Upsilon Andromedae d
| Exoplanet | List of exoplanets | |
|---|---|---|
| Parent star | ||
| Star | Upsilon Andromedae A | |
| Constellation | Andromeda | |
| Right ascension | (α) | 01h 36m 47.8s |
| Declination | (δ) | +41° 24′ 20″ |
| Apparent magnitude | (mV) | 4.09 |
| Distance | 44.0 ± 0.1 ly (13.49 ± 0.03 pc) |
|
| Spectral type | F8V | |
| Mass | (m) | 1.28 M☉ |
| Radius | (r) | 1.480 ± 0.087 R☉ |
| Temperature | (T) | 6074 ± 13.1 K |
| Metallicity | [Fe/H] | 0 |
| Age | 3.3 Gyr | |
| Orbital elements | ||
| Semi-major axis | (a) | 2.54 ± 0.15 AU (~380 Gm) |
| ~188 mas | ||
| Periastron | (q) | 1.88 ± 0.18 AU (~282 Gm) |
| Apastron | (Q) | 3.19 ± 0.28 AU (~478 Gm) |
| Eccentricity | (e) | 0.299±0.072[1] |
| Orbital period | (P) | 1276.46±0.57[1] d (~3.49626[1] y) |
| Inclination | (i) | 23.8 ± 1[2]° |
| Argument of periastron |
(ω) | 279 ± 10° |
| Time of periastron | (T0) | 2,448,827 ± 30 JD |
| Semi-amplitude | (K) | 63.4 ± 1.5 m/s |
| Physical characteristics | ||
| Mass | (m) | 10.25[2] MJ |
| Discovery information | ||
| Discovery date | April 15, 1999 | |
| Discoverer(s) | Butler, Marcy et al. | |
| Discovery method | Radial velocity | |
| Discovery site | California and Carnegie Planet Search  USA |
|
| Discovery status | Published | |
| Other designations | ||
|
Majriti, 50 Andromedae d, Upsilon Andromedae Ad
|
||
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
| Exoplanet Archive | data | |
| Open Exoplanet Catalogue | data | |
Upsilon Andromedae d (abbreviated υ Andromedae d, υ And d), also named Majriti, is an extrasolar planet orbiting the Sun-like star Upsilon Andromedae A every 241.2 days. Its discovery in April 1999 by Geoffrey Marcy and R. Paul Butler made this the first multiple-planet system to be discovered around a main-sequence star, and the first multiple-planet system known in a multiple star system. Upsilon Andromedae d is the third known planet in order of distance from its star.
In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars.[3] The process involved public nomination and voting for the new names.[4] In December 2015, the IAU announced the winning name was Majriti for this planet.[5] The winning name was submitted by the Vega Astronomy Club of Morocco and honours the 10th and early 11th Century astronomer Maslama al-Majriti of Muslim Spain.[6]
Discovery
Like the majority of known extrasolar planets, Upsilon Andromedae d was detected by measuring variations in its star's radial velocity as a result of the planet's gravity. This was done by making precise measurements of the Doppler shift of the spectrum of Upsilon Andromedae A. At the time of discovery, Upsilon Andromedae A was already known to host one extrasolar planet, the hot Jupiter Upsilon Andromedae b; however, by 1999, it was clear that the inner planet could not explain the velocity curve.
In 1999, astronomers at both San Francisco State University and the Harvard-Smithsonian Center for Astrophysics independently concluded that a three-planet model best fit the data.[7] The two new planets were designated Upsilon Andromedae c and Upsilon Andromedae d.
Orbit and mass
Upsilon Andromedae d orbits its star in an eccentric orbit, more eccentric than that of any of the major planets in the Solar System (including Pluto).[8] The orbit's semimajor axis puts the planet in the habitable zone of Upsilon Andromedae A.[9]
To explain the planet's orbital eccentricity, some have proposed a close encounter with a (now lost) outer planet of Upsilon Andromedae A. The encounter would have moved Upsilon Andromedae d into an eccentric orbit closer to the star and ejected the outer planet from the system. Subsequently, gravitational perturbations from Upsilon Andromedae d moved the inner planet Upsilon Andromedae c into its present eccentric orbit.[10] If so, the rogue planet would have had to be ejected immediately; it is unclear how likely this situation might be. Other models are possible.[11]
A limitation of the radial velocity method used to detect Upsilon Andromedae d is that the orbital inclination is unknown, and only a lower limit on the planet's mass can be obtained. However, by combining radial velocity measurements from ground-based telescopes with astrometric data from the Hubble Space Telescope, astronomers have determined the orbital inclination as well as the actual mass of Upsilon Andromedae d, which is about 10.25 times the mass of Jupiter.[2]
Preliminary astrometric measurements suggest the orbit of Upsilon Andromedae d may be inclined at 155.5° to the plane of the sky.[12] However, these measurements were later proved useful only for upper limits;[13] worthless for HD 192263 b and probably 55 Cancri c, and contradict even the inner planet u And b's inclination of >30°. The mutual inclination between c and d meanwhile is 29.9 degrees.[2]
Characteristics
Given the planet's high mass, it is likely that it is a gas giant with no solid surface and surface gravity of over 25 times that of Earth. Since the planet has only been detected indirectly through observations of its star, properties such as its radius, composition, and temperature are unknown.
Upsilon Andromedae d lies in the habitable zone of Upsilon Andromedae A as defined both by the ability for an Earthlike world to retain liquid water at its surface and based on the amount of ultraviolet radiation received from the star.[9]
See also
References
- ↑ 1.0 1.1 1.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
- ↑ NameExoWorlds The Process
- ↑ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
- ↑ NameExoWorlds The Approved Names
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found. (web version)
- ↑ 9.0 9.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
