At just 50 light-years away from Earth, there are about 1,560 stars, probably orbited by several thousand planets. About one thousand of these extrasolar planets – so-called exoplanets – can be rocky and have an earth-like composition. Some can even accommodate life. Over 99 percent of these alien worlds are still undiscovered – but that will change soon.
NASA's new Exoplanet Hunter Space Telescope TESS is looking for potentially habitable planets near our solar system. TESS – orbiting Earth every 13.7 days – and ground-based telescopes are ready to find hundreds of planets over the next few years. This could change the astronomers' understanding of alien worlds around us and provide goals that can be scanned for signatures of life with next-generation telescopes.
In just over a year, TESS has identified more than 1
These are exciting times for astronomers and especially for those of us exploring exoplanets. We are members of the planetary hunting project EDEN, which also supports the work of TESS. We use telescopes on the ground and in space to search for exoplanets to understand their properties and their potential for housing life.
Undiscovered Worlds Around Us
Worlds around us are waiting to be discovered. Take, for example, Proxima Centauri, a modest, faint red star invisible without a telescope. It is one of over a hundred billion such stars in our galaxy, unobtrusive, except for its status as our nearest neighbor. Orbiting Proxima is a fascinating but mysterious world called Proxmia b that was discovered in 2016.
Scientists know surprisingly little about Proxima b. Astronomers call the first planet "b" discovered in a system. This planet has never been seen with human eyes or with a telescope. However, we know that it exists because of its attraction to the star of hosts, causing the star to wobble very slightly. This slight wobble was found in measurements taken by a large international group of astronomers based on data from multiple ground-based telescopes. It is very likely that Proxima b has a rocky composition that resembles that of Earth, but has a higher mass. It receives about the same amount of heat as the earth from the sun.
And that's what makes this planet so exciting: it's in the "habitable" zone and may have properties similar to Earth's, like a surface or liquid of water and – who knows? – maybe even an atmosphere with telltale chemical signs of life.
The NASA TESS mission started in April 2018 to look for other planets the size of the Earth, but with a different method. TESS looks for rare dimming events that occur when planets pass in front of their host stars and block starlight. These transit events not only indicate the presence of the planets, but also their size and orbit.
The search for a new exoplanet in transit is a great challenge for astronomers like us, because unlike those found by the star's wobbly movements, worlds observed during transit can be examined for their density and atmospheric composition to determine.
Red Dwarf Suns
The most exciting exoplanets for us are the smallest that TESS can detect as they circle little stars called red dwarfs – stars with masses smaller than half the mass of our Sun. are.
] Each of these systems is unique. For example, LP 791-18 is a red dwarf star that is 86 light-years from Earth and has found two worlds around the TESS. The first is a "Super Earth," a planet larger than Earth, but probably still largely rocky, and the second is a "Mini Neptune," a planet smaller than Neptune but rich in gas and ice cream. None of these planets has a counterpart to our solar system.
One of Astronomers 'recent big-scale astronomers' favorites is LHS 3884b, a scorching "hot earth" orbiting their sun so fast that you can celebrate it birthday every 11 hours.
No earth-like worlds yet
But how earth-like are earth-sized planets? The promise to find nearby worlds for detailed studies is already paying off. A team of astronomers observed the hot super earth LHS 3884b with the Hubble Space Telescope and found that the planet is a terrible vacation destination with no atmosphere. It is just a bare rock with temperatures in excess of 700 ° C at midday to near zero at midnight.
The TESS mission was originally funded for two years. However, the spacecraft is in excellent shape, and NASA has recently extended the mission to 2022, doubling the time that TESS needs to search nearby, bright stars for transits C (4900 F) – still becomes due to its extreme powerlessness to be a challenge. Because ultracool dwarfs have the best opportunity to find and investigate exoplanets with Earth-like sizes and temperatures, other focused planet searches begin where TESS ends.
The Worlds TESS Can not Find
In May 2016, a Belgian-led group announced the discovery of a planetary system around the ultra-cool dwarf they christened TRAPPIST-1. The discovery of the seven exoplanets the size of a transiting earth in the TRAPPIST-1 system was groundbreaking.
It also showed how small telescopes – compared to the mighty giants of our time – can still make transformative discoveries. With patience and perseverance, the TRAPPIST telescope in the vicinity of faint red dwarf stars from its high mountain bass in the Atacama Desert searched for small, telltale intrusions into their brightness. Finally, transits were found in the data for the red dwarf TRAPPIST-1, which, although only 41 light-years away, is too weak for the four 10-cm lenses of TESS. His earth-sized worlds would have gone undetected if the larger telescope of the TRAPPIST team had not found them.
Two projects have improved the game in the search for Exo Earth candidates for nearby Red Dwarfs. The SPECULOOS team installed four robotic telescopes – also in the Atacama Desert – and one in the northern hemisphere. Our Exoearth Discovery and Exploration Network – Project EDEN – Uses Nine Telescopes in Arizona, Italy, Spain, and Taiwan to Monitor Red Dwarf Stars Continually TESS is hard to investigate, including some planets the size of Earth closest to us ,
The Decade The New World
The next decade is likely to be remembered as the time when we open our eyes to the incredible diversity of other worlds. TESS is expected to find between 10,000 and 15,000 exoplanet candidates by 2025. By 2030, another 20,000 to 35,000 planets are expected for the GAIA and PLATO missions of the European Space Agency. GAIA will search for stellar shaking motions caused by planets, while PLATO, like TESS, will search for planetary transits.
But even among the thousands of planets soon to be found, the exoplanets closest to our solar system will continue to be special. Many of these worlds can be studied down to the smallest detail – including the search for signs of life. Discoveries of the nearest worlds are also important steps in humanity's progress in exploring the universe in which we live. After mapping our own planet and then the solar system, we now turn to the nearby planetary systems. Perhaps one day Proxima b or another world that astronomers have not found nearby will be the target for interstellar probes such as Project Starshot or even starships with crew. But first we have to put these worlds on the map.
This article was republished from The Conversation by Daniel Apai, Associate Professor of Astronomy and Planetary Sciences at the University of Arizona and Benjamin Rackham, 51 Pegasi b Postdoctoral Fellow at the Massachusetts Institute of Technology under a Creative Commons license. Read the original article.