image: Adina Feinstein
Credit: Paul Henderson
Scientists suspect powerful solar flares helped strip away the atmospheres of planets like Mars. A Michigan State University researcher is now searching for evidence of how those same forces shape planets beyond our solar system.
Adina Feinstein, assistant professor of physics and astronomy, believes exoplanets are the key to understanding the early days of our solar system. This week, she received a Schmidt Sciences FirstLight grant to investigate how space weather influences young planets.
The five year, $500,000 per year grant is part of a larger effort by Schmidt Sciences to boost scientific discovery through a new fleet of coordinated observatories, known as the Schmidt Observatory System. Over the next few years, the organization plans to build three ground-based facilities and one space telescope to advance astronomical research. While government-funded telescopes and observatories can take decades to develop, Schmidt Sciences hopes to shorten that timeline.
With the help of the grant, Feinstein will use these facilities to monitor outbursts from young stars and search for evidence that the planets orbiting them are losing their atmospheres.
“Having Schmidt Sciences build these distinct facilities for the community and provide the financial support to develop software analysis tools and preparatory science for them is career-making,” Feinstein said.
Young stars, wild weather
The sun we know today was once wilder and less predictable billions of years ago. Scientists believe young stars experience more frequent and powerful outbursts than older stars like our sun, potentially stripping away parts of the atmospheres of nearby planets.
Today, young stars beyond our solar system are still in their rebellious phase, unleashing powerful flares that could wreak havoc on Earth's electrical grid if they occurred close to home. The young exoplanets that revolve around these stars may be especially vulnerable, with their atmospheres at risk of losing substantial amounts of gas.
“We’re trying to tie distinct observations together to see how space weather affects the entire evolutionary path of these planets,” Feinstein said.
Solar flares happen when magnetic field lines around a star become twisted and release enormous amounts of energy. Some stellar outbursts also eject charged particles into space. When that energy and material reaches a planet, they can heat and alter its atmosphere, allowing some particles, like hydrogen and helium, to escape into space while triggering chemical reactions that form new molecules.
“It’s a huge source of energy that can change whatever is going on in the atmosphere at any given time,” Feinstein said. “That atmosphere might go back to what it looked like before and equilibrate, but it may not always do that.”
Searching for clues in starlight
Feinstein hopes to connect the dots between what young stars are doing and how their planets respond.
The new observatories will allow her team to monitor thousands of stars for flares and other outbursts, using optical and radio observations to build a clearer picture of space weather around young planetary systems.
The team will also repeatedly observe young exoplanets, searching for changes in how quickly their atmospheres are escaping into space. By comparing those measurements with activity on the planets’ host stars, researchers hope to determine whether powerful outbursts are responsible for atmospheric loss.
To find evidence of this effect, Feinstein relies on observing the moment a planet passes in front of its star, known as a transit. When starlight passes through a planet’s atmosphere, astronomers can split that light into different wavelengths. By observing planetary transits at wavelengths sensitive to hydrogen and helium, Feinstein and her team will measure how much gas is being lost and how the lost gas is structured. In extreme cases, a planet may have a cometary tail-like structure of an escaping atmosphere trailing behind it.
The five-year grant will support an international team of researchers, including graduate students and postdoctoral scholars, as they prepare to use the new facilities and eventually conduct the survey.
Exoplanets offer a glimpse of our solar system’s earliest days, Feinstein said. By studying planets of different ages, researchers can better understand how planets evolve and why some planets in our solar system have thick atmospheres while others have almost none.
“This research allows us to piece together what might have happened in the early solar system and understand why planets look the way they do today,” Feinstein said.