HD 40307

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Stern
HD 40307
Position of HD 40307
Position of HD 40307
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation painter
Right ascension 05 h 54 m 4.24 s
declination -60 ° 01 ′ 24.5 ″
Apparent brightness 7.17 likes
Typing
Known exoplanets 6th
B − V color index (0.95) 
U − B color index (0.72) 
R − I index (0.48) 
Spectral class K3 V
Astrometry
Radial velocity (31.30 ± 0.16) km / s
parallax (77.27 ± 0.03)  mas
distance (42.19 ± 0.02)  Lj
(12.941 ± 0.005)  pc
Visual absolute brightness M vis +6.60 mag
Proper movement 
Rec. Share: (−52.42 ± 0.07)  mas / a
Dec. portion: (−60.15 ± 0.06)  mas / a
Physical Properties
Dimensions (0.77 ± 0.05)  M ☉
Luminosity

(0.23)  L ☉

Effective temperature (4977 ± 59)  K.
Metallicity [Fe / H] (−0.31 ± 0.03)
Rotation time 19.4 d
Age 4.5 billion  a
Other names
and catalog entries
Cordoba Survey CD −60 ° 1303
Henry Draper Catalog HD 40307 [1]
Gliese catalog FY 2046 [2]
Hipparcos catalog HIP 27887 [3]
SAO catalog SAO 249388 [4]
Tycho catalog TYC 8892-1247-1 [5]Template: Infobox star / maintenance / specification of the TYC catalog
2MASS catalog 2MASS J05540421-6001245 [6]
annotation
  1. ↑ Calculated from apparent brightness and distance.

HD 40307 is a 41.8 light-years distant main sequence star of spectral class K 3 in the constellation Maler . A total of six planets orbiting HD 40307 have been detected so far. The star has no proper name, so its catalog number is used as a designation in the Henry Draper catalog .

Physical Properties

HD 40307 is both slightly smaller and less luminous than the sun . Both stars are dwarf stars , but HD 40307 with K3 belongs to a later spectral class than the sun with G2. This difference is due to the slightly cooler surface temperature of almost 5000 K compared to the sun .

Like the sun, HD 40307 is a main sequence star of luminosity class  V. As a result, they are in the stable phase of hydrogen burning. The deviations in 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 one another on the main sequence. The mass of HD 40307 is about 0.77 solar masses. Therefore, the star will remain in the main sequence for about 15 to 20 billion years, and thus a few billion years longer than the sun (11.4 billion years).

At the end of its life, HD 40307 will use up its supply of hydrogen, reach the state of a red giant that will devour its planets, and eventually end up as a white dwarf .

Planetary system

HD 40307 is orbited by at least six planets , which have been given the provisional designations HD 40307 b , HD 40307 c , HD 40307 d , HD 40307 e , HD 40307 f and HD 40307 g . These are all so-called super-earths , the smallest of them is about four times as heavy as the earth . Exactly how the planets are is still unclear. Their mass is given as 4.2 times, 6.7 times and 9.4 times the mass of the earth. With 4.3, 9.6, 20.4, 34.6 and 51.6 days, the five inner companions orbit their star much faster than the planet Mercury, the closest to the sun .

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

Thanks to a more precise measurement with a new method with which natural luminous fluctuations of the star separate from the signals of its possible satellites, three more planets emerged. The outermost of these, HD 40307 g , has about seven times the mass of the earth and orbits within the habitable zone around its star. Because of this, there may be water and an atmosphere there.

HD 40307 planets
Planet
(according to the distance from the central star) 		Discovered Mass
(in M J ) 		Cycle time
(in days ) 		Major semi-axis
(in AU )
HD 40307 b 2008 0.0120 4.31 0.047
HD 40307 c 2008 0.0202 9.62 0.081
HD 40307 d 2008 0.0275 20.42 0.134
HD 40307 e 2012 0.0110 34.62 0.189
HD 40307 f 2012 0.0114 51.56 0.249
HD 40307 g 2012 0.0223 197.8 0.60

Web links

Commons : HD 40307  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f g HD 40307. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed December 7, 2018 .
  2. ↑ a b Hipparcos catalog (ESA 1997)
  3. ↑ a b c HD 40307 g. In: Extrasolar Planets Encyclopaedia . Retrieved July 7, 2018 .
  4. ↑ a b HD 40307 b. In: NASA Exoplanet Archive . Retrieved July 7, 2018 .
  5. ↑ Planet HD 40307 g Astronomers marvel at Super-Earth. Spiegel Online, November 8, 2012, accessed November 8, 2012 .
  6. ↑ Mini-Invasion of Exoplanets - Article in Telepolis , June 17, 2008
  7. ↑ Mikko Tuomi, Guillem Anglada-Escudé, Enrico Gerlach, Hugh RA Jones, Ansgar Reiners, Eugenio J. Rivera, Steven S. Vogt & R. Paul Butler: Habitable-zone super-Earth candidate in a six-planet system around the K2 .5V star HD 40307. Astronomy & Astrophysics , November 8, 2012 PDF
  8. ↑ Exoplanet.eu: Exoplanet Catalog. Retrieved July 7, 2018 .