Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?

Context. The discovery of pulsations in low-mass stars opens an opportunity to probe their interiors and determine their evolution by employing the tools of asteroseismology. Aims. We aim to analyse high-speed photometry of SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25 and discover brightn...

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Detalles Bibliográficos
Autores principales:	Corti, Mariela Alejandra, Kanaan, A., Córsico, Alejandro Hugo, Kepler, S. O., Althaus, Leandro Gabriel, Koester, D., Sánchez Arias, Julieta Paz
Formato:	Articulo
Lenguaje:	Inglés
Publicado:	2016
Materias:	Ciencias Astronómicas Stars: individual: SDSSJ145847.02+070754.46 Stars: individual: SDSSJ173001.94+070600.25 Stars: low-mass White dwarfs
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/86256
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

id	I19-R120-10915-86256
record_format	dspace
institution	Universidad Nacional de La Plata
institution_str	I-19
repository_str	R-120
collection	SEDICI (UNLP)
language	Inglés
topic	Ciencias Astronómicas Stars: individual: SDSSJ145847.02+070754.46 Stars: individual: SDSSJ173001.94+070600.25 Stars: low-mass White dwarfs
spellingShingle	Ciencias Astronómicas Stars: individual: SDSSJ145847.02+070754.46 Stars: individual: SDSSJ173001.94+070600.25 Stars: low-mass White dwarfs Corti, Mariela Alejandra Kanaan, A. Córsico, Alejandro Hugo Kepler, S. O. Althaus, Leandro Gabriel Koester, D. Sánchez Arias, Julieta Paz Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
topic_facet	Ciencias Astronómicas Stars: individual: SDSSJ145847.02+070754.46 Stars: individual: SDSSJ173001.94+070600.25 Stars: low-mass White dwarfs
description	Context. The discovery of pulsations in low-mass stars opens an opportunity to probe their interiors and determine their evolution by employing the tools of asteroseismology. Aims. We aim to analyse high-speed photometry of SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25 and discover brightness variabilities. In order to locate these stars in the Teff - log g diagram, we fit optical spectra (SDSS) with synthetic non-magnetic spectra derived from model atmospheres. Methods. To carry out this study, we used the photometric data we obtained for these stars with the 2.15 m telescope at CASLEO, Argentina. We analysed their light curves and applied the discrete Fourier transform (FT) to determine the pulsation frequencies. Finally, we compare both stars in the Teff - log g diagram, with two known pre-white dwarfs and seven pulsating pre-ELM white dwarf stars, δ Scuti, and SX Phe stars Results. We report the discovery of pulsations in SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25. We determine their effective temperature and surface gravity to be Teff = 7972 ± 200 K, log g = 4.25 ± 0.5 and Teff = 7925 ± 200 K, log g = 4.25 ± 0.5, respectively. With these parameters, these new pulsating low-mass stars can be identified with either ELM white dwarfs (with ∼0.17 MO) or more massive SX Phe stars. We identified pulsation periods of 3278.7 and 1633.9 s for SDSS J145847.02+070754.46 and a pulsation period of 3367.1 s for SDSS J173001.94+070600.25. These two new objects, together with those of Maxted et al. (2013, 2014), indicate the possible existence of a new instability domain towards the late stages of evolution of low-mass white dwarf stars, although their identification with SX Phe stars cannot be discarded.
format	Articulo Articulo
author	Corti, Mariela Alejandra Kanaan, A. Córsico, Alejandro Hugo Kepler, S. O. Althaus, Leandro Gabriel Koester, D. Sánchez Arias, Julieta Paz
author_facet	Corti, Mariela Alejandra Kanaan, A. Córsico, Alejandro Hugo Kepler, S. O. Althaus, Leandro Gabriel Koester, D. Sánchez Arias, Julieta Paz
author_sort	Corti, Mariela Alejandra
title	Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
title_short	Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
title_full	Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
title_fullStr	Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
title_full_unstemmed	Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
title_sort	two new pulsating low-mass pre-white dwarfs or sx phoenicis stars?
publishDate	2016
url	http://sedici.unlp.edu.ar/handle/10915/86256
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Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?

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