Located only 35 light-years from the Sun.
Astronomers presented the results of studies of the multiplanetary system L 98-59, which is located 35 light-years from the Sun. They managed to find two new exoplanets in it, and also determine that the system includes a planet with large reserves of water and a planet located in the habitable zone.
Everything you need to know about the L 98-59 system and its “ocean worlds”
Searching for signs of life in the universe
As part of the search for signs of life outside the solar system, scientists need not only to discover exoplanets with a mass similar to that of the Earth but also to look among them for bodies that would be in the habitable zone of their bright star and periodically pass through its disk (transit) from the point of view of an earthly observer.
In this case, researchers will have the opportunity to spectroscopically study the planet’s atmosphere (if any), roughly determine its composition, and even identify the presence of biomarkers. In addition, from the point of view of habitability, scientists are interested in multi-planetary systems like the Solar System. When it comes to exoplanets like Earth, however, the ones that draw the most attention are the ones that show signs of the existence of water.
The L 98-59 system
A group of astronomers led by Olivier Demangeon from the Institute of Astrophysics and Space Research of the University of Porto has published the results of a study of the L 98-59 system, which is 35 light-years from the Sun and consists of a bright red dwarf and three known exoplanets with radii from 0, 8 to 1.6 of the Earth’s radius.
The observations were carried out using the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) spectrograph installed on one of the telescopes of the VLT complex. In addition, the researchers used observational data from the TESS telescope and the HARPS spectrograph.
Scientists have discovered the fourth exoplanet in the system, which has a minimum mass of 3.06 Earth masses and an orbital period of 12.79 Earth days. In this case, the planet was not transit.
A fifth planet in the habitable zone?
In addition, there is a fifth planet in the system, which has a minimum mass of 2.46 Earth masses and an orbital period of 23.15 Earth days. This planet is located in the center of the habitable zone of the L 98-59 system.
Exoplanets L 98-59b and c
In addition, the researchers determined that exoplanets L 98-59b and L 98-59c have an average density of 3.6 and 4.57 grams per cubic centimeter, which indicates a similar composition – both planets can have an iron-containing core, the mass of which will be from 12 up to 14 percent of the total mass of the planet, and contain little water.
In addition, L 98-59 b has a mass half that of Venus, which makes it the lightest exoplanet discovered using the radial velocity method. In the case of exoplanet L 98-59d, which has an average density of 2.95 grams per cubic centimeter, 30 percent of its mass may be water.
L 98-59 is one of the most important systems for research
Scientists note that the L 98-59 system, due to its structure and proximity to the Sun, is one of the main goals for the comparative study of the atmospheres of rocky planets within the same system.
It is expected to be observed in the future by the James Webb Space Telescope and the ELT ground-based telescope. Exoplanet L 98-59d, in particular, will be of key importance due to the possible existence of a lot of water (30% of its total mass). As you know, there is a simple rule for the possibility of life – if there is even the smallest amount of water, life could be possible.
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• Demangeon, O. D. S. (n.d.). A warm terrestrial planet with half the mass of Venus transiting a nearby star.
• EarthSky. (2021, August 6). An inner solar system much like OURS, 35 light-years away.
• ESO. (n.d.). New ESO observations show Rocky exoplanet has just half the mass of Venus.
• O’Neill, M. (2021, August 5). Astronomers find small rocky planet – just half the mass of venus. SciTechDaily.
• Phys.org. (2021, August 5). New observations show Rocky exoplanet has just half the mass of Venus.