J/AJ/151/13 LAMOST-Kepler MKCLASS spectral classification (Gray+, 2016)
LAMOST observations in the Kepler field: spectral classification with
the MKCLASS code.
Gray R.O., Corbally C.J., De Cat P., Fu J.N., Ren A.B., Shi J.R., Luo A.L.,
Zhang H.T., Wu Y., Cao Z., Li G., Zhang Y., Hou Y., Wang Y.
<Astron. J., 151, 13 (2016)>
=2016AJ....151...13G 2016AJ....151...13G (SIMBAD/NED BibCode)
ADC_Keywords: Spectral types ; Stars, barium ; Surveys
Keywords: stars: chemically peculiar - stars: general - surveys
Abstract:
The LAMOST-Kepler project was designed to obtain high-quality,
low-resolution spectra of many of the stars in the Kepler field with
the Large Sky Area Multi Object Fiber Spectroscopic Telescope (LAMOST)
spectroscopic telescope. To date 101086 spectra of 80447 objects over
the entire Kepler field have been acquired. Physical parameters,
radial velocities, and rotational velocities of these stars will be
reported in other papers. In this paper we present MK spectral
classifications for these spectra determined with the automatic
classification code MKCLASS. We discuss the quality and reliability of
the spectral types and present histograms showing the frequency of the
spectral types in the main table organized according to luminosity
class. Finally, as examples of the use of this spectral database, we
compute the proportion of A-type stars that are Am stars, and identify
32 new barium dwarf candidates.
Description:
The data for the LAMOST-Kepler project are supplied by the Large Sky Area
Multi Object Fiber Spectroscopic Telescope (LAMOST, also known as
the Guo Shou Jing Telescope). This unique astronomical instrument is
located at the Xinglong observatory in China, and combines a large
aperture (4 m) telescope with a 5° circular field of view (Wang et al.
1996ApOpt..35.5155W 1996ApOpt..35.5155W).
Our role in this project is to supply accurate two-dimensional spectral
types for the observed targets. The large number of spectra obtained
for this project (101086) makes traditional visual classification
techniques impractical, so we have utilized the MKCLASS code to perform
these classifications.
The MKCLASS code (Gray & Corbally 2014AJ....147...80G 2014AJ....147...80G, v1.07
http://www.appstate.edu/~grayro/mkclass/), an expert system designed
to classify blue-violet spectra on the MK Classification system, was
employed to produce the spectral classifications reported in this paper.
MKCLASS was designed to reproduce the steps skilled human classifiers
employ in the classification process.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 120 81170 LAMOST-Kepler MKCLASS spectral types
table3.dat 26 32 Candidate Ba Dwarfs
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
V/149 : LAMOST DR2 catalogs (Luo+, 2016)
J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)
J/A+A/594/A39 : LAMOST-Kepler parameters and activity indicators
(Frasca+, 2016)
J/AJ/152/6 : Parameters of Kepler stars using LAMOST + seismic data
(Wang+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 38 A38 --- SpecID Original LAMOST spectrum FITS file name (1)
40- 42 A3 --- --- [KIC]
43- 50 I8 --- KIC [01023665/13132080]? Kepler Input Catalog
identifier (2)
52- 55 A4 --- n_KIC Note on KIC (from De Cat et al. 2015,
J/ApJS/220/19) (3)
57- 77 A21 --- Header Stellar designation in FITS header
79 I1 --- n_Header [1]? Note on Header (from De Cat et al. 2015,
J/ApJS/220/19) (4)
81- 83 I3 --- S/N ?=999 [0/989] Sloan g band Signal-to-Noise value
85-112 A28 --- SpType MK spectral type (5)
114-118 A5 --- Q Quality flag (6)
120 A1 --- n_Q [?] Additional note on the quality (7)
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Note (1): Many of these fits files are already in the public domain and may be
downloaded from the LAMOST spectral archive (http://www.lamost.org).
The unreleased spectra may be obtained upon request after becoming
an external collaborator of the LAMOST-Kepler project.
Note (2): The table is ordered in terms of the Kepler ID, except for those
objects that do not have a Kepler designation; those objects are
appended to the end of the table and the column is left blank.
Note (3): Note as follows:
2 = KIC identification for a target with a Kepler number in the input
target list found in the KIC after increasing the search radius around
the coordinates of the object (maximum radius =0.16 arcmin =10 arcsec).
This identification should be treated with caution.
3 = KIC identification for a target without a Kepler number in the input
target list found in the KIC after increasing the search radius around
the coordinates of the object (maximum radius= 0.16 arcmin =10 arcsec).
This identification should be treated with caution.
4 = KIC09674346 has a Kp magnitude that matches well with the Kp given in
the headers of the FITS file while KIC09674345 has no Kp entry
in the KIC.
6 = KIC10230725 has a Kp magnitude that matches well with the Kp given
in the headers of the FITS file while KIC10230722 has no Kp entry
in the KIC.
