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Superflares from young red dwarf stars imperil planets

Violent outbursts of seething gas from young red dwarf stars may make conditions uninhabitable on fledgling planets. In this artist's…



Violent outbursts of seething gas from young red dwarf stars may make conditions uninhabitable on fledgling planets. In this artist’s rendering, an active, young red dwarf (right) is stripping the atmosphere from an orbiting planet (left). Scientists found that flares from the youngest red dwarfs they surveyed – about 40 million years old – are 100 to 1,000 times more energetic than when the stars are older. They also detected one of the most intense stellar flares ever observed in ultraviolet light – more energetic than the most powerful flare ever recorded from our Sun. Credit: NASA, ESA and D. Player (STScI)

The word “HAZMAT” describes substances that pose a risk to the environment, or even to life itself. Imagine de termen worden toegepast op hele planeten, waar gewelddadige flares van de gastster kunnen maken werelden uninhabitable door affecting hun atmosferes.

NASA’s Hubble Space Telescope is observing such stars through a large program called HAZMAT-Habitable Zones and M Dwarf Activity across Time.

“M Dwarf” is the astronomical term for a red dwarf star-the smallest, most abundant and longest-lived type of star in our galaxy. The HAZMAT program is an ultraviolet survey of red dwarfs at three different ages: young, intermediate, and old.

Stellar flares from red dwarfs are particularly bright in ultraviolet wave lengths, compared to Sun-like stars. Hubble’s ultraviolet sensitivity makes the telescope very valuable for observing these flares. The flares are believed to be powered by intense magnetic fields that get tangled by the roiling motions of the stellar atmosphere. When the tangling gets too intense, the fields break and reconnect, unleashing tremendous amounts of energy.

The team has found that the flares from the youngest red dwarfs they surveyed-just about 40 million years old-are 100 to 1,000 times more energetic than when the stars are older. This young age is when terrestrial planets are forming around their stars.

About three-quarters of the stars in our galaxy are red dwarfs. Most of the galaxy’s “habitable-zone” planets plan orbiting their stars at a distance where temperatures are moderate enough for liquid water to exist on their surface-likely orbit red dwarfs. In fact, the closest star to our Sun, a red dwarf named Proxima Centauri, has an Earth-sized planet in its habitable zone.

However, young red dwarfs are active stars, producing ultraviolet flares that blast so much energy that They could influence atmospheric chemistry and possibly strip off the atmospheres of these fledgling planets.

“The goal of the HAZMAT program is to help understand the habitability of planets around low-mass stars,” explained Arizona State University’s Evgenya Shkolnik, the program’s principal investigator. “These low-mass stars are critically important in understanding planetary atmospheres.”

The results of the first part of this Hubble program are being published in The Astrophysical Journal. This study examines the flare frequency of 12 young red dwarfs. “At this state of affairs,” said Arizona State University’s Parke Loyd, the first author on this paper.

The observing program has been particularly important, because the difference in their flare activity is quite large compared to older stars. detected one of the most intense stellar flares ever observed in ultraviolet light. Dubbed the “Hazflare,” this event was more energetic than the most powerful flare from our Sun ever recorded.

“With the Sun, we have a hundred years of good observations,” Loyd said. “And in that time we We have seen one, maybe two, and have a energy approaching that of the Hazflare. In a little less than a day’s worth of Hubble observations of these young stars, we caught the Hazflare, which means we’re looking at superflares happening every day or even a few times a day. “

Could super-flares of such frequency and intensity bathe young planets in so much ultraviolet radiation that they forever doom chances of habitability? According to Loyd, “Flares like we observed have the ability to strip away the atmosphere from a planet. But that does not necessarily mean doom and gloom for life on the planet. be other processes that could replenish the atmosphere of the planet. It’s certainly a harsh environment, but I would hesitate to say that it’s a sterile environment. “

The next part of the HAZMAT study will be to study intermediate-aged red dwarfs that are 650 million years old. Derefter vil de eldste røde dværgene blive analyseret og sammenlignet med de unge og mellemstjernede stjerner for at forstå udviklingen af ​​ultraviolet strålingsmiljøet eller lavmasseplanetene omkring disse lavmassestjerner.


Explore further:
Astronomers catch red dwarf star in a superflare outburst

Provided By:
NASA’s Goddard Space Flight Center


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