Exocomets around Beta Pictoris | Matthew A. Kenworthy

The light curves of three exocomets seen towards Beta Pictoris.

In 2019 we saw the transit of a comet’s tail in broadband light in another stellar system, Beta Pictoris (Zieba et al., 2019). The sensitivity of the TESS satellite enabled the detection of the distinctive shark’s tooth shape predicted over 20 years earlier by Lecavelier Des Etangs.

The raw light curve of Beta Pictoris, dominated by the Delta Scuti pulsations of the star. Three black triangles indicate the location of the exocomet transits.

The star itself is a Delta Scuti pulsator, ringing like a bell due to an internal pulsation driven by the Kappa-mechanism. Over 35 separate frequencies were removed from the light curve to reveal the shape of three exocomets during the 2019 TESS observations.

The Delta Scuti pulsations of Beta Pictoris, fit by a multi frequency pulsation model. The black points are the data from TESS, the red line is the fit from the pulsation model, and the residuals from the fit are shown in the lower panel.

A later paper (Lecavelier des Etangs et al., 2022) discovered an additional 27 exocomet transits over a total of 156 days, enabling a power law fit to the size distribution of the exocomets and showing similarities to those in our own Solar system.

The histogram of the exocomets detected in Beta Pictoris (Lecavelier des Etangs et al., 2022) and the power law distribution compared to the Solar system comets.

References

2022

2019