Minimal record and other amazing discoveries: Astronomers have gained new knowledge about the nearby planetary system like our Sun. One of the celestial bodies is only half the mass of Venus – the lightest exoplanet measured by radial velocity. According to data, another planet in the system may be very waterlogged. Researchers have previously reported mysterious observations: in addition to the now-confirmed four planets, they have found evidence of a fifth planet where Earth-like conditions may exist.
Astronomers have already discovered thousands of exoplanets orbiting distant stars – now the task is to stare at particularly exciting systems. L 98-59 is this: The system 35 light-years away from us has a red dwarf star and its interesting planetary structure. So far, three planets have been discovered in 2019 using the transit method. Astronomers used the shadow of the star caused by the passing planets to identify them and determine their size. To uncover and identify more details about these celestial bodies, a team of international astronomers is targeting the L98-59 system with the European Southern Laboratory (ESO) Largest Telescope (VLT) in Chile.
Stellar oscillation reveals light
Researchers use the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) to obtain data called the radial velocity method. Simply put, the motion of a star is determined by the gravitational forces of the planets orbiting it. In this way, they can be detected indirectly and conclusions can be drawn about their masses and their compositions. “If we want to know what a planet is made of, at least we need its mass and its radius,” says Olivier Dimanzion, the first writer at the University of Porto. As he and his colleagues explain, a detailed understanding of the features of the planets in the system is possible only by combining radial velocity measurements with previous data.
As they report, they made a technological breakthrough using ESPRESSO. Was able to establish that the inner planet of its data system is only half the mass of Venus. Astronomers say this is the previous minimum record of this detection technique. “This is a step in determining the masses of small planets outside the solar system,” says Maria Rosa Zapatero Osorio, co-author of the Astronomical Center in Madrid.
Astronomers also report that three previously known planets of L98-599 may have water in their interior or atmosphere. However, the two closest to the star are very dry. But this is probably not number three: scientists write that the density data give indications that 30 percent of the water is present.
As part of the investigation, the system also identified a fourth Exoplanet previously unknown in the group, but no further details are known about it. They also indicate a promising trace of a possible fifth planet. “We have evidence of an Earth-like planet in the habitable zone of this system,” Dimanjian said. Zapatero Osorio thinks this is a wonderfully exciting way: “In this region, a planet can have an atmosphere that can save and activate life,” says the astronomer.
The planetary system of L98-59 is now an attractive target for future observations of exoplanet atmospheres. Astronomers believe that biological signatures can be identified by atmospheric perspective. So far, however, telescopes have not been able to achieve the resolution required for small rocky planets. First, the team now hopes to further explore the system with NASA’s James Webb Space Telescope, which will be launched at the end of 2021. Later, ESO’s largest telescope, currently built in the Atacama Desert in Chile, is scheduled to be operational in 2027 and can provide insights. “The HIRES instrument in the ELT could explore the atmospheres of some of the planets in the L 98-59 system,” says Osorio.
Source: ESO, Technical Article: Astronomy & Astronomy, Doi: 10.1051 / 0004-6361 / 202140728
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