Visual and Near-Infrared Photometry of Nearby Dwarf Spheroidals

Autor(en)

Franz Kerschbaum, Walter Nowotny-Schipper, Josef Hron, Mathias Schultheis

Abstrakt

This paper is based on photometry from two different observational approaches. Both are of an explorative character and act as feasibility studies. First, results on broad-band photometry in Bessel V and I as well as narrow-band measurements in the Wing 778 nm and 812 nm filters of nearby dwarf spheroidals and galactic globular clusters using the new Austrian OEFOSC (OEsterreich Faint Object Spectrograph and Camera), a copy of the ESO Instrument EFOSC mounted on our 1.5-m telescope are presented. Whereas V and I are used as temperature indicators, Wing 778 nm and 812 nm measure TiO or CN band strengths in the case of O-rich or C-rich AGB stars, respectively. By such means these objects can be identified quite easily. By now we only have a few observations of some selected objects but for the future we plan long-term monitoring and follow up low-resolution spectroscopy of selected AGB stars. The second part of the contribution deals with the possibilities of using Gunn-I, J and K_S measurements originating from the DENIS (DEep Near Infrared Survey of the southern sky) project on similar objects. A few southern dwarf spheroidals already observed within DENIS (covering now some 35% of the southern hemisphere) are selected. It turns out that with DENIS limiting magnitudes of about 18.5, 16.5, and 14.0 in I, J, and K, respectively, AGB stars situated in the most nearby galaxies like Sculptor, Sextans and Carina, with distance moduli between 19 and 20 are just within the limits of this survey. At such small distances, confusion because of the low resolution of DENIS plays a minor role, too.

Organisation(en)

Institut für Astrophysik

Seiten

455

Publikationsdatum

01-1999

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/25956040-2120-4f33-a615-71d25c0b5fcb