Stars with characteristics similar to the Sun can give off superflares in a relatively short period. A recent analysis by an international team of astronomers estimates that every 100 years a star of the same size and temperature as the Sun tends to generate a burst of radiation, with the power of a billion hydrogen bombs.
Not all stars are the same. The Sun is a G2V spectral type star, also known as a yellow dwarf. They are characterized by having a moderate temperature (between 5,500 to 6,000 degrees Celsius), being stable and having a half-life of billions of years in their main sequence. They are noticeably different from red dwarfs, the most common stars in the galaxy, which are cooler and less luminous in comparison.
Some scientists think that research on yellow dwarfs has underestimated their eruptive potential. To obtain an approximation of the frequency of these explosive events, a team of scientists led by the Max Planck Institute analyzed data from 56,450 stars similar to the Sun, both in temperature and size. Each record was captured by NASA’s Kepler space telescope between 2009 and 2013. According to the study published in Sciencethe data provide a view of stellar behavior spanning 220,000 years. In other words, the effort was like having seen the Sun under a time machine.
The eruptive potential of the Sun
The work identified 2,889 superflares in 2,527 stars. On average, a twin star of the Sun produces a huge burst of radiation once every century. The authors have been surprised by the frequency of superflares in stars that until now were considered quiet. Previous studies of a similar nature revealed explosions at intervals of between 1,000 and 10,000 years on average.
Solar flares are generated by the release of energy stored in the magnetic fields of stars. On the Sun, the high activity that produces these phenomena occurs every 11 years. When a flare occurs, plasma (a gas-like state of matter) shoots from the star’s surface, along with radiation and high-energy particles to form a space stream. A part of that wind can reach Earth and seriously affect telecommunications or space missions. It also causes the phenomenon of the northern lights.
Since the space age began, solar flares from the Sun have been light. However, there is evidence in fossils from Earth that reveals supereruptions hundreds or billions of years ago. Scientists can claim that the star is capable of sending out enormous amounts of energy, but they are not able to estimate how often it does so. Studies like the recent one allow us to get closer to a rate of solar superflares and call for prevention. “The new data are a stark reminder that even the most extreme solar events are part of the Sun’s natural repertoire,” says Dr. Natalie Krivova, co-author of the study.
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