The star HD 40307 planet is potentially habitable. Article scientists accepted for publication in the journal Astronomy & Astrophysics, and its summary results Space.com. Preprint of the paper is available at arXiv.org. HD 40307 is located at a distance of 42 light-years (41.8 light-years with an uncertainty 0.8 light years) from Earth in the constellation Pictoris.
It has in the past attracted the attention of scientists – in 2008, scientists at the European Southern Observatory (ESO) have discovered three planets around the star. All three are so-called super-Earths – planets whose mass is 1-10 earth. Mass planets detected was 4.2, 6.8 and 9.2 of the earth.
Under the new international team of researchers conducted a re-analysis of the data collected by HARPS – Spirograph installed in the La Silla Observatory. As a result, they have found at least another three planets. Two of them are relatively small mass (1-3 Earth) orbit the star with periods of 34 and 51 days. The third planet, designated HD 40307g, orbits the star with a period of about 200 days. Its mass is about 7 earth. According to scientists, given spectral type, to which the star (Type K – intermediate between a star similar to the Sun), the planet is located in the so-called habitable zone – the region where the surface of the planet may be liquid water. Moreover, astrophysicists say that the planet is likely located far enough from the sun to avoid the tidal capture. Scientists refer to this term rotation mode, in which one of the bodies is always turned to another of the same side as, for example, the Moon to the Earth. In the case of the planets and the stars of the tidal capture means that half of the planet will always be heated by the sun, and the other half – in the shadow. It is believed that such conditions are not conducive to the origin of life. It is noteworthy that astrophysicists do not exclude the possibility that their planet is a small gas giant, a smaller version of Neptune. In addition, in September 2012 published a work group of researchers led by Vlada Stamenkovic of the Massachusetts Institute of Technology, who argue that the geological structure of super-Earths is fundamentally different from the Earth. This, in their view, be an obstacle to the formation of life on this planet. Who knows six candidates for the title of the world, potentially habitable. To fall into this category should be rocky planet and its surface should be a condition for the existence of liquid water. Four of the six candidates – Gliese 581d, Gliese 667Cc, Gliese 581g and Gliese 163c – located around red dwarfs (generally speaking, astronomers debated whether to consider as a red dwarf stars, around which could be habitable planets). Another candidate, HD 85512, orbits the star of the class K (and HD 40307g). Finally, the only exoplanet moving around nontransferable Star (G-Class) – Kepler-22b. It was opened in December 2011. It is located at a distance of 600 light years from Earth.