Astron. Astrophys. 358, 1077-1089 (2000)

Strömgren photometry towards the region of the Cometary Globules CG 30/31/38 ^*

A.S. Nielsen, H. Jonch-Sorensen and J. Knude

Niels Bohr Institute for Astronomy, Geophysics and Physics, Juliane Maries Vej 32, 2100 Kobenhavn O, Denmark (alan@astro.ku.dk)

Received 24 March 2000 / Accepted 26 April 2000

Abstract

With the Danish 1.54 m telescope at La Silla, Chile, we have obtained deep () CCD frames in the Strömgren system towards the region of the cometary globules CG 30/31/38. Also, a nearby reference field, with a minor amount of visible molecular material, has been observed in order to estimate the expected normal foreground reddening in this direction of the Galaxy. We have obtained complete information for 698 and 526 stars in these two regions, respectively, allowing a determination of individual stellar extinctions and distances for the A- to G-type star subsample meeting the criteria in the calibrations. A lower envelope in the distance-reddening diagram () indicates that the minimum total absorption through half the Galactic disk along the line of sight is in this direction. The distance to the CG 30/31/38 complex is not directly derived from the -diagram but two faint foreground M-dwarfs are identified, and based on the obtained photometry a lower distance limit of 21540 pc is derived.

We also report the discovery of a galaxy seen in V and I-band exposures in spite of the high extinction, located at the very low galactic latitude of .

Key words: ISM: clouds ISM: dust, extinction

* Based on observations ESO, La Silla

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and data reductions
  • 2.1. Photometry
  • 2.2. Standard stars
• 3. Calibration of and
• 4. The samples
• 5. The obtained accuracy
• 6. Distance and reddening
  • 6.1. The nearest 2 kpc
  • 6.2. Late type dwarfs
  • 6.3. V and I photometry for selected dwarfs
• 7. Discussions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: June 20, 2000
helpdesk.link@springer.de