55 Cancri d
| Exoplanet | List of exoplanets | |
|---|---|---|
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| Parent star | ||
| Star | 55 Cancri A | |
| Constellation | Cancer | |
| Right ascension | (α) | 08h 52m 35.8s |
| Declination | (δ) | +28° 19′ 51″ |
| Apparent magnitude | (mV) | 5.95 |
| Distance | 40.3 ± 0.4 ly (12.3 ± 0.1 pc) |
|
| Spectral type | G8V | |
| Mass | (m) | 0.95 ± 0.10 M☉ |
| Radius | (r) | 1.152 ± 0.035 R☉ |
| Temperature | (T) | 5373 ± 9.7 K |
| Metallicity | [Fe/H] | 0.29 |
| Age | 7.4–8.7 Gyr | |
| Orbital elements | ||
| Semi-major axis | (a) | 5.77 ± 0.11AU (863 Gm) |
| 462 mas | ||
| Periastron | (q) | 5.63 AU (842 Gm) |
| Apastron | (Q) | 5.92 AU (885 Gm) |
| Eccentricity | (e) | 0.025 ± 0.03 |
| Orbital period | (P) | 5218 ± 230d (14.29 y) |
| Argument of periastron |
(ω) | 181.3 ± 32° |
| Time of periastron | (T0) | 2,452,500.6 ± 230JD |
| Semi-amplitude | (K) | 46.85 ± 1.8m/s |
| Physical characteristics | ||
| Minimum mass | (m sin i) | 3.835 ± 0.08MJ |
| Stellar flux | (F⊙) | 0.019 ⊕ |
| Discovery information | ||
| Discovery date | June 13, 2002 | |
| Discoverer(s) | Marcy et al. | |
| Discovery method | Radial velocity | |
| Discovery site | California, USA | |
| Discovery status | Published | |
| Other designations | ||
|
Lippershey, 55 Cancri Ad, Rho1 Cancri d, HD 75732 d
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| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
| Exoplanet Archive | data | |
| Open Exoplanet Catalogue | data | |
55 Cancri d (abbreviated 55 Cnc d), also named Lipperhey, is an extrasolar planet in a long-period orbit around the Sun-like star 55 Cancri A. Located at a similar distance from its star as Jupiter is from our Sun, it is the fifth and outermost known planet in its planetary system. 55 Cancri d was discovered on June 13, 2002.
In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Lippershey for this planet. The winning name was submitted by the Royal Netherlands Association for Meteorology and Astronomy of the Netherlands. It honors the spectacle maker and telescope pioneer Hans Lippershey. In January 2016, in recognition that his actual name was Lipperhey (with Lippershey an error introduced in the 19th century), the exoplanet name was corrected to Lipperhey by the IAU and that name was submitted to the official sites that keep track of astronomical information.
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 the Doppler shift of the star's spectrum. 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.
In 2002, further measurements revealed the presence of a long-period planet in an orbit at around 5 AU from the star. The same measurements also indicated the presence of another inner planet, designated 55 Cancri c.
When 55 Cancri d was discovered, it was thought to be on a fairly low eccentricity orbit similar to Jupiter in the Solar System, though the orbital elements were not well determined. As more data were collected, the best-fit solution for this planet turned out to be highly eccentric, more so than any of the planets in the Solar System. 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 14 year orbit was in fact near-circular, located about 5.77 AU from the star.
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