Red dwarfs are the coolest type of star. As such, they potentially allow liquid water to have on the planets near them. In the search for habitable earths beyond the boundaries of our solar system, this is a huge advantage: the distance between an exoplanet and the star is an important factor for its discovery. The closer the two are, the higher the chance that astronomers will see the planet from Earth.
“But these stars are relatively small and emit very little light compared to most other stars, such as our Sun,”; said Brice-Olivier Demory, lead author of the study and Professor of Astrophysics at the University. of Bern explaining. These factors make it challenging for them to observe in detail. Without proper instruments, any planets that can rotate around them would be easy to spot – especially terrestrial plans, such as Earth, would be comparable.
A dedicated telescope
One instrument, where it is possible to study red dwarfs and their planets, is the Mexico-based SAINT-EX telescope, compiled by NCCR PlanetS. SAINT-EX is an acronym that represents the Search and description of Transiting EXoplanets. The project is named in honor of Antoine de Saint-Exupéry (Saint-Ex), the famous writer, poet and actor.
The SAINT-EX Observatory is a full robotic facility that hosts a 1-meter telescope. It is equipped with an instrument specifically suited to enable high-precision detection of small planets orbiting cool stars. Now, this specialization pays off: earlier this year, the telescope saw two exoplanets orbiting the star TOI-1266, located around 120 light years from Earth. The research, recently published in the journal Astronomy and Astrophysics, gives a first impression of their characteristics.
A strange pair
Compared to the planets in our solar system, TOI-1266 b and c are closer to their star – they only last 11 and 19 days respectively. However, because their host star is cooler than the Sun, their temperature is not very intense: the outer planet has an approximate temperature of Venus (although it is 7 times closer to its star than Venus in the Sun. ). The two planets are of similar density, possibly corresponding to a composition of almost half rocky and metallic material and half water. They make them half rocky like Earth or Venus but also farther away than Uranus or Neptune.
In size, the planets are clearly different from each other. The inner planet, TOI-1266 b, measures up to a little under two and a half times the diameter of the Earth. This makes it a so-called “sub-Neptune.” The outer planet, TOI-1266 c, is more than one and a half times the size of our planet. Therefore, it belongs to the category of “super-Earths.”
It places the two planets on the edges of the so-called radius-valley, as Brice-Olivier Demory explains: “The planets between the radius of TOI-1266 b and c are rare, probably due to the effect of strong lighting from the star, which can damage their skies. “Yilen Gómez Maqueo Chew, SAINT-EX Project Coordinator and researcher at the National Autonomous University of Mexico adds:” The ability to study two different types of planets in both systems is a great opportunity to better understand how different sizes come into being. “
Good timing and help from the embassy
Having this opportunity, especially this year, is something given. Scientists are fortunate to have completed their observations shortly before the lockdown associated with COVID-19 in Mexico. Shortly after the observations were made, the observatory had to close due to the consequences of the pandemic. It has not changed until now. Scientists expect to continue SAINT-EX operations in the coming months and target the next red dwan and the potential planets. “Also, the Mexican Embassy in Bern has been a great help in facilitating discussions with the Mexican government and in providing ongoing project support,” Demory said.
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B.-O. Demory et al, A super-Earth and a sub-Neptune orbiting the bright, quiet M3 dwarf TOI-1266, Astronomy and Astrophysics (2020). DOI: 10.1051 / 0004-6361 / 202038616
Provided by the University of Bern
Citation: Found two planets orbiting a red dwarf (2020, October 16) obtained on October 16, 2020 from https://phys.org/news/2020-10-planets-orbiting-red-dwarf. html
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