- 55 Cancri b
Planetbox begin
name=55 Cancri bPlanetbox star
star=55 Cancri A
constell=Cancer
RA=RA|08|52|35.8
DEC=DEC|+28|19|51
dist_ly=40.9
dist_pc=12.5
class=G8VPlanetbox orbit
semimajor=0.115 ± 0.0000011cite journal | author =DA Fischer "et al." | title=Five Planets Orbiting 55 Cancri |journal=Astrophysical Journal |issue=675| page=790-801 |doi=10.1086/525512 |month=March |year=2008]
eccentricity=0.014 ± 0.008
period=14.65162 ± 0.0007
ang_dist = 8.582
long_peri=131.94 ± 30
t_peri=2,450,002.94749 ± 1.2
semi-amp=71.32 ± 0.41Planetbox character
mass=>0.824 ± 0.007Planetbox discovery
discovery_date=April 12, 1996
discovery_site=California, USA
discovery_method=Radial velocity
discoverers=Butler, Marcy
discovery_status=PublishedPlanetbox catalog
names=55 Cancri Ab, Rho1 Cancri b, HD 75732 b55 Cancri b (occasionally referred to as 55 Cancri Ab in order to distinguish it from the
star 55 Cancri B) is anextrasolar planet orbiting theSun -like star 55 Cancri A every 14.65day s. It is the second planet in order of distance from its star, and is an example of ahot Jupiter . Discovered in 1996 byGeoffrey Marcy andR. Paul Butler , 55 Cancri b was the fourth known extrasolar planet, excludingpulsar planet s.Discovery
Like the majority of known extrasolar planets, 55 Cancri b was discovered by detecting variations in its star's
radial velocity caused by the planet'sgravity . By making sensitive measurements of theDoppler shift of thespectrum of 55 Cancri A, a 15-day periodicity was detected. The planet was announced in 1996, together with the planet ofTau Boötis and the innermost planet ofUpsilon Andromedae . [cite journal|url=http://www.journals.uchicago.edu/doi/full/10.1086/310444|author=Butler, R. et al.|title=Three New 51 Pegasi-Type Planets|journal=The Astrophysical Journal |volume=474|year=1997|pages=L115 – L118|doi=10.1086/310444]Even when this inner planet, with a
mass at least 78% times that ofJupiter was accounted for, the star still showed a drift in its radial velocity. This eventually led to the discovery of the outer planet55 Cancri d in 2002.Orbit and mass
55 Cancri b is in a short-period orbit, though not so extreme as that of the previously detected hot Jupiter
51 Pegasi b . The orbital period indicates that the planet is located close to a 1:3mean motion resonance with55 Cancri c , however investigations of the planetary parameters in a Newtonian simulation indicate that while the orbital periods are close to this ratio, the planets are not actually in the resonance.A limitation of the radial velocity method used to discover the planet is that only a lower limit on the mass can be determined. Astrometric measurements made with the
Hubble Space Telescope suggest that the outer planet is inclined at around 53° with respect to the plane of the sky. [cite journal|url=http://xxx.lanl.gov/abs/astro-ph/0408585|author=McArthur et al.|title=Detection of a NEPTUNE-mass planet in the ρ1 Cnc system using the Hobby-Eberly Telescope|journal=The Astrophysical Journal |volume=614|year=2004|pages=L81 – L84|doi=10.1086/425561] The system is further expected to be coplanar. Assuming all this is confirmed, the planet'strue mass is around 1.03 Jupiter masses.Characteristics
Given the planet's high mass, it is likely that 55 Cancri b is a
gas giant with nosolid surface. Since the planet has only been detected indirectly, properties such as itsradius , composition andtemperature are unknown. Assuming a composition similar to that of Jupiter and that its environment is close tochemical equilibrium , 55 Cancri b is predicted to have acloud less upperatmosphere with aspectrum dominated byalkali metal absorption. [cite journal|url=http://adsabs.harvard.edu/abs/2003ApJ...588.1121S|author=Sudarsky, D. et al.|title=Theoretical Spectra and Atmospheres of Extrasolar Giant Planets|journal=The Astrophysical Journal |volume=588|issue=2|pages=1121 – 1148|year=2003|doi=10.1086/374331]The planet is unlikely to have large moons, since tidal forces would either eject them from orbit or destroy them on short timescales relative to the age of the system. [cite journal|url=http://adsabs.harvard.edu/abs/2002ApJ...575.1087B|author=Barnes, J., O'Brien, D.|title=Stability of Satellites around Close-in Extrasolar Giant Planets|journal=
The Astrophysical Journal |volume=575|issue=2|pages=1087 – 1093|year=2002|doi=10.1086/341477]References
ee also
*
55 Cancri c
*55 Cancri d
*55 Cancri e
*55 Cancri f
*Appearance of extrasolar planets External links
* [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=%2A+55+Cnc+b SIMBAD: * 55 Cnc b -- Extra-solar Planet Candidate]
* [http://exoplanet.eu/planet.php?p1=55+Cnc&p2=b The Extrasolar Planets Encyclopaedia: Notes for Planet 55 Cnc b]
* [http://www.extrasolar.net/planettour.asp?StarCatId=normal&PlanetId=9 Extrasolar Visions: 55 Cancri b]
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