ALMA Detects Powerful Flare from Proxima Centauri

[bystander]

Powerful Flare from Star Proxima Centauri Detected with ALMA
ALMA | NRAO | NAOJ | ESO | 2018 Feb 26

Puts habitability of nearby system into question

Artist impression of a red dwarf star like Proxima Centauri, the nearest star to our sun. New analysis of ALMA observations reveal that Proxima Centauri emitted a powerful flare that would have created inhospitable conditions for planets in that system. Credit: NRAO/AUI/NSF; D. Berry

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Space weather emitted by Proxima Centauri, the star closest to our sun, may make that system rather inhospitable to life after all.

Using data from the Atacama Large Millimeter/submillimeter Array (ALMA), a team of astronomers discovered that a powerful stellar flare erupted from Proxima Centauri last March. This finding raises questions about the habitability of our solar system’s nearest exoplanetary neighbor, Proxima b, which orbits Proxima Centauri.

At its peak, the newly recognized flare was 10 times brighter than our sun’s largest flares, when observed at similar wavelengths. Stellar flares have not been well studied at the millimeter and submillimeter wavelengths detected by ALMA, especially around stars of Proxima Centauri’s type, called M dwarfs, which are the most common in our galaxy. ...

The flare increased Proxima Centauri’s brightness by 1,000 times over 10 seconds. This was preceded by a smaller flare; taken together, the whole event lasted fewer than two minutes of the 10 hours that ALMA observed the star between January and March of last year. ...

Detection of a Millimeter Flare from Proxima Centauri - Meredith A. MacGregor et al

• Astrophysical Journal Letters 855(1):L2 (2018 Mar 01) DOI: 10.3847/2041-8213/aaad6b
  arXiv.org > astro-ph > arXiv:1802.08257 > 22 Feb 2018

[Ann]

To me, this result suggests that tiny M-type stars are not good hosts for life-bearing planets.

I know I read someplace, quite recently, that late M-type dwarfs like Proxima Centauri are unlikely to host life-bearing planets. The best life-friendly stars, according to what I read, are K-type stars.

I haven't been able to find the article that I read, but I found another article or blog post, admittedly from 2009, which also touted K-class stars as ideal for life-bearing planets.

Ann

[rstevenson]

About 12% of local stars are K-type, while about 7.5% are G-type, including our Sun. So in our neighbourhood, nearly 1 in 5 stars are amenable to hosting life, assuming suitable planets in the Mama Bear zone, that is. Must get out there and start knocking on doors!

Rob