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large group of exoplanets
The catalog features exoplanets ranging from Jupiter-sized, to Neptune-like and rocky Earth-like worlds (Image credit: W. M. Keck Observatory/Adam Makarenko)

An international scientific team, with major contributions by astronomers at the University of Hawaiʻi Institute for Astronomy (IfA), has announced a new catalog of 120 confirmed and six new candidate exoplanets. They were discovered using NASA’s Transiting Exoplanet Survey Satellite (TESS), in collaboration with the W. M. Keck Observatory on Maunakea, Hawaiʻi.

With the TESS-Keck Survey’s Mass Catalog, astronomers now have a new database to explore the latest worlds found by TESS, paving the way for them to study their properties and environments in finer detail, particularly those planets that could harbor life as we know it.

planetary system illustration
Artist’s rendition of TOI-1798, a planetary system that is home to two planets. (Credit: W. M. Keck Observatory/Adam Makarenko)

The latest installment of the survey, in which UH is a major partner, provides thousands of radial velocity (RV) observations—a measurement of the reflex motion of a star due to an orbiting planet’s gravity. These observations reveal a fascinating mix of planet types beyond our solar system, from rare worlds with extreme environments to ones that could possibly support life.

The study is published in The Astrophysical Journal Supplement.

“The TESS-Keck Survey demonstrates the very important role of ground-based observations for advancing our understanding of the Universe and in this case, planets outside our system”, said Dan Huber, an associate astronomer at IfA who co-authored the paper and is a co-principal investigator of the TESS-Keck Survey.

Ground-based insights

Huber and fellow IfA astronomer Fei Dai, and IfA alumna Ashley Chontos, partnered with a global team of astronomers to develop the new exoplanet catalog. More than half of the measurements were taken over the course of 301 observing nights using Keck Observatory’s planet-hunting spectrometer instrument.

Exploring alien worlds

The TESS-Keck Survey revealed a vast diversity of exotic worlds. UH astronomers honed in on planets orbiting so-called subgiant stars—future versions of the Sun. In a companion paper, Chontos, a former IfA graduate student who is now a postdoctoral fellow at Princeton, led the largest homogeneous study of such planets to date.

planetary system illustration
Artist’s rendition of TOI-1824, a star system with an exoplanet that’s unusually dense for its size. (Credit: W. M. Keck Observatory/Adam Makarenko)

“The Sun will eventually expand into a giant star after it has fused all hydrogen in its core,” said Chontos. “We have some ideas for what might happen to the planets in our solar system but by directly observing these more evolved systems, we can begin to put together the puzzle pieces and tie the observations to the theory.”

The results may help predict the future fate of our planet when the Sun swells up and possibly engulfs the Earth.

Dai and Caltech student Ryan Rubenzahl discovered the largest rocky planet ever found (TOI-1347 b). Their work suggests that planets with rocky surfaces like Earth likely cannot have masses much more than 10 times that of Earth.

For more go to Institute for Astronomy’s website.

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