An international team of astronomers has detected for the first time an ejection of material from a star into space; The explosion was so powerful that it would have ripped off the atmosphere of any planet located in its path, details a study published this Wednesday in the Nature magazine.
The coronal mass ejections (CMEs) They are explosions that we often see happen on the Sun and in which the star expels enormous amounts of material into the surrounding space (from Earth they look like auroras).
Until now, these spectacular ejections, which shape and drive space weather and can erode the atmospheres of nearby planets, have not been conclusively detected in any star other than the Sun.
“Previous findings have inferred its existence or hinted at its presence, but they have not really confirmed that the material has definitively escaped into space. We have achieved it,” emphasizes Joe Callingham, from the Netherlands Institute for Radio Astronomy (ASTRON) and author of the research.
The discovery was possible thanks to the LOFAR telescope and the XMM-Newton space observatory of the European Space Agency, which has been observing stars and the surroundings of black holes for more than twenty years.
An ejecta in a red dwarf
When a CME emerges from a star into outer space, it produces a shock wave and an associated burst of radio waves.
The team of scientists captured this brief, intense radio signal and discovered that it came from a star located about 40 light years away.
“This type of radio signal would not exist unless the material had completely left the star’s bubble of powerful magnetism,” says Joe, that is, “it is caused by a CME.”
The ejecta came from a red dwarf, a star much fainter, colder and smaller than the Sun, with half its mass, rotating 20 times faster and with a magnetic field 300 times more powerful than the Sun’s.
Most of the planets known to exist in the Milky Way orbit around these types of stars.
The radio signal was detected using the Low Frequency Array (LOFAR) radio telescope at the Paris Observatory-PSL. The team then used XMM-Newton to determine the star’s temperature, rotation and brightness, which was essential for interpreting the radio signal and figuring out what was really happening.
Thus, they discovered that the CME was moving at a supersonic speed of 2,400 km per second, which is only observed in one in twenty solar CMEs. Furthermore, the ejecta was fast and dense enough to completely obliterate the atmosphere of any planet orbiting near the star.
An exciting discovery
The CME’s ability to strip planets of their atmosphere is an exciting discovery for our search for life around other stars.
A planet is considered habitable or suitable for life as we know it, depending on the distance it is from its parent star, that is, it has to be at the necessary distance for there to be liquid water on the surface of the planet and have an adequate atmosphere to protect it.
But What if the star regularly releases dangerous eruptions of material and causes violent storms? A planet regularly bombarded by powerful coronal mass ejections could completely lose its atmosphere and become an uninhabitable world, despite having a suitable orbit.
“This work opens a new observational frontier for studying and understanding flares and space weather around other stars,” adds Henrik Eklund, an ESA researcher based at the European Space Research and Technology Center (ESTEC) in Noordwijk, the Netherlands.
“We are no longer limited to extrapolating our knowledge of the Sun’s CMEs to other stars. It appears that intense space weather may be even more extreme around smaller stars, the main hosts of potentially habitable exoplanets, which has important implications for how these planets retain their atmospheres and possibly remain habitable over time.”