HD 187123

'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

Planets

HD 187123 b

HD 187123 c

References

External links

Planets

HD 187123 b

'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.

HD 187123 c

The planet 'HD 187123 c' was discovered in 1998 and published in 2007. The radius of the planet's orbit is wide, at 8.77 AU, 200 times more distant from the star than first companion, placing between the orbits of Jupiter and Saturn in the solar system. This takes 24.9 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 5.7 AU and at apastron, the distance is 11.84 AU, going beyond Saturn-Sun distance at times.
The planet's mass is nearly 4 times that of Jupiter, classing as superjovian (2.5-13 M_J).

References

1. BBC News | Sci/Tech | British student shows Nasa new planet -
Friday, September 25, 1998
2. A Planet with a 3.1 Day Period around a Solar Twin, Butler et al., , , Publications of the Astronomical Society of the Pacific, 1998

External links

★ SIMBAD star entry, planet entry

★ The Extrasolar Planets Encyclopaedia entry

★ Extrasolar Visions entry