NASA has confirmed nearly 6,000 planets orbiting stars beyond our solar system, and thousands more "candidates" are waiting to be confirmed.
"Exoplanets are primarily found through methods like the transit method (observing a dip in a star's brightness when a planet passes in front of it) and radial velocity (measuring the "wobble" of a star caused by a planet's orbit)," reports Space.com.
There's a red dwarf star named L 98-59, about 35 light-years from Earth, with five rocky planets in orbit. The fifth planet discovered, just announced by the team led by the Trottier Institute for Research on Exoplanets (IREx) at the Université de Montréal, and soon to be published in "The Astronomical Journal," has generated a lot of excitement in the astronomical community.
Charles Cadieux of the Université de Montréal said "Finding a temperate planet in such a tight system is thrilling. It shows how diverse exoplanet systems can be, and why low-mass stars deserve our focus.”
Red dwarf stars are, by far, the most common stars in the universe. They make up 70-80% of all the stars in our Milky Way galaxy. Until recently, the prospect of finding life on a planet orbiting a red dwarf star was dismissed as very unlikely. A planet that could support life would have to be orbiting very close to the red dwarf, and the temperate zone where liquid water could exist is extremely narrow. A planet's proximity to a red dwarf would mean that the planet was tidally locked with one side facing the sun all the time. On top of all that, red dwarfs are notoriously unstable with frequent blasts from solar flares that could rip away any planetary atmospheres.
While the prospects of life might not be the best on a planet orbiting L 98-59, finding any planet that resides in the "Goldilocks Zone" (not too warm not too cold, but just right) is always cause for excitement. The red dwarf features five planets in that zone.
The four other planets are an interesting mix, according to the science magazine Futura.
* Sub-Earth: Only 84 % of Earth’s width and half its mass.
* Volcanic Neighbor: About 1.33 R⊕—likely tidally heated, like Jupiter’s moon Io.
* Ocean Candidate: At 1.63 R⊕, its low density hints at a deep water layer.
* Heavy Hitter: Nearly three Earth masses, rounding out the inner foursome.
L 98-59 is now a top target for the James Webb Space Telescope, the most powerful optical telescope ever built. JWST will not only be able to image the planet and gather huge amounts of information about it but also possibly be able to identify unmistakable "signatures of life" as we know and understand it.
As well as allowing for the presence of liquid water, the habitable zone of a solar system is the region where, potentially, planetary conditions could allow for the development of life. Each star has its own habitable zone, determined by its type and the amount of energy it emits.
The L 98-59 star system is gradually gaining attention among the science community. Each confirmed exoplanet is as intriguing as the rest, and all are in the habitable band. The planet closest to the star is half the mass of Venus but 85 percent the size of Earth. The second is almost 2.5 times more massive than our planet. The third may be 30 percent oceanic. Little is known about the fourth, except that it is also a “super-Earth”—a term used to describe planets larger than our own but smaller than the ice giants of our solar system.
"TRAPPIST-1, which is 39 light-years from Earth. It is an ultracool dwarf star with at least seven rocky exoplanets, three of which are in the habitable region," reports Wired. The Sci-Fi channel series "The Ark" features a trip to Trappist 1, where they hope to colonize one of the planets.
It's interesting simply because if we ever do organize a mission to colonize another Earth, Trappist 1 would be close to the top of the list.
