Astronomers Find Small Rocky Planet – Just Half the Mass of Venus

L 98–59 Planetary System

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This artist’s impression reveals L 98-59b, among the worlds in the L 98-59 system 35 light-years away. The system includes 4 verified rocky worlds with a possible 5th, the outermost from the star, being unofficial.
In 2021, astronomers utilized information from the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) instrument on ESO’s VLT to determine the mass of L 98-59b, discovering it to be half that of Venus. This makes it the lightest world determined to date utilizing the radial speed strategy.
Credit: ESO/M. Kornmesser

A group of astronomers has actually utilized the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile to shed brand-new light on worlds around a close-by star, L 98-59, that look like those in the inner Solar System. Amongst the findings are a world with half the mass of Venus — the lightest exoplanet ever to be determined utilizing the radial speed strategy — an ocean world, and a possible world in the habitable zone.

“The planet in the habitable zone may have an atmosphere that could protect and support life,” states María Rosa Zapatero Osorio, an astronomer at the Centre for Astrobiology in Madrid, Spain, and among the authors of the research study released today (August 5, 2021) in Astronomy & Astrophysics.

The outcomes are a crucial action in the mission to discover life on Earth-sized worlds outside the Solar System. The detection of biosignatures on an exoplanet depends upon the capability to study its environment, however existing telescopes are not big enough to attain the resolution required to do this for little, rocky worlds. The recently studied planetary system, called L 98-59 after its star, is an appealing target for future observations of exoplanet environments. Its orbits a star just 35 light-years away and has actually now been discovered to host rocky worlds, like Earth or Venus, which are close adequate to the star to be warm.

Comparison of the L 98-59 Exoplanet System With Inner Solar System

This infographic reveals a contrast in between the L 98-59 exoplanet system (top) with part of the inner Solar System (Mercury, Venus, and Earth), highlighting the resemblances in between the 2.
L 98-59 includes 4 verified rocky worlds (marked in color in the leading panel), orbiting a red-dwarf star 35 light-years away. The world closest to the star is around half the mass of Venus, making it the lightest exoplanet ever discovered utilizing the radial speed strategy. Up to 30% of the 3rd world’s mass might be water, making it an ocean world. The presence of the 4th world has actually been verified, however researchers don’t yet understand its mass and radius (its possible size is suggested by a dotted line). The group likewise discovered tips of a possible 5th world, the outermost from the star, though the group understands little about it. If verified, it would being in the system’s habitable zone where liquid water might exist on its surface area.
The ranges from the stars and in between the worlds in the infographic are not up to scale. The diagram has actually been scaled to make the habitable zone in both the Solar System and in L 98-59 correspond. As suggested by the infographic, that includes a temperature level scale (in Kelvin [K]), the Earth and the 5th (unofficial) world in L 98-59 get comparable quantities of light and heat from their particular stars. Assuming their environments are comparable, this 5th world would have a comparable typical surface area temperature level to Earth and would support liquid water at its surface area.
Credit: ESO/L. Calçada/M. Kornmesser (Acknowledgment: O. Demangeon)

With the contribution of ESO’s VLT, the group had the ability to presume that 3 of the worlds might include water in their interiors or environments. The 2 worlds closest to the star in the L 98-59 system are most likely dry, however may have percentages of water, while as much as 30% of the 3rd world’s mass might be water, making it an ocean world.

Furthermore, the group discovered “hidden” exoplanets that had actually not formerly been found in this planetary system. They found a 4th world and think there is a 5th, in a zone at the ideal range from the star for liquid water to exist on its surface area. “We have hints of the presence of a terrestrial planet in the habitable zone of this system,” discusses Olivier Demangeon, a scientist at the Instituto de Astrofísica e Ciências do Espaço, University of Porto in Portugal and lead author of the brand-new research study.

The research study represents a technical development, as astronomers had the ability to figure out, utilizing the radial speed approach, that the inner world in the system has simply half the mass of Venus. This makes it the lightest exoplanet ever determined utilizing this strategy, which determines the wobble of the star brought on by the small gravitational yank of its orbiting worlds.

The group utilized the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) instrument on ESO’s VLT to study L 98-59. “Without the precision and stability provided by ESPRESSO this measurement would have not been possible,” states Zapatero Osorio. “This is a step forward in our ability to measure the masses of the smallest planets beyond the Solar System.”

