Astron. Astrophys. 322, 825-834 (1997)

The distance to the T Tauri stars in Taurus determined from their rotational properties

Thomas Preibisch and Michael D. Smith

Astronomisches Institut der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

Received 22 July 1996 / Accepted 12 December 1996

Abstract

We have determined the average distance to the young stars in the Taurus star formation region through their rotational properties. While most other distance estimates to star forming regions give the distance to the associated molecular clouds, the method used here gives the distance to the stars. Our statistical method assumes that the photometric variations are due to surface starspots that co-rotate with the equatorial surface speed and the rotation axes of the stars are randomly distributed. Furthermore, we pay much attention to possible unresolved binaries. A "best fit" distance of parsecs is derived from our sample of 25 weak line T Tauri stars in Taurus. This is within the range of distances found for the molecular cloud (140 pc - 160 pc) and confirms that the T Tauri stars are embedded within.

Alternatively, the agreement of the distances to the stars and dark cloud, along with their intimate sky location, lends support to the interpretation and assumptions. This means that we find a random orientation of the rotation axes, which excludes a preferential orientation that might be caused by large scale magnetic fields in the molecular cloud. Another aspect is that our results seem to exclude strong differential rotation for the T Tauri stars.

Key words: methods: statistical stars: pre-main-sequence stars: rotation stars: distances ISM: Taurus clouds

Send offprint requests to: Th. Preibisch

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Contents

• 1. Introduction
• 2. The stellar sample
  • 2.1. Input data
  • 2.2. The effect of binarity
• 3. Method
  • 3.1. Measurement errors
  • 3.2. Selection effects
  • 3.3. Monte Carlo simulation of the model distribution
• 4. Results
  • 4.1. Simple qualitative analysis
  • 4.2. Quantitative statistical analysis
  • 4.3. Confidence limits from a Bootstrap analysis
• 5. The effect of unresolved binaries
• 6. Conclusions
• Acknowledgements
• Appendix
• Appendix A: determination of radius corrections from the speckle flux ratios
• Appendix B: simulated corrections for unresolved binaries
• References

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

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