New Delhi: The Sun frequently erupts in Coronal Mass Ejections (CMEs) where charged plasma from the surface is hurled outwards into space. These CMEs influence all the worlds that they encounter, including the Earth. Astronomers had long suspected that other stars have to erupt in similar explosions too, but none have been spotted so far. For the first time, a team of astronomers have detected a CME from a nearby star. The CME was identified by the telltale signature of light, an associated burst of radio waves. The star is at a distance of about 130 lightyears from the Earth.
The star that produced the CME is much cooler and dimmer than the Earth. The star is also much smaller, containing roughly half the mass of the Sun, and is rotating about 20 times faster. It has a magnetic field 300 times as powerful as the Sun. Such small, cool red dwarf stars are believed to host most of the exoplanets in the galaxy. The CME was determined to be moving at an incredible velocity of 2,400 km per second. For comparison, the average solar wind speed from the Sun is about 450, with CMEs moving in excess of 700 km/s considered ‘fast’. Only about one in 2,000 CMEs from the Sun reach comparable velocities.
Implications for habitability
Red dwarf stars are particularly violent and eruptive in their infancy, but can last for billions of years longer than the Sun. The extreme flaring and associated CMEs during the turbulent childhood of the Star can easily strip away the atmospheres of planets in the habitable zone, adversely impacting their habitability. An explanet continuously bombarded by such blasts from the host star may end up losing its atmosphere entirely, and stripped to the ground despite containing orbital characteristics conducive to liquid water on the surface. A paper describing the findings has been published in Nature.