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Exotic worlds: TESS unveils 126 new exoplanets

An international team of scientists, with significant contributions from the University of Hawaii Institute for Astronomy (IfA), has unveiled a new catalog of 120 confirmed and six candidate exoplanets.

Telescopes involved in the discovery

These celestial discoveries were made using NASA’s Transiting Exoplanet Survey Satellite (TESS) and the W. M. Keck Observatory on Maunakea, Hawaii.

Transiting Exoplanet Survey Satellite (TESS)

NASA’s Transiting Exoplanet Survey Satellite (TESS) was launched in April 2018. Its primary mission is to search for exoplanets – planets outside our solar system. TESS uses the transit method to detect these planets.

This method involves observing the slight dimming of a star’s light when a planet passes in front of it. TESS monitors large swaths of the sky, focusing on bright, nearby stars. This approach allows TESS to discover a diverse array of exoplanets, from Earth-sized rocky worlds to large gas giants.

W. M. Keck Observatory

The W. M. Keck Observatory is home to two of the world’s largest optical and infrared telescopes. Each telescope has a 10-meter mirror, which provides exceptional sensitivity and resolution. Established in 1993, the observatory has contributed to numerous discoveries in astronomy.

The high elevation and stable atmospheric conditions on Maunakea make it an ideal location for observing the universe. Keck Observatory plays a crucial role in follow-up observations of exoplanets discovered by TESS.

By measuring the radial velocities of stars, Keck helps determine the masses of these planets, providing vital information about their composition and potential habitability. Together, TESS and Keck Observatory form a powerful partnership in the search for and study of exoplanets.

Detailed database for studying exoplanets

The TESS-Keck Survey’s Mass Catalog offers astronomers a detailed database to study the latest worlds found by TESS.

This new resource paves the way for in-depth exploration of these exoplanets’ properties and environments, especially those that might harbor life.

The University of Hawaii (UH) played a major role in this survey, which includes thousands of radial velocity (RV) observations.

These observations measure a star’s reflex motion caused by an orbiting planet’s gravity, revealing a diverse range of planet types beyond our solar system, from extreme environments to potentially habitable worlds.

Ground-based observations

“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, co-author of the paper, and co-principal investigator of the TESS-Keck Survey.

“Space telescopes like TESS can tell us about the sizes of planets, but follow-up observations such as those obtained with Keck provide mass measurements that are required to learn about what these planets are made of.”

Huber, along with IfA astronomer Fei Dai and IfA alumna Ashley Chontos, collaborated with a global team to develop the new exoplanet catalog.

This effort involved analyzing 9,204 RV measurements, with over half taken during 301 observing nights using Keck Observatory’s planet-hunting spectrometer.

The team used the University of California Observatories’ Automated Planet Finder at Lick Observatory for additional radial velocities. Combined, these measurements allowed the calculation of masses for 120 confirmed and six candidate exoplanets.

Detailed database for studying exoplanets

The TESS-Keck Survey unveiled a vast diversity of exotic worlds. UH astronomers focused on planets orbiting subgiant stars – future versions of the Sun.

“The Sun will eventually expand into a giant star after it has fused all hydrogen in its core,” explained Chontos, now a postdoctoral fellow at Princeton.

“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 findings could help predict the fate of our planet when the Sun eventually swells and possibly engulfs the Earth.

By studying these evolved systems, researchers can better understand the processes that allow some exoplanets to survive this stage or remain in the process of being engulfed by their expanding stars.

Discovering extreme worlds

In another notable discovery, Dai and Caltech student Ryan Rubenzahl found the largest rocky planet ever recorded (TOI-1347 b).

The research suggests that rocky planets like Earth cannot have masses much more than 10 times that of Earth. Larger planets would likely accrete thick envelopes of lighter gases, becoming more similar to icy or gas giants in our solar system.

The TESS-Keck Survey’s discoveries highlight the critical role of combining space-based observations with ground-based follow-up.

This approach not only enhances our understanding of exoplanets but also provides insights into the potential for life beyond Earth.


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