HD 40307

0.191 L ☉

HD 40307 is a 41.8 light years distant main sequence star of spectral type K 2.5 in the constellation of painters. Overall, so far six planets could be detected orbiting HD 40307. The star has no proper name, so its catalog number is used in the Henry Draper Catalogue as a label.

Physical Properties

HD 40307 is provided with a radius of 0.77 sun radii both somewhat smaller and less bright than the sun. Both stars are dwarf stars, with K2.5 part of HD 40307 but a later spectral class than the sun with G2. This difference is due to the to the sun slightly cooler surface temperature of about 4500 ° C ( 4730 ± 50 K).

As the sun is a main sequence star HD 40307 of luminosity class V. Thus, they are situated in the stable phase of hydrogen burning. The deviations of the physical parameters between HD 40307 and the Sun are essentially due to the different stellar masses. This is also reflected in the position of the stars to each other reflected on the main sequence. The mass of HD 40307 is about 0.77 solar masses. Therefore, the star about 15 to 20 billion years, and thus a few billion years is longer than the sun ( 11.4 billion years ), stay in the main sequence.

At the end of his life HD 40307 will consume its supply of hydrogen to reach the state of a red giant that will engulf his planet, and eventually end up as a white dwarf.

Planetary system

HD 40307 is orbited by at least six planets that have e 40307, HD 40307 and HD get f 40307 g the provisional designations HD 40307 b, HD 40307 c, HD 40307 d, HD. These are all so-called super-Earths, the smallest of them is about four times as heavy as the earth. As the planets are exact nature is still unclear. Their mass is indicated by the 4.2 -fold, 6.7 -fold and 9.4 - times the mass of Earth. At 4.3, 9.6, 20.4, 34.6 and 51.76 days orbiting the inner five companions their star much faster than the sun closest planet Mercury.

The discovery of the first three exoplanets came with the spectrograph HARPS at Chilean La Silla Observatory of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO ).

Thanks to a more accurate measurement using a new method to separate the natural light variations of the star of the signals of its possible satellites, kicked three more planets to light. The outermost of HD 40307 g, has about seven times the mass of Earth and orbits within the habitable zone around its star. For this reason, water and atmosphere is there maybe exist.