J/ApJ/761/16 IR colors of the Sun from Line-Depth Ratios (Casagrande+, 2012)
The infrared colors of the Sun.
Casagrande L., Ramirez I., Melendez J., Asplund M.
<Astrophys. J., 761, 16 (2012)>
=2012ApJ...761...16C 2012ApJ...761...16C
ADC_Keywords: Sun ; Photometry, infrared
Keywords: stars: fundamental parameters; Sun: fundamental parameters;
techniques: photometric
Abstract:
Solar infrared colors provide powerful constraints on the stellar
effective temperature scale, but they must be measured with both
accuracy and precision in order to do so. We fulfill this requirement
by using line-depth ratios to derive in a model-independent way the
infrared colors of the Sun, and we use the latter to test the zero
point of the Casagrande et al. (Cat. J/A+A/512/A54) effective
temperature scale, confirming its accuracy. Solar colors in the widely
used Two Micron All Sky Survey (2MASS) JHKs and WISE W1-4 systems
are provided: (V-J)☉=1.198, (V-H)☉=1.484,
(V-Ks)☉=1.560, (J-H)☉=0.286, (J-Ks)☉=0.362,
(H-Ks)☉=0.076, (V-W1)☉=1.608, (V-W2)☉=1.563,
(V-W3)☉=1.552, and (V-W4)☉=1.604. A cross-check of the
effective temperatures derived implementing 2MASS or WISE magnitudes
in the infrared flux method confirms that the absolute calibration of
the two systems agrees within the errors, possibly suggesting a 1%
offset between the two, thus validating extant near- and mid-infrared
absolute calibrations. While 2MASS magnitudes are usually well suited
to derive Teff, we find that a number of bright, solar-like stars
exhibit anomalous WISE colors. In most cases, this effect is spurious
and can be attributed to lower-quality measurements, although for a
couple of objects (3%±2% of the total sample) it might be real, and
may hint at the presence of warm/hot debris disks.
Description:
Our sample consists of the 112 stars used in Ramirez et al.
(2012ApJ...752....5R 2012ApJ...752....5R), from whom we have adopted V magnitudes and
stellar parameters. For each star, we have queried the 2MASS
J(1.25um), H(1.65um), Ks(2.17um) and the WISE W1(3.4um), W2(4.6um),
W3(12um), W4(22um ) catalogs for photometry.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 45 100 *(V-Ks)sun color inferred from line-depth
ratio (LDR) measurements
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Note on table1.dat: Here, we use the line-depth ratio (LDR) technique as
described in Ramirez et al. (2012ApJ...752....5R 2012ApJ...752....5R) to derive the infrared
colors of the Sun in a model-independent way.
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/ApJ/746/101 : Diameters and temperatures of AFG stars (Boyajian+, 2012)
J/MNRAS/426/91 : Kepler stars with infrared excess (Kennedy+, 2012)
J/MNRAS/417/2230 : BVRI+SDSS+2MASS & WISE phot. of 289 stars (Bilir+, 2011)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/AN/328/938 : Teff/line-depth ratio for ELODIE spectra (Biazzo+, 2007)
J/MNRAS/373/13 : Lower MS stars fundamental param. (Casagrande+, 2006)
J/A+A/411/559 : Effective temperature for 181 F-K dwarfs (Kovtyukh+, 2003)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 0.1nm lam1 [5490/6747] Wavelength λ1 of
first line in pair (Å)
10- 12 A3 --- S1 First line species identifier
14- 20 F7.2 0.1nm lam2 [5517/6758] Wavelength λ1 of
second line in pair (Å)
22- 24 A3 --- S2 Second line species identifier
26- 27 I2 mag N* [29/85] Number of stars used for fit
29- 33 F5.3 mag sigFit Standard deviation of fit (σfit)
35- 39 F5.3 mag V-Ks [1.542/1.592] The solar (V-Ks) color index
41- 45 F5.3 mag e_V-Ks [0.003/0.08] Standard deviation of color (1)
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Note (1): Inferred from the nine reflected Sun-light asteroid observations
used for solar reference.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 31-Jul-2014