Astronomers have reported the possible discovery of the first exomoon

Astronomers have received evidence of the existence of a massive exosatellite in the CD-35 2722 star system. The object does not revolve around a planet, but around a brown dwarf, which, in turn, revolves around a star. If the discovery is confirmed, it may become the first known exomoon. This was announced on July 22 by the European Southern Observatory (ESO).

CD-35 2722 is a young star system. Its central star has a mass about half that of the sun. Orbiting it is the brown dwarf CD-35 2722 B, an object that is more massive than a planet but not large enough to support the thermonuclear reactions characteristic of stars.

According to the researchers, the mass of the brown dwarf is more than 30 times the mass of Jupiter. The exosatellite discovered next to it has a minimum mass of about 0.9 Jupiter masses and completes a complete revolution in about 170 days.

For the observations, the scientists used the CRIRES+ spectrograph installed on the Very Large Telescope of the European Southern Observatory (ESO) in Chile. The researchers applied the radial velocity method, which makes it possible to detect small fluctuations in a celestial body under the influence of gravity of an object orbiting it. Previously, using this method, the first exoplanet was found in a solar-type star.

The received periodic signal, according to the authors of the work, indicates the existence of at least one satellite of the brown dwarf. This is the first time that the radial velocity method has made it possible to obtain similar data for an object of this type.

The unusual structure of the system has raised the question of astronomers about the classification of the found body. An exomoon is usually referred to as a natural satellite of a planet or other object outside the Solar System, but there is no officially accepted definition of this term yet. Therefore, the authors of the study use the broader concept of "exosatellite".

To date, astronomers have discovered more than 6 thousand exoplanets, but the existence of not a single exomoon has yet been confirmed with complete certainty. Only a few candidates are known, the data about which remains the subject of scientific debate. The authors of the work call the new result the first plausible detection of an exosatellite, but emphasize that additional observations will be required for final confirmation.

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Phys.org On July 16, he announced the discovery of the giant exoplanet Beta Pictoris d. According to astronomers, the celestial body remained invisible for a long time inside one of the brightest circumstellar disks. According to the publication, the mass of Beta Pictoris d is about two to four times the mass of Jupiter. The exoplanet orbits the star at a distance of at least 30 astronomical units.