HD 60431, the CP2 star with the shortest rotational period Physical parameters and period analysis

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F22%3A00128601" target="_blank" >RIV/00216224:14310/22:00128601 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.aanda.org/articles/aa/full_html/2022/12/aa43622-22/aa43622-22.html" target="_blank" >https://www.aanda.org/articles/aa/full_html/2022/12/aa43622-22/aa43622-22.html</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202243622" target="_blank" >10.1051/0004-6361/202243622</a>

Jazyk výsledku

angličtina

Název v původním jazyce

HD 60431, the CP2 star with the shortest rotational period Physical parameters and period analysis

Popis výsledku v původním jazyce

Context. CP2 stars show periodic photometric, spectroscopic, and magnetic variations with the rotational period. They are generally slow rotators, with rotational periods exceeding half a day, except for the late B-type star HD 60431, which has an unusually short rotational period of 0.4755 days. As slow rotation is deemed a necessary criterion for the establishment of chemical peculiarities, this characteristic renders HD 60431 a special object that might o ffer valuable insight into, and constraints on, the formation and evolution of CP2 stars. Aims. The aims of our study are to analyse the light variability, derive atmospheric abundances, and determine the detailed physical parameters of HD 60431 to confirm its status as the CP2 star with the shortest known rotational period, with special emphasis on the rotational period evolution. Methods. Photometric indices and high-resolution spectroscopy were employed to derive the physical parameters, evolutionary status, and atmospheric abundances of our target star. A light variability study was carried out using combined sets of photometric data from ground- and space-based facilities. A circularly polarised spectrum was employed to check the presence of a longitudinal magnetic field in the star. Results. With an age of only 10 Myr, an e ffective temperature of T-eff = 13 000 +/- 300 K, surface gravity log g = 4:10 +/- 0:10, radius R = 1:97 +/- 0:09 R-circle dot, and mass M = 3:1 +/- 0:1 M-circle dot, HD 60431 is situated close to the zero age main sequence; it is a member of the open cluster NGC 2547 in the Vela OB2 complex. We confirm its status as a classical late B-type CP2 star showing strong overabundances of Mg (1.8 dex), Si (1.9 dex), Ca (1.6 dex), Ti (2.2 dex), and Fe (1.8 dex). No conclusive evidence for the presence of a strong magnetic field was found in the available spectroscopic data. The light curve of HD 60431 has remained constant over the last four decades. The available photometric time series data confirm the short rotational period and indicate a slight secular increase in the rotational period of &lt;(P)over dot&gt; = 2:36(19) x 10(-10) = 7:5 (6) ms yr(-1). The following quadratic ephemeris has been derived: HJD(min)(E) = 2 459 212:969 35 + 0(d).475 516 64 E + 5(d).62 x 10(-11)E(2). Conclusions. HD 60431 is indeed the CP2 star with the shortest known rotational period. Theory needs to explain the establishment and maintenance of chemical peculiarities in such a young and fast-rotating object. Our results furthermore raise the question of whether period variability on timescales significantly shorter than stellar evolution is inherent to all magnetic chemically peculiar stars.

Název v anglickém jazyce

HD 60431, the CP2 star with the shortest rotational period Physical parameters and period analysis

Popis výsledku anglicky

Context. CP2 stars show periodic photometric, spectroscopic, and magnetic variations with the rotational period. They are generally slow rotators, with rotational periods exceeding half a day, except for the late B-type star HD 60431, which has an unusually short rotational period of 0.4755 days. As slow rotation is deemed a necessary criterion for the establishment of chemical peculiarities, this characteristic renders HD 60431 a special object that might o ffer valuable insight into, and constraints on, the formation and evolution of CP2 stars. Aims. The aims of our study are to analyse the light variability, derive atmospheric abundances, and determine the detailed physical parameters of HD 60431 to confirm its status as the CP2 star with the shortest known rotational period, with special emphasis on the rotational period evolution. Methods. Photometric indices and high-resolution spectroscopy were employed to derive the physical parameters, evolutionary status, and atmospheric abundances of our target star. A light variability study was carried out using combined sets of photometric data from ground- and space-based facilities. A circularly polarised spectrum was employed to check the presence of a longitudinal magnetic field in the star. Results. With an age of only 10 Myr, an e ffective temperature of T-eff = 13 000 +/- 300 K, surface gravity log g = 4:10 +/- 0:10, radius R = 1:97 +/- 0:09 R-circle dot, and mass M = 3:1 +/- 0:1 M-circle dot, HD 60431 is situated close to the zero age main sequence; it is a member of the open cluster NGC 2547 in the Vela OB2 complex. We confirm its status as a classical late B-type CP2 star showing strong overabundances of Mg (1.8 dex), Si (1.9 dex), Ca (1.6 dex), Ti (2.2 dex), and Fe (1.8 dex). No conclusive evidence for the presence of a strong magnetic field was found in the available spectroscopic data. The light curve of HD 60431 has remained constant over the last four decades. The available photometric time series data confirm the short rotational period and indicate a slight secular increase in the rotational period of &lt;(P)over dot&gt; = 2:36(19) x 10(-10) = 7:5 (6) ms yr(-1). The following quadratic ephemeris has been derived: HJD(min)(E) = 2 459 212:969 35 + 0(d).475 516 64 E + 5(d).62 x 10(-11)E(2). Conclusions. HD 60431 is indeed the CP2 star with the shortest known rotational period. Theory needs to explain the establishment and maintenance of chemical peculiarities in such a young and fast-rotating object. Our results furthermore raise the question of whether period variability on timescales significantly shorter than stellar evolution is inherent to all magnetic chemically peculiar stars.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy and Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

668

Číslo periodika v rámci svazku

December

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

13

Strana od-do

1-13

Kód UT WoS článku

000899861100001

EID výsledku v databázi Scopus

2-s2.0-85145346151