A Better Way to Look

K-type dwarf stars are dimmer than the Sun but brighter than faint stars. These stars live for a very long time, 17 to 70 billion years, compared to 10 billion years for the Sun. This gives plenty of time for life to evolve on any planets in their habitable zones. Also, they have less extreme activity in their youth than M-type stars (red dwarfs), the most common star type in the Milky Way Galaxy.

K-stars may be in a ‘sweet spot’ between Sun-analog stars and M-type stars astronomers at NASA’s Goddard Space Flight Center and writers of a paper published in the Astrophysical Journal Letters.

Scientists consider the simultaneous presence of oxygen and methane in a planet’s atmosphere to be a strong biosignature because these gases like to react with each other, destroying each other. So if they are present in an atmosphere together, that implies something is producing both of them quickly, quite possibly life.

However, because exoplanets are so remote, there needs to be significant amounts of oxygen and methane in an exoplanet’s atmosphere for it to be seen by observatories on Earth. The researchers found that the oxygen-methane biosignature is likely to be stronger around a K-type star than a Sun-like star.

This stronger oxygen-methane signal has also been predicted for planets around M-type stars, but their high activity levels might make M-stars unable to host habitable worlds. K-type stars can offer the advantage of a higher probability of simultaneous oxygen-methane detection compared to Sun-like stars without the disadvantages that come along with an M-star host.

Additionally, exoplanets around K-type stars will be easier to see than those around Sun-like stars simply because K-stars are dimmer. The Sun is 10 billion times brighter than an Earth-like planet around it. That’s a lot of light you have to suppress if you want to detect an orbiting planet. A K-star might be ‘only’ a billion times brighter than an Earth-like planet orbiting it.

Dark Side of the Sun

Whelp, the sun has a giant hole in it.

A colossal dark hole was recently spotted on the sun’s surface, and it has been spewing solar wind our way. According to NASA, the high-speed wind triggered a light show of several auroras on Earth.

A photo of the “coronal hole” (below) was taken by a camera aboard the space agency’s Solar Dynamics Observatory on Oct. 10:

The hole is located on the outermost layer of the sun, called the corona (thus the name), in the sun’s northern hemisphere. It is about the size of 50 Earths and is releasing wind at up to 500 miles per second.

When solar winds reach Earth, it can disturb the magnetosphere and cause geomagnetic storms. While such storms create beautiful auroras and can also affect satellite and radio communication systems.

NASA scientists haven’t indicated whether the recently spotted hole will stick around for Halloween, but coronal holes can last for months.