A planet in formation identified in the HD 97048 system

Planet's position pinpointed by the gas flow deviation (Image ESO/ALMA)
Planet’s position pinpointed by the gas flow deviation (Image ESO/ALMA)

An article published in the journal “Nature Astronomy” reports the discovery of evidence of the existence of a planet in formation within the protoplanetary disk surrounding the star HD 97048. A team led by Christophe Pinte used a technique that was tested in a previous occasion that identifies areas where the flow of gas around a star is disturbed by the presence of a planet. The data collected using the ALMA radio telescope made it possible to identify a planet with a mass estimated between two and three times Jupiter’s.

About 600 light years from Earth, the HD 97048 system, also known as CU Chamaeleontis, is very young, to the point that the star still has a variable brightness because it still has to reach the equilibrium that’s typical of what’s called the main sequence, the period of normal life for a star. For these reasons it’s very interesting and was already studied in the past with the ALMA (Atacama Large Millimeter / submillimeter Array) radio telescope, inaugurated in March 2013, but also with the SPHERE instrument, for example in a research published in April 2018 about star systems in formation.

The gaps in the protoplanetary disks of these systems in formation are interpreted by astronomers as the possible presence of planets that are absorbing the materials present in that area but could have been created by other phenomena. The direct detection of those planets is difficult even with extraordinary instruments such as ALMA and SPHERE, so the doubts remain.

Christophe Pinte and some colleagues proposed a method to discover those planets, explained in an article published in June 2018 in “The Astrophysical Journal” that used another system for their test, HD 163296, with a confirmation arrived from another team that published the results in another article in the same journal.

In simple words, Christophe Pinte’s team examined the data collected by the ALMA radio telescope in search for anomalies in the gas flow within the protoplanetary disk surrounding the young star by exploiting the large presence of carbon monoxide in the disk. ALMA can detect the chemical “signature” of that gas mapping its position and movements and this makes it possible to reveal cases in which the flow is disturbed by the presence of a planet in formation, creating a deviation (kink in the image).

In this new research, Christophe Pinte’s team focused on the HD 97048 system. The star has a mass about 2.4 times the Sun’s with a large protoplanetary disk from which a gas giant much more massive than Jupiter is being born at a distance from the star which is about 130 times that of the Earth from the Sun.

For now this technique makes it possible to identify the traces of gas giant exoplanets in formation but there’s still room to perfect it. The researchers will keep on studying star systems in formation to search for more newborn exoplanets, also to gather more information on those processes, including those about the formation of planetary atmospheres.

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