UCLA astronomers have identified 366 new exoplanets, thanks in large part to
an algorithm developed by a UCLA postdoctoral scholar. Among their most
noteworthy findings is a planetary system that comprises a star and at least
two gas giant planets, each roughly the size of Saturn and located unusually
close to one another.
The discoveries are described in a paper published today in the Astronomical
Journal.
The term "exoplanets" is used to describe planets outside of our own solar
system. The exoplanets that have been identified by astronomers number fewer
than 5,000 in all, so the identification of hundreds of new ones is a
significant advance. Studying such a large new group of bodies could help
scientists better understand how planets form and orbits evolve, and it
could provide new insights about how unusual our solar system is.
"Discovering hundreds of new exoplanets is a significant accomplishment by
itself, but what sets this work apart is how it will illuminate features of
the exoplanet population as a whole," said Erik Petigura, a UCLA astronomy
professor and co-author of the research.
The paper's lead author is Jon Zink, who earned his doctorate from UCLA in
June and is currently a UCLA postdoctoral scholar. He and Petigura, as well
as an international team of astronomers called the Scaling K2 project,
identified the exoplanets using data from the NASA Kepler Space Telescope's
K2 mission.
The discovery was made possible by a new planet detection algorithm that
Zink developed. One challenge in identifying new planets is that reductions
in stellar brightness may originate from the instrument or from an
alternative astrophysical source that mimics a planetary signature. Teasing
out which ones are which requires extra investigation, which traditionally
has been extremely time consuming and can only be accomplished through
visual inspection. Zink's algorithm is able to separate which signals
indicate planets and which are merely noise.
"The catalog and planet detection algorithm that Jon and the Scaling K2 team
came devised is a major breakthrough in understanding the population of
planets," Petigura said. "I have no doubt they will sharpen our
understanding of the physical processes by which planets form and evolve."
Kepler's original mission came to an unexpected end in 2013 when a
mechanical failure left the spacecraft unable to precisely point at the
patch of sky it had been observing for years.
But astronomers repurposed the telescope for a new mission known as K2,
whose objective is to identify exoplanets near distant stars. Data from K2
is helping scientists understand how stars' location in the galaxy
influences what kind of planets are able to form around them. Unfortunately,
the software used by the original Kepler mission to identify possible
planets was unable to handle the complexities of the K2 mission, including
the ability to determine the planets' size and their location relative to
their star.
Previous work by Zink and collaborators introduced the first fully automated
pipeline for K2, with software to identify likely planets in the processed
data.
For the new study, the researchers used the new software to analyze the
entire dataset from K2—about 500 terabytes of data encompassing more than
800 million images of stars—to create a "catalog" that will soon be
incorporated into NASA's master exoplanet archive. The researchers used
UCLA's Hoffman2 Cluster to process the data.
In addition to the 366 new planets the researchers identified, the catalog
lists 381 other planets that had been previously identified.
Zink said the findings could be a significant step toward helping
astronomers understand which types of stars are most likely to have planets
orbiting them and what that indicates about the building blocks needed for
successful planet formation.
"We need to look at a wide range of stars, not just ones like our sun, to
understand that," he said.
The discovery of the planetary system with two gas giant planets was also
significant because it's rare to find gas giants—like Saturn in our own
solar system—as close to their host star as they were in this case. The
researchers cannot yet explain why it occurred there, but Zink said that
makes the finding especially useful because it could help scientists form a
more accurate understanding of the parameters for how planets and planetary
systems develop.
"The discovery of each new world provides a unique glimpse into the physics
that play a role in planet formation," he said.
Reference:
Jon K. Zink et al, Scaling K2. IV. A Uniform Planet Sample for Campaigns 1–8
and 10–18, The Astronomical Journal (2021).
DOI: 10.3847/1538-3881/ac2309
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