HD 187123
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| Observation data Epoch 2000 |
|
|---|---|
| Constellation (pronunciation) |
Cygnus |
| Right ascension | 19h 46m 58.11s |
| Declination | +34° 25' 10.29" |
| Apparent magnitude (V) | 7.89 |
| Distance | 156.28 ly (47.92 pc) |
| Spectral type | G5 V |
| Other designations | |
|
BD+34°3708, HIP 97336, SAO 68845
|
|
HD 187123 is an 8th magnitude star in the constellation of Cygnus. Like our Sun, it is a yellow dwarf (spectral type G5 V). Being at a distance of about 160 light-years it is not visible to the unaided eye. However, it should be easy target with binoculars or small telescope.
In 1998 the California and Carnegie Planet Search team, after following a suggestion by Kevin Apps, a Briton who at the time was an undergraduate student[1] found a possible planet orbiting the star.[2] There are also indications of another, more distant body orbiting the star; and the claim was published in 2007.
Contents |
[edit] Planets
[edit] HD 187123 b
| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Orbital elements | ||
| Semimajor axis | (a) | 0.0426 AU |
| Eccentricity | (e) | 0.035 ± 0.015 |
| Orbital period | (P) | 3.097 d |
| Angular distance | (θ) | 0.84 mas |
| Longitude of periastron |
(ω) | 20° |
| Time of periastron | (T0) | 2,451,029.73 JD |
| Semi-amplitude | (K) | 70.6 m/s |
| Physical characteristics | ||
| Mass | (m) | >0.52 MJ |
| Radius | (r) | 1.2 RJ |
| Discovery information | ||
| Discovery date | 1998 | |
| Discoverer(s) | Butler, Marcy, Vogt, Apps |
|
| Detection method | radial velocity | |
| Discovery status | Published | |
HD 187123 b is a typical "hot Jupiter". It has a mass about half that of Jupiter and it orbits in a very tight, round orbit around the star every three days. However, there is a very slight possibility that the signal, thought to be caused by the planet, may be from starspots and stellar pulsations instead.
The star has also been monitored for possible transits by the planet, but none was found.
[edit] HD 187123 c
| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Orbital elements | ||
| Semimajor axis | (a) | 4.80 AU |
| Eccentricity | (e) | 0.249 ± 0.030 |
| Orbital period | (P) | 3700 ± 530 d |
| Angular distance | (θ) | 100.2 mas |
| Longitude of periastron |
(ω) | 250 ± 170° |
| Time of periastron | (T0) | 2,459,910 ± 610 JD |
| Semi-amplitude | (K) | 25.1 ± 1.5 m/s |
| Physical characteristics | ||
| Mass | (m) | >1.95 MJ |
| Radius | (r) | 1.06 RJ |
| Discovery information | ||
| Discovery date | 1998-2007 | |
| Discoverer(s) | Butler, Marcy, Vogt, Apps |
|
| Detection method | radial velocity | |
| Discovery status | Published | |
The planet HD 187123 c was discovered in 1998 and published in 2007. The radius of the planet's orbit is 4.80 AU, 113 times more distant from the star than first companion. This takes 10 years to orbit. As it is typical for very long-period planets, the orbit is eccentric, referring to as "eccentric Jupiter". At periastron, the orbital distance is 3.60 AU and at apastron, the distance is 6.00 AU.
The planet's mass is nearly 2 times that of Jupiter, classing as jovian (0.2-3 MJ) but is likely to be smaller in size than the inner planet.
[edit] References
- ^ BBC News | Sci/Tech | British student shows Nasa new planet - Friday, September 25, 1998
- ^ Butler et al. (1998). "A Planet with a 3.1 Day Period around a Solar Twin" ([dead link]). Publications of the Astronomical Society of the Pacific 110: 1389-1393. doi:.
[edit] External links
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