HD 213258 is a Rapidly Oscillating, Strongly Magnetic Ap Star; a Study Discovers
Utilizing the Canada-France-Hawaii Telescope (CFHT), astronomers have observed a chemically peculiar star called as HD 213258. In the outcome, they found that HD 213258 is a quickly oscillating, strongly magnetic Ap star. The finding is reported in a paper released on December 24 on the arXiv pre-print server.
Chemically peculiar (CP) stars are those with uncommon metal abundances, therefore exhibiting strong or weak spectral lines for certain aspects. Some CP stars are observed to have strong magnetic fields than classic A- or B-type stars, differing from few tens of Gauss (G) to tens of kiloGauss (KG), and are hence called magnetic chemically peculiar (mCP) stars (Ap and also Bp stars). This class of things is perceived by astronomers as a natural atomic and magnetic lab to study stellar formation and evolution.
Found some 363 light-years away in the constellation of Lacerta, HD 213258 (also called BD +35 4815) is a CP star of spectral kind A3E, estimated to be some 2.4 times larger than the sunlight. The star’s absolute magnitude is 2.39 mag, and also its efficient temperature level is estimated to be between 7,500 and 10,000 K.
Lately, a group of astronomers carried by Gautier Mathys of European Southern Observatory (ESO) in Chile has seen HD 213258 with the ESPaDOnS spectrograph at CFHT. The observational campaign enabled them to unveil more insights into the nature of this star.
“We report concerning HD 213258, an Ap star that we recently determined as showing a unique mix of uncommon, remarkable properties,” the scientists wrote in the paper.
ESPaDOnS was utilized to record Stokes I and V spectra of HD 213258 at 7 epochs between November 2020 and October 2022. The research study was complemented by information from NASA’s Transiting Exoplanet Survey Satellite (TESS) and also from the CORrelation-RAdial-VELocities (CORAVEL) spectrometer.
The observations discovered that the mean magnetic field modulus of HD 213258 is roughly 3.8 kG, with no substantial variants over the observing duration of 2 years. This finding suggests that HD 213258 is a strongly magnetic Ap star.
The astronomers estimated that the stellar turning duration of HD 213258 is of the order to fifty years, making it one of the slowest rotating Ap stars understood to date. It was also discovered that this star is quickly oscillating, exhibiting high overtone pulsations with a duration of roughly 7.58 mins. Thus, the researchers classified HD 213258 as a roAp– rapidly oscillating Ap star.
Moreover, it turned out that the radial velocity of HD 213258 shows low amplitude variants, which recommends that it may be a single-line spectroscopic binary system with a low-mass companion. The researchers assume that the secondary things in this system can be a brown dwarf. If confirmed, it would make HD 213258 the initial roAp star known to have a brownish dwarf companion.
Read the original article on PHYS.
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