Ukrainian astronomers confirm presence of exocometers around young star Beta Pictoris

We all remember the extraordinary success of the The Rosetta Mission and its Philae Module with the comet 67P / Churioumov-Guérassimenko. But remember that its discoverers, Klim Ivanovich Churioumov and Svetlana Ivanovna Guerassimenko, are from Ukrainian and that they observed thestar in photographic plates in 1969 while working at Astronomical Observatory of Kyiv University ?

Today, several of his colleagues and compatriots are stationed at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (Main Astronomical Observatory of the Ukrainian Academy of Sciences), also in Kyiv, who have just confirmed the existence of exoskeletons around the famous star Beta Pictoris by discovering five more stars of this type acting traffic.

This sequence begins with a broad view of the southern sky and ends with the bright star Beta Pictoris in the constellation of Pictor (the artist’s easel). This young star is surrounded by a disk of dust with a large planet orbiting around it, which is the first exoplanet whose rotational speed has been measured. It has an equatorial rotation speed of about 100,000 kilometers per hour, much faster than any of the planets in the Solar System. © ESO, Digitized Sky Survey 2, Nick Risinger (, L. Road. Music: Movetwo

Beta Pictoris, a laboratory for understanding the formation of the Solar System

In fact, this is not the first time that exocomets have been discovered around Beta Pictoris, as Futura had explained on several occasions and in particular in the previous article below, also exposing some of the characteristics of this mythical star studied for decades. to understand young stars. and planetary cosmogony.

The theory of structure and stellar evolution tells us that Beta Pictoris, with his too 1.8 times that of Ground and located about 63 light years from Earth, it would only be about twenty million years old. That kind of star At 5 so close is therefore a goal of choice for astronomers who have been watching him for a long time Exoplanet exploration satellite in transit (Tess).

Ukrainian astronomers were already aware of the detection of three transits that could be interpreted as those of exocometers, the discovery of which was announced in 2019 and already with Tess, and had set out to find others by analyzing the data already collected. of Tess which is available at Mikulski Archive for Space Telescopes (MAST).

The orbital distances of the five newly discovered exocomets in transit are between 0.5 and 1.5 AUas the researchers explain in an article published in Astronomy and Astrophysicsavailable free of charge at arXiv.

Artist impression of exocometers around Beta Pictoris. © Southern European Observatory (ESO)

What you have to remember

  • The laws of physics suggest, and observations confirm, that the formation of planets must involve generally universal processes and stages.
  • We still don’t understand them as well as we would like, and that’s why young stars with forming planets are being studied.
  • We see that these stars are surrounded not only by young exoplanets but also by young exocometers.
  • This is the case with Beta Pictoris, which therefore serves as a laboratory for understanding the formation of the Solar System.

Three exocetus discovered around the young star Beta Pictoris

Article by Laurent Sacco published on 01/06/2019

Over the last thirty years, indications and measures have multiplied about the existence of a large number of exocometers on the waste disk of the young star Beta Pictoris. These exometers are becoming more and more noticeable through the transit method and this is the telescopes Tess just got this great first with this star.

It has been almost 35 years since the star Beta Pictoris (β Pic) was mentioned in the field of the cosmogony of planetary systems. In fact, in the mid-1980s, astronomers turned their eyes to barely available infrared of the Iras satellite (Infrared astronomical satellite) to this very young white star, located at a distance of about 63 light-years from solar system in the constellation austral of the Painter.

Iras revealed that around this sun present in the main sequence of the Hertzsprung-Russel diagram for approximately 23 million years, there was a disk of strongly depleted gas but still rich in dust to allow the formation ofexoplanetsas evidenced by the measures taken at the beginning of the 21sti century. This waste disk contains dust resulting from ongoing collisions between embryos planetary or asteroids. So it gives us an insight into what our solar system must have looked like more than 4.5 billion years ago.

