European astronomers discover four new brown dwarfs

(ORDO NEWS) — Astronomers from the Astronomical Observatory of Padova (Italy) and other countries observed 25 stars as part of the COPAINS pilot study.

As a result, they discovered four new brown dwarfs, designated HIP 21152 B, HIP 29724 B, HD 60584 B and HIP 63734 B. This is reported in an article published on May 4 on the arXiv preprint server.

Brown dwarfs are intermediate objects between planets and stars, occupying a mass range of 13 to 80 Jupiter masses (0.012 to 0.076 solar masses). Although many brown dwarfs have been discovered to date, such objects orbiting other stars are a rare find.

Now a group of astronomers led by Mariangela Bonavita reports the discovery of four such objects. The discovery was made using a new tool known as the Code for Orbital Parametrization of Astrometrically Inferred New Systems (COPAINS).

This was part of a pilot study conducted with the SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), an extreme adaptive optics instrument on ESO’s Very Large Telescope (VLT), which used the COPAINS instrument to make informed target selection.

“We present the results of the SPHERE/VLT COPAINS survey searching for substellar companions of stars with significant differences in proper motion (∆µ) between different astrometric catalogs.

We have observed twenty-five stars and discovered ten companions, including four new brown dwarfs: HIP 21152 B, HIP 29724 B, HD 60584 B and HIP 63734 B,” the authors explain.

Recently discovered brown dwarfs are substellar companions of relatively young stars (less than one billion years old). The masses of these stars are estimated to range from 1.04 to 1.44 solar masses.

According to the study, HIP 21152 B, HIP 29724 B, HD 60584 B, and HIP 63734 B have masses of 0.032, 0.063, 0.028, and 0.012, respectively. They are 18.3, 6.3, 16.6, and 30 AU from their host stars, respectively.

The researchers note that their discovery highlights COPAINS’ ability to limit the population of planets and substellar companions.

They added that studies such as COPAINS offer an undeniably effective screening method, providing a much higher success rate (compared to other studies) in much less time.

“The high detection rate obtained here strongly argues for the use of such approaches in compiling surveys, despite the many assumptions and limitations of the work carried out in this experimental survey,” the astronomers noted.

They hope that the forthcoming third data release (DR3) from ESA’s Gaia satellite, expected in June 2022, will combine with COPAINS to yield even more interesting substellar companion discoveries.

They added that this would greatly improve the method in terms of uncertainty, allowing future research to really focus on objects with accelerations caused by planetary-mass companions.


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