Artist's impression of Proxima Centauri b

Proxima Centauri b: Did We Find Earth’s Cousin?

On august 24, 2016, a group of scientists led by Dr. Guillem Anglada-Escude at the Queen Mary University of London, announced the discovery of a terrestrial exoplanet orbiting the red dwarf Proxima Centauri, the nearest known star to the Sun. Proxima Centauri is a Latin idiom, meaning “nearest (star) of Centaurus(1)“. The new planet is named Proxima Centauri b and it is predicted to be orbiting within the habitable zone!

Proxima Centauri is the third component of the Alpha Centauri binary star system (α Cen), the closest star system to the Solar System at a distance of 4.37 light-years. It consists of three stars: the pair Alpha Centauri A and Alpha Centauri B and a small and faint red dwarf, Proxima Centauri, that may be gravitationally bound to the other two. To the unaided eye, the two main components appear as a single object of an apparent visual magnitude of −0.27, forming the brightest star in the southern constellation Centaurus and the third-brightest star in the night sky, outshone only by Sirius and Canopus.

Alpha, Beta and Proxima Centauri
α Centauri and β Centauri, with Proxima circled. Photo: wikipedia

On August 24, 2016, the researchers of European Southern Observatory in Chile announced the discovery of the newest member of the exoplanets(2). Shortly after the discovery, it turned out that that the exoplanet may be the nearest possible location for life beyond our solar system.

Artist's impression of Proxima Centauri b
This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Image: ESO/M. Kornmesser

Proxima Centauri b is close enough to its star, approx. 7.5 million kilometers (4.7 million miles), that it might be tidally locked. This means one side of the planet is constantly faces to its star, while the other side is in a permanent darkness. It’s very likely that the daytime side of the planet would be extremely hot while the temperatures at the nighttime side below freezing.

The planet orbits its host star every 11.186 days, so if there is some sort of intelligent life on the planet, they celebrate the new year very frequently.

Intelligent Life?

It is too early to getting excited about an intelligent life (or even simply life) on the planet. The planet is at the right place to have a temperature that allows the presence of liquid water on its surface, but the researchers still not sure if the planet is a rocky planet like Earth, or a bigger ball of gas (a baby Neptune?). It is also so close to its star, the result is, it is bombarded with X-rays 400 times stronger than the Earth receiving from Sun. This makes the existing of the life even more unlikely.

We still don’t know if planet has big satellites. Our moon played an important role in the evolution of life on Earth. On the other hand, the red dwarfs can live hundreds of times longer than Sun-like stars. So, maybe there may be plenty of time for the life to adapt and prosper.

Researchers think that its proximity to Earth offers an opportunity for possible robotic exploration of the planet “in the coming centuries”.

Artist's conception of Proxima Centauri b, with Proxima Centauri and the Alpha Centauri binary system in the background
Artist’s conception of Proxima Centauri b, with Proxima Centauri and the Alpha Centauri binary system in the background. Image: ESO/M. Kornmesser

Notes

  • Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse (another constellation named after a centaur is one from the zodiac: Sagittarius). Notable stars include Alpha Centauri, the nearest star system to the Solar System.
  • An exoplanet is a planet that orbit around a star other than our own Sun. The first exoplanet was discovered in 1995. As of August 2016, there are total of 2951 confirmed exoplanets. There are also 2503 unconfirmed Kepler candidates, and the grand total is 5454 (confirmed exoplanets + Kepler candidates). Source: exoplanets.org. NASA’s Kepler Space Telescope proved that there are on average two exoplanets per star in our galaxy, the Milky Way. Kepler has also shown that most of these planets are terrestrial (like Earth or bigger – so-called “super-Earths”). The exoplanets discovered by Kepler are very distant—too far away for us to observe (and thereby study) using techniques available today.

Sources

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