J/A+A/703/A102 Spectra of 18 ssrAp star candidates (Mathys+, 2025)
Super-slowly rotating Ap (ssrAp) stars: New spectroscopic observations.
Mathys G., Holdsworth D.L., Giarrusso M., Kurtz D.W., Catanzaro G., Leone F.
<Astron. Astrophys. 703, A102 (2025)>
=2025A&A...703A.102M 2025A&A...703A.102M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Ap ; Rotational velocities; Magnetic fields
Keywords: stars: chemically peculiar - stars: magnetic fields -
stars: oscillations - stars: rotation
Abstract:
The rotation periods of Ap stars range over five to six orders of
magnitude. The origin of their differentiation remains unknown.
We carry out a systematic study of the longest period Ap stars to gain
insight into their properties.
We analyse newly obtained spectra of a sample of super-slowly rotating
Ap (ssrAp) star candidates identified by a TESS photometric survey to
confirm that their projected equatorial velocity v sin i is consistent
with (very) long rotation periods, to obtain a first determination of
their magnetic fields, and to test their binarity.
The value of vsini in 16 of the 18 studied stars is low enough for
them to have moderately to extremely long rotation periods. All stars
but one are definitely magnetic; for five of them, the magnetic field
was detected for the first time. Five new stars with resolved
magnetically split lines were discovered. Five stars that were not
previously known to be spectroscopic binaries show radial velocity
variations; in one of them, lines from both components are observed.
Description:
The reduced, normalised spectra of 18 super-slowly rotating Ap (ssrAp)
stars identified from a TESS photometric survey are presented. These
spectra were used to confirm that the studied stars are indeed Ap
stars, to check that their projected equatorial velocities are
compatible with super-slow rotation, and to obtain a first estimate of
their magnetic field strengths. For the corresponding measurements, a
local continuum was defined for each spectral line. Accordingly, the
overall normalisation of the whole spectrum may only be approximate,
hence unsuitable for some purposes (for instance, characterisation of
the hydrogen Balmer line profiles). The file summary below gives for
each spectrum the star ID in the TESS Input Catalogue (TIC), the
Julian Date of the observation, and the spectrograph that was used:
HARPS-N at the Telescopio Nazionale Galileo, HRS at the Southern
African Large Telescope (SALT), UVES at the Unit Telescope 2 (UT2) of
the Very Large Telescope (VLT) of the European Southern Observatory
(ESO), HARPS at the 3.6-m telescope of ESO, or FEROS at the
2.2m-telescope of ESO.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 71 35 List of studied atars and spectra
sp/* . 35 Individual spectra
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Star name (TIC NNNNNNNNN)
15- 16 I2 h RAh Simbad right ascension (J2000)
18- 19 I2 min RAm Simbad right ascension (J2000)
21- 25 F5.2 s RAs Simbad right ascension (J2000)
27 A1 --- DE- Simbad declination sign (J2000)
28- 29 I2 deg DEd Simbad declination (J2000)
31- 32 I2 arcmin DEm Simbad declination (J2000)
34- 37 F4.1 arcsec DEs Simbad declination (J2000)
39- 52 A14 --- FileName Name of the spectrum file in subdirectory sp
54- 62 F9.1 d JD Julian date of observation
64- 71 A8 --- Inst Instrument
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 12 F12.4 0.1nm lambda Wavelength in heliocentric reference frame (1)
13- 21 F9.4 --- Flux Flux normalised to continuum
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Note (1): The FEROS spectra represent an exception, with the wavelength
approximately in the laboratory reference frame.
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Acknowledgements:
Gautier Mathys, gmathys(at)eso.org)
(End) Gautier Mathys [ESO, Chile], Patricia Vannier [CDS] 25-Sep-2025