Two new potentially habitable super-Earths around a red dwarf
Located about 15 light years away, two new super-Earths have just been discovered by a team of astronomers. Orbiting around a red dwarf star, they are located in the habitable zone and are good candidates for an in-depth atmospheric study!
What are exoplanets, where are they found and why are they so interesting? Video answer!
Will we soon find extraterrestrial life? While waiting to answer this question, astronomers are looking for worlds whose conditions would be favorable to life. Two new elements have just been added to the already long list of possibly habitable worlds: super -Earths located around a red dwarf star, GJ 1002, or Gliese 1002. Their discovery has just been published in the journal Astronomy & Astrophysics .
Located 15.78 light-years away in the constellation of the Whale, the star GJ 1002 has a mass of approximately 0.12 solar masses, for a radius of 0.137 solar radius. Nothing unusual for a red dwarf . But what interests the researchers is that GJ 1002 is “one of the few known nearby systems with planets that could potentially host habitable environments,” the researchers explain.
RED DWARFS ARE THE MOST NUMEROUS STARS IN THE UNIVERSE.
NASA, T PYLETwo new potentially habitable exoplanets in a system near us
The two new worlds were discovered using the radial velocity method. It consists of scrutinizing the radial velocity of the central star, and looking for variations, however small they may be. If it harbors planets, then these exert a gravitational influence on it, which leads it to revolve around a center of gravity different from its center of mass.
THE PLANET, EVEN IF MUCH SMALLER THAN THE STAR, EXERTS A GRAVITATIONAL INFLUENCE ON IT. THUS, THE TWO OBJECTS GRAVITATE AROUND A COMMON CENTER OF GRAVITY (BARYCENTRE), DIFFERENT FROM THE CENTER OF MASS OF THE SINGLE STAR.
ZHAT, WIKIMEDIA COMMONSBy looking at its light spectrum , it is possible to observe a shift towards red if it is moving away, or towards blue if it is approaching. The researchers then probe the spectrum of the star, and deduce the presence of an object which disturbs it gravitationally. This is what the researchers did, using the Espresso and Carmenes spectrographs, the first being located on ESO's VLT ( Very Large Telescope ) in Chile, and the second being at the observatory. from Calar Alto, Spain.
By combining 139 spectra collected between 2017 and 2021, they thus identified at least two exoplanets in the GJ 1002 system. Named GJ 1002b and GJ 1002c, they are both super-Earths, rocky planets with a mass similar to that of the Earth. The first has a mass of 1.08 Earth masses and goes around its star in 35 days. The other has a mass of 1.36 Earth masses and orbits its star in 21.2 days. And above all, they are both located in the habitable zone!
A DIAGRAM SHOWING THE EVOLUTION OF THE HABITABILITY ZONE (HABITABLE ZONE) AROUND A STAR. ON THE ABSCISSA, ON A LOGARITHMIC SCALE, IT IS THE DISTANCE IN ASTRONOMICAL UNITS ( DISTANCE FROM STAR ) AND ON THE ORDINATE, THE MASS OF THE STAR ( MASS OF STAR ) IN SOLAR MASS. THE CASE OF THE SOLAR SYSTEM IS SHOWN AT THE TOP, IN COMPARISON WITH THE CASE OF A RED DWARF AT THE BOTTOM.
ESOAtmospheric studies needed for GJ 1002c
According to the researchers, GJ 1002c would be the most suitable for further studies. Indeed, the study explains that "the proximity of the host star to the Sun makes the angular sizes of the two planets' orbits large enough that their atmospheres can be studied via high-resolution, high-contrast spectroscopy with instruments such as the future Andes spectrograph or the Life mission”. And since the angular size of GJ 1002c exceeds that of GJ 1002b, it would be easier to probe.
The study concludes on the possible presence of a third planet, which would also be located in the zone of habitability , in the outer part. But a much more distant and much more massive! “Data from Gaia DR3 shows excess astrometric noise, which could indicate a massive companion with large orbital separation,” the scientists describe.
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