Three exocometes discovered around the star Beta Pictoris

About a year after the launch of NASA's TESS mission, the first three comets orbiting neighboring star Beta Pictoris outside our solar system were discovered with the help of space telescope data. The main goal of TESS is to search for exoplanets, planets orbiting other stars. The recognition of exocomets signals much smaller compared to planets requires the analysis of a precise light curve, which can now be achieved thanks to the technical sophistication of the new space telescope.

Sebastian Zieba, master student in the team of Konstanze Zwintz at the Institute of Particle Physics and Astronomical Particles of the University of Innsbruck, discovered the exocomete signal during his investigation of the Beta Pictoris TESS light curve in March of this year. "The data showed a significant decrease in the intensity of the star light observed.These variations due to obscuration due to an object located on the orbit of the Earth. star can clearly be connected to a comet, "explain this sensational discovery by Sebastian Zieba and Konstanze Zwintz.

In collaboration with Matthew Kenworthy of the University of Leiden (The Netherlands) and Grant Kennedy of the University of Warwick (UK), they analyzed and interpreted the exocomets' signals. The results will now be published in the international journal Astronomy and astrophysics. Three similar exocomet systems have recently been discovered around three other stars during data analysis performed by NASA's Kepler mission. The researchers suggest that exocometes are found more often around young stars. "The Kepler Space Telescope is focused on older stars, similar to the Sun, in a relatively small area of ​​the sky.TESS, on the other hand, observes the stars in the sky, including the young stars. therefore new discoveries of this type in the future ", says Konstanze Zwintz. Zwintz's research focuses on young stars and she is considered an internationally renowned expert in the field of asteroseismology.

Dr. Grant Kennedy, from the Department of Physics at the University of Warwick, contributed to the modeling and interpretation of the data. He said: "This discovery is really important for the science of extrasolar comets for several reasons.It was thought that Beta Pictoris had housed exocometes for three decades from a different technique, and the TESS data provide independent evidence and The next goal is to find similar signatures around other stars, and this discovery shows that TESS is up to the task. "

Famous star

The young and very bright star Beta Pictoris is a "celebrity" among astronomers for many reasons: "Already in the 1980s, surveys of Beta Pictoris provided compelling evidence of the existence of planetary systems around the world. other stars that our Sun – a decade before exoplanets are discovered In addition, there was already at the time indirect evidence of comets based on the characteristic signature of the evaporation of gas escaping from them " , says Konstanze Zwintz, about 23 million years old, Beta Pictoris is a relatively young star, "a young adult star compared to the human age," says the astronomer.

The discovery of exocometes around Beta Pictoris was predicted in 1999 in an article written by astrophysicists Alain Lecavelier des Etangs, Alfred Vidal-Madjar and Roger Ferlet. "With our colleagues from Leiden and Warwick, we are happy to have finally confirmed this theory," say Zieba and Zwintz. Scientists expect to discover many more comets and asteroids in this region because it is a young star. "In the future, we want to find answers to the question of how often exocometes occur and if their numbers actually decrease with the age of a star. important because by analyzing the comets around a young star, we can also draw conclusions on the history of our own solar system.Because we know that our solar system has shown considerably more comets in the early years ", says Konstanze Zwintz.

In the future, researchers want to study the composition of exocomets, for example with regard to their water content. The comets themselves are smaller than the exoplanets, but have a very large tail that can reach several million kilometers long. "What we see is not the core of the comet itself, but the material blown out of the comet and trailing behind.TESS data do not tell us what was the size of the comets because the The extent of the dust tail could be very large and not very dense, or smaller and denser, and the two situations would give the same light curve, "says Zwintz.