Related papers: Identifying Blue Horizontal Branch Stars Using the…

We present a deep BVrIK multicolor catalog of galaxies in the field of the high redshift (z=4.7) quasar BR 1202-0725. Reliable colors have been measured for galaxies selected down to R=25. The choice of the optical filters has been…

We aim to determine the fundamental parameters of a sample of B stars with apparent visual magnitudes below 8 in the field-of-view of the CoRoT space mission, from high-resolution spectroscopy. We developed an automatic procedure for the…

Context: Blue horizontal-branch stars are very old objects that can be used as markers in studies of the Galactic structure and formation history. To create a clean sky catalogue of blue horizontal-branch stars, we cross-matched the Gaia…

Surface temperature distribution of horizontal-branch (HB) stars is very sensitive to age in old stellar systems, which makes it an attractive age indicator. In this paper, we present the recent revision of our model calculations for the HB…

We describe the algorithm for selecting quasar candidates for optical spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected via their non-stellar colors in "ugriz" broad-band photometry, and by matching unresolved…

This paper describes the design principles for a CCD-based photometric system that is highly optimized for ground-based measurement of the size of the Balmer jump in stellar energy distributions. It is shown that, among ultraviolet filters…

We present a new method to effectively select objects which may be low-mass active black holes (BHs) at galaxy centers using high-cadence optical imaging data, and our first spectroscopic identification of an active 2.7x10^6 Msun BH at…

Information on the spectral types of stars is of great interest in view of the exploitation of space-based imaging surveys. In this article, we investigate the classification of stars into spectral types using only the shape of their…

Blue supergiant stars can be exceptionally bright objects in the optical, making them prime targets for the determination of extragalactic distances. I describe how their photometric and spectroscopic properties can be calibrated to provide…

We use Legacy Survey photometric data to probe the stellar halo in multiple directions of the sky using a probabilistic methodology to identify Blue Horizontal Branch (BHB) stars. The measured average radial density profile follows a double…

A sample of about 3,800 Low Surface Brightness (LSB) galaxies was selected using the all-sky near-infrared (J, H and K_s-band) 2MASS survey. The selected objects have a mean central surface brightness within a 5 arcsec radius around their…

We report on the initial results of a spectroscopic investigation of galaxies in the Hubble Deep Field which exhibit spectral discontinuities between the F450W and F300W passbands, indicative of the presence of the Lyman continuum break in…

Measuring distances to galaxies, determining their chemical composition, investigating the nature of their stellar populations and the absorbing properties of their interstellar medium are fundamental activities in modern extragalactic…

We describe the selection of a sample of photometrically-defined Lyman break galaxies (LBGs) at z~5 using the multi-wavelength imaging data of the ESO Remote Galaxy Survey (ERGS). The data is drawn from ten widely-separated fields covering…

We present a case study of using a novel method to identify red supergiant (RSG) candidates in NGC 6822, based on their 1.6 $\mu$m "H-bump". We collected 32 bands of photometric data for NGC 6822 ranging from optical to MIR. By using the…

In this paper we report on a curious feature in the V, (U-B) color-magnitude diagrams of globular clusters. In our database, we find that a considerable fraction of blue horizontal branch stars, hotter than the instability strip and cooler…

We report the first determination of the distance to the Galactic centre based on the kinematics of halo objects. We apply the statistical-parallax technique to the sample of ~2500 Blue Horizontal Branch (BHB) stars compiled by Xue et al.…

We describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey from the photometric data obtained by the imaging survey. Galaxy photometric properties are measured using the Petrosian…

Applying photometric catalogs to the study of the population of the Galaxy is obscured by the impossibility to map directly photometric colors into astrophysical parameters. Most of all-sky catalogs like ASCC or 2MASS are based upon…

(Abridged) The color and luminosity distribution of horizontal branch (HB) stars in globular clusters are sensitive probes of their original helium abundances. However, recent analyses based on visual and near-ultraviolet (UV) CMDs have…