[ad_1]
This artist’s impression shows L 98-59b, one of the planets in the L 98-59 system 35 light years away. The system contains four confirmed rocky planets with a potential fifth, furthest from the star, unconfirmed.
In 2021, astronomers used data from the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) instrument on ESO’s VLT to measure the mass of L 98-59b, finding it to be half of that of Venus. This makes it the lightest planet measured to date using the radial velocity technique.
Credit: ESO / M. Grain knives
A team of astronomers used the European Southern Observatory Very large telescope (THIS‘s VLT) in Chile to shed new light on the planets around a nearby star, L 98-59, which resemble those in the inner solar system. Among the discoveries there is a planet with half the mass of Venus – the brightest exoplanet never to be measured using the radial velocity technique – an oceanic world and a possible planet in the habitable zone.
“The planet in the habitable zone may have an atmosphere that could protect and support life,” says María Rosa Zapatero Osorio, astronomer at the Center for Astrobiology in Madrid, Spain, and one of the authors of the study published today ‘hui (August 5, 2021) in Astronomy & Astrophysics.
The results are an important step in the quest for life on Earth-sized planets outside the solar system. Detecting biosignatures on an exoplanet depends on the ability to study its atmosphere, but current telescopes are not large enough to achieve the resolution needed to do so for small, rocky planets. The newly studied planetary system, named L 98-59 after its star, is an attractive target for future observations of exoplanet atmospheres. It orbits a star just 35 light years away and is now home to rocky planets, like Earth or Venus, which are close enough to the star to be hot.
This infographic shows a comparison between the exoplanet system L 98-59 (top) with part of the inner solar system (Mercury, Venus, and Earth), highlighting the similarities between the two.
L 98-59 contains four confirmed rocky planets (marked in color in the top panel), orbiting a red dwarf star 35 light years away. The planet closest to the star is about half the mass of Venus, making it the lightest exoplanet ever detected using the radial velocity technique. Up to 30% of the mass of the third planet could be water, making it an ocean world. The existence of the fourth planet has been confirmed, but scientists do not yet know its mass and radius (its possible size is indicated by a dotted line). The team also found clues to a potential fifth planet, furthest from the star, although the team knows little. If confirmed, it would be in the living area of the system where liquid water could exist on its surface.
The distances between stars and between planets in the infographic are not to scale. The diagram has been scaled to match the habitable zone in the solar system and in L 98-59. As indicated by the infographic, which includes a temperature scale (in Kelvin [K]), Earth and the (unconfirmed) fifth planet of L 98-59 receive similar amounts of light and heat from their respective stars. Assuming their atmospheres are similar, this fifth planet would have an average surface temperature similar to that of Earth and would support liquid water on its surface.
Credit: ESO / L. Sidewalk / M. Kornmesser (Thanks: O. Demangeon)
With input from ESO’s VLT, the team was able to deduce that three of the planets may contain water inside or in their atmosphere. The two planets closest to the star in the L 98-59 system are likely dry, but could hold small amounts of water, while up to 30% of the third planet’s mass could be of water, which would make it an oceanic world.
In addition, the team found “hidden” exoplanets that had not been spotted before in this planetary system. They have discovered a fourth planet and suspect that there is a fifth, in an area the right distance from the star for liquid water to exist on its surface. “We have indications of the presence of a terrestrial planet in the habitable zone of this system”, explains Olivier Demangeon, researcher at the Instituto de Astrofísica e Ciências do Espaço, University of Porto in Portugal and principal author of the new study .
The study represents a technical breakthrough because astronomers were able to determine, using the radial velocity method, that the innermost planet in the system is only half the mass of Venus. This makes it the lightest exoplanet ever measured using this technique, which calculates the star’s oscillation caused by the tiny gravitational pull of its orbiting planets.
The team used the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) instrument on the ESO VLT to study L 98-59. “Without the precision and stability provided by ESPRESSO, this measurement would not have been possible,” says Zapatero Osorio. “This is a step forward in our ability to measure the masses of the smallest planets beyond the solar system.”
Astronomers first spotted three of L 98-59’s planets in 2019, using NasaSatellite for the study of exoplanets in transit (TESS). This satellite uses a technique called the transit method – where the drop in light from the star caused by a planet passing in front of it is used to infer the properties of the planet – to find the planets and measure their sizes. However, only with the addition of radial speed measurements made with ESPRESSO and its predecessor, the High Accuracy Radial speed Planet Searcher (HARPS) at ESO La Silla’s 3.6-meter telescope, which Demangeon and his team were able to find additional planets and measure the masses and radii of the first three. “If we want to know what a planet is made of, the minimum we need is its mass and radius,” says Demangeon.
The team hopes to continue studying the system with the upcoming NASA / ESA / CSA James Webb Space Telescope (JWST), while ESO’s Extremely Large Telescope (ELT), under construction in the Chilean Atacama Desert. and which should start its observations in 2027, also be ideal for studying these planets. “The ELT’s HIRES instrument could have the power to study the atmosphere of some of the planets in the L 98-59 system, complementing the JWST from the ground,” says Zapatero Osorio.
