Astronomers discover two super-Earths orbiting a nearby star

Astronomers discover two super-Earths orbiting a nearby star

Astronomers discover two super-Earths orbiting a nearby star

TESS phase-folded light curves after subtracting photometric variability for TOI-2095b (top left) and TOI-2095c (top right). Photo credit: Murgas et al., 2023

Using NASA’s Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has spotted two “super-Earth” exoplanets orbiting a nearby M dwarf star dubbed TOI-2095. The newly discovered extraterrestrial worlds have short orbital periods and are slightly larger than Earth. The results were presented on April 18th arXiv preprint server.

TESS is conducting a survey of about 200,000 of the brightest stars near the Sun to search for passing exoplanets ranging from small rocky worlds to gaseous giants. So far it has identified 6,400 possible exoplanets (TESS Objects of Interest or TOI), of which 330 have been confirmed to date.

Now, a team of astronomers led by Felipe Murgas of La Laguna University, Spain, reported that two more candidates for extrasolar planets monitored by TESS have been confirmed. Through photometric observations and radial velocity measurements, they found that transit signals in TOI-2095’s light curve are planetary in nature.

“We report the validation of two transiting planets around the M dwarf TOI-2095 discovered by TESS. We use ground-based high-resolution imaging, TESS photometric data and CARMENES radial velocities to discard false positive scenarios that measure planetary radii and impose strict upper bounds on the mass of transit candidates,” the researchers explained.

The exoplanet closer to the star, about 0.1 AU from it, was given the designation TOI-2095 b. According to the study, the planet is about 25% larger than Earth and has an orbital period of 17.66 days. The equilibrium temperature of TOI-2095 b has been determined to be 347 K, while its mass is estimated to be no more than 4.1 Earth masses.

The second planet in the system, TOI-2095 c, has a radius of about 1.33 Earth radii and orbits its host every 28.17 days at a distance of about 0.137 AU from it. TOI-2095 c has an equilibrium temperature of approximately 297 K and its maximum mass has been calculated to be 7.4 Earth masses.

The parent star TOI-2095 is about 56% smaller and less massive than the Sun. It has a spectral type M2.5 V, an effective temperature of 3,759 K and metallicity at the level of -0.24. The star’s age is estimated to be at least a billion years.

The study authors summarized the results, noting that the two newly discovered exoplanets are located close to the inner edge of TOI-2095’s habitable zone and that their parameters make them attractive targets for further follow-up observations.

“In particular, extremely precise radial velocity follow-up observations may help improve planetary mass measurements (and hence bulk densities) and pose some limitations to future prospects for atmospheric characterization,” the researchers wrote.

More information:
F. Murgas et al, Two super-Earths at the edge of the habitable zone of nearby M dwarf TOI-2095, arXiv (2023). DOI: 10.48550/arxiv.2304.09220

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