Astron. Astrophys. 343, 916-922 (1999)

Photometric stellar variation due to extra-solar comets

A. Lecavelier des Etangs, A. Vidal-Madjar and R. Ferlet

Institut d'Astrophysique de Paris, CNRS, 98bis Boulevard Arago, F-75014 Paris, France

Received 19 August 1998 / Accepted 18 December 1998

Abstract

We performed numerical simulations of stellar occultations by extra-solar cometary tails. We find that extra-solar comets can be detected by the apparent photometric variations of the central stars. In most cases, the light curve shows a very peculiar "rounded triangular" shape. However, in some other cases, the curve can mimic a planetary occultation. Photometric variations due to comet occultations are mainly achromatic. Nevertheless, if comets with small periastrons have smaller particles, these occultations could be chromatic with a larger extinction in the blue by few percents.

We also estimate the number of detections expected in a large photometric survey at high accuracy. By the observation of several tens of thousand of stars, it should be possible to detect several hundreds of occultation per year. We thus conclude that a spatial photometric survey would detect a large number of extra-solar comets. This would allow to explore the time evolution of cometary activity, and consequently would probe structure and evolution of extra-solar planetary systems.

Key words: occultations comets: general stars: planetary systems

Send offprint requests to: A. Lecavelier des Etangs

SIMBAD Objects

Contents

• 1. Introduction
• 2. A model of cometary occultation
  • 2.1. Distribution of dust in a cometary tail
  • 2.2. Stellar parameter
  • 2.3. Grain properties
    • 2.3.1. Extinction
    • 2.3.2. Scattering
• 3. Light curves
  • 3.1. First order estimations
    • 3.1.1. Extinction
    • 3.1.2. Scattering
  • 3.2. Light curves
  • 3.3. Color signatures
  • 3.4. Conclusion
• 4. Probability of detection
  • 4.1. Orbital parameters
  • 4.2. Dust production rate
  • 4.3. Results
• 5. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999
helpdesk.link@springer.de