- 55 Cancri d
Planetbox begin
name=55 Cancri dPlanetbox 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=5.77 ± 0.11cite journal | url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2008ApJ...675..790F&db_key=AST&nosetcookie=1| 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=0.025 ± 0.03
period=5218 ± 230
ang_dist=430
long_peri=181.3 ± 32
t_peri=2,452,500.6 ± 230
semi-amp=46.85 ± 1.8Planetbox character
mass=>3.835 ± 0.08Planetbox discovery
discoverers=Marcy et al.
discovery_site=California, USA
discovery_method=Radial velocity
discovery_date=June 13, 2002
discovery_status=PublishedPlanetbox catalog
names=Rho1 Cancri d, HD 75732 d55 Cancri d is an
extrasolar planet in a long-periodorbit around theSun -like star 55 Cancri A. Located at a similar distance from its star asJupiter is from our Sun, it is the fifth and outermost known planet in itsplanetary system . 55 Cancri d was discovered on June 13, 2002.Discovery
Like the majority of known extrasolar planets, 55 Cancri d was detected by observing changes in its star's
radial velocity . This was achieved by making sensitive measurements of theDoppler shift of the star'sspectrum . At the time of discovery, 55 Cancri A was already known to possess one planet (55 Cancri b ), however there was still a drift in the radial velocity measurements which was unaccounted-for. [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]In 2002, further measurements revealed the presence of a long-period planet in an orbit at around 5 AU from the star.cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2002ApJ...581.1375M&db_key=AST&nosetcookie=1|author=Marcy, G. et al.|title=A planet at 5 AU Around 55 Cancri|journal=
The Astrophysical Journal |volume=581|pages=1375 – 1388|year=2002|doi=10.1086/344298] The same measurements also indicated the presence of another inner planet, designated55 Cancri c .Orbit and mass
When 55 Cancri d was discovered, it was thought to be on a fairly low eccentricity orbit similar to Jupiter in our solar system, though the
orbital elements were not well determined. As more data was collected, the best-fit solution for this planet turned out to be highly eccentric, more so than any of the planets in oursolar system (includingPluto ).cite journal|url=http://xxx.lanl.gov/abs/astro-ph/0408585|author=McArthur, B. 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] In 2008, after a complete orbit of this planet had been observed, the true orbit was revealed, indicating that as had been originally suspected, the planet's orbit was in fact near-circular, located about 5.77 AU from the star.A limitation of the radial velocity method used to discover 55 Cancri d is that only a lower limit on the planet's
mass can be obtained. In the case of 55 Cancri d, this lower limit was around 3.835 times the mass ofJupiter . In 2004, astrometric measurements with the Fine Guidance Sensors on theHubble Space Telescope suggest that the planet's orbit is inclined by around 53° with respect to the plane of the sky. If this measurement is confirmed, it implies that the planet'strue mass is 25% greater than the lower limit, at around 4.8 Jupiter masses.Characteristics
Given the planet's high mass, the planet is a
gas giant with nosolid surface. Since the planet has only been detected indirectly, parameters such as itsradius , composition andtemperature are unknown.Assuming a composition similar to that of Jupiter and that the planet's
atmosphere is close tochemical equilibrium , it is predicted that 55 Cancri d is covered in a layer ofwater cloud s: the planet's internalheat probably keeps it too warm to form theammonia -based clouds that are typical of Jupiter. Its surface gravity is likely to be about 4 times stronger than Jupiter, or about 10 times that of Earth which is because the radius of the planet is unlikely to be much more than Jupiter's. [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]References
ee also
*
55 Cancri b
*55 Cancri c
*55 Cancri e
*55 Cancri f External links
* [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=%2A+55+Cnc+d SIMBAD: * 55 Cnc d -- Extra-solar Planet Candidate]
* [http://exoplanet.eu/planet.php?p1=55+Cnc&p2=d The Extrasolar Planets Encyclopaedia: Notes for Planet 55 Cnc d]
* [http://www.extrasolar.net/planettour.asp?StarCatId=normal&PlanetId=192 Extrasolar Visions: 55 Cancri d]
Wikimedia Foundation. 2010.