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New space exploration reveals how planets emerge



  New space exploration illuminates the formation of planets
Data on the brightness of a young star led to the discovery of the exoplanet DS Tuc Ab. Red arrows indicate "transits" in which the planet crossed between the Earth and the host star of the planet. The big, soft variations are caused by the star, which is a result of his youth. Picture credits: Elisabeth Newton

Researchers at Dartmouth College have discovered a planet orbiting one of the brightest young stars known. This emerges from a study published in The Astrophysical Journal Letters . The approximately 45 million year old star and its planet could provide valuable information about the formation of planetary bodies.

The planet, known as an exoplanet because it is outside the solar system, was found in NASA's Transition Exoplanet Survey Satellite (TESS). While thousands of explorations of exoplanets have already been made, only a few have been discovered orbiting relatively young stars.

The exoplanet observed in Dartmouth research ̵

1; known as DS Tuc Ab – can be thought of as a "teenager" in planetary time. The planet is no longer growing, but due to its young age it is still subject to rapid changes, such as the loss of atmospheric gas due to the radiation of its host star.

It may take millions or billions of years for planets to reach maturity. Because this process can not be observed in real time, researchers are searching for planets around young stars to capture the process in action and to learn how planets form and develop.

"One of the main goals of astronomy is to understand the big picture. We learned here how solar systems and galaxies take shape and why," said Elisabeth Newton, assistant professor of physics and astronomy at Dartmouth College. "By finding solar systems that are different from our own – especially the young ones – we can hope to find out why the Earth and our own solar system have evolved as they did."

DS Tuc Ab is about six times the size of Earth, between the greats of Neptune and Saturn. Considering the size, it probably has a similar composition to the giant planets in our solar system. The exoplanet has two suns and completely circles its main star in just eight days.

The planet was first observed by the NASA satellite in November 2018 and confirmed in March by the Dartmouth team based on data from the NASA Spitzer Space Telescope and other ground- and space-based observatories such as the South African Large Telescope (SALT).

The planet is about 150 light-years from Earth. Every light year is a distance of nearly 6 trillion miles.

"We were really excited when we confirmed this discovery because the planet is orbiting such a bright, well-known young star, and our entire team worked together to learn all we could about this solar system," Newton said led a team of scientists from the University of North Carolina at Chapel Hill, the University of Texas at Austin, and other research centers around the world.

The NASA TESS mission searches for planets around nearby stars using the transit method. The approach recognizes when light is blocked as a planet moves between the Earth and the star of the planet. The researchers then review the observations of other telescopes to confirm the discovery.

"With the brightness of the star, we can study the planet in detail, because the more photons you have, the better your statistics are, and a discovery of this kind with such a unique age and an unusual planetary size would not be possible without TESS," said Newton.

Planets are larger when they form for the first time, and are thought to get smaller over time as they cool and lose their atmosphere. As this planet still forms, the team hopes to see the evaporation of the atmosphere in action. Understanding this process could help researchers predict what could happen to the exoplanet over the next billions of years, and can also be used to understand how atmospheric flight could have affected older planets, including the Earth.

"We can provide a snapshot of what planets look like at a young age," said Newton.

The TESS satellite was launched on April 18, 2018. According to NASA, the TESS mission will transact 200,000 of the brightest stars near the Sun for finding exoplanets, including those that could support life.

The research team knows the size of DS Tuc Ab, but the total mass is unknown. This limits what the team can currently say about the density and composition of the planet. Thanks to the brightness of the star, future investigations could measure the mass of the planet or determine which molecules are present in its atmosphere.


The NASA TESS mission finds its smallest planet yet


Further information:
Elisabeth R. Newton et al., TESS Hunting for Young and Mature Exoplanets (THYME): A Planet in the Myr-Tucana Horologium Society, The Astrophysical Journal (2019). DOI: 10.3847 / 2041-8213 / ab2988

Provided by
Dartmouth College




Quote :
New space research sheds light on the formation of planets (2019, 25 July)
retrieved on July 25, 2019
from https://phys.org/news/2019-07-space-discovery-planets.html

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