J/A+A/692/A231 Super-slowly rotating Ap (ssrAp) stars sample (Hummerich+, 2024)
A new sample of super-slowly rotating Ap (ssrAp) stars from the
Zwicky Transient Facility survey.
Hummerich S., Bernhard K., Paunzen E.
<Astron. Astrophys. 692, A231 (2024)>
=2024A&A...692A.231H 2024A&A...692A.231H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Stars, Ap ; Photometry ; Optical
Keywords: stars: chemically peculiar - stars: early-type - stars: rotation -
stars: variables: general
Abstract:
The magnetic chemically peculiar Ap stars exhibit an extreme spread of
rotational velocities, the cause of which is not clearly understood.
Ap stars with rotation periods of 50 days or longer are know as
super-slowly rotating Ap (ssrAp) stars. Photometrically variable Ap
stars are commonly termed α2 Canum Venaticorum (ACV)
variables.
Our study aims to enlarge the sample of known ssrAp stars using data
from the Zwicky Transient Facility (ZTF) survey to enable more robust
and significant statistical studies of these objects.
Using selection criteria based on the known characteristics of ACV
variables, candidate stars were gleaned from the ZTF catalogues of
periodic and suspected variable stars and from ZTF raw data. ssrAp
stars were identified from this list via their characteristic
photometric properties, {DELTA}a photometry, and spectral
classification.
The final sample consists of 70 new ssrAp stars, which mostly exhibit
rotation periods of between 50 and 200 days. The object with the
longest period has a rotation period of 2551.7 days. We present
astrophysical parameters and a Hertzsprung-Russell diagram for the
complete sample of known ssrAp stars. With very few exceptions, the
ssrAp stars are grouped in the middle of the main sequence with ages
in excess of 150Myr. ZTF J021309.72+582827.7 was identified as a
possible binary star harbouring an Ap star and a cool component,
possibly shrouded in dust.
With our study, we enlarge the sample of known ssrAp stars by about
150%, paving the way for more in-depth statistical studies.
Description:
We have carried out a search for new ssrAp stars using data from the
ZTF survey. Using suitable selection criteria based on known
astrophysical and light curve properties of this group of stars and,
where available, {DELTA}a photometry and LAMOST spectra, we identified
70 new ssrAp stars. With a mean magnitude of G∼15mag, we extend the
sample of known ssrAp stars to significantly lower magnitudes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 72 104 Astrophysical parameters and synthetic {DELTA}a
photometry for the merged samples of ssrAp
stars and candidates
tablea2.dat 103 70 Basic parameters for the newly identified sample
of ssrAp stars and candidates.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- Name Identifier
30- 34 I5 K Teff Effective temperature
37- 40 I4 K e_Teff Effective temperature error
42- 46 F5.3 [cm/s2] logg Surface gravity
48- 52 F5.3 [cm/s2] e_logg Surface gravity error
54- 59 F6.3 mag g1-y ? g1-y colour index
61- 65 F5.3 mag aindex ? a index
67- 72 F6.3 mag Da ? {DELTA}a value
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- Name Identifier
29- 30 I2 h RAh Right ascension (J2000) from Gaia DR3
32- 33 I2 min RAm Right ascension (J2000) from Gaia DR3
35- 39 F5.2 s RAs Right ascension (J2000) from Gaia DR3
41 A1 --- DE- Declination sign (J2000) from Gaia DR3
42- 43 I2 deg DEd Declination (J2000) from Gaia DR3
45- 46 I2 arcmin DEm Declination (J2000) from Gaia DR3
48- 52 F5.2 arcsec DEs Declination (J2000) from Gaia DR3
54- 61 A8 --- Source Source of data (1)
63- 68 F6.3 mag Gmag Gaia DR3 G magnitude
70- 75 F6.1 d Per Photometric variability period,
as derived in this study
77- 93 A17 --- SpType Spectral type, where available,
as derived in this study
95-103 A9 --- Remark Remark (2)
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Note (1): Source of data as follows:
ZTF_per = ZTF catalogue of periodic variables
(Chen et al., 2020ApJS..249...18C 2020ApJS..249...18C, Cat. J/ApJS/249/18)
ZTF_sus = ZTF catalogue of suspected variables
(Chen et al., 2020ApJS..249...18C 2020ApJS..249...18C, Cat. J/ApJS/249/18)
raw_data = ZTF raw data
Note (2): Remark, concerning the main photometric property the star was
selected for, as follows:
antiphase = indicates that the g and r light curves are in antiphase,
ampr>ampg = indicates that the amplitude of the variations in r
is larger than the amplitude in g,
ampr∼ampg = indicates that the amplitude of the variations in r is about the
same as the amplitude in g
LC shape = stands for characteristic light curve shape
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 19-May-2025