The Hubble Space Telescope has imaged the changing shadow of a planetary disk on background dust and gas clouds, and like a shadow puppet of a bat, it appears to flap dark wings.

Astronomers studying the young star HBC 672 made this discovery entirely by accident. It had previously been known that the star has what has been nicknamed a “Bat Shadow” behind it in the Serpens Nebula. This shadow is cast by the star’s planetary disk, which blocks a band of light. That flapping? That is the eddy of a planet moving around the star in that disk. 

This amazing change in light and shadow was seen serendipitously in data that was taken over 404 days. The team had requested images of this region in a variety of filters and because of how Hubble schedules time, these images were acquired over thirteen months. It was in trying to create a final image by combining all the data that this motion was suddenly revealed. The data wasn’t designed to study this phenomenon, so our understanding of the system is still shadowed. As best it can be measured, this newly discovered baby world is orbiting no faster than every 180 days and is about the same distance from its star as the Earth is from the Sun. This discovery carries on a recent theme that worlds form fast: this star is just one or two million years old, and already it is host to at least one world. This work was published in the Astrophysical Journal and was led by Klaus Pontoppidan.

More Information

ESA press release 

Hubblesite press release 

“Variability of the Great Disk Shadow in Serpens,” Klaus M. Pontoppidan et al., 2020, to appear in the Astrophysical Journal (Preprint on arxiv.org)