ar X iv : a st ro - p h / 04 07 63 6 v 1 3 0 Ju l 2 00 4 Red giant stars in NGC 5128
نویسنده
چکیده
I present a selection of results obtained from VLT FORS1 and ISAAC photometric monitoring of late-type giants in NGC 5128 (=Centaurus A). The combination of optical and near-IR photometry allows to probe the full metallicity range of the stars on the upper red giant branch, thanks to combined low-metallicity sensitivity of the optical and high-metallicity sensitivity of the near-IR bands. The metallicity distribution covers a wide range with the mean value around [M/H] ∼ −0.45 dex. The near-IR monitoring of the variable AGB stars allows to gain insights into the age distribution. The period distribution of these long period variables indicates only about 10% contribution of the intermediate-age component (age ∼ < 5 Gyr) to the predominantly old stellar halo. Among the brightest, large amplitude and long period variables only very few have near-IR and optical colors consistent with carbon-rich giants.
منابع مشابه
ar X iv : a st ro - p h / 04 12 44 9 v 1 1 7 D ec 2 00 4 Planetary Nebulae in NGC 5128 ( Centaurus A ) Eric
The study of planetary nebulae (PNe) in the nearby post-merger elliptical galaxy NGC 5128 (Cen A) now has a history of nearly twenty years. As the nearest giant elliptical, it is a prime target for extragalactic PN studies. These studies have addressed many issues including the galaxy’s distance, dark matter content, halo structure, merger history, and stellar populations. We review the main PN...
متن کاملar X iv : a st ro - p h / 04 07 23 2 v 1 1 2 Ju l 2 00 4 B The Saas Fee Lectures on Strong Gravitational Lensing
متن کامل
ar X iv : a st ro - p h / 04 08 01 0 v 1 3 1 Ju l 2 00 4 On the nature of the unidentified X - ray / γ - ray sources
We present a multiwavelength study of the environment of the unidentified X-ray/γ-ray sources IGR J18027−1455 and IGR J21247+5058, recently discovered by the IBIS/ISGRI instrument, onboard the INTEGRAL satellite. The main properties of the sources found inside their position error circles, give us clues about the nature of these high-energy sources.
متن کاملar X iv : a st ro - p h / 04 10 39 6 v 1 1 5 O ct 2 00 4 The Rise of the s - Process in the
From newly-obtained high-resolution, high signal-to-noise ratio spectra the abundances of the elements La and Eu have been determined over the stellar metallicity range −3 <[Fe/H]< +0.3 in 159 giant and dwarf stars. Lanthanum is predominantly made by the s-process in the solar system, while Eu owes most of its solar system abundance to the r-process. The changing ratio of these elements in star...
متن کامل