HAT-P-4
Wide binary star system in the constellation Boötes
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HAT-P-4 is a wide binary star consisting of a pair of G-type main-sequence stars[5] in the constellation of Boötes.[1] It also has the BD designation BD+36°2593.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes[1] |
| HAT-P-4A | |
| Right ascension | 15h 19m 57.9204s[2] |
| Declination | +36° 13′ 46.738″[2] |
| Apparent magnitude (V) | 11.159±0.010[3] |
| HAT-P-4B | |
| Right ascension | 15h 20m 00.0127s[4] |
| Declination | +36° 12′ 18.520″[4] |
| Apparent magnitude (V) | 11.534±0.01[3] |
| Characteristics | |
| HAT-P-4A | |
| Spectral type | G0V[5] |
| B−V color index | 0.771 |
| Variable type | planetary transit[6] |
| HAT-P-4B | |
| Spectral type | G2V[5] |
| Astrometry | |
| HAT-P-4A | |
| Radial velocity (Rv) | −1.13(37)[2] km/s |
| Proper motion (μ) | RA: −21.513(13) mas/yr[2] Dec.: −24.255(19) mas/yr[2] |
| Parallax (π) | 3.1071±0.0154 mas[2] |
| Distance | 1,050 ± 5 ly (322 ± 2 pc) |
| HAT-P-4B | |
| Radial velocity (Rv) | −1.31(35)[4] km/s |
| Proper motion (μ) | RA: −21.424(13) mas/yr[4] Dec.: −24.182(20) mas/yr[4] |
| Parallax (π) | 3.0777±0.0155 mas[4] |
| Distance | 1,060 ± 5 ly (325 ± 2 pc) |
| Position (relative to HAT-P-4A)[5] | |
| Component | HAT-P-4B |
| Epoch of observation | 1999/02/07 |
| Angular distance | 91.760±0.099″ |
| Position angle | 163.97±0.06° |
| Projected separation | 28446 AU |
| Details | |
| HAT-P-4A | |
| Mass | 1.260+0.043 −0.042[7] M☉ |
| Radius | 1.573±0.015[7] R☉ |
| Luminosity | 2.8[2] L☉ |
| Surface gravity (log g) | 4.145±0.015[7] cgs |
| Temperature | 5927+57 −47[7] K |
| Metallicity [Fe/H] | 0.277±0.007[8] dex |
| Rotational velocity (v sin i) | 5.6 ± 0.9[9] km/s |
| Age | ~4.2 Gyr |
| HAT-P-4B | |
| Mass | 1.0[4] M☉ |
| Radius | 1.3[4] R☉ |
| Luminosity | 2.0[4] L☉ |
| Surface gravity (log g) | 4.38±0.14[8] cgs |
| Temperature | 6037±37[8] K |
| Metallicity [Fe/H] | 0.175±0.006[8] dex |
| Age | 7.8[4] Gyr |
| Other designations | |
| HAT-P-4A: BD+36°2593, SAO 64638, TYC 2569-1599-1, GSC 02569-01599, 2MASS J15195792+3613467[10] | |
| HAT-P-4B: TYC 2569-744-1, 2MASS J15200001+3612185[11] | |
| Database references | |
| SIMBAD | A |
| B | |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
The star exhibits an infrared excess of unknown origin.[12]
Binary companion
The companion star is located at a distance of 28446 astronomical units and therefore has an orbital period that is extremely long.[5]
Planetary system
The primary star is home to the transiting extrasolar planet HAT-P-4b.[6] This planet is a fairly typical hot Jupiter type planet in a 3-day orbit.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.651+0.033 −0.037 MJ |
0.04449+0.00083 −0.0012 |
3.0565254±0.0000012 | <0.0073 | — | 1.28+0.016 −0.015[7] RJ |
