Artist’s rendition of a variety of exoplanets featured in the new NASA TESS-Keck Survey Mass Catalog, the largest homogenous analysis of TESS planets released by any survey thus far. Credit: W. M. Keck Observatory/Adam Makarenko
A collaborative international effort has produced a catalog detailing 126 (120 confirmed, 6 candidates) exoplanets using 
Artist’s rendition of TOI-1798, a planetary system that is home to two planets. The new TESS-Keck Survey Mass Catalog shows the outer planet is a sub-Neptune with an orbital period of eight days; the inner planet is a strange Super-Earth that orbits so close to its star, one year on this alien world lasts only half an Earth day. Credit: W. M. Keck Observatory/Adam Makarenko
“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. “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.”
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 
From Jupiter-sized, to Saturn-sized, Neptune-like, sub-Neptunes, and rocky Earth-like worlds, this artist’s rendition depicts the exoplanets detected by TESS then characterized by W. M. Keck Observatory and Lick Observatory; all are profiled in a newly released catalog as part the TESS-Keck Survey. Credit: W. M. Keck Observatory/Adam Makarenko
“The results that have come from the TESS-Keck Survey represent the single largest contribution to understanding the physical nature and system architectures of new planets TESS has discovered,” said Alex Polanski, a physics and astronomy graduate student at the University of Kansas who is the paper’s lead author. “Catalogs like this help astronomers place individual worlds in context with the rest of the exoplanet population.”
The team also obtained additional radial velocities using the University of California Observatories’ Automated Planet Finder at Lick Observatory.
With all of the RVs combined, they were able to calculate the masses of 120 confirmed planets plus six candidate planets.
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.
Artist’s rendition of TOI-1824, a star system with an exoplanet that’s unusually dense for its size. It is one of the densest sub-Neptunes profiled in the newly-released TESS-Keck Survey catalog. 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. In particular, the study bridges the gap to other systems that have been shown to have somehow survived this fate or are currently in the process of being engulfed.
In another example of extreme worlds, 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. A larger planet would almost certainly accrete a thick envelope of lighter gasses (such as hydrogen and helium) from its nascent gas disk, and thus produce planets more similar to the icy giants or gas giants in our solar system.
Reference: “The TESS-Keck Survey. XX. 15 New TESS Planets and a Uniform RV Analysis of All Survey Targets” by Alex S. Polanski, Jack Lubin, Corey Beard, Joseph M. Akana Murphy, Ryan Rubenzahl, Michelle L. Hill, Ian J. M. Crossfield, Ashley Chontos, Paul Robertson, Howard Isaacson, Stephen R. Kane, David R. Ciardi, Natalie M. Batalha, Courtney Dressing, Benjamin Fulton, Andrew W. Howard, Daniel Huber, Erik A. Petigura, Lauren M. Weiss, Isabel Angelo, Aida Behmard, Sarah Blunt, Casey L. Brinkman, Fei Dai, Paul A. Dalba, Tara Fetherolf, Steven Giacalone, Lea A. Hirsch, Rae Holcomb, Molly R. Kosiarek, Andrew W. Mayo, Mason G. MacDougall, Teo Močnik, Daria Pidhorodetska, Malena Rice, Lee J. Rosenthal, Nicholas Scarsdale, Emma V. Turtelboom, Dakotah Tyler, Judah Van Zandt, Samuel W. Yee, David R. Coria, Shannon D. Dulz, Joel D. Hartman, Aaron Householder, Sarah Lange, Andrew Langford, Emma M. Louden, Jared C. Siegel, Emily A. Gilbert, Erica J. Gonzales, Joshua E. Schlieder, Andrew W. Boyle, Jessie L. Christiansen, Catherine A. Clark, Rachel B. Fernandes, Michael B. Lund, Arjun B. Savel, Holden Gill, Charles Beichman, Rachel Matson, Elisabeth C. Matthews, E. Furlan, Steve B. Howell, Nicholas J. Scott, Mark E. Everett, John H. Livingston, Irina O. Ershova, Dmitry V. Cheryasov, Boris Safonov, Jorge Lillo-Box, David Barrado and María Morales-Calderón, 23 May 2024, The Astrophysical Journal Supplement Series.
DOI: 10.3847/1538-4365/ad4484
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