by Astronomers have discovered a rare system of six young planets and a seventh that may be dancing around a misbehaving baby star.
Not only could this system provide much-needed insight into how planets form and evolve around a baby star, but its similarity to the solar system could give astronomers a glimpse of what it might look like to be our cosmic neighbor about 4 billion years ago.
The six exoplanets, possibly seven, orbit a relatively close dwarf star in the Milky Way called TOI-1136; it is located approximately 270 light years from Earth. The large number of exoplanets in the system encouraged scientists to investigate more deeply.
“Because small star systems have as many planets as this one, it’s passing close to our own solar system,” Tara Fetherolf, a team member and visiting professor of astrophysics at the University of California, said in a statement. “It’s similar enough and different enough that we can learn a lot.”
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A rare young multiplanet star system with a hyperactive infant star
The TOI-1136 planetary system was first studied by scientists using NASA’s exoplanet-hunting Transiting Exoplanet Survey Satellite (TSES) in 2019. Fetherolf and colleagues followed up this initial study with observations from multiple telescopes, revealing the mass of planet, the shape of their orbits, and even the characteristics of their atmosphere.
The planets in the system, designated names TOI-1136 b to TOI-1136 g, are classified as “sub-Neptune” planets. The smallest of the six confirmed worlds is twice the width of Earth, and some of its sibling planets are as much as four times the size of our planet – about the size of the solar system ice giants Uranus and Neptune.
All of the TOI-1136 exoplanets are so close to their parent star that they complete an orbit in less than 88 Earth days. This is significant because the orbital period of Mercury, the planet closest to the sun, is 88 days, which means that all these planets could be closer to their star than that tiny planet to our star.
“They are strange planets to us because there is nothing exactly like them in our solar system,” Rae Holcomb, team member and Ph.D. candidate at the University of California, said in a separate statement. “But the more we study other planetary systems, they seem to be the most common type of planet in the galaxy.”
What really makes TOI-1136 stand out is how young this planet and its central dwarf star are. TOI-1136 is only 700 million years old, which may seem ancient, but compared to the 4.5 billion year old solar system and its star, the sun, it makes the system a relative toddler.
“This allows us to look at planets right after they form, and solar system formation is a hot topic,” Fetherolf said. “Anytime we find a multiplanet system it gives us more information to inform our theories about how systems come to be and how our system got here.”
Just like an overactive human toddler, it can be difficult to keep track of these young stars due to their hyperactivity. For infant stars, this hyperactivity comes in the form of intense magnetism, more widespread and intense sunspots and louder solar flares.
Not only is observing the radiation emitted by infant stars challenging, it also shapes the planets that orbit them, shaping their atmospheric characteristics in particular.
“Young stars misbehave all the time. They are very active, just like young children. That can make high-precision measurements difficult,” said Stephen Kane, team leader and professor of planetary astrophysics at Univ. California Riverside, in the statement . “This will help us not only make a head-to-head comparison of how planets change over time, but also how their atmospheres have changed at different distances from the star, and perhaps that is the most important thing.”
Could any of the planets of TOI-1136 host life?
Not only are the planets in the TOI-1136 system all aligned, but they are all close to each other in terms of physical distance as well. This allowed researchers to examine something that is not easily studied in another planetary system.
“Normally, when we’re looking for planets, we’re looking at the effect the planets have on their star. We watch the star move around and interpret it as the gravitational influence of the planets,” said Kane. “Here, we can also see the planets pulling each other.”
This proximity allowed the team to detect a “resonant force” in the system indicating that the seventh world could exert a gravitational influence on the confirmed sixth worlds.
Using the Automated Planet Finder telescope at the Lick Observatory, located on Mount Hamilton in California, and the High Resolution Echelle Spectrometer at the WM Keck Observatory on the inactive Mauna Kea volcano in Hawaii, the team was able to “wobble” the volcano see. dwarf star TOI-1136 caused it as its planets called it.
By observing this “wobble” with computer models and data of the planets crossing the face of their star, the researchers have allowed researchers to determine the mass of the planets to an unprecedented level of accuracy.
“It took a lot of trial and error, but we were very pleased with our results after developing one of the most complex planetary system models in the exoplanet literature to date,” lead research author and UC Irvine Ph.D. said physics candidate Corey Beard.
It was believed that the first stirrings of life had arisen on Earth about 600 million years after the formation of the solar system in a period of our planet’s history called the Archean. We see the exoplanets of the TOI-1136 system at a similar point in their history.
However, the planets in this system are unlikely to be able to support life due to their proximity to their host. This means that intense radiation from the star is likely to remove the atmosphere of these worlds as it boils liquid water, a vital ingredient for life as we know it.
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“Are we rare? I am more convinced that our system is very unusual in the universe,” said Kane. “The discovery of systems as diverse as our own is making it increasingly clear how our solar system fits into the wider context of the formation of other stars.”
The team now plans to investigate the TOI-1136 system further, hoping to confirm the seventh planet and also determine the composition of the planets’ atmospheres. This is something that could be achieved using the James Webb Space Telescope.
The team’s research has been published in The Astronomical Journal.
