A new scientific study reveals the discovery of a new “compact” planetary system that revolves around the star Gliese 887, one of the closest to our planet. It is about two confirmed “super-lands” and a possible third planet than would be in the habitable zone of his star, so that could have liquid water on its surface and harbor life, states the study published in Science.
A compact planetary system is made up of more than one planet, which have close and dynamically tight orbits around a star, and this it is the closest to Earth found so far.
At “only” 11.8 light years away, Gliese 887 is the 10th closest star to the Sun, is about half the mass of the Sun and is the brightest red dwarf that can be seen from Earth, although not with the naked eye .
The two planets now located fall into the category of super-earths, that is, with a mass greater than our planet but substantially less than Uranus or Neptune.
“We know that these types of planetary systems are quite common in other stars – between 15 and 30 percent of solar-type stars – but we had not found any very close to the Sun,” Guillem Anglada-Escudé told Efe, from the Spanish Institute of Space Sciences.
This “will be, a bit, a reference system to understand this type of planetary systems so common in other stars, but so different from the one in the Solar System,” adds the also astronomer from Queen Mary University of London.
So far, scientists have identified two planets, Gliese 887b and Gliese 887c, with orbital periods of 9.3 and 21.8 days, respectively, which is much faster and closer than Mercury’s orbit around the Sun.
With temperatures between 200 and 70 degrees, both planets might be a little too hot to have liquid water on their surface.
Planetary system more common than the Solar system
The existence of two planets with such closed orbits is not “surprising”, indicates Anglada-Escudé, who points out that, in this sense, “the ‘abnormal’ is the Solar System, which has almost no planets in internal orbits”.
There are other closer planetary systems, such as Proxima Centauri and Wolf359, located at 4.2 and 7.9 light years, respectively, but they are not compact, as is the case with GJ887.
A third planet in the system could host life
The team led by Sandra Jeffers from the University of Göttingen (Germany) has also found evidence, not yet confirmed, of the existence of a third exoplanet.
This possible third planet would have an orbital period of about 50 days, which can locate it in the so-called habitable zone of the star, in which the existence of liquid water on the surface would be possible.
If it finally exists, it would be -indicates Anglada-Escudé- “of the few so close and located in the good area” of its star, in addition to the exoplanet Proxima-b, which orbits Proxima Centauri, a red dwarf that is the closest star to the Sun.
To confirm the existence of this third planet around GJ 887, some more data is needed and the scientist believes that they can be obtained in a couple more observation campaigns of a few months.
Planetary system revolves around a ‘young’ star
GJ 887 is an old and very inactive star, if it were as much as our Sun, the solar wind is likely to sweep the atmosphere of its two planets, but in this case they may retain it or even be thicker than that of Earth , indicates the University of Göttingen in a statement.
The team observed GJ 887 for three months thanks to the High Accuracy Radial Velocity Planet Searcher (HARPS), a high-precision spectrograph to find planets, from one of the telescopes of the European Southern Observatory (ESO) in La Silla (Chile).
In addition, he used a method called Doppler spectroscopy, which measures the star’s round-trip motion caused by the gravitational pull of orbiting planets and other archival data spanning more than twenty years.
Although there are still many things to know about GJ 887 and its system, Anglada-Escudé says that being an old and one of the most inactive stars known could indeed “favor” the development of life, having had more time to evolve.
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