The two temperate Earth-mass planets are located within the habitably zone of Gliese 1002, a red dwarf star that lies just 4.84 parsecs (16 light-years) from the Sun.
“The search for potentially habitable Earth-like worlds is one of the most exciting endeavors in the field of exoplanets,” said Dr. Alejandro Suárez Mascareño, an astronomer at the Instituto de Astrofísica de Canarias and the Universidad de La Laguna, and colleagues.
“Thanks to radial-velocity and transit surveys, over 5,000 exoplanets have been discovered.”
“The first exoplanets detected were, for the most part, giant planets, as was predicted to happen.”
“Then, our technical capabilities rapidly expanded, allowing us to reach increasingly lower mass and smaller radius planets and eventually enter the realm of Earth-mass planets, but only at short orbital periods.”
“95% of the planets with measured masses less than 2 Earth masses orbit with periods shorter than 25 days.”
“Currently, we know a few tens of exoplanets with masses similar to that of the Earth (67 planets with less than 2 Earth masses), and hundreds with radii comparable to that of the Earth (855 planets with radius less than 1.5 Earth radii),” they added.
“However, the number of known exoplanets in the habitable zones of their parent stars (i.e. the region in which liquid water can exist in the surface of the planet) with prospects for atmospheric characterization remains very small.”
Using the ESPRESSO and CARMENES spectrographs, the authors detected the signal of two planets orbiting nearby M5.5-type star Gliese 1002 (also known as LHS 2, GJ 1002 and TIC 176287658).
“Gliese 1002 is a red dwarf star, with barely one eighth the mass of the Sun,” said Dr. Vera María Passegger, an astronomer at the Instituto de Astrofísica de Canarias, the Universidad de La Laguna, Hamburger Sternwarte, and the University of Oklahoma.
“It is quite a cool, faint star. This means that its habitability zone is very close to the star.”
Gliese 1002 was observed by the CARMENES instrument between 2017 and 2019, and by ESPRESSO between 2019 and 2021.
“Because of its low temperature the visible light from Gliese 1002 is too faint to measure its variations in velocity with the majority of spectrographs,” said Dr. Ignasi Ribas, an astronomer at the Institute of Space Sciences and director of the Institut d’Estudis Espacials de Catalunya.
The two new planets, named Gliese 1002b and Gliese 1002c, have masses similar to that of the Earth, and are located within the habitably zone of their parent star.
“Gliese 1002b is a planet with a minimum mass of 1.08 Earth masses and an orbital period of 10.3 days at a distance of 0.046 AU from the parent star,” the astronomers said.
“Gliese 1002c is a planet with a minimum mass of 1.36 Earth masses and an orbital period of 20.2 days at a distance of 0.074 AU from the star.”
“The closeness of Gliese 1002 to the Sun makes the angular sizes of the orbits of both planets large enough for their atmosphere to be studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission,” they concluded.
Their paper was published online in the journal Astronomy & Astrophysics.
A. Suárez Mascareño et al. 2022. Two temperate Earth-mass planets orbiting the nearby star GJ 1002. A&A, in press; doi: 10.1051/0004-6361/202244991
Source link: https://www.sci.news/astronomy/gliese-1002-exo-earths-11494.html