The astronomers initially found 3 of L 98-59’s worlds in 2019, utilizing NASA’s Transiting Exoplanet Survey Satellite (TESS). This satellite depends on a strategy called the transit approach — where the dip in the light originating from the star brought on by a world passing in front of it is utilized to presume the homes of the world — to discover the worlds and determine their sizes. However, it was just with the addition of radial speed measurements made with ESPRESSO and its predecessor, the High Accuracy Radial speed Planet Searcher (HARPS) at the ESO La Silla 3.6-metre telescope, that Demangeon and his group had the ability to discover additional worlds and determine the masses and radii of the very first 3. “If we want to know what a planet is made of, the minimum that we need is its mass and its radius,” Demangeon discusses.

The group intends to continue to study the system with the upcoming NASA/ESA/CSA James Webb Space Telescope (JWST), while ESO’s Extremely Large Telescope (ELT), under building in the Chilean Atacama Desert and set to begin observations in 2027, will likewise be perfect for studying these worlds. “The HIRES instrument on the ELT may have the power to study the atmospheres of some of the planets in the L 98-59 system, thus complementing the JWST from the ground,” states Zapatero Osorio.

“This system announces what is to come,” includes Demangeon. “We, as a society, have been chasing terrestrial planets since the birth of astronomy and now we are finally getting closer and closer to the detection of a terrestrial planet in the habitable zone of its star, of which we could study the atmosphere.”

More info

This research study existed in a paper entitled to appear in Astronomy & Astrophysics.

Reference: “A warm terrestrial planet with half the mass of Venus transiting a nearby star” 5 August 2021, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202140728

The group is made up of Olivier D. S. Demangeon (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Portugal [IA/UPorto], Centro de Astrofísica da Universidade do Porto, Portugal [CAUP] and Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal [FCUP]), M. R. Zapatero Osorio (Centro de Astrobiología, Madrid, Spain [CSIC-INTA]), Y. Alibert (Physics Institute, University of Bern, Switzerland [Bern]), S. C. C. Barros (IA/UPorto, CAUP and FCUP), V. Adibekyan (IA/UPorto, CAUP and FCUP), H. M. Tabernero (IA/UPorto and CAUP), A. Antoniadis-Karnavas (IA/UPorto & FCUP), J. D. Camacho (IA/UPorto & FCUP), A. Suárez Mascareño (Instituto de Astrofísica de Canarias, Tenerife, Spain [IAC] and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain [ULL]), M. Oshagh (IAC/ULL), G. Micela (INAF – Osservatorio Astronomico di Palermo, Palermo, Italy), S. G. Sousa (IA/UPortol & CAUP), C. Lovis (Observatoire de Genève, Université de Genève, Geneva, Switzerland [UNIGE]), F. A. Pepe (UNIGE), R. Rebolo (IAC/ULL & Consejo Superior de Investigaciones Científicas, Spain), S. Cristiani (INAF – Osservatorio Astronomico di Trieste, Italy [INAF Trieste]), N. C. Santos (IA/UPorto, CAUP and FCUP), R. Allart (Department of Physics and Institute for Research on Exoplanets, Université de Montréal, Canada and UNIGE), C. Allende Prieto (IAC/ULL), D. Bossini (IA/UPorto), F. Bouchy (UNIGE), A. Cabral (Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Portugal [IA/FCUL] and Departamento de Física da Faculdade de Ciências da Universidade de Lisboa, 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 (Bern), J. I. González Hernández (IAC/ULL), B. Lavie (UNIGE), J. Lillo-Box (CSIC-INTA), G. Lo Curto (European Southern Observatory, Garching bei München, Germany [ESO]), C. J. A. P. Martins (IA/UPorto and CAUP), D. Mégevand (UNIGE), A. Mehner (ESO-Chile), P. Molaro (INAF Trieste and IFPU), N. J. 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 Torino), and S. Udry (UNIGE).

ESO is the primary intergovernmental astronomy company in Europe and the world’s most efficient ground-based huge observatory without a doubt. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland, and the United Kingdom, in addition to the host state of Chile and with Australia as a Strategic Partner. ESO performs an enthusiastic program concentrated on the style, building, and operation of effective ground-based observing centers allowing astronomers to make essential clinical discoveries. ESO likewise plays a leading function in promoting and arranging cooperation in huge research study. ESO runs 3 special first-rate observing websites in Chile: La Silla, Paranal, and Chajnantor. At Paranal, ESO runs the Very Large Telescope and its world-leading Very Large Telescope Interferometer along with 2 study telescopes, VISTA operating in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and run the Cherenkov Telescope Array South, the world’s biggest and most delicate gamma-ray observatory. ESO is likewise a significant partner in 2 centers on Chajnantor, PEAK, and ALMA, the biggest huge task around. And on Cerro Armazones, near to Paranal, ESO is constructing the 39-meter Extremely Large Telescope, the ELT, which will end up being “the world’s biggest eye on the sky.”

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