Red dwarfs always let me think of the classic British TV science comedy show in the 90s, which was named after them. However, the stars themselves are better similar to the show. They are small, not surprisingly red stars that can create torches and coronal masses that can keep up with many of the much larger stars. A team of astronomers recently used the Chandra X-ray observatory to study Wolf 359 and found that it unleash brutal X-ray spots that are extremely harmful to nearby planets.
Red dwarf stars are small, cool and very durable stars that only shine with a fraction of the brightness of our sun. They have less than half of the sun and their surface temperatures are between 2,500 and 4,000 degrees Celsius. Because they slowly burn their fuel, red dwarfs can take years of years, which survives far more massive stars. They are common in the entire cosmos, about 70-80% of all stars in the galaxy, but they are still difficult to recognize with the naked eye.
An artistic impression of Trappist-1 B, shortly before it runs behind the cool, red dwarf star Trappist-1. Such stars are known for their activity with large star spots and eruptions. Trappist-1 B can experience intensive volcanism. Credit Thomas Müller (hda.mpia)
Wolf 359 is such a red dwarf star, which is about 7.8 light years away from the earth, which makes it one of the closest stars in our solar system. It is still too dark to be seen without a telescope, although it only shines a thousandth of the brightness of the sun. It is part of the constellation Leo and has a mass of only about 12% of our sun with a surface temperature of about 4,000 degrees Celsius. Wolf 359 is a relatively young star, but due to its small mass, it will slowly burn its hydrogen fuel and could remain stable for ten billion years.
With the intensive radiation emissions from Wolf 359, it is very likely that all planets in the orbit can be maintained for a stable lifelong atmosphere. However, a team of astronomers examined it with the Chandra X-ray observatory of the NASA and the XMM Newton from ESA. They have found that only a planet with greenhouse gases, just like the earth, could maintain life in its atmosphere. In view of the fact that red dwarfs are the most common stars in the universe, astronomers have examined them in order to find evidence of exoplanets, but so far little success. The team found evidence of two planets in orbit about Wolf 359, but not all scientists are convinced.
Illustration of the artist of Chandra
Each star has a habitable zone and its location is determined by the temperature and the energy output of the star itself. The external limits for this zone around Wolf 359 is about 15% of the distance between the earth and the sun. The two are not yet confirmed to confirm exoplanets to the star outside the habitable zone; One is too close, the other to far.
When they examined the system for over 3.5 days, they watched 18 X -ray lacquer from Wolf 359. However, this took a little more than 3.5 days and the team suggested that from time to time more powerful and more harmful torches. These intensive X -ray spots are the main reason that planets in the orbit must lie in the habitable zone and need an atmosphere that is rich in carbon dioxide to maintain habitable conditions. However, it is unlikely that each planet will be able to keep its atmosphere within the habitable zone due to the strength of the wind.
Source: Exoplanets must be prepared for extreme space weather, find Chandra
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