Goldilocks Zones and Stars
Explanation:
The Goldilocks zone is the habitable zone
around a star where it's not too hot and not too cold for liquid water
to exist on the surface of orbiting planets.
This
intriguing infographic includes
relative sizes of those zones for yellow G stars like the Sun, along
with orange K dwarf stars and red M dwarf stars,
both cooler and fainter than the Sun.
M stars (top) have small,
close-in Goldilocks zones.
They are also seen to live long (100 billion years or so) and are very
abundant, making up about 73 percent of the stars in the Milky Way.
Still, they have very active magnetic fields and
may produce too much radiation harmful to life,
with an estimated X-ray irradiance 400 times the quiet Sun.
Sun-like G stars (bottom) have large Goldilocks zones and are relatively calm,
with low amounts of harmful radiation.
But they only account for 6 percent of Milky Way stars and are
much shorter lived.
In the search for habitable planets,
K dwarf stars could be just right, though.
Not too rare
they have 40 billion year lifetimes, much longer than the Sun.
With a relatively wide habitable zone
they produce only modest amounts of harmful radiation.
These Goldilocks stars
account for about 13 percent of the stars of the Milky Way.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
