A new catalog of 126 extrasolar worlds contains a plethora of newly discovered planets – some extreme and exotic in nature, but others could potentially support life as we know it.
The mix of planets in the catalog is further evidence of the vast and wild variety of worlds beyond our cosmic backyard; it even shows that our solar system might be a bit boring. But despite how different these planets are from Earth and its neighbors, they may still help us better understand why our planetary system looks the way it does, and thus reveal our place in the wider cosmos.
The catalog of extrasolar planets, or “exoplanets,” was created using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) in collaboration with the WM Keck Observatory in Hawaii.
“With this information, we can begin to answer questions about where our solar system fits in the grand tapestry of other planetary systems,” Stephen Kane, TESS-Keck Survey Principal Investigator and astrophysicist at the University of California, Riverside, said in a study. rack.
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The new TESS-Keck Survey of 126 exoplanets really stands out from previous exoplanet surveys because it contains complex data on most of the planets involved.
“Relatively few of the previously known exoplanets have a measurement of both mass and radius,” Kane added. “The combination of these measurements tells us what the planets might be made of and how they formed.”
“Seeing red” to measure the mass of exoplanets
The catalog was compiled over the course of three years, with the team using 13,000 measurements of small ‘wobbles’ that planets cause as they orbit their stars and exert a small gravitational pull on them. This jerk causes a star to move slightly away from Earth and then slightly towards Earth.
When stars are pulled away slightly, it stretches the wavelengths of light they emit, causing them to move towards the ‘red end’ of the electromagnetic spectrum. When stars move toward Earth, the wavelength of light they omit is slightly compressed, making it “bluer.”
The exploitation of redshift and blueshift in this way by astronomers is called the ‘radial velocity method’. Because the strength of gravity a planet exerts on a star is proportional to its mass, this is a good way to determine mass. The radial velocity method thus allowed Kane and his team to determine the masses of 120 confirmed exoplanets and six exoplanet candidates.
“These radial velocity measurements allow astronomers to detect and learn the properties of these exoplanetary systems,” said Ian Crossfield, astrophysicist and co-author of the University of Kansas catalog. ‘If we see a star regularly wobble back and forth, we can infer the presence of a planet in orbit and measure the planet’s mass.’
Excitingly, some of the 126 exoplanets in the TESS-Keck Survey could deepen astronomers’ understanding of how a range of different planets form and evolve.
A strange super-Earth, a sub-Saturn and more!
Two of the new planets in the TESS-Keck Survey orbit a Sun-like star called TOI-1386, which is about 479 light-years away.
One of these exoplanets has a mass and width that puts it somewhere between the gas giant Saturn and the smaller, less massive ice giant Neptune. That makes this planet, called TOI-1386 b, a ‘sub-Saturn’ planet and a fascinating target for planetary scientists.
“There is an ongoing debate about whether planets below Saturn are really rare, or whether we are just bad at finding planets like this,” discoverer and UCR graduate Michelle Hill said in the statement. “So this planet, TOI-1386 b, is an important addition to this demographic of planets.”
At a distance from its parent star, equivalent to about 17% of the distance between Earth and the Sun, TOI-1386 b takes just 26 Earth days to complete an orbit.
The newly discovered nearest neighbor is a bit quieter. TOI-1386 c is a puffy gas giant about as wide as Jupiter, but with only 30% of the mass of the largest planet in the Solar System. It is located about 70% of the Earth-Sun distance from its parent star, and has a year that lasts about 228 Earth days.
Another fascinating world among this group of exoplanets is about half the size of Neptune, with more than ten times the mass of Earth, orbiting TOI-1437 (also known as HD 154840) and located at about 337,000 light years away.
The sub-Neptunian planet, designated TOI-1437 b, orbits its star at about 14% of the Earth-Sun distance, and has a year lasting about 19 Earth days. TOI-1437 b, discovered by TESS via the small dip in light it causes as it crosses the leading edge of its star, is one of the few sub-Neptunes known to pass through its star which has a well-defined mass and has a radius.
TOI-1437 b also highlights a curious absence in our cosmic backyard.
“Planets smaller than Neptune but larger than Earth are the most common worlds in our Milky Way, yet they are missing from our own solar system,” discoverer and UCR graduate Daria Pidhorodetska said in the statement. “Every time a new one is discovered, we are reminded how diverse our universe is and that our existence in the cosmos may be more unique than we can understand.”
Another interesting exoplanet described for the first time in this new catalog is TOI-1798 c, a super-Earth that orbits so close to an orange dwarf star that its year is only about 12 Earth hours.
“A year on this planet is less than half a day on Earth,” lead author Alex Polanski, a graduate student in physics and astronomy at the University of Kansas, said in the statement. “Because of their proximity to their host stars, planets like these are also ultra-hot and receive more than 3,000 times the radiation that Earth receives from the Sun.”
This makes the planetary system TOI-1798, which also hosts a planet south of Neptune that completes an orbit in about eight days, one of the few galaxies known to have an inner ultra-short-period super-terrestrial planet (USP). ) track.
“Although most planets we know today orbit their star faster than Mercury orbits the Sun, USPs take this to the extreme,” Pidhorodetska added. “TOI-1798 c orbits its star so quickly that a year on this planet is less than half a day on Earth. Due to their proximity to their parent star, USPs are also ultra-hot – receiving more than 3,000 times the radiation that Earth receives. Existing in this extreme environment means that this planet has likely lost any atmosphere it initially formed.”
The publication of the TESS-Keck Survey mass catalog means astronomers now have a way to deeply investigate the work of TESS, which launched in April 2018, and measure how it has changed our understanding of exoplanets.
With thousands of planets from the TESS mission alone yet to be confirmed, publications of exoplanet catalogs such as this will become increasingly common.
“Are we unusual? The jury is still out on that, but our new mass catalog represents an important step toward answering that question,” Kane said.
The exoplanets are described in Thursday’s edition (May 23) of The Astrophysical Journal Supplement.