International planet hunters unveil vast catalog of strange worlds

Although thousands of planets have been discovered around other stars, relatively little is known about them. A NASA catalog showcasing 126 newly discovered exotic worlds includes detailed measurements allowing comparisons with our own solar system.

The catalog details a fascinating mix of planet types beyond our solar system, from rare worlds with extreme environments to those that could possibly support life.

The planets were analyzed by a large international team of scientists using NASA’s Transiting Exoplanet Survey Satellite (TESS) in collaboration with the WM Keck Observatory in Maunakea, Hawai’i. They are described in today’s edition of The Astrophysical Journal Supplement Series.

“Relatively few previously known exoplanets have a measurement of both mass and radius. The combination of these measurements tells us what planets might be made of and how they formed,” said Stephen Kane, an astrophysicist at UC Riverside and principal investigator of the study. the TESS-Keck survey.

“With this information, we can begin to answer questions about where our solar system fits into the grand tapestry of other planetary systems,” Kane said.

The research team spent three years developing the catalog. They analyzed more than 13,000 radial velocity (RV) measurements to calculate the masses of 120 confirmed planets, as well as six candidate planets, spread across the northern sky.

Even though the planets themselves are not visible, they have a visible effect. As they orbit, planets pull on their host stars, causing them to “wobble.” As the star moves toward a telescope, its visible light becomes slightly bluer; as it moves away from us, the light becomes slightly redder.

This is very similar to the behavior of sound. Due to the Doppler effect, a fire truck’s siren becomes louder as it gets closer and sounds deeper as it gets farther away.

“These VR measurements allow astronomers to detect and learn the properties of these exoplanetary systems. When we see a star regularly oscillate back and forth, we can infer the presence of an orbiting planet and measure the mass of the planet,” said Ian Crossfield of the University of Kansas. astrophysicist and co-author of the catalog.

Several planets from the TESS-Keck survey stand out as touchstones for deepening astronomers’ understanding of the diverse ways planets form and evolve.

A related investigative paper published in The astronomical journal and authored by UCR graduate student Michelle Hill, announces the discovery of two new planets orbiting a star like our sun. The first is a “sub-Saturn” planet whose mass and radius are between those of Neptune and Saturn.

“There is an ongoing debate about whether sub-Saturn planets are truly rare, or whether we are simply unable to find such planets,” Hill said. “So this planet, TOI-1386 b, is an important addition to this planetary demographic.”

TOI-1386 b takes only 26 days to orbit its star. Meanwhile, its neighbor, a planet with a mass close to that of Saturn, takes 227 days to orbit the same star.

Another investigative paper, written by UCR graduate student Daria Pidhorodetska and available on the arXiv preprint server, describes a planet about half the size of Neptune that takes just 19 days to orbit its star, which is very similar to our sun.

“Planets smaller than Neptune but larger than Earth are the most common worlds in our galaxy, and yet they are absent from our own solar system. Every time a new one is discovered, we are reminded how important our universe is diverse and that our existence in the cosmos is perhaps more unique than we can understand,” Pidhorodetska said.

There are many stars that are not like our sun. If scientists want to make meaningful comparisons between our world and others, they need to find stars of similar age, size and mass. “Then we can make apples-to-apples comparisons,” Kane said. “That’s the exciting part of the articles that Michelle and Daria produce, because they make that possible.”

Planets with even more extreme and ultra-short orbits around stars unlike our sun are also detailed in the catalog. One of them is so close to its orange dwarf star that it completes its orbit in less than 12 hours.

“TOI-1798 c orbits its star so quickly that a year on this planet lasts less than half a day on Earth. Because of their proximity to their host stars, planets like this are also ultra hot , receiving more than 3,000 times the radiation that Earth receives from the sun,” said Alex Polanski, a graduate student in physics and astronomy at the University of Kansas and lead author of the catalog article.

“Existing in this extreme environment means that this planet has likely lost all of the atmosphere that it originally formed,” Polanski said.

Ultimately, this new catalog represents a major contribution to NASA’s TESS mission and to answering the question of whether other planets are capable of supporting life as we know it.

“Are we unusual? The jury is still out on that question, but our new mass catalog represents a major step toward answering that question,” Kane said.