J/A+A/666/A142 Classification of A-F spectral type stars (Skarka+, 2022)
Periodic variable A-F spectral type stars in the northern TESS continuous
viewing zone. I. Identification and classification.
Skarka M., Zak J., Fedurco M., Paunzen E., Henzl Z., Masek M.,
Karjalainen R., Sanchez Arias J.P., Sodor A., Auer R.F., Kabath P.,
Karjalainen M., Liska J., Stegner D.
<Astron. Astrophys. 666, A142 (2022)>
=2022A&A...666A.142S 2022A&A...666A.142S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, F-type; Stars, A-type
Keywords: stars: variables: general - stars: oscillations - stars: rotation -
methods: data analysis - catalogs
Abstract:
In the time of large space surveys that provide tremendous amounts of
precise data, it is highly desirable to have a commonly accepted
methodology and system for the classification of variable stars. This
is especially important for A-F stars, which can show intrinsic
brightness variations due to both rotation and pulsations.
The goal of our study is to provide a reliable classification of the
variability of A-F stars brighter than 11 mag located in the northern
TESS continuous viewing zone. We also aim to provide a thorough
discussion about issues in the classification related to data
characteristics and the issues arising from the similar light-curve
shape generated by different physical mechanisms.
We used TESS long- and short-cadence photometric data and
corresponding Fourier transform to classify the variability type of
the stars. We also used spectroscopic observations to determine the
projected rotational velocity of a few stars.
We present a clear and concise classification system that is
demonstrated on many examples. We find clear signs of variability in
3025 of 5923 studied stars (51%). For 1813 of these 3025 stars, we
provide a classification; the rest cannot be unambiguously classified.
Of the classified stars, 64.5% are pulsating stars of g-mode γ
Doradus (GDOR) and p-mode δ Scuti types and their hybrids. We
realised that the long- and short-cadence pre-search data conditioning
simple aperture photometry data can differ significantly not only in
amplitude but also in the content of instrumental and data-reduction
artefacts, making the long-cadence data less reliable. We identified a
new group of stars that show stable light curves and characteristic
frequency spectrum patterns (8.5% of the classified stars). According
to the position in the Hertzsprung-Russell diagram, these stars are
likely GDOR stars but are on average about 200K cooler than GDORs and
have smaller amplitudes and longer periods. With the help of
spectroscopic measurements of vsini, we show that the variability of
stars with unresolved groups of peaks located close to the positions
of the harmonics in their frequency spectra (16% of the classified
stars) can be caused by rotation rather than by pulsations. We show
that without spectroscopic observations it can be impossible to
unambiguously distinguish between ellipsoidal variability and
rotational variability. We also applied our methodology to three
previous studies and find significant discrepancies in the
classification.
Description:
We present a classification of A-F spectral type stars brighter than
11 mag that are located in the TESS continuous viewing zone. We found
clear signs of variability in 3025 of 5923 studied stars (51%). For
1813 of these 3025 stars, we provide a classification. From the
classified stars, 64.5% are pulsating stars of GDOR and DSCT types
and their hybrids. We identified a new group of stars showing stable
light curves and characteristic frequency spectra pattern (8.5% of
the classified stars).
The classification is based on the light-curve shape and Fourier
transform of photometric data. We used TESS SPOC and QLP data
products. For ech star we give identification in the TIC catalogue,
equatorial coordinates, variability type, spectral type based on
LAMOST spectra, dominant frequency value, zero epoch (for eclipsing
binaries), amplitude of the photometric variations in TESS filter, VSX
designation, VSX variability type, information about blending stars,
and number of stars that are closer than 5 pixels having brightness
difference less than 5mag.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 162 5923 Classification of A-F spectral type stars in the
northern TESS viewing zone
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See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)
Byte-by-byte Description of file:table5.dat
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Bytes Format Units Label Explanations
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1- 10 I10 ---- Name Number in the TIC catalogue
(Paegert et al., 2021, Cat. IV/39)
12- 26 F15.11 deg RAdeg Right ascension (J2000)
28- 41 F14.11 deg DEdeg Declination (J2000)
43- 56 A14 ---- VType Variability type
58- 75 A18 ---- SpType Spectral type
77- 84 F8.5 c/d f ? Dominant frequency
86- 98 F13.5 d M0 ? Zero epoch (MJD)
100 A1 --- l_dT Limit flag on dT
101-106 F6.1 mmag dT ? Amplitude of the light variations
108-135 A28 ---- VSX Designation of the variable star in VSX
(Watson et al, 2014, Cat. B/vsx)
137-149 A13 ---- VSXtype VSX variability type
151-159 I9 ---- Blend ? TIC designation of the blending star that is
variable
161-162 I2 ---- N ? Number of blending stars with brightness
difference less than 5mag
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Acknowledgements:
Marek Skarka, skarka(at)asu.cas.cz
(End) Patricia Vannier [CDS] 29-Jul-2022