GSC 02620-00648

GSC 02620-00648 is a binary star system located approximately 1,660 light-years away in the constellation Hercules. The brighter of the pair is a magnitude 12 star about 1.45 times as massive as the Sun. It hosts one known exoplanet, TrES-4b.^[4]

GSC 02620-00648

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Hercules[1]
A[2]
Right ascension	17h 53m 13.0490s[3]
Declination	+37° 12′ 42.586″[3]
Apparent magnitude (V)	11.592[4]
C[a]
Right ascension	17h 53m 13.0496s[5]
Declination	+37° 12′ 44.139″[5]
Apparent magnitude (V)	13.85[2]
Characteristics
Spectral type	F8[2]/K or M[2]
Apparent magnitude (B)	12.1120005±0.007[4]
Apparent magnitude (J)	10.583±0.018[6]
Apparent magnitude (H)	10.350±0.015[6]
Apparent magnitude (K)	10.330±0.019[6]
Astrometry
A
Radial velocity (Rv)	−15.65±0.82[3] km/s
Proper motion (μ)	RA: −6.382 mas/yr[3] Dec.: −20.891 mas/yr[3]
Parallax (π)	1.9686±0.0136 mas[3]
Distance	1,660 ± 10 ly (508 ± 4 pc)
C
Proper motion (μ)	RA: −6.307 mas/yr[5] Dec.: −20.387 mas/yr[5]
Parallax (π)	1.9657±0.1076 mas[5]
Distance	1,660 ± 90 ly (510 ± 30 pc)
Details[7]
A
Mass	1.45±0.05 M☉
Radius	1.81±0.08 R☉
Luminosity	4.6[3] L☉
Surface gravity (log g)	4.09±0.03 cgs
Temperature	6,295±65 K
Metallicity [Fe/H]	+0.28±0.09 dex
Rotational velocity (v sin i)	8.5±0.5 km/s
Age	2.2±0.4 Gyr
C
Mass	0.59[2] M☉
Other designations
TrES-4 Parent Star, TOI-2124, TIC 159742538, TYC 2620-648-1, GSC 02620-00648, 2MASS J17531304+3712426[8]
Database references
SIMBAD	A
	C
Exoplanet Archive	data

Nomenclature

The designation GSC 02620-00648 comes from the Guide Star Catalog.

The star is sometimes called TrES-4,^[9] in reference to its planet discovered by the Trans-Atlantic Exoplanet Survey (TrES). The discovery paper^[4] and the SIMBAD database^[8] use this designation for the planet itself, but other sources call the star TrES-4^[10] and the planet TrES-4b,^[7] following the standard exoplanet naming convention.

Binary star

In 2008 a study was undertaken of 14 stars with exoplanets that were originally discovered using the transit method through relatively small telescopes. These systems were re-examined with the 2.2M reflector telescope at the Calar Alto Observatory in Spain. This star system, along with two others, was determined to be a previously unknown binary star system. The previously unknown secondary star is a dim magnitude 14 K or M-type star separated by about 755 AU from the primary, appearing offset from the primary by about one arc second in the images. This discovery resulted in a recalculation of parameters for both the planet and the primary star.^[2]

Planetary system

In 2006, the Trans-Atlantic Exoplanet Survey discovered the exoplanet TrES-4b using the transit method.^[4] This planet orbits the primary star.^[2] The planet is a low-density hot Jupiter, with a larger size than Jupiter but a smaller mass, and an orbital period of only four days.^[7]

The GSC 02620-00648 planetary system^[11]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	0.498+0.033 −0.032 MJ	0.05159+0.00059 −0.00061	3.55392771(47)	<0.015	83.07+0.51 −0.44°	1.838+0.081 −0.090 RJ

See also

• List of extrasolar planets

Notes

1. The secondary star is identified with a "C" suffix so as not to confuse it with the planetary designation suffix "b".