7 = Possible confusion with KIC07090801 (RA=18:43:51.813; DE=+42:37:25.34;
Kp=9.233) which is at an angular separation of 0.050' from the input
catalog coordinates as given in the file headers of the FITS file.
8 = Possible confusion with KIC09512071 (RA=18:57:23.777; DE=46:11:03.19;
Kp unknown) which is at an angular separation of 0.029' from the input
catalog coordinates as given in the file headers of the FITS file.
9 = Possible confusion with KIC09402224 (RA=19:24:21.992; DE=45:58:21.88;
Kp unknown) which is at an angular separation of 0.034' from the input
catalog coordinates as given in the file headers of the FITS file.
11 = Possible confusion with KIC11026769 (RA=19:21:25.232; DE=48:30:53.02;
Kp unknown) which is at an angular separation of 0.040' from the input
catalog coordinates as given in the file headers of the FITS file.
12 = Possible confusion with KIC10456516 (RA=19:01:38.638; DE=47:38:47.25;
Kp unknown) which is at an angular separation of 0.022' from the input
catalog coordinates as given in the file headers of the FITS file.
13 = Possible confusion with KIC05166449 (RA=18:57:07.599; DE=40:20:04.36;
Kp unknown) which is at an angular separation of 0.042' from the input
catalog coordinates as given in the file headers of the FITS file.
14 = KIC03934458 has a Kp magnitude that matches well with the Kp given
in the headers of the FITS file while KIC03934457 is not found within
a radius of 0.16 arcmin from the coordinates.
15 = KIC03324929 has a Kp magnitude that matches well with the Kp given
in the headers of the FITS file while KIC03324051 is not found within
a radius of 0.16 arcmin from the coordinates.
Note (4): Note as follows:
1 = Large offset from the coordinates in the input target list reported.
(The name of the target was found in the input target list based on
these coordinates).
Note (5): The temperature type first, the luminosity type second, followed by a
list of detected peculiarities. For stellar types that are not on the
MK system (such as white dwarfs), Table 2 lists the codes that
MKCLASS uses for those types; not all of those codes can be found
in Table 1. The spectral-type notation for the Am stars, described
in Section 3.2, gives separate spectral types for the Ca II K-line,
the hydrogen lines, and the metallic-line spectrum.
Note (6): These ratings are based on χ2 differences between the program
spectrum and the best matched interpolated MK standard.
Quality flag as follows:
excel = Very few classifications are given a rating of "excellent"; this
requires almost exact correspondence between the program spectrum and
the interpolated spectral standard;
vgood = Spectral types with a "vgood" quality rating will have, typically, an
uncertainty (one standard deviation) similar to that reported in
Gray & Corbally (2014AJ....147...80G 2014AJ....147...80G), that is ±0.6 spectral subtype
in the temperature dimension where 1 spectral subtype is the
difference between, for instance, F5 and F6. In the luminosity
dimension, the uncertainty is about 0.5 luminosity class, where one
luminosity class is the difference between, for instance, "V" and
"IV". This uncertainty is somewhat dependent on spectral type.
Luminosity classification is particularly difficult in the mid A-type
stars, where the uncertainty might rise to ±1.0 luminosity class;
good = For spectra with a "good" quality rating, the errors are typically
twice those for the "vgood" category;
fair = Spectral types with "fair" are much more uncertain;
poor = Spectral types with "poor" are unreliable.
The last two quality categories (fair, poor) can usually be traced to either
low signal-to-noise ratio (S/N) spectra, or spectra with obvious defects.
Note (7): Note as follows:
? = Spectrum with some negative points (which may arise either from too much
background subtraction, or from noise).
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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- 3 A3 --- --- [KIC]
4- 11 I8 --- KIC [01720728/12736952] Star Kepler Input Catalog
identifier
13- 24 A12 --- SpType MK Spectral type
26 I1 --- n_SpType [1/4]? Note on SpType (1)
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Note (1): Note as follows:
1 = Two spectra exist for this star in the database, and MKCLASS assigns the
same or very similar spectral types to both;
2 = Three spectra are available in the database, and MKCLASS assigns the same
spectral type to all three;
3 = This star has been classified by MKCLASS (and verified visually) as
an F6 III-IV giant, and thus is considerably more evolved than other known
barium "dwarfs". We have obtained a spectrum of this star with the
spectrograph on the Vatican Advanced Technology Telescope, and that
spectrum confirms the MKCLASS spectral type. This star may therefore
provide a link between barium dwarfs and barium giants, almost all of
which must have been contaminated with s-process elements while on the
main sequence (cf. Bohm-Vitense et al. 2000ApJ...533..969B 2000ApJ...533..969B; North et al.
2000IAUS..177..269N 2000IAUS..177..269N);
4 = Metal-weak.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 13-Jul-2016