Violent flares from young stars may endanger planets: NASA

Several planets may suffer damaging effects from violent flares emanating from the host star, NASA scientists say.

Scientists using NASA’s Hubble Space Telescope say that superflares from the host star may make planets orbiting it uninhabitable, NASA said in a statement. Hubble, under the programme HAZMAT—Habitable Zones and M dwarf Activity across Time, is observing such stars.

What is M dwarf?

M dwarf is the astronomical term for a red dwarf star—the smallest, most abundant and longest-lived type of star in our galaxy, according to the study published in The Astrophysical Journal.

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

What is HAZMAT programme?

HAZMAT programme is an ultraviolet survey of red dwarfs at three different ages: young, intermediate, and old.

NASA says that stellar flares from red dwarfs, powered by intense magnetic fields, are bright in ultraviolet wavelengths, compared with Sun-like stars. The magnetic fields get tangled by the roiling motions of the stellar atmosphere.

Hubble’s ultraviolet sensitivity helps to observe these flares, NASA says.

When the tangling gets too intense, the fields break and reconnect, unleashing tremendous amounts of energy.

About three-quarters of the stars in our galaxy are red dwarfs and the youngest red dwarfs are about 40 million years old. This younger age is when terrestrial planets are forming around their stars, NASA said.

The flares from these youngest red dwarfs are 100 to 1,000 times more energetic than when the stars are older, the scientists say.

Most of the galaxy’s “habitable-zone” planets—planets 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 nearest star to our Sun, a red dwarf named Proxima Centauri, has an Earth-size planet in its habitable zone.

The study examined the flare frequency of 12 young red dwarfs. The observing programme detected one of the most intense stellar flares ever observed in ultraviolet light.

The most powerful flare – Hazflare

Dubbed the “Hazflare,” this event was more energetic than the most powerful flare from our Sun ever recorded.

“Flares like we observed have the capacity to strip away the atmosphere from a planet. But that doesn’t necessarily mean doom and gloom for life on the planet,” said Parke Loyd from Arizona State University in the US.

“It just might be different life than we imagine. Or there might be other processes that could replenish the atmosphere of the planet. It is certainly a harsh environment, but I would hesitate to say that it is a sterile environment,” Loyd said.

“The goal of the HAZMAT programme is to help understand the habitability of planets around low-mass stars,” said Arizona State University’s Evgenya Shkolnik, the programme’s principal investigator.

(With PTI inputs)