J/AJ/124/2164 SDSS photometry in the field of L1457 (Andersson+, 2002)
A spectroscopic and photometric survey of stars in the field of L1457:
a new distance determination.
Andersson B.-G., Idzi R., Uomoto A., Wannier P.G., Chen B., Jorgensen A.M.
<Astron. J. 124, 2164 (2002)>
=2002AJ....124.2164A 2002AJ....124.2164A
ADC_Keywords: Molecular clouds ; Photometry, SDSS ; Photometry, UBV
Keywords: ISM: individual (L1457)
Abstract:
We present a spectroscopic and photometric survey of a sample of field
stars in the region of the molecular cloud L1457. High-quality coude
feed spectra, together with five-band photometry in the Sloan Digital
Sky Survey system and near-infrared archival data from the Two Micron
All Sky Survey, are used to derive color excesses and distances for
the stars. Based on these data, a new distance estimate of 360±30pc
is derived for the cloud, supporting recent results by K.L. Luhman,
2001ApJ...560..287L 2001ApJ...560..287L. The data further indicate that the north-south
velocity gradient seen in the millimeter-wave CO data is mirrored in a
distance gradient, with the northern part of the cloud being closer to
us. A second, less opaque, layer of extinction is detected at ∼80pc.
This distance is consistent with the earlier distance estimates to the
cloud, based on Na I absorption. We identify this layer with the wall
of the hot Local Bubble. Hence, the dense cloud is not, as previously
thought, associated with the Local Bubble.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 84 172 Observational Data for Stars in the L1457 Field
table3.dat 96 172 Derived Data for Stars in the L1457 Field
table4.dat 57 68 Rejected stars
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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- 9 A9 --- GSC Guide Star Catalog identification number
11 A1 --- f_GSC [T] Flag GSC (1)
13 I1 h RAh Hour of Right Ascension (J2000)
15- 16 I2 min RAm Minute of Right Ascension (J2000)
18- 21 F4.1 s RAs Second of Right Ascension (J2000)
22 A1 --- DE- Sign of Declination (J2000)
23- 24 I2 deg DEd Degree of Declination (J2000)
26- 27 I2 arcmin DEm Arcminute of Declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of Declination (J2000)
34- 39 F6.3 mag u'mag ? The SDSS u'-band magnitude (2)
41- 46 F6.3 mag g'mag ? The SDSS g'-band magnitude (2)
48- 53 F6.3 mag r'mag ? The SDSS r'-band magnitude (2)
55- 60 F6.3 mag i'mag ? The SDSS i'-band magnitude (2)
62- 67 F6.3 mag z'mag ? The SDSS z'-band magnitude (2)
68 A1 --- u_z'mag [:] Uncertainty flag on z'mag (3)
70- 76 A7 mag Kmag ? K-band magnitude, transformed
from the 2MASS Ks magnitude
78- 82 F5.3 mag e_Kmag ? Error in Kmag
84 A1 --- f_Kmag [B] Indicates Kmag from Bhatt et al.,
1994A&A...289..946B 1994A&A...289..946B
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Note (1): T = BV photometry available from the Tycho database
(Hog et al., 2000, Cat. I/259).
Note (2): For the SDSS system photometry, the uncertainties are 0.02mag in
u'mag and 0.01mag in g'mag, r'mag, i'mag, and z'mag.
Note (3): For stars measured on JD 2451960, the z'mag errors are 0.04mag.
These z'mag magnitudes have been have been marked by with colons.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- GSC Guide Star Catalog identification number
11- 15 F5.2 mag Bmag The B-band magnitude
17- 20 F4.2 mag e_Bmag Error in Bmag
22- 26 F5.2 mag Vmag The V-band magnitude
28- 31 F4.2 mag e_Vmag Error in Vmag
33- 37 A5 --- SpType MK Spectral classification
39- 48 A10 --- n_SpType Range of uncertainty for SpType (1)
50- 54 F5.2 mag (B-V)0 The intrinsic (B-V)0 color
56- 59 F4.2 mag e_(B-V)0 Error in (B-V)0
61- 65 F5.2 mag VMAG The absolute V-band magnitude
67- 70 F4.2 mag e_VMAG Error in VMAG
72- 76 F5.2 mag E(B-V) The E(B-V) color excess
78- 81 F4.2 mag e_E(B-V) Error in E(B-V)
83- 88 F6.2 mag R(V) ? The total-to-selective extinction (2)
90- 95 F6.2 mag e_R(V) ? Error in R(V)
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Note (1): If no explicit uncertainty is given, the estimated uncertainty in the
spectral classification is one subclass.
Note (2): R(V)=1.1*E(V-K)/E(B-V).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- GSC Guide Star Catalog identification number
12 I1 h RAh Right ascension (J2000.0)
14- 15 I2 min RAm Right ascension (J2000.0)
17- 20 F4.1 s RAs Right ascension (J2000.0)
22 A1 --- DE- Declination sign (J2000.0)
23- 24 I2 deg DEd Declination (J2000.0)
26- 27 I2 arcmin DEm Declination (J2000.0)
29- 32 F4.1 arcsec DEs Declination (J2000.0)
34- 38 F5.2 mag Vmag V magnitude
39 A1 --- n_Vmag [cd] Note on Vmag (1)
41- 51 A11 --- SpType MK Spectral type
53- 57 A5 --- Code Rejection code (2)
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Note (1): GSC magnitude unless otherwise noted.
c: SDSS photometry.
d: Estimated from comparisons with GSC stars.
Note (2): Rejection codes:
(A) missing/bad photometry data
(B) missing/bad spectral data
(C) emission-line (T Tauri) star
(D) derived color excess unreasonable (significantly less than 0).
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History:
* 12-Nov-2002: From electronic version of the journal
* 22-Jun-2003: Several errors detected in table2, which have been corrected
in interaction with the author (Rafal Idzi). They concern les GSC numbers
or positions of stars at lines 11, 40, 89, 90, 101, 109, 171.
Table3 was corrected accordingly.
(Erratum in AJ 126, 2087 (2003))
(End) Greg Schwarz [AAS], Patricia Bauer, Francois Ochsenbein [CDS] 22-Jun-2003