Privileged Planet: our sun less common (Introduction)

by David Turell , Tuesday, January 04, 2022, 15:25 (1055 days ago) @ David Turell

Red dwarfs much more common:

https://www.sciencealert.com/why-the-heck-aren-t-we-orbiting-a-red-dwarf-star

"On the grand cosmic scale, our little corner of the Universe isn't all that special – this idea lies at the heart of the Copernican principle. Yet there's one major aspect about our planet that's peculiar indeed: Our Sun is a yellow dwarf.

"Because our home star is what we know most intimately, it would be tempting to assume that yellow and white dwarf stars (FGK dwarfs) are common elsewhere in the cosmos. However, they're far from the most multitudinous stars in the galaxy; that particular feather belongs in the cap of another type of star – red dwarf (M dwarfs).

"Not only do red dwarfs make up as much as 75 percent of all stars in the Milky Way, they are much cooler and longer-lived than stars like the Sun. Much, much longer lived.

"We expect our Sun to live around 10 billion years; red dwarf stars are expected to live trillions. So long, in fact, that none have yet reached the end of their main sequence lifespan during the entire 13.4 billion years since the Big Bang.

"Since red dwarfs are so abundant, and so stable, and since we shouldn't automatically consider ourselves to be cosmically special, the fact we're not orbiting a red dwarf should therefore be somewhat surprising. And yet, here we are, orbiting a not-so-common yellow dwarf.

"Red dwarf stars are an attractive prospect for the search for extraterrestrial life. They don't burn as hot as Sun-like stars, which means any exoplanets orbiting them need to be closer to reach habitable temperatures. In turn, this could make any such exoplanets easier to find and study, since they orbit their stars more frequently than Earth does the Sun.

"Indeed, astronomers have found quite a few rocky exoplanets – like Earth, Venus and Mars – orbiting red dwarf stars in this habitable zone. And some of them are even relatively close. It's tantalizing stuff, and it certainly seems like red dwarf stars ought to host life at least somewhere, which is why astrobiologists are looking."

Comment: Looking but will they find evidence of life? This is an other example of our Earth's specialness.