Hide and seek between Andromeda's halo, disk, and giant stream
| Autor: | Rodrigo Contreras Ramos, Roberto Ragazzoni, Marcella Marconi, Michele Bellazzini, Carla Cacciari, Vincenzo Ripepi, Stefano Gallozzi, Vincenzo Testa, Flavio Fusi Pecci, Giacomo Beccari, Andrea Di Paola, Bruno Marano, Emiliano Diolaiti, Michele Cignoni, Luciana Federici, Monica Tosi, Giulia Macario, Riccardo Smareglia, Gisella Clementini, Emanuele Giallongo |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
stars: variables: RR Lyrae
Cosmology and Nongalactic Astrophysics (astro-ph.CO) Andromeda Galaxy STELLAR CONTENT Cepheid variable CEPHEID PULSATION MODELS galaxies: individual (M31) stars: variables FOS: Physical sciences LARGE METAL-POOR VARIABLES Astrophysics RR Lyrae variable Cepheids RR-LYRAE STARS LOCAL GROUP GALAXIES GALACTIC GLOBULAR-CLUSTERS galaxies: stellar content BINOCULAR TELESCOPE GROUP DWARF GALAXIES FORMATION HISTORY CCD PHOTOMETRY Physics Astronomy and Astrophysics Horizontal branch Galaxy Andromeda Space and Planetary Science Variable star Instability strip Astrophysics - Cosmology and Nongalactic Astrophysics |
| Popis: | Photometry in B, V (down to V ~ 26 mag) is presented for two 23' x 23' fields of the Andromeda galaxy (M31) that were observed with the blue channel camera of the Large Binocular Telescope during the Science Demonstration Time. Each field covers an area of about 5.1kpc x 5.1kpc at the distance of M31 ((m-M)o ~ 24.4 mag), sampling, respectively, a northeast region close to the M31 giant stream (field S2), and an eastern portion of the halo in the direction of the galaxy minor axis (field H1). The stream field spans a region that includes Andromeda's disk and the giant stream, and this is reflected in the complexity of the color magnitude diagram of the field. One corner of the halo field also includes a portion of the giant stream. Even though these demonstration time data were obtained under non-optimal observing conditions the B photometry, acquired in time-series mode, allowed us to identify 274 variable stars (among which 96 are bona fide and 31 are candidate RR Lyrae stars, 71 are Cepheids, and 16 are binary systems) by applying the image subtraction technique to selected portions of the observed fields. Differential flux light curves were obtained for the vast majority of these variables. Our sample includes mainly pulsating stars which populate the instability strip from the Classical Cepheids down to the RR Lyrae stars, thus tracing the different stellar generations in these regions of M31 down to the horizontal branch of the oldest (t ~ 10 Gyr) component. 59 pages, 26 figures, 12 tables, ApJ in press |
| Databáze: | OpenAIRE |
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