J/A+A/645/A34 LAMOST DR4 New mercury-manganese stars (Paunzen+, 2021)
New mercury-manganese stars and candidates from LAMOST DR4.
Paunzen E., Hummerich S., Bernhard K.
<Astron. Astrophys., 645, A34 (2021)>
=2021A&A...645A..34P 2021A&A...645A..34P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, peculiar ; Parallaxes, trigonometric ;
Magnitudes ; Optical
Keywords: stars: chemically peculiar - stars: abundances -
stars: variables: general
Abstract:
The present work presents our efforts at identifying new
mercury-manganese (HgMn/CP3) stars using spectra obtained with the
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST).
Suitable candidates were searched for among pre-selected early-type
spectra from LAMOST DR4 using a modified version of the MKCLASS code
that probes several HgII and MnII features. The spectra of the
resulting 332 candidates were visually inspected. Using parallax data
and photometry from Gaia DR2, we investigated magnitudes, distances
from the Sun, and the evolutionary status of our sample stars. We also
searched for variable stars using diverse photometric survey sources.
We present 99 bona fide CP3 stars, 19 good CP3 star candidates, and
seven candidates. Our sample consists of mostly new discoveries and
contains, on average, the faintest CP3 stars known (peak distribution
9.5≤G≤13.5mag). All stars are contained within the narrow spectral
temperature-type range from B6 to B9.5, in excellent agreement with
the expectations and the derived mass estimates (2.4≤M☉≤4 for
most objects). Our sample stars are between 100Myr and 500Myr old and
cover the whole age range from zero-age to terminal-age main sequence.
They are almost homogeneously distributed at fractional ages on the
main sequence ≤80%, with an apparent accumulation of objects between
fractional ages of 50% to 80%. We find a significant impact of
binarity on the mass and age estimates. Eight photometric variables
were discovered, most of which show monoperiodic variability in
agreement with rotational modulation.
Together with the recently published catalogue of APOGEE CP3 stars,
our work significantly increases the sample size of known Galactic CP3
stars, paving the way for future in-depth statistical studies.
Description:
Using an altered version of Richard O. Gray's MKCLASS code, which
was tailored to probe several HgII and MnII features relevant to
the identification of CP3 stars, we searched for CP3 stars among the
LAMOST DR4 spectra of a colour-preselected sample of early-type stars.
The spectra of all selected candidates were visually inspected;
non-CP3 objects were sorted out and the strength of the HgII and
MnII features was estimated. Depending on this estimate, the
resulting sample was divided into bona fide CP3 stars, good CP3 star
candidates, and candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 161 125 Essential data for our sample stars,
sorted by increasing right ascension
tablea2.dat 42 117 Upper limits of variability for the stars
identified as non-variable in the accuracy
limits of the employed data sources
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/125] Sequential number
5- 23 A19 --- LAMOST LAMOST designation (JHHMMSS.ss+DDMMSS.s)
24 A1 --- n_LAMOST [abcd] Note (1)
26- 53 A28 --- OName Alternative name (HD number, TYC identifier or
Gaia DR2 number)
55- 56 I2 h RAh Right ascension (J2000)
58- 59 I2 min RAm Right ascension (J2000)
61- 65 F5.2 s RAs Right ascension (J2000)
67 A1 --- DE- Declinaiton sign (J2000)
68- 69 I2 deg DEd Declinaiton (J2000)
71- 72 I2 arcmin DEm Declinaiton (J2000)
74- 78 F5.2 arcsec DEs Declinaiton (J2000)
80- 96 A17 --- SpType Final spectral type, as derived in this study
98-100 I3 --- S/Ng Sloan g-band sigma-to-noise ratio of the
analysed spectrum
102-108 F7.4 mag Gmag Gaia DR2 G magnitude
110-115 F6.4 mag e_Gmag rms uncertainty on Gmag
117-122 F6.4 mas plx ?=- Gaia DR2 parallax
124-129 F6.4 mas e_plx ?=- rms uncertainty on Plx
131-136 F6.3 mag (BP-RP)0 ?=- Deredenned Gaia DR2 BP-RP colour index
138-142 F5.3 mag e_(BP-RP)0 ?=- rms uncertainty on (BP-RP)0
144-148 F5.3 mag AG Absorption in G band
150-155 F6.3 mag GMAG0 ?=- Intrinsic absolute magnitude in
Gaia DR2 G band
157-161 F5.3 mag e_GMAG0 ?=- rms uncertainty on GMAG0
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Note (1): Note as follows:
a = Contained in the sample of APOGEE CP3 stars of
Chojnowski et al. (2020MNRAS.496..832C 2020MNRAS.496..832C).
b = Renson & Manfroid (2009A&A...498..961R 2009A&A...498..961R, cat. III/260):
Renson 8947; spectral type: B9 Si. LAMOST spectrum shows typical
signature of a CP3 star; not a classical CP2 star.
c = Renson & Manfroid (2009A&A...498..961R 2009A&A...498..961R, cat. III/260):
Renson 10597; spectral type: B8 Si; CP star of doubtful nature.
LAMOST spectrum shows typical signature of a CP3 star;
not a classical CP2 star.
d = Renson & Manfroid (2009A&A...498..961R 2009A&A...498..961R, cat. III/260):
Renson 11944; spectral type: A0; CP star of doubtful nature.
LAMOST spectrum shows typical signature of a CP3 star.
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/165] Sequential number
5- 23 A19 --- LAMOST LAMOST designation (JHHMMSS.ss+DDMMSS.s)
25- 28 F4.1 mmag ULSW ? Upper limit of variability as derived from
SWASP data (semiamplitude)
30- 33 F4.1 mmag ULAS ? Upper limit of variability as derived from
ASAS-SN data (semiamplitude)
35- 38 F4.1 mmag ULAS3 ? Upper limit of variability as derived from
ASAS-3 data (semiamplitude)
40- 42 F3.1 mmag ULTE ? Upper limit of variability as derived from
TESS data (semiamplitude)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Feb-2021