The small planets can sometimes stir up a great clamor. For weeks the media report rumors about the discovery of a potentially habitable planet orbiting the nearest star to our Sun, a red dwarf called Proxima Centauri.
Today, finally, astronomers have confirmed the discovery of this alien world with an article published on magazine Nature .
the observations conducted with a huge telescope in Chile have indeed revealed a mass Earth-like planet orbiting Proxima Centauri, located a stone’s throw – cosmically speaking – from us, namely to “only” 4.24 years distance light. In addition, the planet would be in a sufficiently hot orbit to allow water to remain on its surface to the liquid state.
Illuminated by a pale reddish light, the planet orbits the smaller star of the triple system of Alpha Centauri, which shines in the southern constellation of Centaurus. This system, widely used as a setting by science fiction authors, is often considered potential destination of the first interstellar journey of humanity,
and possible refuge for future civilization on the run from the inevitable end of the Earth as we know it today.
“a rocky, habitable planet that orbits around Proxima is the most obvious place where our civilization could think about moving when, in five billion years, the Sun will go out,” says Avi Loeb of the Harvard-Smithsonian Center for Astrophysics and advisor to the San Francisco Rush Breakthrough project.
Even before the discovery of the project Breakthrough Francisco Rush had announced plans to send spacecraft to Alpha Centauri lower by the end of the century. But do not expect any postcard from the system in a short time: while traveling at a monstrous rate of one twentieth of that of light, it would take twenty years to the spacecraft arrived at Proxima Centauri, and other 4.24 years before qualsiati information could reach the Earth.
the exoplanets fans may recall that in 2012 was already announced the discovery of a planet in the Alpha Centauri system, the planet of which later they failed to confirm the existence; subsequent observations revealed instead that it was altered data and the activity of the star itself.
The new observations, conducted over 54 nights, however, appear to be very difficult to refute: the planet’s presence continues to appear evident even when the data are controlled by a human eye and not dall’algoritma a computer.
“the information is quite unequivocal”, says Greg Laughlin of Yale University. “it’s not one of those cases when you have to resort to black magic to fetch a signal. “
looking for Proxima
Baptized Proxima b, the planet has been discovered by a group of scientists working on Pale red dot design (or light red dot, named in homage to the “blue dot” used by Carl Sagan to describe the Earth as seen from space).
from a point of view scientific discovery is not exactly a surprise. The harvest of exoplanets discovered in the last decade has shown us that it is quite likely that red dwarfs like Proxima harboring planets, and that most of these planets are like the one just discovered: the small, rocky, and hot enough to have water at liquid flowing on the surface.
Although the research done so far around Proxima had not officially come to nothing, there had been encouraging signs that indicated the possible presence of at least one planet that could have been identified by performing more extensive research.
circling around a star, the planet exerts on it its force of gravity, and gravitational pull produces an oscillation; the largest planets cause oscillation greater. smaller planets of mass similar to that of Earth, induce an oscillation smaller, harder to detect, and to locate them more extensive observations and performed with much more sensitive instruments are needed.
The observations made in sporadically between 2000 and 2014 they had suggested the presence of a planet with an orbit of 11 days around Proxima, but the information gathered was too confusing to draw more than a clue. Determined to find out if the oscillations of Proxima was indeed caused by a planet, earlier this year researchers from Pale Red Dot have pointed toward the red dwarf the most precise tool available to the Earth, ie the High Accuracy Radial velocity Planet Searcher (HARPS).
Located at the European Southern Observatory in La Silla, Chile, HARPS has measured the flicker of the night star after night, allowing the team to almost immediately identify in the data same recurring signal every 11 days. After 20 nights, Guillem Anglada-Escudé, Queen Mary University of London, he began to believe that perhaps it had identified, and after another 10 started to throw down a first draft of the article published on August 24 to Nature .
“We tried not to let us get carried away, because we collected only one measurement per night,” Anglada-Escudé said. “We did not want to make an announcement and then having to disprove two months later “. The measurements indicate that Proxima b has about 1.3 times the mass of Earth and orbits in 11.2 days around its star.
planet or star?
With the ghost of Alpha Centauri B that hovered over them, the Pale Red Dot team tried very carefully to confirm their discovery. First, he took a step back and reworked the observations made since the beginning of the century. Then, it had to be able to exclude that the same star was the signal source from 11.2 days. It was not an easy task, considering the capricious nature of Proxima Centauri, which is constantly producing plasma eruptions emettonio radiation in space.
“There are some tests that can show that what seems to be a planet is actually stellar activity, “explains Lauren Weiss of the University of California, Berkeley. “Researchers have performed them all, and the result is that the hypothesis of the planet holds.”
There are even some indications that Proxima b may have brothers: from the data seems to indicate the presence of a super-Earth with an orbit of 200 days, but researchers will have to collect more data before we can determine the origin of the signal.
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