Not exact matches
For small,
red -
dwarf stars, habitable
zone planets might gather close, like marshmallow - roasting campers
around the fire.
The best estimates for the occurrence rates of habitable
zone earth - sized planets
around sun - like
stars is about 50 %, and for lower - mass
stars this value is likely to be even higher: most
red dwarf stars are expected to have one or more habitable
zone, approximately earth - sized planets.
The results show that even though
red dwarfs are much more numerous, they have a narrower habitable
zone than yellow
dwarfs, so our existence
around a
star like the sun is actually to be expected.
NASA's Kepler space observatory has shown that almost all
red dwarf stars host planets in the range of one to four times the size of Earth, with up to 25 percent of these planets located in the temperate, or «habitable,»
zone around their host
stars.
The close - in orbit
around the cool
star implies a mean surface temperature of between 0 and 40 degrees C - a range over which water would be liquid - and places the planet in the
red dwarf's habitable
zone.
Previously discussed in a November 24, 2011 pre-print, the astronomers «surveyed a carefully chosen sample of 102
red dwarf stars in the southern skies over a six - year period» and found a «total of nine super-Earths (planets with masses between one and ten times that of Earth),» of which two orbiting within the habitable
zones of Gliese 581 and Gliese 667 C. By combining all the radial - velocity data of
red dwarf stars (including those without undetected planets) and examining the fraction of confirmed planets that was found, the astronomers were able to estimate the probable distribution of different types of planets
around red dwarfs: for example, only 12 percent of such
stars within 30 light - years may have giant planets with masses between 100 and 1,000 times that of the Earth (ESO news release; Bonfils et al, 2011; and Delfosse et al, 2011).
In addition to 10 unconfirmed, weaker «signals,» the team was able to detect eight super-Earths
around red dwarfs between 15 and 80 light - years away from our Sun, Sol, of which three orbit within the habitable
zones of their host
stars.
Whilst all the exoplanets discovered
around the
red dwarf, known as TRAPPIST - 1, are capable of hosting liquid water on their surfaces, three are in orbit in what is known as a
star's habitable
zone, making them an attractive prospect for scientists searching for life outside of our solar system.