Many of us have asked themselves, “Are we alone in this universe?” While humanity does not yet have definitive answers to this question, scientists are continuously on the search for indicators that could hint to the existence of extraterrestrial life.

And what better way to begin than by looking for other Earth-like planets that may be capable of supporting life?

There has recently been a considerable influx of study into exoplanets, albeit the reason for these investigations varies across organizations. Some are simply looking for an answer to the alien life mystery, while others are looking for a second home for us Earthlings.

We may have some good news for all you exoplanet fans now. The Subaru Strategic Program, launched in 2007 to deliver remarkable scientific results utilizing Japan’s Subaru Telescope, has assisted in the discovery of a super-Earth skimming the outskirts of a red dwarf star’s habitable zone, just 37 light-years from our home planet!

Home away from home?

The recently discovered Ross 508 planetary system is depicted schematically. The green region indicates the habitable zone (HZ), which is a region on the planet’s surface where liquid water can exist. A blue line represents the planetary orbit. The planet is expected to be closer than the HZ (solid line) during more than half of its orbit and within the HZ (dashed line) for the remainder. (Astrobiology Institute)
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.

The research findings have been detailed in the Publication of the Astronomical Society of Japan and can be accessed here.Reference(s):