69 Herculis
Star in the constellation Hercules
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69 Herculis is a binary star[2] system in the northern constellation Hercules. It has the Bayer designation e Herculis, while 69 Herculis is the Flamsteed designation. This object is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 4.63.[2] The distance to this system can be estimated from parallax measurements, which yields a range of 175 light years. It is moving closer to the Earth with a heliocentric radial velocity of −10 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Hercules |
| Right ascension | 17h 17m 40.25320s[1] |
| Declination | +37° 17′ 29.4226″[1] |
| Apparent magnitude (V) | 4.63 (4.66 + 8.68)[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | A2V[3] |
| B−V color index | 0.043±0.003[4] |
| Astrometry | |
| Radial velocity (Rv) | −9.90±1.78[5] km/s |
| Proper motion (μ) | RA: −43.05[1] mas/yr Dec.: +64.36[1] mas/yr |
| Parallax (π) | 18.6546±0.0849 mas[1] |
| Distance | 174.8 ± 0.8 ly (53.6 ± 0.2 pc) |
| Absolute magnitude (MV) | 0.99[4] |
| Details | |
| 69 Her A | |
| Mass | 2.12[6] M☉ |
| Radius | 2.2[7] R☉ |
| Luminosity | 36.64[4] L☉ |
| Surface gravity (log g) | 4.02[8] cgs |
| Temperature | 9,141[8] K |
| Metallicity [Fe/H] | 0.29[8] dex |
| Rotational velocity (v sin i) | 141[8] km/s |
| Age | 155[9] Myr |
| Other designations | |
| e Her, 69 Her, BD+37°2864, HD 156729, HIP 84606, HR 6436, SAO 65921[10] | |
| Database references | |
| SIMBAD | data |
The magnitude 4.66[2] primary, designated component A, is an A-type main-sequence star with a stellar classification of A2V.[3] It is 155[9] million years old with 2.12[6] times the mass of the Sun. The star is spinning with a projected rotational velocity of 155 km/s, which is creating an equatorial bulge that is 5% larger than the star's polar radius.[9] It is about 2.2[7] times the size of the Sun and is radiating 37[4] times the Sun's luminosity from its photosphere at an effective temperature of 9,141 K.[8]
The secondary, component B, is magnitude 8.68 star with an angular separation of 0.840″ from the primary, as of 2008.[2] X-ray emission has been detected from this system. As A-type stars are not expected to be X-ray sources, this emission is most likely coming from the companion.[11]