Nu Herculis
Variable star in the constellation Hercules
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Nu Herculis, Latinized from ν Herculis, is a binary and variable star in the constellation of Hercules. With an apparent magnitude of about 4.4, it is faintly visible to the naked eye. Parallax measurements made by the Hipparcos spacecraft put it at a distance of about 860 light years (260 parsecs).
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 17h 58m 30.14909s[1] |
| Declination | +30° 11′ 21.3870″[1] |
| Apparent magnitude (V) | 4.38 - 4.48[2] |
| Characteristics | |
| Spectral type | F2II[3] (kA9hF2mF2(IV)[4] + B9.5[5]) |
| U−B color index | +0.13[6] |
| B−V color index | +0.35[6] |
| Variable type | SRd?[2] |
| Astrometry | |
| Radial velocity (Rv) | -22.30 ± 0.6[7] km/s |
| Proper motion (μ) | RA: -0.81[1] mas/yr Dec.: 2.18[1] mas/yr |
| Parallax (π) | 3.79±0.39 mas[1] |
| Distance | approx. 860 ly (approx. 260 pc) |
| Absolute magnitude (MV) | −2.67[8] |
| Details | |
| Mass | 5.31[9] M☉ |
| Luminosity | 799[10] L☉ |
| Surface gravity (log g) | 2.29[9] cgs |
| Temperature | 6410[9] K |
| Metallicity [Fe/H] | −0.33[11] dex |
| Rotational velocity (v sin i) | 28.0[10] km/s |
| Age | 200[10] Myr |
| Other designations | |
| ν Her, BD+30°3093, HD 164136, HIP 87998, HR 6707, SAO 66524[12] | |
| Database references | |
| SIMBAD | data |
This is a binary system with the two components separated by 0.446″. The secondary is nearly three magnitudes fainter than the primary at magnitude 7.5,[14] and is hotter than the primary with a spectral type of B9.5.[5]
Nu Herculis's spectral type of F2 II means that it is an F-type bright giant, with a luminosity 799 times that of the Sun. Its effective temperature is 6,410 K, hotter than the Sun.[9] Its mass is about 5.3 solar masses.[9] It is a possible semiregular variable star with a range of about a tenth of a magnitude. A period of 29 days has been derived.[2]