With its proximity, it is therefore an extraordinary window to understand the formation of the planets and since 1999, the astrophysicists French, Alain Lecavelier des Étangs, Alfred Vidal-Madjar and Roger Ferlet, had predicted that we would detect comets, therefore exocometers, in orbit around Beta Pictoris. This is really what happened. Hundreds have even been discovered using the famous one harp spectrographfiber-powered lobby Cassegrain of the 3.6-meter telescopeESO, at the La Silla Observatory in Chile. The instrument is in fact famous for its detection of exoplanets by the Radial velocity method.

Exocomets betrayed by their transits

Today, the existence ofexocometers around Beta Pictoris is confirmed by another method of detecting exoplanets, that of transit. It is the successor to the Kepler satellite Exoplanet exploration satellite in transit (in French, Satellite for the census of exoplanets in transit) that was used for this discovery. He is best known for his acronyms TESS and was released on April 18, 2018 by Nasa.

It is an international team of astronomers from the universities of Innsbruck, Warwick and Leiden that has just announced it first. via an open access article on arXiv and by a press release from the University of Innsbruck, the former announcing the discovery of an exocet comet, and the latter explaining that it was finally three of these stars that were identified by the transit method and, therefore, by drops of the brightness in the Beta Pictoris light curve.

Tess has more powerful instruments than Kepler. However, we just learned that the analysis of the archived data from Kepler had allowed to identify exocometas, still by the method of transit, in three other planetary systems. Tess should have done so far by only inspecting the tip of an iceberg that the probe should reveal in more detail in the coming years.

The number of exocomets is expected to decrease as a star gets older, and it would be interesting to study how this decrease occurs over time because this would allow us to have clues to better understand the evolution of young planetary systems and therefore , in shortto better understand what happened to the young solar system.

In the near future, it should even be possible to impose restrictions on the composition of exocomets, according to researchers.

Two types of exoskeletons around the young star Beta Pictoris

ESO article published on 10/26/2014

The Harps instrument, which equips the La Silla observatory in Chile, has made it possible to make the most complete census to date of comets orbiting the young star Beta Pictoris. A French team of astronomers, after carefully studying half a thousand of them, was able to discover that they belong to two different families.

Located about 63 light-years from the Sun, Beta Pictoris is a star about twenty million years old, surrounded by a vast disk of matter. It is a very active young planetary system, the gas and dust of which come from the evaporation of comets and collisions between asteroids.

Flavier Kiefer (IAP, CNRS, UPMC), lead author of this new study published in the October 23 issue of Natureset the stage: “Beta Pictoris is a favorite target! Detailed observations of its exocetus provide us with clues to understanding the processes that work in this type of young planetary system.”.

For almost 30 years, astronomers have observed subtle variations in intensity in the brightness of Beta Pictoriswhich they attributed to the passage of quotation marks in front of the star. Comets are small bodies a few miles in diameter, rich in ice, that evaporate near their star, creating gigantic tails of gas and dust capable of partially absorbing the light that passes through them.

About 500 exocometers and two families

To carry out the study of Exocomets Beta Pictoristhe team analyzed more than a thousand observations made between 2003 and 2011 using the Harps instrument that equips the 3.6 m Eso telescope, installed at the La Silla Observatory in Chile.

The researchers selected a sample of 493 different exocomets. Some of them were observed several times and for a few hours. A thorough analysis made it possible to determine the speed as well as the size of the clouds gas. Some of the orbital properties of each of the exocomets could also be deduced, such as shape, trajectory, and distance to the star.

Such an analysis that includes several hundredexocometers belonging to the same exoplanetary system is unique. He revealed the existence of two families: on the one hand, ancient exocomets whose orbits are controlled by the gravitational pull of a massive planet, and on the other hand, exocomets probably the result of the recent division of a more larger objects. A distinction comparable to that observed within our solar system.

He exocometers of the first family are characterized by a great diversity of orbits in addition to low emissions gas and dust. This suggests that they have depleted their ice reserves during their multiple passes near parent star Beta Pictoris.

Exocometers classified within the second family are much more active and describe similar orbits. This suggests its common origin: probably the division of a larger object whose remains now orbit near the star.

Flavien Kiefer concludes: “For the first time, a statistical study has determined the shape and orbit of a large number of exocometers. This work provides a great overview of the mechanisms that work in the Solar System shortly after its formation 4.6 billion years ago. years”..

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