Detection of a thick disk in the edge-on low surface brightness galaxy ESO 342–G017^*

I. VLT Photometry in and bands

¹ Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands
² Universitäts–Sternwarte München, Scheinerstr. 1, 81679 München, Germany
³ European Space Agency, Research and Science Support Department, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁴ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany

Corresponding author: M. J. Neeser, neeser@usm.uni-muenchen.de

Received: 5 October 2001
Accepted: 6 December 2001

Abstract

We report the detection of a thick disk in the edge-on, low surface brightness (LSB), late-type spiral , based on ultra-deep images in the V and R bands obtained with the VLT Test Camera during Science Verification on UT1. All steps in the reduction procedure are fully described, which, together with an extensive analysis of systematic and statistic uncertainties, has resulted in surface brightness photometry that is reliable for the detection of faint extended structure to a level of and  . The faint light apparent in these deep images is well-modeled by a thick exponential disk with an intrinsic scale height about 2.5 times that of the thin disk, and a comparable or somewhat larger scale length. Deprojection including the effects of inclination and convolution with the PSF allow us to estimate that the thick disk contributes 20–40% of the total (old) stellar disk luminosity of . To our knowledge, this is the first detection of a thick disk in an LSB galaxy, which are generally thought to be rather unevolved compared to higher surface brightness galaxies.