at)mpa-garching.mpg.de
(End) Luca Casagrande [MPA, Germany], Patricia Vannier [CDS] 04-Feb-2010