“Are we alone in this universe?” is something many of us have asked ourselves. While humanity has no definitive answers to this question yet, scientists are constantly on the lookout for clues that might point to the existence of extraterrestrial life.
And what better way to start than to find other Earth-like
planets that might be capable of sustaining life?
Of late, there’s been a large influx of research probing
into exoplanets, although the motivation behind these studies varies across
organisations. Some are merely looking for a solution to the alien life puzzle,
while others are hunting for a second home for us Earthlings to settle on.
Now, we might have some good news for all you
exoplanet-enthusiasts. The Subaru Strategic Program — initiated in 2007 to
produce outstanding scientific outcomes using Japan’s Subaru Telescope — has
helped discover a super-Earth skimming the edges of the habitable zone of a red
dwarf star just 37 light-years from our home planet!
Home away from home?
 |
Schematic diagram of the newly discovered Ross 508 planetary
system. The green region represents the habitable zone (HZ) where liquid water
can exist on the planetary surface. The planetary orbit is shown as a blue
line. For more than half of its orbit, the planet is estimated to lie closer
than the HZ (solid line) and within the HZ (dashed line) for the rest of the
orbit. (Astrobiology Center) |
Named Ross 508b, this ‘super-Earth’ is a rocky world with a
mass around four times that of our Earth.
And a year on Ross 508b lasts for just 11 Earth-days! This,
of course, means that its orbit is not very large — which is understandable
because red dwarfs are a lot smaller than the Sun that centres our solar
system.
But their smaller sizes mean that their gravitational fields
are also not as expansive as the Sun’s. Therefore, Ross 508b revolves around it
at a distance of just 5 million kilometres. Considering Mercury, for
comparison, the planet is about 60 million kilometres from the Sun.The short
distance between this super-Earth and its red dwarf begs the question: how
could it possibly be deemed habitable?Well, the Ross 508b’s orbit is
elliptical, meaning it isn’t always as close to the star, and pretty much dips
in and out of the habitable zone.
A planet like this may be able to retain water on its
surface. Whether or not water or life actually thrives there is still up for
debate and some serious research.
The relationship between red dwarfs and habitable planets
Three-quarters of the stars in the Milky Way galaxy are red
dwarfs smaller than the Sun and such stars are abundant in the solar
neighbourhood. Because of this, they are crucial targets in humanity’s hunt for
neighbouring extrasolar planets and extraterrestrial life.
However, red dwarfs are cooler than other types of stars and
emit less visible light, which makes studying them challenging.
What makes this find even more special is that it is the
first exoplanet to be found by the Subaru Strategic Program using the infrared
spectrograph IRD on the Subaru Telescope (IRD-SSP).The team at Astrobiology
Center in Japan developed IRD specifically to search for red dwarf-orbiting
exoplanets like Ross 508b. It relies on a planet-hunting technique that looks
for minute deviations in the velocity of a star to infer a planet orbiting it.
It wouldn’t be a stretch to assume that the Subaru Telescope
could bestow us even better candidates for habitable planets around red dwarfs.
“It has been 14 years since the start of IRD’s development.
We have continued our development and research with the hope of finding a
planet exactly like Ross 508b,” said Tokyo Institute of Technology’s Professor
Bun’ei Sato, the principal investigator of IRD-SSP.
This study has opened doors for future observations to
confirm the possibility of life around low-mass stars.