Listar Ciencias Exactas y Naturales por tema "Estrelas variaveis"
Mostrando ítems 41-60 de 60
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Redefining the empirical ZZ Ceti instability strip
(2004) [Artículo de periódico]We use the new ZZ Ceti stars (hydrogen-atmosphere white dwarf variables; DAVs) discovered within the Sloan Digital Sky Survey (Mukadam et al. 2004) to redefine the empirical ZZ Ceti instability strip. This is the first ... -
Revealing the pulsational properties of the V777 Herculis star KUV 05134+2605 by its long-term monitoring
(2014) [Artículo de periódico]Context. KUV 05134+2605 is one of the 21 pulsating DB white dwarfs (V777 Her or DBV variables) known so far. The detailed investigation of the short-period and low-amplitude pulsations of these relatively faint targets ... -
Search for RR Lyrae stars in DES ultrafaint systems : Grus I, Kim 2, Phoenix II, and Grus II
(2019) [Artículo de periódico]This work presents the first search for RR Lyrae stars (RRLs) in four of the ultrafaint systems imaged by the Dark Energy Survey using SOAR/Goodman and Blanco/DECam imagers. We have detected two RRLs in the field of Grus ... -
Seismological studies of ZZ Ceti stars - II. Application to the ZZ Ceti class
(2009) [Artículo de periódico]We used the detected pulsation modes and adiabatic pulsation models to do seismology of the class of ZZ Ceti stars and measure the H layer mass for 83 stars. We found the surface hydrogen layer to be within the range 10−9.5 ... -
Seismological studies of ZZ Ceti stars - I. The model grid and the application to individual stars
(2008) [Artículo de periódico]We calculate and explore an extensive adiabatic model grid for pulsating white dwarfs with hydrogen-dominated atmospheres, the ZZ Ceti stars. We also compared the computed modes with the observed ones for fiveZZCeti stars ... -
Seismology of a massive pulsating hydrogen atmosphere white dwarf
(2012) [Artículo de periódico]We report our observations of the new pulsating hydrogen atmosphere white dwarf SDSS J132350.28+010304.22. We discovered periodic photometric variations in frequency and amplitude that are commensurate with nonradial g-mode ... -
Separating c-Stars from dust in the central region of the Seyfert 2 galaxy NGC 1241
(2005) [Artículo de periódico]The Seyfert 2 galaxy NGC 1241 presents a 1.5 kpc large circumnuclear ring (CNR) of star formation embracing a small bar plus leading arms. Those structures are Paα emitters but barely seen in Haα. It also presents stellar ... -
The 1051 s period of the interacting binary white dwarf amcvn
(1984) [Artículo de periódico]The close binary system AM CVn consists of two white dwarfs; the lower mass white dwarf, a helium white dwarf, is transferring mass to its higher mass companion. The light curve of AM CVn has a double humped variation with ... -
The Curious Case of PHL 293B : a long-lived transient in a Metal-poor Blue Compact Dwarf Galaxy
(2020) [Artículo de periódico]We report on small-amplitude optical variability and recent dissipation of the unusually persistent broad emission lines in the blue compact dwarf galaxy PHL 293B. The galaxy's unusual spectral features (P Cygni-like ... -
The discovery of a new DAV star using IUE temperature determination
(1992) [Artículo de periódico]We report the discovery of a new ZZ Ceti star observed on the assumption that most DA stars with temperature near 11,000 K are pulsators and on a temperature determination using lUE data. Even though BPM 37093 had already ... -
The everchanging pulsating white dwarf GD358
(2003) [Artículo de periódico]We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired more than 232 000 independent ... -
The light curve of the ZZ ceti star G226-29
(1983) [Artículo de periódico]G226-29 is a pulsating DA white dwarf, or ZZ Ceti star. Using 65 hr of high-speed photometry accumulated from 1980 to 1982, we have decomposed the light curve of G226-29 into its component pulsations. There are three ... -
The ZZ Ceti red edge
(2002) [Artículo de periódico]With a time-series CCD photometric survey, we have demonstrated clearly that the observed red edge for the ZZ Ceti stars instability strip at 11 000 K is real, with the pulsation amplitude decreasing at least by a factor ... -
Thirty-five new pulsating DA white dwarf stars
(2004) [Artículo de periódico]We present 35 new pulsating DA (hydrogen atmosphere) white dwarf stars discovered from the Sloan Digital Sky Survey (SDSS) and the Hamburg Quasar Survey (HQS). We have acquired high-speed time series photometry of preselected ... -
Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?
(2016) [Artículo de periódico]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 ... -
Whole Earth Telescope observations and seismological analysis of the pre-white dwarf pg 2131+066
(1995) [Artículo de periódico]As transition objects between the asymptotic giant branch (AGB) and cooling white dwarfs, the PG 1159 stars are key objects for understanding the late stages of stellar evolution. The pulsations exhibited by many members ... -
Whole Earth Telescope observations of BPM 37093 : a seismological test of crystallization theory in white dwarfs
(2005) [Artículo de periódico]BPM 37093 is the only hydrogen-atmosphere white dwarf currently known which has sufficient mass (~1.1 Mʘ) to theoretically crystallize while still inside the ZZ Ceti instability strip (Teff ~ 12 000 K). As a consequence, ... -
Whole Earth Telescope observations of the DAV white dwarf G226-29
(1995) [Artículo de periódico]We observed G226-29 for 121 hr in 1992 February and confirm the presence of the three previously identified frequencies close to 109 s. We find no evidence of other pulsation periods down to our noise level of about 0.35 ... -
Whole Earth Telescope observations of the DBV white dwarf GD 358
(1994) [Artículo de periódico]We report on the analysis of 154 hours of early continuous high-speed photometry on the pulsating DB white dwarf (DBV) GD 358, obtained during the Whole Earth Telescope (WET) run of 1990 May. The power spectrum of the light ... -
Whole Earth Telescope observations of V471 Tauri : the nature of the white dwarf variations
(1992) [Artículo de periódico]We have conducted time-series photometric observations of the binary star V471 Tauri using the Whole Earth Telescope observing network. Our purpose was to determine the mechanism responsible for causing the 555 and 277 s ...
