This massive, scorching exoplanet whips around its sun twice a day
This solar system never had much, but they stayed close
Orbiting TOI-561, a star residing in thethick diskof our Milky Way, astronomers spotted three previously-unknown exoplanets. This region, surrounding the brighter, inner disk of stars, contains older stars than those in brighter regions of the Milky Way.
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“Thick disk stars are chemically distinct, with fewer trace heavy elements (and especially less iron) than typical stars of the Milky Way, suggesting they formed early, approximately 10 billion years ago. They also have wandering motions that can lift them out of the galactic plane, providing an epic view of our own spiral galaxy,” TheInstitute for Astronomyat the University of Hawaii reports.
The innermost world, TOI-561 b, is less than 50%larger than Earth, but it contains about three times as much mass as ourhomeworld. Together, this means that this newly-found world has a density about the same as Earth.
This finding was unexpected since the density “should” have been higher. A lower density suggests an ancientexoplanet.
Heavy elements, produced during stellar reactions, were rare in the early Universe. Therefore, the first worlds would have been composed largely of hydrogen and helium (the first two elements produced), resulting in low densities for ancient exoplanets.
“Planet b has a mass and density… consistent with a rocky composition. Its lower-than-average density is consistent with an iron-poor composition, although an Earth-like iron-to-silicates ratio is not ruled out,” researchers describe inThe Astronomical Journal.
The next planet out, TOI-561c, is nearly three times larger than Earth, and orbits its stellar parent once every 11 days, at a distance less than 10% of the distance between the Earth and Sun. It may possess a significant atmosphere.
The furthest-flung of these newly-found exoplanets is TOI-561d, two-and-a-third times larger than Earth, circling once every twenty-five days, sixteen hours. Few details are known about thisplanet, although further studies may reveal details unknown to astronomers today.
TESS, TESS, TESS, TESS me now…
As these worlds passed “in front” of their star as seen from Earth, astronomers saw dips in the amount of light arriving from the star, using theTransiting Exoplanet Survey Satellite (TESS), launched in April 2018.
Follow-up observations conducted at Keck Observatory measured the gravitational wobble in the star produced by the planets, allowing researchers to determine the masses of these three worlds.
The star at the center of this system is number 561 in a database of objects to be studied by TESS (Hence, TOI-561 for “TESS Object of Interest 561”). It is roughly 80%of the mass of the Sun, and 85% as large. Much like our ownSun, it is classified as a G-type star, still fusing hydrogen into helium, producing energy.
There is also evidence for two additional worlds within the system, in addition to this hat trick of planetary discovery. The massive TOI-561e could have about six times the mass of Earth, orbiting its sun once every 77 days. The other, TOI-561f, is thought to contain between two and five times as much mass as Earth, circling the central star every 16 days.
There are now more than 4,400 exoplanets known to astronomers. And the innermost planet of the TOI-561 system appears to be traveling as fast as new discoveries aboutalien worlds.
This article was originally published onThe Cosmic CompanionbyJames Maynard, founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat. You can read this original piecehere.
Astronomy News with The Cosmic Companionis also available as a weekly podcast, carried on all major podcast providers. Tune in every Tuesday for updates on the latest astronomy news, and interviews with astronomers and other researchers working to uncover the nature of the Universe.
Story byThe Cosmic Companion
Exploring the wonders of the Cosmos, one mystery at a time.Exploring the wonders of the Cosmos, one mystery at a time.
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