High resolution spectroscopy of HD 207538 from Far-UV (FUSE) to Visible (SARG-TNG)

A global picture of the stellar and interstellar features modeled

¹ INAF - Catania Astrophysical Observatory, Via S. Sofia 78, 95123 Catania, Italy e-mail: fleone@ct.astro.it
² Institut d'Astrophysique de Paris, CNRS, 98bis boulevard Arago, 75014 Paris, France e-mail: andre@iap.fr
³ The Johns Hopkins University, Center for Astrophysical Sciences, 3400 N. Charles St., Baltimore, MD 21218-2695, USA e-mail: sonnentr@pha.jhu.edu

Corresponding author: G. Catanzaro, gca@ct.astro.it

Received: 20 December 2002
Accepted: 31 March 2003

Abstract

We present a detailed study of the suspected Chemically Peculiar star HD 207538 based on high resolution spectroscopy in the far Ultraviolet (1000–3350 Å) and visible (4600–7000 Å) ranges. The stellar abundance synthesis analysis was performed by using Kurucz's codes ATLAS9 and SYNTHE to compute the atmospheric model and the synthetic spectrum respectively. Observations were obtained with the Far Ultraviolet Spectroscopic Explorer, the International Ultraviolet Explorer satellites whereas the optical spectrum was collected with the ground-based Telescopio Nazionale Galileo telescope. With our analysis we refine the value of the rotational velocity to km s^-1 and the microturbulence velocity to  km s^-1. The stellar abundances inferred in this study show that C, N, O, Al, Si, P, S and Mn are compatible with the standard solar abundances, within the experimental errors. On the other hand, Fe, Ni and Zn are definitively underabundant. We also show that the helium content is comparable to the typical abundance of B-type stars. Because this spectrum is rich in stellar and interstellar features, we computed simultaneously a synthetic spectrum of the stellar and interstellar lines in order to disentangle the different absorption contributions. We thus also determined the column densities of several interstellar elements (Feii, Ni, Pii, Hi, H₂, HD, CO, Cli and Ari) present in the gas in front of the star. Although several components are present along this sightline, our results suggest the presence of some translucent interstellar gas among the diffuse components. With this work, we demonstrate that it is possible to perform a stellar spectroscopic analysis from the far-UV to visible spectral range, with consistent results in both ranges within errors, based on one single atmosphere model.