J/ApJS/242/13 Am stars from LAMOST DR5 (Qin+, 2019)
Metallic-line stars identified from low-resolution spectra of LAMOST DR5.
Qin L., Luo A.-L., Hou W., Li Y.-B., Zhang S., Wang R., Wang L.-L.,
Kong X., Han J.-S.
<Astrophys. J. Suppl. Ser., 242, 13-13 (2019)>
=2019ApJS..242...13Q 2019ApJS..242...13Q (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar; Spectra, optical; Spectral types; Colors;
Photometry, infrared; Parallaxes, trigonometric;
Equivalent widths; Abundances, [Fe/H]
Keywords: catalogs; infrared: stars; methods: data analysis
methods: statistical; stars: chemically peculiar; surveys
Abstract:
The Large Sky Area Multi-Object Fibre Spectroscopic Telescope data
release 5 (DR5) released more than 200,000 low-resolution spectra of
early-type stars with a signal-to-noise ratio >50. The search for
metallic-line (Am) stars in such a large database and a study of their
statistical properties are presented in this paper. Six
machine-learning algorithms were experimented with using known Am
spectra, and both the empirical criteria method and the MKCLASS
package were also investigated. Comparing their performance, the
random forest (RF) algorithm won, not only because the RF has high
successful rate, but because it can also derive rank features. Then
the RF was applied to the early-type stars of DR5, and 15269 Am
candidates were picked out. Manual identification was conducted based
on the spectral features derived from the RF algorithm; 9372 Am stars
and 1131 Ap candidates were compiled into a catalog. Statistical
studies were conducted including temperature distribution, space
distribution, and infrared photometry. The spectral types of Am stars
are mainly between F0 and A4 with a peak around A7, which is similar
to previous works. With the Gaia distances, we calculated the vertical
height Z from the Galactic plane for each Am star. The distribution of
Z suggests that the incidence rate of Am stars shows a descending
gradient with an increasing |Z|. On the other hand, Am stars do not
show a noteworthy pattern in the infrared band. As the wavelength gets
longer, the infrared excess of Am stars decreases, until there is
little or no excess in W1 and W2 bands.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table8.dat 368 10503 Catalog of Am stars
--------------------------------------------------------------------------------
See also:
III/106 : MK Classification of Visual Multiples (Abt, 1981)
III/162 : General Catalogue of Ap and Am stars (Renson+ 1991)
III/260 : General Catalogue of Ap and Am stars (Renson+ 2009)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/MNRAS/449/1401 : Am stars candidates from LAMOST DR1 (Hou+, 2015)
J/AJ/151/13 : LAMOST-Kepler MKCLASS spectral classification (Gray+, 2016)
J/AJ/153/218 : New IR photometric study of Ap and Am stars (Chen+, 2017)
J/ApJS/259/63 : Chemically peculiar stars from LAMOST (Shang+, 2022)
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Seq [1/10503] Sequential running identifier
7- 46 A40 --- Name Name of FITS file of each spectrum
48- 58 F11.7 deg RAdeg Right Ascension (J2000)
60- 69 F10.7 deg DEdeg [-9.8/61.8] Declination (J2000)
71- 75 I5 K Teff [6750/10500] Surface effective temperature (1)
77- 89 F13.10 0.1nm FeEW [5.8/17.6] Equivalent width, Fe-group lines,
observed
91- 103 F13.10 0.1nm FeEW-m [1.2/14.2] Equivalent width, Fe-group lines,
Kurucz template
105- 117 F13.10 0.1nm KEW [-0.13/5.6] Equivalent width, CaII K line,
observed
119- 130 F12.10 0.1nm KEW-m [0.4/6.8] Equivalent width, CaII K line,
Kurucz template
132- 136 A5 --- SpT-K Spectral subtype, CaII K line,
138- 142 A5 --- SpT-H Spectral subtype, Balmer lines
144- 148 A5 --- SpT-m Spectral subtype, metallic lines
150- 165 F16.10 pc Z [-7299/5684]? Vertical distance from the
Galactic plane
167- 181 F15.10 pc rest [42/7362]? Estimated distance (2)
183- 197 F15.10 pc b_rest [41/6291]? Lower bound on the confidence
interval of rest (2)
199- 213 F15.10 pc B_rest [43/9358]? Upper bound on the confidence
interval of rest (2)
215- 221 F7.4 mas Plx [0.0063/23.7]? GAIA DR2 Parallax
223- 228 F6.4 mas e_Plx [0.012/1.3]? Uncertainty in Parallax
230- 235 F6.3 mag Jmag [7.47/14.9]? 2MASS J band magnitude
237- 241 F5.3 mag e_Jmag [0.017/0.08]? Uncertainty in Jmag
243- 248 F6.3 mag Hmag [7.28/14.8]? 2MASS H band magnitude
250- 254 F5.3 mag e_Hmag [0.014/0.08]? Uncertainty in Hmag
256- 261 F6.3 mag Kmag [7.15/14.65]? 2MASS K band magnitude
263- 267 F5.3 mag e_Kmag [0.01/0.1]? Uncertainty in Kmag
269- 274 F6.3 mag W1mag [7/14.6]? WISE band 1 [3.4um] band magnitude
276- 280 F5.3 mag e_W1mag [0.013/0.05]? Uncertainty in W1mag
282- 287 F6.3 mag W2mag [7/14.6]? WISE band 2 [4.6um] band magnitude
289- 293 F5.3 mag e_W2mag [0.014/0.05]? Uncertainty in W2mag
295- 301 F7.4 mag E(B-V) [0.0047/14.5]? Reddening color excess (3)
303- 311 F9.6 mag (J-H)0 [-3.7/0.7]? Extinction corrected J-H color
313- 321 F9.6 mag (H-K)0 [-2.3/0.5]? Extinction corrected H-K color
323- 332 F10.7 mag (W1-W2)0 [-0.4/0.8]? Extinction corrected W1-W2 color
334- 339 F6.3 --- FeH [-0.66/0.95]? LAMOST FeH metallicity
341- 353 F13.10 --- EW4077 [-0.018/1.9] EW of 4077Å spectral line,
observed
355- 366 F12.10 --- EW4077-m [0.27/2.1] EW of 4077Å spectral line,
Kurucz template
368 I1 --- FlAp [0/1] Ap flag column; 1=Ap candidate.
--------------------------------------------------------------------------------
Note (1): Teff is the effective temperature obtained through matching with the
Kurucz grid in the [3900Å, 5600Å] wavelength range.
Note (2): The estimated distance and the upper and lower bounds are taken
from the catalog in Bailer-Jones+ (2018, I/347).
Note (3): E(B-V) values are taken from
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jul-2022