This image highlights the main features of TOI 451, a three-planet system located 400 light-years away in the constellation Eridanus. Credit: NASA Goddard Space Flight Center
Using observations from NASA’s Transop Exoplanet Survey Satellite (TESS), an international team of astronauts has discovered a trio of hotter worlds larger than Earth orbiting a much younger version of our sun called TOI 451. The system resides in the recently discovered Pisces-Eridanus stream. , a collection of stars less than 3% of the age of our solar system that stretches over a third of the sky.
The planets were found in TESS images taken between October and December 2018. Follow-up studies on TOI 451 and its planets included observations made in 2019 and 2020 using NASA’s now-retired Space Spitzer Telescope, as well as many ground-based facilities. Archived infrared data from NASA’s Near-Earth In-Field Intelligence Explorer (NEOWISE) satellite – collected between 2009 and 2011 under the previous moniker, WISE – suggest that the ‘keep a cool disc of rocky dust and debris. Other observations indicate that two distant stellar companions at TOI 451 appear to orbit each other far beyond the planets.
“This system examines many boxes for astronauts,” said Elisabeth Newton, associate professor of physics and astronomy at Dartmouth College in Hanover, New Hampshire, who led the research. “It is only 120 million years old and just 400 light-years away, allowing detailed views of this young planetary system. And with three planets between two and four times the size of the Earth, they make very promising targets for testing theories about how a planet’s atmosphere grows. ”
A paper reporting the findings was published on January 14 in the Astronomical Journal and is available online.
Stellar currents form when the gravity of our Milky Way galaxy separates from dwarf stars or galaxies. The individual stars move outward across the original orbit of the brace, creating a long group that gradually disperses.
In 2019, a team led by Stefan Meingast at the University of Vienna used data from the European Space Agency’s Gaia mission to determine the flow of Pisces-Eridanus, named for the constellations containing the largest stars. Stretching over 14 constellations, the stream is about 1,300 light years old. However, the age initially determined for the flow was much older than we now think.
Later in 2019, researchers led by Jason Curtis at Columbia University in New York City analyzed TESS data for dozens of stream members. Younger stars spin faster than their older peers do, and they usually have prominent star spots – darker, colder regions like sun spots. As these spots rotate in and out of our view, they can produce small changes in star brightness that can be measured by TESS.
The TESS measurements revealed very large evidence of star positions and rapid circulation among the stars of the stream. Based on this result, Curtis and his colleagues discovered that the stream was only 120 million years old – similar to the famous Pleiades group and eight times younger than previous estimates. The mass, adolescence and proximity of the Pisces-Eridanus stream make it an interesting basic laboratory for studying the shape and evolution of stars and planets.
“Thanks to TESS coverage almost entirely, measurements that could support a study for planets orbiting members of this orbit were already available when the eclipse was identified, ”Said Jessie Christiansen, co-author of the paper and associate lead scientist at NASA’s Exoplanet Archive, a resource for exploring the world outside our solar system managed by Caltech in Pasadena, California. “TESS data will continue to allow us to push the boundaries of what we know about exoplanets and their systems for years to come. ”
The young star TOI 451, better known to astronomers as CD-38 1467, lies about 400 light-years away in the constellation Eridanus. We have 95% of the mass of the sun, but it is 12% smaller, slightly colder, and emits 35% less energy. TOI 451 orbits every 5.1 days, which is more than five times faster than the sun.
TESS sees a new world by looking for transmissions, the constant small discounts that occur when a planet passes in front of the star from our perspective. Motions from the three planets are shown in the TESS data. Newton’s team obtained measurements from Spitzer that supported TESS’s decisions and helped rule out other possible interpretations. Further follow-up comments came from the Las Cumbres Observatory – a global telescope network with headquarters in Goleta, California – and the Perth Exoplanet Study Telescope in Australia.
Even the most distant planet at TOI 451 moves three times closer than Mercury ever comes to the Sun, so all of these worlds are so hot and unstable to life as it is. we know it. Temperature estimates range from about 2,200 degrees Fahrenheit (1,200 degrees Celsius) for the innermost planet to around 840 F (450 C) for the outermost.
TOI 451 ba moves around every 1.9 days, about 1.9 times the size of the Earth, and its estimated mass ranges from two to 12 times the Earth. The next outer planet, TOI 451 c, completes orbit every 9.2 days, about three times larger than Earth, and holds between three and 16 times the mass of Earth. The world’s longest and largest, TOI 451 d, orbits the star every 16 days, four times the size of our planet, and weighs between four and 19 Earth’s masses.
Astronomers expect planets as large as these to retain much of the atmosphere despite the intense heat from the nearby star. Different theories about how an atmosphere grows with the time a planet’s system reaches the age of TOI 451 predict a wide range of properties. Observing star light passing through the atmosphere of these planets allows this stage of development to be studied and may help to disrupt conventional models.
“By measuring a star’s light entering a planet’s atmosphere at different waves, we can detect its chemical representation and the presence of clouds or high hazards,” said Elisa Quintana, a psychologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “TOI 451 planets offer excellent targets for such studies with Hubble and the upcoming James Webb Space Telescope. ”
Comments from WISE show that the system is remarkably bright in infrared light, which is invisible to the human eye, at 12 and 24 micrometers wavelengths. This suggests the presence of a debris disc, where asteroid-like rocky bodies collide and erode themselves into dust. Although Newton and her team cannot determine the size of the disk, they see it as a loose ring of rock and dust located as far away from the star as Jupiter is from our sun.
The researchers also studied a nearby star that appears about two pixels away from TOI 451 in TESS images. Based on Gaia data, Newton’s team concluded that this star was a companion with a grave connection so far from TOI 451 that its light takes 27 days to get there. In fact, the researchers believe that the companion is likely a binary system of two type M stars, each with about 45% of the mass of the sun and emitting only 2% of its energy.
TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA Ames Research Center in Silicon Valley California; Astrophysics Center Harvard & Smithsonian in Cambridge, Massachusetts; MIT Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatory centers around the world are participating in the mission.
The NASA Jet Dedication Laboratory in Southern California manages NEOWISE for the NASA Science Mission Steering Group in Washington. Thog Ball Aerospace & Technologies Corp. from Boulder, Colorado, the spacecraft. Science data processing takes place at IPAC at Caltech in Pasadena. Caltech manages JPL for NASA.
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Claire Andreoli
NASA Goddard Space Flight Center, Greenbelt, Md.
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