Proxima Centauri reminds our Sun ... on steroids

Proxima Centauri reminds our Sun ... on steroids

An amazing discovery revealed that the tiny dwarf star has its own “star spot” cycle. This is a real puzzle, and probably another sign that Proxim b is “habitable” - this is not the best place to visit.

Imagine that you go out into the yard on a clear day and look at the sun. However, this is not our sun. It turns out that it is much closer in the sky and, wait, if you look closely, you can see that something is wrong with its radiation. This star seems to be a vast, sinister, dark spot, shimmering against a bright solar disk. The fact is that it is Proxima Centauri. And, although it seems as if she suffers from terrible decay, these black spots, in fact, make this tiny red dwarf more “sun-shaped” than we could have imagined.

“If intelligent beings live on Proxima B, then they have real drama there,” said Brad Vargelin of the Harvard-Smithsonian Center for Astrophysics (CfA) and lead author of a study published in the Monthly Notices magazine of the Royal Astronomical Community.

In recent months, Proxima Centauri has become famous as the closest exoplanet to the Earth’s mass in the Solar System. Astronomers of the La Silla Observatory (European Southern Observatory) in Chile discovered the world with a mass similar to Earth, measuring the "oscillations" of the star when the gravity of the small exopallets "pulled" it during a short 11-day orbit. This orbit places Proxima b in the middle of the “habitable zone” of Proxima Centauri, a distance from a star that is not too hot and not too cold to form water on the surface of a rocky planet. On Earth, where there is water, there is life. This discovery is surprising, because it gives the prospect of believing that Proxima B can be a haven for aliens, or even become a stopping point for future human colonists. However, there are serious problems with the assumption that Proxima b is a remote object of the “earth type”. First of all, we have no data on whether there is an atmosphere on the planet. We also have a zero idea of ​​whether there is water on an exoplanet. But there is another problem - Proxima b orbit is located too close to the star, which, as is well known, generates powerful flashes that bring waves of radiation to any nearby planets. And radiation, as we all know, is bad for life.

So it may seem surprising that Proxima Centauri has sun-like qualities. But these qualities probably will not make Proxima b more “habitable” and, in fact, only create new questions for physicists studying the solar system.

Magnetic voltage

Ground-based observatories, including the All Sky Automated Survey (global sky automatic survey) and space telescopes (NASA mission Swift and Chandra and the European observatory XMM-Newton) measured X-rays from Proxima Centauri. Vargelina's team was able to detect the usual 7-year cycle, but with some oddities.

Proxima Centauri is a tiny, cold star that occupies 0.1 of our Sun size. The Sun has a regular “solar cycle” with a duration of 11 years, during which its magnetic activity increases and decreases. During periods of intense magnetic activity (solar maximum) in the lower atmospheric layer of the Sun (corona), frequent flashes and ejections of coronal mass can be expected. At this time, dark spots appear on the surface, highlighting those areas where the internal magnetic field of the sun erupts through the surface. It sounds dramatic, but at a solar maximum, only about 1% of the surface is covered by these spots. But when studying Proxima Centauri, measurements show that as many as 20% of a tiny star can cover with star spots.

This is interesting information that can help you better understand how our own Sun works.

A key theory explaining the 11-year solar cycle talks about differential rotation. That is, the upper layer of the Sun rotates faster at the equator than at the poles. Since its magnetic field moves from north to south, it is believed that the internal magnetic field at the equator “bends” around the sun. It looks like a gum wrapped around a ball. At a certain point, when the magnetic field is most stressed (solar maximum), the pressure is released after a flip of the magnetic polarity. Magnetic solar “north” replaces “south” and vice versa, and the cycle begins again.

But red dwarfs like Proxima Centauri do not possess this very upper layer of differential rotation due to their small size. Instead, they experience convection (energy transfer in streams and jets) from the core to the topmost layer. It remains a mystery how, without differential rotation, Proxima Centauri has a cycle, not to mention a 7-year stellar cycle.

“The presence of Proxima Centauri’s cycle shows that we are not fully aware of the process of generating a stellar magnetic field,” said co-author Jeremy Drake of CfA.

So there are gaps in our understanding of the solar cycle or the internal composition of red dwarfs is much more complicated than we assume. In the case of Proxima Centauri, its stellar cycle is built on steroids, which probably create a rather devastating comic storm. And this may sterilize the exoplanet, which makes it less and less like the Earth.

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