WASP-2
Multiple star system in the constellation Delphinus
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WASP-2 is a binary star system located about 496 light-years away in the Delphinus constellation.[12] The primary is a magnitude 12 orange dwarf star, orbited by a red dwarf star on a wide orbit.[8][13] The star system shows an infrared excess noise of unknown origin.[14]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Delphinus[1] |
| A[2] | |
| Right ascension | 20h 30m 54.1282s[3] |
| Declination | +06° 25′ 46.341″[3] |
| Apparent magnitude (V) | +11.98[4] |
| C[a 1] | |
| Right ascension | ~20h 30m 54s[2] |
| Declination | ~+06° 25′ 46″[2] |
| Characteristics | |
| Spectral type | K1.5V + K2-M3[5] |
| Apparent magnitude (J) | 10.166±0.027[6] |
| Apparent magnitude (H) | 9.752±0.026[6] |
| Apparent magnitude (K) | 9.632±0.024[6] |
| Variable type | planetary transit[7] |
| Astrometry | |
| Radial velocity (Rv) | −27.70±0.46[3] km/s |
| Proper motion (μ) | RA: 5.631 mas/yr[3] Dec.: −48.491 mas/yr[3] |
| Parallax (π) | 6.5777±0.0270 mas[3] |
| Distance | 496 ± 2 ly (152.0 ± 0.6 pc) |
| Orbit[8] | |
| Primary | WASP-2A |
| Name | WASP-2B |
| Semi-major axis (a) | 106″ |
| Details | |
| WASP-2A | |
| Mass | 0.843±0.033[9] M☉ |
| Radius | 0.821±0.013[9] R☉ |
| Luminosity | 0.507+0.023 −0.029[10] L☉ |
| Surface gravity (log g) | 4.536±0.015[9] cgs |
| Temperature | 5170±60[9] K |
| Metallicity [Fe/H] | 0.1±0.2[11] dex |
| Rotational velocity (v sin i) | 0.9±0.5[11] km/s |
| Age | 7.6+2.5 −3.3[9] Gyr |
| WASP-2B | |
| Mass | 0.40±0.02[9] M☉ |
| Temperature | 3523+28 −19[9] K |
| Other designations | |
| V357 Del, TOI-5797, TIC 374530847, WASP-2, GSC 00522-01199, 2MASS J20305413+0625463, 1SWASP J203054.12+062546.4, USNO-B1.0 0964-00543604, UCAC2 34018636[12] | |
| Database references | |
| SIMBAD | A |
| B | |
| Exoplanet Archive | data |
The primary star hosts one known exoplanet, WASP-2b.[15] Since the planet transits the star, the star is classified as a planetary transit variable and has received the variable star designation V357 Delphini.[7]
Binary star
In 2008 a study was undertaken of fourteen stars with exoplanets that were originally discovered using the transit method through relatively small telescopes. These systems were re-examined with the 2.2 m (87 in) 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 15 M-type star separated by about 111 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]
A re-examination of the WASP-2 spectrum in 2015 resulted in the measurement of the stellar companion's temperature as 3513±28 K, and an angular separation of 0.73 arcseconds.[16]
Planetary system
The primary star has one exoplanet, WASP-2b, a hot Jupiter detected by the SuperWASP project in 2006 using the transit method.[15]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.892±0.027 MJ | 0.0308±0.0004 | 2.15222163(42) | <0.013 | 84.81+0.35 −0.27° |
1.060±0.024 RJ |