J/AJ/160/130 SpT & NIR color excess of Solar-type stars (Lewin+, 2020)
Near-infrared spectral characterization of Solar-type stars in the northern
hemisphere.
Lewin C.D., Howell E.S., Vervack R.J., Fernandez Y.R., Magri C.,
Marshall S.E., Crowell J.L., Hinkle M.L.
<Astron. J., 160, 130 (2020)>
=2020AJ....160..130L 2020AJ....160..130L
ADC_Keywords: Stars, G-type; Spectra, infrared; Colors; Photometry, VRI;
Spectral types
Keywords: Standard stars ; Solar analogs
Abstract:
Although solar-analog stars have been studied extensively over the
past few decades, most of these studies have focused on visible
wavelengths, especially those identifying solar-analog stars to be
used as calibration tools for observations. As a result, there is a
dearth of well-characterized solar analogs for observations in the
near-infrared, a wavelength range important for studying solar system
objects. We present 184 stars selected based on solar-like spectral
type and V-J and V-K colors whose spectra we have observed in the
0.8-4.2µm range for calibrating our asteroid observations. Each
star has been classified into one of three ranks based on spectral
resemblance to vetted solar analogs. Of our set of 184 stars, we
report 145 as reliable solar-analog stars, 21 as solar analogs usable
after spectral corrections with low-order polynomial fitting, and 18
as unsuitable for use as calibration standards owing to spectral
shape, variability, or features at low to medium resolution. We
conclude that all but five of our candidates are reliable solar
analogs in the longer wavelength range from 2.5 to 4.2µm. The
average colors of the stars classified as reliable or usable solar
analogs are V-J=1.148, V-H=1.418, and V-K= 1.491, with the entire set
being distributed fairly uniformly in R.A. across the sky between
-27° and +67° in decl.
Description:
All of our near-infrared star spectra were collected using SpeX at the
NASA Infrared Telescope Facility (IRTF) on 133 nights spanning 2008
May to 2018 October, in both prism (0.8-2.5µm) and LXD1.9
(2.0-4.2µm) modes. Spectra collected after 2014 August using
post-upgrade SpeX cover an extended wavelength range of 0.7-5.3µm
between both the prism and LXD modes. The spectral resolution is
λ/(Δλ)=200 in prism mode, and 2500 in LXD mode.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 17 Final set of 17 primary solar analogs
table2.dat 108 184 Rankings for solar analog candidates
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See also:
II/183 : UBVRI Photometric Standards (Landolt 1992)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VI/19 : UBV Photoelectric Sequences in SA 92-115 (Landolt 1973)
J/ApJ/555/932 : IR fluxes of solar-type stars (Spangler+, 2001)
J/ApJ/705/89 : IRS spectra of solar-type stars (Lawler+, 2009)
J/ApJS/181/62 : Survey of young solar analogs (Metchev+, 2009)
J/ApJS/212/10 : WISE IR excesses for stars within 75pc (Patel+, 2014)
J/A+A/587/A65 : Visible and near-infrared solar spectra (Reiners+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star Name
12- 21 A10 --- SAO SAO number
23- 32 A10 --- OName Alternative name
34- 38 A5 --- SpT Spectral Type
40- 41 I2 h RAh [0/23] Hour of Right Ascension (J2000)
43- 44 I2 min RAm Minute of Right Ascension (J2000)
46- 50 F5.2 s RAs Second of Right Ascension (J2000)
52- 52 A1 --- DE- [±] Sign of the Declination (J2000)
53- 54 I2 deg DEd Degree of Declination (J2000)
56- 57 I2 arcmin DEm Arcminute of Declination (J2000)
59- 62 F4.1 arcsec DEs Arcsecond of Declination (J2000)
64- 67 F4.2 mag Vmag [5.46/9.74] V band magnitude (1)
69- 74 F6.4 mag e_Vmag [0.0005/0.05] Uncertainty in Vmag
76- 77 I2 --- Nights [3/33] Nights observed
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Note (1): V band magnitudes taken from the
Hipparcos (Perryman+, 1997A&A...323L..49P 1997A&A...323L..49P) or
Tycho (Hog+, 2000, I/259) catalogs.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star Name
13- 22 A10 --- SAO SAO number
24- 31 A8 --- SpT Spectral Type
33- 34 I2 h RAh [0/23] Hour of Right Ascension (J2000)
36- 37 I2 min RAm Minute of Right Ascension (J2000)
39- 43 F5.2 s RAs Second of Right Ascension (J2000)
45- 45 A1 --- DE- [-+] Sign of the Declination (J2000)
46- 47 I2 deg DEd Degree of Declination (J2000)
49- 50 I2 arcmin DEm Arcminute of Declination (J2000)
52- 55 F4.1 arcsec DEs Arcsecond of Declination (J2000)
57- 61 F5.2 mag Vmag [5.46/12.43] V band magnitude (1)
63- 67 F5.3 mag (V-J) [0.77/2.12] V-J color (1)
69- 73 F5.3 mag (V-H) [0.88/2.43] V-H color (1)
75- 79 F5.3 mag (V-Ks) [0.95/2.5] V-Ks color (1)
81- 85 F5.3 mag e_Vmag [0.001/0.11] Uncertainty in Vmag
87- 91 F5.3 mag e_(V-J) [0.01/0.11] Uncertainty in (V-J)
93- 97 F5.3 mag e_(V-H) [0.01/0.12] Uncertainty in (V-H)
99-103 F5.3 mag e_(V-Ks) [0.01/10] Uncertainty in (V-Ks)
105-105 I1 --- Rank [1/3] Rank based on the magnitude (Δ) of
the deviation of the relative slope (2)
107-108 A2 --- Notes Notes (3)
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Note (1): V band magnitudes taken from the
Hipparcos (Perryman+, 1997A&A...323L..49P 1997A&A...323L..49P) or
Tycho (Hog+, 2000, I/259) catalogs.
JHK photometry taken from the 2MASS catalog (Cutri+, 2003, II/246)
except for HD217014, which is from Gezari+, 1993, II/225.
Note (2): Rank as follows:
1 = Star is a reliable solar analog; no corrections needed (Δ<10% for
prism spectra, Δ<20% for LXD spectra)
2 = Star requires polynomial fitting corrections to be a usable solar
analog (10%≤Δ<20% for prism spectra)
3 = Star is effectively non-solar in that it is not correctable by
polynomial fitting owing to variability, non-solar features, or
spectral shape (Δ?20% for both prism and LXD spectra).
Note (3): Notes as follows:
1 = LXD Signal-to-noise too low to adequately characterize;
2 = Listed as a spectroscopic binary in SIMBAD;
3 = Broad features from 1.0 to 1.7 microns;
4 = Rank 3 in LXD range, spectral slope from 3 to 4 microns;
5 = Nonlinear spectral shape, smooth but indicative of potential
time-variability that one may want to avoid ;
6 = Non-repeatability in spectral shape changed significantly
between February 2012 and June 2012. Further investigation
encouraged.;
7 = Spectral shape increases significantly (∼ 15%) towards the
blue end of the prism spectrum (near 0.8 microns);
8 = Spectral changes from 2012 to 2015 indicate non-repeatability;
9 = Spectral type not listed on SIMBAD;
10 = Ample features, many of which are broad and deep. Prism spectrum
decreases rapidly towards the blue end (near 0.8 microns).;
11 = V-J, V-K colors from Gezari+, 1993, II/225.
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History:
From electronic version of the journal
(End) Prerpared by [AAS], Coralie Fix [CDS], 06-Nov-2020