Two Earth-sized Exoplanets Found Orbiting Red Dwarf GJ 1002

By James Anderson •  Updated: 12/16/22 •  3 min read

Two planets with Earth-like masses have been found in orbit around the red dwarf star GJ 1002, which is close to our solar system, by an international team of scientists led by IAC researchers. The habitability zone of the star is home to both planets.

“Nature seems bent on showing us that Earth-like planets are very common. With these two we now know 7 in planetary systems quite near to the sun,”

said first author Alejandro Suárez Mascareño, an IAC researcher. Less than 16 light years separate GJ 1002 from our solar system.

GJ 1002b And GJ 1002c

GJ1002b and c infographic

The relative distance between the discovered planets and their star with the inner planets of the Solar System.
The region marked in green represents the habitable zone of the two planetary systems.
Credit: Design: Alejandro Suárez Mascareño (IAC). Planets of the Solar System: NASA

The inner of the two exoplanets, GJ 1002b, completes an orbit of the star in just over 10 days, whereas GJ 1002c needs just over 21 days.

“GJ 1002 is a red dwarf star, with barely one eighth the mass of the sun. It is quite a cool, faint star. This means that its habitability zone is very close to the star,”

explained co-author Vera María Passegger, also of IAC.

Because of the star’s proximity to our solar system, the two planets, particularly GJ 1002c, are excellent candidates for the characterization of their atmospheres based on either reflected light or thermal emission.

“The future ANDES spectrograph for the ELT telescope at ESO in which the IAC is participating, could study the presence of oxygen in the atmosphere of GJ 1002c,”

noted co-author Jonay I. González Hernández, an IAC researcher.

Low Temperature Star

Both planets meet the criteria for being potential targets for the future LIFE mission, which is currently in the planning stages.

The discovery was made during a collaboration between the ESPRESSO and CARMENES instrument consortia. CARMENES observed GJ 1002 between 2017 and 2019, and ESPRESSO observed it between 2019 and 2021.

The visible light from GJ 1002 is too faint to measure its velocity variations with the majority of spectrographs due to its low temperature.

CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs) has superior sensitivity over a wide range of near infrared wavelengths to other spectrographs aimed at detecting variations in star velocities, allowing it to study GJ 1002 from the 3.5m telescope at Calar Alto.

The combination of ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) and the light-gathering power of ESO’s VLT 8m telescopes allowed measurements to be made with an accuracy of only 30 cm/sec, which no other instrument on the planet could match.

If either of the two groups had attempted this work on their own, they would have encountered numerous difficulties. They have gotten much further together than they would have gotten separately.

Reference: A. Suárez Mascareño, E. González-Alvarez, M. R. Zapatero Osorio, J. Lillo-Box, J. P. Faria, V. M. Passegger, J. I. González Hernández, P. Figueira, S. Sozzetti, R. Rebolo, F. Pepe, N. C. Santos, S. Cristiani, C. Lovis, A. M. Silva, I. Ribas, et al. Two temperate Earth-mass planets orbiting the nearby star GJ 1002. arXiv:2212.07332 [astro-ph.EP]

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