HD 40307 g

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HD 40307 g
Extrasolar planet List of extrasolar planets
Parent star
Star HD 40307
Constellation Pictor
Right ascension (α) 05h 54m 04.2409s[1]
Declination (δ) −60° 01′ 24.498″[1]
Apparent magnitude (mV) 7.17[1]
Distance 41.8 ± 0.3 ly
(12.83 ± 0.09[1] pc)
Spectral type K2.5V[1]
Radius (r) 0.716 ± 0.010[2] R
Temperature (T) 4977 ± 59[3] K
Metallicity [Fe/H] −0.31 ± 0.03[3]
Age 1.2 (≥ 0.2)[4] Gyr
Orbital elements
Semimajor axis (a) 0.600[5] AU
Eccentricity (e) 0.22[5]
Orbital period (P) 197.8 ± 9.0[5] d
Semi-amplitude (K) 0.95 ± 0.3[5] m/s
Physical characteristics
Mass (m) 8.19[6] M
Radius (r) 2.39 [6] R
Temperature (T) 279[7] K
Discovery information
Discovery date October 28, 2012
Discoverer(s) Mikko Tuomi et al.
Discovery method radial velocity, using HARPS
Discovery site La Silla Observatory, Chile
Discovery status Announced[5]
Database references
Extrasolar Planets
Encyclopaedia
data
SIMBAD data

HD 40307 g is an exoplanet orbiting in the habitable zone of HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus[5][8][9] by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Goettingen, Germany.[9]

Composition theories[edit]

The codiscoverer Hugh Jones, of the University of Hertfordshire in England, surmised: "The longer orbit of the new planet means that its climate and atmosphere may be just right to support life." [8]

However another astronomer, Rory Barnes of the University of Washington, had already studied the orbits of the planets b, c, and d. First, Barnes had presumed b to take on too much tidal heating for it to be terrestrial, instead predicting a "mini-Neptune". He thought that b, c, and d had all migrated inward;[10] and this must be extrapolated to e and f as well which are further out but not by much. It is possible that HD 40307 g has also migrated into where it is now. The discoverers of HD 40307 g did not try to refute Barnes, on the nature of b and its extrapolation to the other planets. The composition of g is unsettled.[11]
Lead author Mikko Tuomi, also of the University of Hertfordshire, stated "If I had to guess, I would say 50-50, But the truth at the moment is that we simply do not know whether the planet is a large Earth or a small, warm Neptune without a solid surface."[8]

See also[edit]


References[edit]

  1. ^ a b c d e "HD 40307". SIMBAD. Centre de Données astronomiques de Strasbourg. 2008. Retrieved 18 June 2008. 
  2. ^ HD 40307, entry, CDS database J/A+A/450/735; described in Effective temperature scale and bolometric corrections from 2MASS photometry, E. Masana, C. Jordi, and I. Ribas, Astronomy and Astrophysics 450, #2 (May 2006), pp. 735–746. Bibcode2006A&A...450..735M. doi:10.1051/0004-6361:20054021.
  3. ^ a b M. Mayor, S. Udry, C. Lovis, F. Pepe, D. Queloz, W. Benz, J.-L. Bertaux, F. Bouchy, C. Mordasini, D. Segransan (2009). "The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 Super-Earths (4.2, 6.9, & 9.2 Earth masses)". Astronomy and Astrophysics 493 (2): 639–644. arXiv:0806.4587. Bibcode:2009A&A...493..639M. doi:10.1051/0004-6361:200810451. 
  4. ^ HD 40307, database entry, Geneva-Copenhagen Survey of Solar neighbourhood, J. Holmberg et al., 2007, CDS database V/117A, accessed November 19, 2008; described in The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14 000 F and G dwarfs, B. Nordström, M. Mayor, J. Andersen, J. Holmberg, F. Pont, B. R. Jørgensen, E. H. Olsen, S. Udry, and N. Mowlavi, Astronomy and Astrophysics 418 (May 2004), pp. 989–1019, Bibcode2004A&A...418..989N, doi:10.1051/0004-6361:20035959.
  5. ^ a b c d e f Tuomi, Anglada-Escude, Gerlach, Jones, Reiners, Rivera, Vogt, Butler, Mikko, Guillem, Enrico, Hugh R. R., Ansgar, Eugenio J., Steven S., R. Paul (2012). "Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307". arXiv:1211.1617v1 [astro-ph].
  6. ^ a b PHL's Exoplanets Catalog - Planetary Habitability Laboratory @ UPR Arecibo
  7. ^ "HEC: Data of Potential Habitable Worlds". University of Puerto Rico at Arecibo (Planetary Habitability Laboratory). November 12, 2012. 
  8. ^ a b c Wall, Mike (November 7, 2012). "'Super-Earth' Alien Planet May Be Habitable for Life". Space.com. Retrieved November 8, 2012. 
  9. ^ a b Tate, Karl (November 7, 2012). "Super-Earth Planet: Potentially Habitable Alien World Explained (Infographic)". Space.com. Retrieved November 8, 2012. 
  10. ^ Barnes, R., Jackson, B., Raymond, S., West, A., Greenberg, R. (2009). "The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?". The Astrophysical Journal 695 (2): 1006. arXiv:0901.1698. Bibcode:2009ApJ...695.1006B. doi:10.1088/0004-637X/695/2/1006. 
  11. ^ University of Toronto astronomer Ray Jayawardhana, author of Strange New Worlds: The Search for Alien Planets and Life beyond Our Solar System. Paraphrased in Dan Vergano (November 7, 2012). Habitable zone 'Super Earth' candidate planet detected. 

External links[edit]

Coordinates: Sky map 05h 54m 04.2409s, −60° 01′ 24.498″