ABSTRACT

Title: A Photometric System for Investigation of Galactic Structure

Author: Davis Philip

Institution: ISO and Union College

E-mail: agdp@union.edu

A PHOTOMETRIC SYSTEM FOR INVESTIGATION OF GALACTIC STRUCTURE V. Strai\^{z}ys (1) and A. G. Davis Philip (2) (1) Institute of Theoretical Physics and Astronomy, Vilnius, Lithuania (2) Institute for Space Observations and Union College, Schenectady, NY 12308, U.S.A. Abstract: A medium-band multicolor photometric system is proposed for the classification of stars in general galactic fields. This system is based on the experience obtained by the authors in selecting optimum passbands for a completely photometric three-dimensional classification of a mixture of stars containing samples of different temperatures, luminosities, metallicities and interstellar reddenings. Many types of peculiar stars (emission-line stars, chemically-peculiar B and A stars, white dwarfs, horizontal-branch stars, carbon stars) are also recognizable. The full system consists of 10 or 11 passbands covering the spectral range from 350 to 1000 nm. Various combinations of passbands are possible, depending on the stellar population in the field and on the presence or absence of interstellar reddening. The system may be supplemented by ultraviolet passbands in the region of the interstellar extinction bump (for determination of the extinction law). Part of the passbands are close to those in the seven color Str\”{o}mvil system which is a combination of filters from the Str\”{o}mgren and Vilnius systems. Depending on telescope aperture, the system will allow one to classify stars as faint as 18 - 20 magnitude. The system will be most useful in the areas near the galactic plane with the largest and most complicated interstellar extinction. All the Milky Way and the central Galactic Bulge will not be covered by medium-band photometry on the Gaia orbiting observatory of ESA due to its insufficient resolving power. A wide-field orbital telescope would be able to classify stars in these overcrowded areas by means of guided exposures.

Design & Maintained by: LMDeGarion