Superflares from young stars may imperil planets: NASA

Washington, October 19: Scientists have found that violent flares from the host star may make planets orbiting it uninhabitable by affecting their atmospheres. NASA said, its Hubble telescope is observing such stars through a large programme called HAZMAT, or Habitable Zones and M dwarf Activity across Time.

 

The programme is an ultraviolet survey of red dwarfs at three different ages, young, intermediate, and old. According to NASA, Stellar flares from red dwarf star, are particularly bright in ultraviolet wavelengths, compared with Sun-like stars. NASA says, Hubble's ultraviolet sensitivity makes it very valuable for observing these flares.

Red dwarf is the smallest, most abundant and longest-lived type of star in our galaxy.

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 younger age is when terrestrial planets are forming around their stars.

Approximately three-quarters of the stars in our galaxy are red dwarfs. 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.

However, 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.