Navegação Ciências Exatas e da Terra por Assunto "Estrelas variaveis"
Resultados 1-20 de 60
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2006 Whole Earth Telescope observations of GD358 : a new look at the prototype DBV
(2009) [Artigo de periódico]We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated ... -
Accuracy of the maximum entropy method
(1980) [Artigo de periódico]Although the maximum entropy method is capable of giving the period of a pure sine wave with very few data points, it is very sensitive to noise. The half power width of a spectral peak obtained by this method is proportional ... -
Amplitude and frequency variability of the pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 observed with the Whole Earth Telescope
(2003) [Artigo de periódico]We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these ... -
Anchoring the distence scale via x-ray/infrared data for Cepheid clusters : SU Cas
(2012) [Artigo de periódico]New X-ray (XMM-Newton) and JHKs (Observatoire du Mont-Mégantic) observations for members of the star cluster Alessi 95, which Turner et al. discovered hosts the classical Cepheid SU Cas, were used in tandem with UCAC3 ... -
Anchors for the cosmic distance scale : the Cepheids U Sagittarii, CF Cassiopeiae, and CEab Cassiopeiae
(2013) [Artigo de periódico]New and existing X-ray, UBVJHKsW(1−4), and spectroscopic observations were analyzed to constrain fundamental parameters for M25, NGC 7790, and dust along their sight-lines. The star clusters are of particular importance ... -
An observational limit to the evolutionary time scale of the 13,000 K white dwarf G117-B15A
(1990) [Artigo de periódico]Nature has provided us with a way of measuring the evolutionary time scale of some stars through aster oseismology, i.e., the study of stellar interiors through their intrinsic variations in brightness. By measuring the ... -
Asteroseismology of a star cooled by neutrino emission : the pulsating pre-white dwarf PG 0122+200
(1998) [Artigo de periódico]Observation of g-mode pulsations in the variable pre-white dwarf (GW Virginis) stars provides a unique means to probe their interiors and to study the late stages of stellar evolution. Multisite campaigns have in several ... -
Asteroseismology of PG 1541 + 651 and BPM 31594 with TESS
(2023) [Artigo de periódico]We present the photometric data from TESS for two known ZZ Ceti stars, PG 1541 + 651 and BPM 31594. Before TESS, both objects only had observations from short runs from ground-based facilities, with three and one period ... -
Asteroseismology of RXJ 2117+3412, the hottest pulsating PG 1159 star
(2002) [Artigo de periódico]The pulsating PG 1159 planetary nebula central star RXJ 2117+3412 has been observed over three successive seasons of a multisite photometric campaign. The asteroseismological analysis of the data, based on the 37 identified ... -
Asteroseismology of the dov star PG 1159-035 with the Whole Earth Telescope
(1991) [Artigo de periódico]We report the results from 264.1 hr of nearly continuous time-series photometry on the pulsating pre-white dwarf star (DOV) PG 1159-035. The high-resolution power spectrum of this data set is dominated by power in the range ... -
Bpm 24754 : a new southern zz ceti star
(1998) [Artigo de periódico]We report the discovery of a new long{period ZZ Ceti star through the analysis of photometric time series gathered on 7 nights between 1995 and 1996. The light curve displays a periodic variation with a period of ~ 18 min ... -
Constraining the evolution of ZZ Ceti
(2003) [Artigo de periódico]We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf ) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the ... -
Delta Scuti Network observations of XX Pyx : detection of 22 pulsation modes and of short-term amplitude and frequency variations
(2000) [Artigo de periódico]We report multisite observations devoted to the main-sequence δ Scuti star XX Pyx, conducted as the 17th run of the Delta Scuti Network. Over 125 nights a total of 550 h of usable time-series photometric B- and V-filter ... -
A detection of the evolutionary time scale of the da white dwarf G117-B15A with the Whole Earth Telescope
(1991) [Artigo de periódico]We have detected the time rate of change for the main pulsation period of the 13,000 K DA white dwarf G117-B15A, using the Whole Earth Telescope (WET). The observed rate of period change, P = (12.0 ± 3.5) x 10- 15 s s - ... -
Direct measurement of a secular pulsation period change in the pulsating hot pre-white dwarf PG 1159-035
(1999) [Artigo de periódico]GW Vir (PG 1159[035) is the prototype of the class of multiperiodic, nonradially pulsating hot white dwarfs, and shows a strong pulsation mode at 516 s. All measurements to date of the secular variation of the 516 s pulsation ... -
Discovery of fourteen new ZZ Cetis with SOAR
(2005) [Artigo de periódico]We report the discovery of fourteen new ZZ Cetis with the 4.1 m Southern Astrophysical Research telescope, at Cerro Pachon, in Chile. The candidates were selected from the SDSS (Sloan Digital Sky Survey) DA white dwarf ... -
Discovery of the 'missing' mode in HR 1217 by the Whole Earth Telescope
(2002) [Artigo de periódico]HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of ... -
Eleven new DA white dwarf variable stars from the Sloan Digital Sky Survey
(2005) [Artigo de periódico]We report the discovery of 11 new variable DAwhite dwarf (ZZ Ceti) stars. Candidates were selected by deriving temperatures from model fits to spectra obtained from the Sloan Digital Sky Survey (SDSS). We also find objects ... -
Ensemble characteristics of the ZZ Ceti stars
(2006) [Artigo de periódico]We present the observed pulsation spectra of all known noninteracting ZZ Ceti stars (hydrogen atmosphere white dwarf variables [DAVs]) and examine changes in their pulsation properties across the instability strip.We confirm ... -
Evidence for temperature change and oblique pulsation from light curve fits of the pulsating white dwarf GD 358
(2010) [Artigo de periódico]Convective driving, the mechanism originally proposed by Brickhill for pulsating white dwarf stars, has gained general acceptance as the generic linear instability mechanism in DAV and DBV white dwarfs. This physical ...