Astron. Astrophys. 363, 755-766 (2000)

Low mass clouds in the Cepheus-Cassiopeia void

I. Khavtassi 15

Cs. Kiss ^1,2, L.V. Tóth ^1,2,3, A. Moór ¹, F. Sato ^4,5, S. Nikoli ^6,7 and J.G.A. Wouterloot <sup>8

1</sup> Department of Astronomy of the Loránd Eötvös University, P.O. Box 32., 1518 Budapest, Hungary
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Helsinki University Observatory, P.O. Box 14, 00014 University of Helsinki, Finland
⁴ Tokyo Gakugei University, Department of Astronomy and Earth Sciences, Koganei Tokyo 184-8501, Japan
⁵ Institut d'Astrophysique Spatiale, bâtiment 121, Campus d'Orsay, 91405 Orsay Cedex, France
⁶ Astronomical Observatory, Volgina 7, 11050 Belgrade, Serbia
⁷ Onsala Space Observatory, 43992 Onsala, Sweden
⁸ Radioastronomisches Institut der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany

Received 12 May 2000 / Accepted 7 September 2000

Abstract

We present the results of optical, far-infrared and radio observations of the small, non-star forming dark cloud Khavtassi 15, located in the Upper Cepheus-Cassiopeia region. We derive an average extinction of and a distance of from Digitized Sky Survey data and star counts using objective prism spectroscopy. A fully computerized algorithm was used for non-biased analysis of starcount data. A kinetic temperature of 7 K and a peak number density of were estimated from multiisotopic, multilevel CO measurements. CO measurements also revealed three main condensations inside the cloud. Kh 15 has a total gas mass of 34 and it is most probably part of a shell seen as a FIR loop called GIRL126+10. We investigated the correlation among optical extinction, radio and FIR emission and masses derived for the dust and gas inside the cloud core. Stability analysis has shown, that Kh 15 is not far from gravitational virial equilibrium, and may be fully stabilized by the external pressure. In addition to Kh 15, the starcounts also indicate the presence of an extended nearby extinction layer at which we consider as the wall of the Local Bubble (LB) towards the Upper Cepheus-Cassiopeia. Distances of the dark clouds LDN 1308, LDN 1333 and Khavtassi 19 are also estimated.

Key words: ISM: clouds ISM: dust, extinction ISM: molecules ISM: individual objects: Kh 15 ISM: individual objects: LDN 1308

Send offprint requests to: Cs. Kiss (pkisscs@innin.elte.hu)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Input data
  • 2.1. Optical data
  • 2.2. IRAS data
  • 2.3. CO data
• 3. Data analysis
  • 3.1. Optical data
    • 3.1.1. Wolf diagrams
    • 3.1.2. Visual extinction from POSS data
  • 3.2. FIR data
  • 3.3. CO data
• 4. Results
  • 4.1. Extinction and distance
    • 4.1.1. Distances from Wolf diagrams
    • 4.1.2. The extinction distribution
  • 4.2. Far-infrared results
  • 4.3. Molecular cloud
• 5. Discussion
  • 5.1. Comparison of various bands
  • 5.2. Stability of Kh 15:
  • 5.3. Connection of Kh 15 to its neighbourhood
  • 5.4. The wall of the Local Bubble?
• 6. Summary
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: December 11, 2000
helpdesk.link@springer.de