Data flows from NASA's TESS mission lead to the discovery of a planet the size of Saturn

In fact, asterosismologists, stellar astronomers who study seismic waves (or "star-tremors") in stars that appear as changes in brightness, often provide crucial information for finding properties of planets recently discovered.

This team work allowed the discovery and characterization of the first planet identified by TESS for which the oscillations of its host star can be measured.

The planet – YOU 197.01 (TOI is the abbreviation for "TESS Object of Interest") – is described as a "hot Saturn" in a recently accepted scientific article. Indeed, the planet is about the same size as Saturn and is also very close to its star. It ends an orbit in just 14 days and is very hot.

the Astronomical Journal will publish the document written by an international team of 141 astronomers. Daniel Huber, astronomer assistant at the Institute of Astronomy Manoa at the University of Hawaii, is the main author of the article. Steve Kawaler, Professor of Physics and Astronomy; and Miles Lucas, an undergraduate student, are co-authors of Iowa State University.

"This is the first bucket of water from the TESS database," said Kawaler.

TESS – the satellite transits of exoplanets study, led by astrophysicists from the Massachusetts Institute of Technology – was launched on April 18, 2018 from Cape Canaveral Air Force Base in Florida. The four cameras of the spacecraft examine nearly 26 vertical bands of the sky for a month – first on the southern hemisphere, then on the north. After two years, TESS will have swept 85% of the sky.

Astronomers (and their computers) sort images in search of transits, tiny dips in the light of a star caused by the passage of a planet in orbit before it. NASA's Kepler mission – a predecessor of TESS – searched the planets in the same way, but swept a narrow slice of the Milky Way galaxy and focused on distant stars.

TESS targets bright, close stars, allowing astronomers to track their discoveries using other spatial and terrestrial observations to deepen and characterize stars and planets. In another article recently published online by The Series of Supplements to the Astrophysical Journal, astronomers from the TESS Asteroseismic Science Consortium (TASC) have identified a target list of sun-like oscillating stars (many of which look like our future sun) to study with the help of TESS data, a list with 25,000 stars.

Kawaler – who attended the Kepler launch in 2009 and was in Florida for the launch of TESS (but a late-minute delay has forced him to miss his departure to return to Ames), is a board member. TASC administration, consisting of seven members. The group is led by Jørgen Christensen-Dalsgaard from the University of Aarhus in Denmark.

TASC astronomers use aseismic modeling to determine the radius, mass, and age of a host star. These data can be combined with other observations and measurements to determine the properties of planets in orbit.

In the case of star host TOI-197, asterosts used its oscillations to determine if they were about 5 billion years old and that they are a little heavier and bigger than the sun . They also determined that the planet TOI-197.01 is a gaseous planet whose radius is about nine times larger than Earth's, which is about the size of Saturn. This is also 1 / 13th of the density of the Earth and about 60 times the mass of the Earth.

These findings speak volumes about the future work of TESS: "TOI-197 provides a first glimpse of the great potential of TESS to characterize exoplanets using asteroseismology," astronomers wrote.

Kawaler expects the flow of data from TESS to also contain scientific surprises.

"What's exciting, is that TESS is the only game in town for a while and the data is so good that we plan to try to do science that we did not have." thought, "said Kawaler. "Maybe we can also look at the very faint stars – the white dwarfs – which are my first love and represent the future of our solar and solar system."

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