HD 188753

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HD 188753 ABC

HD 188753 in the Cygnus constellation
Observation data
Epoch J2000.0
Constellation Cygnus
Right ascension 19h 54m 58.37s
Declination +41° 52′ 17.5″
Apparent magnitude (V) +7.43
Spectral Characteristics
Spectral type GV / K0V / MV
U-B color index  ?
B-V color index  ?
Variable type  ?
Astrometry
Radial velocity (Rv) -23.5 km/s
Proper motion (μ) RA: -52.76 mas/yr
Dec.: 284.44 mas/yr
Parallax (π) 22.31 ± 0.78 mas
Distance 149 ly (46 pc)
Absolute magnitude (MV) 4.17
Visual binary orbit
Companion HD 188753 BC
Period (P) 25.7 years
Semimajor axis (a) 12.3 AU"
Eccentricity (e) 0.5
Inclination (i)  ?°
Node (Ω)  ?°
Periastron epoch (T)  ?
Physical Characteristics
Mass 1.06 / ? / ? M☉
Radius 1.28 / ? / ? R☉
Luminosity 1.6 / ? / ? L☉
Temperature 5750 K
Metallicity  ?
Rotation  ?
Age 5600 million years
Other designations
HO 581

HD 188753 is a triple star system approximately 149 light-years away in the constellation Cygnus. The system is also known as ADS 13125, Ho 581, BD+41°3535 [1] [2], HIP 98001, and WDS 19550+4152 [3]. This star system is only the second triple-star system known to have a planet orbiting it [4], HD 188753 Ab, which was discovered in 2005 by Polish astronomer Dr. Maciej Konacki.

Contents

[edit] Stars

The primary star (HD 188753 A) is a 1.06 solar mass G-type (yellow dwarf).

Orbiting this at a distance separated from the primary star at approximately midway between the Sun-Saturn and Sun-Uranus distance: 12.3 AU, are two stars orbitting each other. These have a total mass of 1.63 solar masses and orbit the primary with an eccentricity of 0.50 (an earlier estimate put the eccentricity at 0.26±0.07 [5]).

The secondary (HD 188753 B) has a spectral class of K (orange dwarf), and the tertiary (HD 188753 C)is an M-type (red dwarf). These orbit each other in 156 days, and the primary in 25.7 years.[6]

[edit] Planetary system

In 2005 the discovery of HD 188753 Ab was the first known planet in a triple star system. It has been discovered by a Polish astronomer working in the United States, Dr. Maciej Konacki [7] [8].

An artist's conception of HD 188753 Ab looking at its suns.
Enlarge
An artist's conception of HD 188753 Ab looking at its suns.

The planet, a gas giant slightly larger than Jupiter, orbits the star HD 188753 A. The planet, which is at least 14% larger than Jupiter, orbits the main star once every 80 hours or so (3.3 days), at a distance of about 8 Gm, a twentieth of the distance between Earth and the Sun.

Companion
(In order from star)		 Mass
(MJ)		 Orbital period
(days)		 Semimajor axis
(AU)		 Eccentricity
b >1.14 ± 0.1 3.3481 ± 0.0009 0.0446 ± 0.001 0.00


[edit] HD 188753 in fiction and mythology

See Rizq for a discussion of the role HD 188753 plays in Nuwaubian mythology.

[edit] See also


[edit] References

  • Griffin, R.F., The multiple star HD 188753 (ADS 13125), The Observatory, Vol. 97, pp. 15-18, 1977
  • Bowman, Lee (Jul. 14, 2005). "Planet with a view: Three suns shine in Cygnus". The Plain Dealer, pg. A2.


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