Newly-found planets on the edge of destruction

Date:
January 13, 2022
Source:
W. M. Keck Observatory
Summary:
Astronomers have found three Jupiter-like exoplanets that are
dangerously close to being 'swallowed up' by their host stars. The
discovery gives new insight into how planetary systems evolve over
time, helping to reveal the fate of solar systems like our own.



FULL STORY ========================================================================== Three newly-discovered planets have been orbiting dangerously close to
stars nearing the end of their lives.


==========================================================================
Out of the thousands of extrasolar planets found so far, these three
gas giant planets first detected by the NASA TESS (Transiting Exoplanet
Survey Satellite) Mission, have some of the shortest-period orbits
around subgiant or giant stars. One of the planets, TOI-2337b, will be
consumed by its host star in less than 1 million years, sooner than any
other currently known planet.

"These discoveries are crucial to understanding a new frontier in
exoplanet studies: how planetary systems evolve over time," explained lead author Samuel Grunblatt, a postdoctoral fellow at the American Museum of Natural History and the Flatiron Institute in New York City. Grunblatt,
who earned his PhD from the University of Hawai?i Institute for Astronomy
(UH IfA), added that "these observations offer new windows into planets
nearing the end of their lives, before their host stars swallow them up." Grunblatt announced the discovery and confirmation of these planets --
TOI- 2337b, TOI-4329b, and TOI-2669b -- at an American Astronomical
Society press conference today; the study has been accepted for
publication in the Astronomical Journal.

The researchers estimate that the planets have masses between 0.5 and
1.7 times Jupiter's mass, and sizes that range from slightly smaller to
more than 1.6 times the size of Jupiter. They also span a wide range
of densities, from styrofoam-like to three times denser than water,
implying a wide variety of origins.

These three planets are believed to be just the tip of the iceberg. "We
expect to find tens to hundreds of these evolved transiting planet systems
with TESS, providing new details on how planets interact with each other, inflate, and migrate around stars, including those like our Sun," said
Nick Saunders, a graduate student at UH IfA and co-author of the study.



==========================================================================
The planets were first found in NASA TESS Mission full-frame image data
taken in 2018 and 2019. Grunblatt and his collaborators identified the candidate planets in TESS data, and then used W. M. Keck Observatory's High-Resolution Echelle Spectrometer (HIRES) on Maunakea, Hawai?i to
confirm the existence of the three planets.

"The Keck observations of these planetary systems are critical to
understanding their origins, helping reveal the fate of solar systems like
our own," said UH IfA Astronomer Daniel Huber, who co-authored the study.

Current models of planet dynamics suggest that planets should spiral in
toward their host stars as the stars evolve over time, particularly in
the last 10 percent of the star's lifetime. This process also heats the planets, potentially causing their atmospheres to inflate. However, this stellar evolution will also cause the orbits of planets around the host
star to come closer to one another, increasing the likelihood that some
of them will collide, or even destabilize the entire planetary system.

The wide variety of planet densities found in the study suggests that
these planetary systems have been shaped through chaotic planet-to-planet interactions. This could also have resulted in unpredictable heating
rates and timescales for these planets, giving them the wide range in
densities we observe today.

Future observations of one of these systems, TOI-4329, with the recently- launched James Webb Space Telescope could reveal evidence for water or
carbon dioxide in the planet's atmosphere. If these molecules are seen,
the data would provide constraints on where these planets formed, and
what sort of interactions had to occur to produce the planetary orbits
we see today.

Continued monitoring of these systems with the NASA TESS telescope
will constrain the rate at which these planets are spiraling into their
host stars.

So far, no clear signal of orbital decay has been observed in any of the systems, but a longer baseline of observations with the TESS Extended
Missions will provide much tighter constraints on planet in-spiral than
are currently possible, revealing how strongly planetary systems are
affected by stellar evolution.

The team hopes that this 'planetary archeology' will help us to
understand the past, present, and future of planetary systems,
moving us one step closer to answering the question: "Are we alone?" ========================================================================== Story Source: Materials provided by W._M._Keck_Observatory. Note:
Content may be edited for style and length.


========================================================================== Related Multimedia:
*
An_artist's_rendition_of_what_a_planetary_system_similar_to_TOI-2337b,
TOI-4329b,_and_TOI-2669b_might_look_like,_where_a_hot_Jupiter-like
exoplanet_orbits_an_evolved,_dying_star.

========================================================================== Journal Reference:
1. Nicholas Saunders, Samuel K. Grunblatt, Meng Sun, Ashley Chontos,
Melinda
Soares-Furtado, Nora Eisner, Filipe Pereira, Thaddeus Komacek,
Daniel Huber, Karen Collins, Gavin Wang, Chris Stockdale,
Samuel N. Quinn, Rene Tronsgaard, George Zhou, Grzegorz Nowak,
Hans J. Deeg, David R. Ciardi, Andrew Boyle, Malena Rice, Fei Dai,
Sarah Blunt, Judah Van Zandt, Corey Beard, Joseph M. Akana Murphy,
Paul A. Dalba, Jack Lubin, Alex Polanski, Casey Lynn Brinkman,
Andrew W. Howard, Lars A. Buchhave, Ruth Angus, George R. Ricker,
Jon M. Jenkins, Bill Wohler, Robert F. Goeke, Alan M.

Levine, Knicole D. Colon, Chelsea X. Huang, Michelle Kunimoto,
Avi Shporer, David W. Latham, Sara Seager, Roland K. Vanderspek,
Joshua N.

Winn. TESS Giants Transiting Giants II: The hottest Jupiters
orbiting evolved stars. The Astronomical Journal, 2022 [abstract] ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220113151415.htm
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