“This system signals what’s to come,” Demangeon adds. “We as a society have been hunting terrestrial planets since the birth of astronomy and now we are finally getting closer and closer to detecting a terrestrial planet in the habitable zone of its star, which we could study. ‘atmosphere.”
More information
This research was featured in an article with permission to appear in Astronomy & Astrophysics.
Reference: “A hot terrestrial planet with half the mass of Venus passing through a nearby star” August 5, 2021, Astronomy & Astrophysics.
DOI: 10.1051 / 0004-6361 / 202140728
The team is composed of Olivier DS Demangeon (Institute of Astrophysics and Space Sciences, University of Porto, Portugal [IA/UPorto], Astrophysical Center of the University of Porto, Portugal [CAUP] and Department of Physics and Astronomy, Faculty of Sciences, University of Porto, Portugal [FCUP]), MR Zapatero Osorio (Center for Astrobiology, Madrid, Spain [CSIC-INTA]), Y. Alibert (Institute of Physics, University of Bern, Swiss [Bern]), SCC Barros (IA / UPorto, CAUP and FCUP), V. Adibekyan (IA / UPorto, CAUP and FCUP), HM Tabernero (IA / UPorto and CAUP), A. Antoniadis-Karnavas (IA / UPorto & FCUP), JD Camacho (IA / UPorto & FCUP), A. Suárez Mascareño (Institute of Astrophysics of the Canaries, Tenerife, Spain [IAC] and Department of Astrophysics, University of La Laguna, Tenerife, Spain [ULL]), M. Oshagh (IAC / ULL), G. Micela (INAF – Osservatorio Astronomico di Palermo, Palermo, Italy), SG Sousa (IA / UPortol & CAUP), C. Lovis (Geneva Observatory, University of Geneva, Geneva , Swiss [UNIGE]), FA Pepe (UNIGE), R. Rebolo (IAC / ULL & Consejo Superior de Investigaciones Científicas, Spain), S. Cristiani (INAF – Astronomical Observatory of Trieste, Italy [INAF Trieste]), NC Santos (IA / UPorto, CAUP and FCUP), R. Allart (Department of Physics and Institute for Research on Exoplanets, University of Montreal, Canada and UNIGE), C. Allende Prieto (IAC / ULL), D. Bossini (IA / UPorto), F. Bouchy (UNIGE), A. Cabral (Institute of Astrophysics and Space Sciences, Faculty of Sciences, University of Lisbon, Portugal [IA/FCUL] and Department of Physics, Faculty of Sciences, University of Lisbon, Portugal), M. Damasso (INAF – Osservatorio Astrofisico di Torino, Italy [INAF Torino]), P. Di Marcantonio (INAF Trieste), V. D’Odorico (INAF Trieste & Institute for Fundamental Physics of the Universe, Trieste, Italy [IFPU]), D. Ehrenreich (UNIGE), J. Faria (IA / UPorto, CAUP and FCUP), P. Figueira (European Southern Observatory, Santiago de Chile, Chile [ESO-Chile] and IA / UPorto), R. Génova Santos (IAC / ULL), J. Haldemann (Berne), JI González Hernández (IAC / ULL), B. Lavie (UNIGE), J. Lillo-Box (CSIC-INTA), G. Lo Curto (European Southern Observatory, Garching bei München, Germany [ESO]), CJAP Martins (IA / UPorto and CAUP), D. Mégevand (UNIGE), A. Mehner (ESO-Chile), P. Molaro (INAF Trieste and IFPU), NJ Nunes (IA / FCUL), E. Pallé ( IAC / ULL), L. Pasquini (ESO), E. Poretti (Fundación G. Galilei – INAF Telescopio Nazionale Galileo, La Palma, Spain and INAF – Osservatorio Astronomico di Brera, Italy), A. Sozzetti (INAF Turin), and S. Udry (UNIGE).
ESO is the leading intergovernmental astronomical organization in Europe and by far the most productive ground-based astronomical observatory in the world. It has 16 member states: Austria, Belgium, Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, Netherlands, Poland, Portugal, l Spain, Sweden, Switzerland and the UK, as well as the host state of Chile and with Australia as a strategic partner. ESO has an ambitious program focused on the design, construction and operation of powerful ground-based observation facilities that enable astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organizing cooperation in the field of astronomical research. ESO operates three unique world-class viewing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its interferometer for the world’s leading Very Large Telescope, as well as two survey telescopes, VISTA working in infrared and the VLT Survey Telescope in visible light. Also in Paranal, ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. ESO is also a major partner in two installations on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, near Paranal, ESO is building the extremely large 39-meter telescope, the ELT, which will become “the world’s largest eye in the sky.”
[ad_2]
Source link