HD 74156

HD 74156

Observation data Epoch 2000      Equinox 2000
Constellation	Hydra
Right ascension	08h 42m 25.1222s
Declination	+04° 34' 41.151"
Apparent magnitude (V)	7.62
Distance	210.6 ly (64.56 pc)
Spectral type	G0V
Other designations
BD+05°2035, HIP 42723

HD 74156 is a yellow dwarf star (spectral type G0V) in the constellation of Hydra, 210 light years from our solar system. It is known to be orbited by three large planets.

Planets

HD 74156 b

Template:Planetbox begin Template:Planetbox orbit Template:Planetbox character Template:Planetbox discovery Template:Planetbox end HD 74156 b is an extrasolar planet at least 88% more massive than Jupiter that orbits very close to the star. Its surface temperatures must be high and its radius about 1.1 to 1.3 that of Jupiter. It is most likely a gas giant.

HD 74156 c

Template:Planetbox begin Template:Planetbox orbit Template:Planetbox character Template:Planetbox discovery Template:Planetbox end HD 74156 c is an extrasolar planet at least eight times the mass of Jupiter but likely to be smaller than the innermost planet (roughtly Jupiter's size), with an eccentric orbit that occasionally passes through the star's habitable zone. It would thus be subject to extreme shifts of temperature. It is most likely a gas giant.

HD 74156 d

Template:Planetbox begin Template:Planetbox orbit Template:Planetbox character Template:Planetbox discovery Template:Planetbox end HD 74156 d is a gas giant 40% the mass of Jupiter. It orbits about the same distance as Earth to the Sun, this puts it in the star's habitable zone. It was first observed by Jacob Bean and his team at the University of Texas.

The existence of HD 74156 d was predicted by computer models created by Rory Barnes, Thomas Quinn and Sean Raymond, operating under the theory that planetary systems would have planets occupying every stable orbital zone. The two previously discovered planets of this system left a stable gap between them where HD 74156 d was ultimately detected. This was the first extrasolar planet whose existence was predicted by theory before it was detected experimentally.

However, doubts have subsequently been raised about whether HD 74156 d has actually been detected; Roman V. Baluev suggests its observed effects may be explained by errors in the data.

See also

• List of stars with confirmed extrasolar planets
• HD 37124
• Upsilon Andromedae

References

• Naef; et al. (2004). "The ELODIE survey for northern extra-solar planets III. Three planetary candidates detected with ELODIE" (abstract). Astronomy and Astrophysics. 414: L351–359. doi:10.1051/0004-6361:20034091. {{cite journal}}: Explicit use of et al. in: |author= (help)
• Jacob L. Bean, Barbara E. McArthur, G. Fritz Benedict, Amber Armstrong (2007). "Detection of a Third Planet in the HD 74156 System Using the Hobby-Eberly Telescope" (abstract). Astronomy and Astrophysics.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External links

• "HD 74156". SIMBAD. Retrieved 2006-04-14.
• "Notes for star HD 74156". The Extrasolar Planets Encyclopaedia. Retrieved 2006-04-14.
• John Whatmough. "HD 74156". Extrasolar Visions. Retrieved 2006-04-14.