HD 40307 g
| Exoplanet | List of exoplanets | |
|---|---|---|
| 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 | ||
| Semi-major 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⊕ |
| Stellar flux | (F⊙) | 0.62,[7][8] 0.68[9] ⊕ |
| Maximum stellar flux | (F⊙max) | 1.03[8] ⊕ |
| Minimum stellar flux | (F⊙min) | 0.42[8] ⊕ |
| Temperature | (T) | 227.4[citation needed][9] |
| 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 | |
| Exoplanet Archive | data | |
| Open Exoplanet Catalogue | 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][10][11] by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Goettingen, Germany.[11]
Composition theories
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." [10]
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,[12] which extrapolates 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.[13] 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."[10]
See also
- Circumstellar habitable zone
- Extrasolar planet
- List of potentially habitable exoplanets
- Planetary habitability
 |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 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. Bibcode: 2006A&A...450..735M. doi:10.1051/0004-6361:20054021.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 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, Bibcode: 2004A&A...418..989N, doi:10.1051/0004-6361:20035959.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 PHL's Exoplanets Catalog - Planetary Habitability Laboratory @ UPR Arecibo
- ↑ http://arxiv.org/pdf/1301.6674.pdf
- ↑ 8.0 8.1 8.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 9.0 9.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 10.0 10.1 10.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found. Cite error: Invalid
<ref>tag; name "Space-20121107b" defined multiple times with different content - ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ University of Toronto astronomer Ray Jayawardhana, author of Strange New Worlds: The Search for Alien Planets and Life beyond Our Solar System. Paraphrased in Lua error in package.lua at line 80: module 'strict' not found.
External links
- Lua error in package.lua at line 80: module 'strict' not found.
Coordinates: 
05h 54m 04.2409s, −60° 01′ 24.498″
