相关论文: Bulge delta Scuti Stars in the MACHO Database

We have measured the central structural properties for a sample of S0-Sbc galaxies down to scales of ~10 pc using HST NICMOS images. We find that the photometric masses of the central star clusters, which occur in 58% of our sample, are…

Aims: We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus…

I review the properties of the Galaxy's stellar halo, specifically as traced by horizontal branch stars, but with reference to and in comparison with other stellar tracers. I discuss the halo density profile, the variation in horizontal…

Recent dramatic improvements in the modeling of abundance evolution due to diffusion in A stars have been achieved with the help of monochromatic opacity tables from the OPAL group. An important result in the context of stellar pulsations…

We identify stars in the $\delta$ Sct instability strip that do not pulsate in p modes at the 50-$\mu$mag limit, using Kepler data. Spectral classification and abundance analyses from high-resolution spectroscopy allow us to identify…

Asteroseismology is a powerful tool for probing the internal structures of stars by using their natural pulsation frequencies. It relies on identifying sequences of pulsation modes that can be compared with theoretical models, which has…

From the Fourier analysis of the catalogue of ~200,000 variable candidates in the OGLE-II Galactic fields, we found a sample of about 230 short-period low-amplitude variable stars. From their position in the colour-magnitude diagram and the…

Metallic-line A (Am) stars are main-sequence stars of around twice the mass of the Sun that show element abundance peculiarities in their spectra. The radiative levitation and diffusive settling processes responsible for these abundance…

We present new HST I-band images of a sample of 77 nearby, late-type spiral galaxies with low inclination. The main purpose of this catalog is to study the frequency and properties of nuclear star clusters. In 59 galaxies of our sample, we…

Pulsating variable stars can be powerful tools to study the structure, formation and evolution of galaxies. I discuss the role that the Magellanic Clouds' pulsating variables play in our understanding of the whole Magellanic System, in…

Results from the Bulge Radial Velocity Assay (BRAVA) are presented. BRAVA uses M giant stars, selected from the 2MASS catalog to lie within a bound of reddening corrected color and luminosity, as targets for the Cerro Tololo Inter-American…

The structure, formation, and evolution of the Milky Way bulge is a matter of debate. Important diagnostics for discriminating between bulge models include alpha-abundance trends with metallicity, and spatial abundance and metallicity…

We use the combined photometric SDSS + GALEX database to look for populations of luminous blue star-forming galaxies. These were initially identified from such a sample at redshifts near 0.4, using SDSS spectra. We make use of the colour…

We report on a new study aimed at understanding the diversity and evolutionary properties of distant galactic bulges in the context of well-established trends for pure spheroidal galaxies. Bulges have been isolated for a sample of 137…

$Aims$. The existence of massive disc galaxies with little or no bulge challenges conventional $\Lambda$ cold dark matter model, which typically favours dynamically hot central structures due to early collapse and mergers. The study of…

In this study, pulsational and physical characteristics of two $\delta$ Scuti stars, V775 Tau and V483 Tau, are analysed by using four-year high-precision photometric data of STEREO satellite. Thus, it is aimed to gain new insights into…

Photometry and long-slit spectroscopy are presented for 14 S0 and spiral galaxies of the Fornax, Eridanus and Pegasus cluster, and NGC 7582 group. The structural parameters of the galaxies are derived from the R-band images by performing a…

If cluster dark matter is in the form of compact objects it will introduce fluctuations into the light curves of distant sources. Current searches for MACHOs in clusters of galaxies focus on monitoring quasars behind nearby systems. This…

F type stars are characterised by several physical processes such as different pulsation mechanisms, rotation, convection, diffusion, and magnetic fields. The rapidly rotating delta Scuti star beta Cas can be considered as a benchmark star…

We investigate the modal stability of stellar models at masses and luminosity levels corresponding to post main sequence luminous delta scuti pulsators. The envelope models have been computed at fixed mass value, luminosity level and…