Exoplanet discovered in nearest star: Now in Proxima Centauri
Proxima Centaui is known as the nearest star to our Sun, at a distance of (only) four light years away. Of course four light years is a lot, but considering the magnitudes of space distances we can consider it to be not that much. It comes up that a second exoplanet (planet outside our Solar System) has been discovered orbiting this star.
This discovernment is added to that of Proxima b, the first exoplanet found in the system of Proxima Centauri. This star with a mass of about 1.3 times Earth’s was found in 2016 and completes a round about its main star every 11 days. The new exoplanet discovered has been named Proxima c and its mass is about 5.8 times that of Earth. This super Earth planet, for which were needed 17 years of data recording, orbits around its star every 5 years.
Different methods exist to discover exoplanets, maybe the most known is analyzing the star’s brightenss in search for an intensity decrease due to an object transit (planet passing in front of the star and therefore blocking part of its light). However this is not the only method which exists to find exoplanets, have a look at this interesting summary of applied techniques for exoplanet finding! Radial velocity method was the technique by which Proxima b was found after analyzing Proxima Centauri’s spectral lines of a 10-year data recording. Proxima c was discovered in april 2019, but confirmed recently. The discovernment was possible thanks to the combination of information from two different telescopes: HARPS and UVES.
Differently to our Sun, Proxima Centauri is a red dwarf, in fact we can very interestingly classify stars in three categories which are in turn related to their probability of holding life on their planets. As a red dwarf, it is dimmer that our Sun; furthermore the smaller the celestial object, the less its gravity force, then its not so likely that many planets orbit it and if they do, distance of habitable zone to this star is shortened with respect to the distance of the habitable zone in our Solar System (which of course Earth is part of) to Sun.
Distance of Proxima b to its main star is only 5% of the distance from Earth to Sun. Being that close to Proxima Centauri then Proxima b is quite likely to be a rocky planet with no atmosphere and liquid water at all. Proxima c is, on the other hand, 1.5 AU far from Proxima Centauri and quite likely wrapped by a hydrogen-and-helium envelope. This distance is equivalent to one-and-a-half times that of Earth to Sun (1 AU is the measurement unit correspondent to the distance from our planet to Sun).
We will have to wait for information coming from Gaia mission, which has the objective of scanning our galaxy, to finally confirm Proxima c exoplanet and its mass. Furthermore, because of its separation from star Proxima Centauri, it could be the closest Earth-like exoplanet to be ever imaged, something that would be possible with future ground and space-based observatories like James Webb, ELT or GMTO coming up this decade.
Thank you for reading!
|Medium (Ethan Siegel). Astronomers Announce Proxima Centauri’s Second Planet, And It’s Perfect For Direct Imaging. Retrieved from: https://medium.com/starts-with-a-bang/astronomers-announce-proxima-centauris-second-planet-and-it-s-perfect-for-direct-imaging-6e868b68da6b|
|El Mundo (Teresa Guerrero). Nuevas pruebas apuntan a que la estrella más cercana alberga un segundo planeta. Retrieved from: https://www.elmundo.es/ciencia-y-salud/ciencia/2020/01/15/5e1f58ccfdddff4d928b464c.html|
|James Webb Space Telescope. Retrieved from: https://www.jwst.nasa.gov/|
|The Planetary Society. How to Search for Exoplanets. Retrieved from https://www.planetary.org/explore/space-topics/exoplanets/how-to-search-for-exoplanets.html|