Astron. Astrophys. 327, 1194-1205 (1997)

On the distance to the Chamaeleon I and II associations

D.C.B. Whittet ^{1, 2}, T. Prusti ³, G.A.P. Franco ⁴, P.A. Gerakines ^{1, 5}, D. Kilkenny ⁶, K.A. Larson ¹ and P.R. Wesselius <sup>2

1</sup> Department of Physics, Applied Physics & Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA
² SRON, P.O. Box 800, 9700 AV Groningen, The Netherlands
³ ISO Science Operations Centre, Astrophysics Division, ESA, Villafranca del Castillo, P.O. Box 50727, E-28080 Madrid, Spain
⁴ Departamento de Física - ICEx - UFMG, Caixa Postal 702, 30.161-970 - Belo Horizonte - MG, Brasil
⁵ Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands
⁶ SAAO, P.O. Box 9, Observatory, Cape 7935, South Africa

Received 23 December 1996 / Accepted 25 June 1997

Abstract

Constraints on the distances to the dark clouds Chamaeleon I and II are investigated in detail. A compilation of photometric data, spectral types and absolute magnitudes for field stars towards each cloud is presented, and results are used to examine the distribution of reddening with distance along each line of sight. The distances to stars associated with reflection nebulae in each cloud are examined in detail. On the basis of these results, we deduce the most probable distance of Cha I to be , and that of Cha II to be . An examination of the mean fluxes of T Tauri stars in each cloud provides independent evidence to suggest that Cha II is significantly more distant than Cha I. Both clouds appear to be embedded in a macroscopic sheet-like structure extending over much of the Chamaeleon-Musca-Crux region. The Chamaeleon III and DC 300.2-16.9 clouds are probably part of the same structure, with probable distances 140-160 .

Key words: stars: distances ISM: clouds; dust, extinction; Chamaeleon clouds; reflection nebulae

Send offprint requests to: D.C.B. Whittet

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Contents

• 1. Introduction
• 2. The distance to Chamaeleon I
  • 2.1. The distribution of reddening
  • 2.2. HD 97048 and HD 97300
  • 2.3. Summary
• 3. The distance to Chamaeleon II
  • 3.1. HD 111830
  • 3.2. The distribution of reddening
  • 3.3. Summary
• 4. Infrared fluxes of T Tauri stars
• 5. Sheet geometry
• 6. Chamaeleon III and DC 300.2-16.9
• 7. Conclusions and future work
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: April 6, 1998
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