New catalogue of chemically peculiar stars, and statistical analysis

Ghazaryan, S.; Alecian, G.; Hakobyan, A. A.

doi:10.1093/mnras/sty1912

Cited by 61 publications

(70 citation statements)

References 43 publications

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“…Nevertheless, at LAMOST resolution, the 3984 Å feature also contains contributions from the Y ii line at 3982.59 Å. Y is strongly overabundant in CP stars (Guthrie 1971;Monier et al 2019), in particularly in CP3 stars. From the compilation of Ghazaryan et al (2018), we derive mean Y abundances of +0.86 dex, +1.26 dex, and +2.64 dex as compared to the solar value for, respectively, CP1, CP2, and CP3 stars. However, considering the strength of the Y ii spectrum, at the resolution of the LAMOST spectra, an extreme overabundance of Y would be needed for a significant detection of the Y ii 3982.59 Å line alone.…”

Section: Customising the Mkclass Codementioning

confidence: 99%

New mercury-manganese stars and candidates from LAMOST DR4

Paunzen

Hümmerich

Bernhard

2021

A&A

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Aims. 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). Methods. 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 Hg ii and Mn ii 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. Results. 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 ≤ 13.5 mag). 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 100 Myr and 500 Myr 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. Conclusions. 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.

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Section: Customising the Mkclass Codementioning

confidence: 99%

New mercury-manganese stars and candidates from LAMOST DR4

Paunzen

Hümmerich

Bernhard

2021

A&A

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“…We have examined all 169 known SrEuCr and Si Ap/Bp stars in TESS sectors 1-7 that are listed in the catalogue of chemically peculiar stars by Ghazaryan, Alecian & Hakobyan (2018). Whereas16 stars show no significant variability, 12 are δ Sct stars, 5 are γ Dor, and13 are eclipsing variables.…”

Section: W H At I S a Roa P S Ta R ?mentioning

confidence: 99%

High frequencies in TESS A–F main-sequence stars

Balona

Holdsworth

Cunha

2019

Monthly Notices of the Royal Astronomical Society

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The driving mechanism for high-frequency oscillations in some chemically peculiar Ap stars, the rapidly oscillating Ap stars (roAp stars), is not understood. The Transiting Exoplanet Survey Satellite mission (TESS) data provide an ideal opportunity to extend the number of roAp stars that might provide further clues to address this problem. From an examination of over 18 000 stars in TESS sectors 1–7, we have discovered high-frequency pulsations in 14 A–F stars, of which only 3 are classified as Ap stars. In addition to these new discoveries, we discuss the frequencies in nine previously known roAp stars. In one of these stars, HD 60435, we confirm a previous finding that the pulsations have lifetimes of only a few days. In another known roAp star, HD 6532, the relative amplitudes of the rotationally modulated sidelobes, which are generally used to estimate the inclination of the magnetic axis relative to the rotational axis, are significantly different from those found in ground-based B-band photometric observations. We also discuss four δ Scuti stars that appear to have independent frequencies similar to those of roAp stars.

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“…The defining characteristic of CP stars is the presence of spectral peculiarities, which indicate unusual elemental abundance patterns. Several groups of CP stars have been defined, such as the metallic-line or Am (CP1) stars, the magnetic Bp/Ap (CP2) stars, the Mercury-Manganese (HgMn/CP3) stars, the He-weak (CP4) stars or the λ Bootis stars (Preston 1974;Maitzen 1984;Paunzen 2004;Ghazaryan et al 2018).…”

Section: Introductionmentioning

confidence: 99%

New and improved rotational periods of magnetic CP stars from ASAS-3, KELT, and MASCARA data

Bernhard

Hümmerich

Paunzen

2020

Monthly Notices of the Royal Astronomical Society

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Magnetic chemically peculiar (mCP) stars allow the investigation of such diverse phenomena as atomic diffusion, magnetic fields and stellar rotation. The aim of the present investigation is to enhance our knowledge of the rotational properties of mCP stars by increasing the sample of objects with accurately determined rotational periods. To this end, archival photometric time-series data from the ASAS-3, KELT and MASCARA surveys were employed to improve existing rotational period information and derive rotational periods for mCP stars hitherto not known to be photometric variables. Our final sample consists of 294 mCP stars, a considerable amount of which (more than 40%) are presented here as photometric variables for the first time. In addition, we identified 24 mCP star candidates that show light variability in agreement with rotational modulation but lack spectroscopic confirmation. The rotational period distribution of our sample agrees well with the literature. Most stars are between 100 Myr and 1 Gyr old, with an apparent lack of very young stars. No objects were found on the zero age main sequence; several stars seem to have evolved to the subgiant stage, albeit well before the first dredge-up. We identified four eclipsing binaries (HD 244391, HD 247441, HD 248784 and HD 252519), which potentially host an mCP star. This is of great interest because mCP stars are very rarely found in close binary systems, particularly eclipsing ones. Using archival spectra, we find strong evidence that the HD 252519 system indeed harbours an mCP star component.

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New catalogue of chemically peculiar stars, and statistical analysis

Cited by 61 publications

References 43 publications

New mercury-manganese stars and candidates from LAMOST DR4

New mercury-manganese stars and candidates from LAMOST DR4

High frequencies in TESS A–F main-sequence stars

New and improved rotational periods of magnetic CP stars from ASAS-3, KELT, and MASCARA data

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