Alpha Herculis (α Herculis, abbreviated Alpha Her, α Her), also designated Rasalgethi and 64 Herculis, is a multiple star system in the constellation of Hercules. Appearing as a single point of light to the naked eye, it is resolvable into a number of components through a telescope. It has a combined apparent magnitude of 3.08, although the brightest component is variable in brightness. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 360 light-years (110 parsecs) distant from the Sun. It is also close to another bright star Rasalhague in the vicinity.
Quick Facts Observation data Epoch J2000 Equinox J2000, Apparent magnitude (V) ...
α Herculis
Location of α Herculis (circled) |
Observation data Epoch J2000 Equinox J2000 |
Constellation |
Hercules |
A |
Right ascension |
17h 14m 38.853s[1] |
Declination |
+14° 23′ 25.34″[1] |
Apparent magnitude (V) |
3.350[1] (2.7–4.0[2]) |
B |
Right ascension |
17h 14m 39.181s[1] |
Declination |
+14° 23′ 23.98″[1] |
Apparent magnitude (V) |
5.322[1] |
Characteristics |
A |
Evolutionary stage |
AGB[3] |
Spectral type |
M5 Ib-II[3] |
U−B color index |
+1.01[4] |
B−V color index |
+1.45[4] |
Variable type |
SRc[2] |
B |
Spectral type |
G8III + A9IV-V[3] |
Astrometry |
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|
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Proper motion (μ) | RA: −7.32[5] mas/yr Dec.: 36.07[5] mas/yr |
Parallax (π) | 9.07 ± 1.32 mas[5] |
Distance | approx. 360 ly (approx. 110 pc) |
Absolute magnitude (MV) | −2.3[6] + 1.8 + 2.8[7] |
|
Details |
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A |
---|
Mass | 2.5+1.6 −1.1[8] M☉ |
Radius | 284 ± 60, 264–303[3] R☉ |
Luminosity | 7,244–9,333[3] L☉ |
Surface gravity (log g) | −0.41±0.19[9] cgs |
Temperature | 3,155–3,365[3] K |
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|
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Ba |
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Mass | ~2.5[3] M☉ |
Luminosity | 126[3] L☉ |
Temperature | 4,900[3] K |
Bb |
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Mass | ~2[3] M☉ |
Luminosity | 26[3] L☉ |
Temperature | 7,350[3] K |
Age | 0.41–1.25[3] Gyr |
Other designations |
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|
A: HD 156014, HR 6406, SAO 102680 |
B: HD 156015, HR 6407, SAO 102681 |
Database references |
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SIMBAD | α Her |
| A |
| B |
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