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 | |
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 | |
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 |
Ba | |
Mass | ~2.5 [3] M☉ |
Luminosity | 126 [3] L☉ |
Temperature | 4,900 [3] K |
Bb | |
Mass | ~2 [3] M☉ |
Luminosity | 26 [3] L☉ |
Temperature | 7,350 [3] K |
Age | 0.41–1.25 [3] Gyr |
Other designations | |
A: HD 156014, HR 6406, SAO 102680 | |
B: HD 156015, HR 6407, SAO 102681 | |
Database references | |
SIMBAD | α Her |
A | |
B |
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.
Alpha Herculis is a triple star system. The primary (brightest) of the three stars, designated α1 Herculis or α Herculis A, is a pulsating variable star on the asymptotic giant branch (AGB). The primary star forms a visual binary pair with a second star, which is itself a spectroscopic binary. [3]
Alpha Herculis also forms the A and B components of a wider system designated WDS J17146+1423, with two additional faint visual companions designated WDS J17146+1423C and D. [11] The two fainter stars are far more distant than the triple system. [12]
α Herculis ( Latinised to Alpha Herculis) is the system's Bayer designation; α1 and α2 Herculis, those of its two visible components. 64 Herculis is the system's Flamsteed designation. WDS J17146+1423 is the wider system's designation in the Washington Double Star Catalog. The designations of Alpha Herculis' main components as Alpha Herculis A and B and the wider system's four components as WDS J17146+1423A, B, C and D, together with the spectroscopic pair - Alpha Herculis Ba and Bb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). [13]
Alpha Herculis bore the traditional name Rasalgethi or Ras Algethi ( Arabic: رأس الجاثي ra‘is al-jāthī 'Head of the Kneeler'). [14] 'Head' comes from the fact that in antiquity Hercules was depicted upside down on maps of the constellation. In 2016, the IAU organized a Working Group on Star Names (WGSN) [15] to catalog and standardize proper names for stars. The WGSN approved the name Rasalgethi for the component Alpha Herculis A (α1) on 30 June 2016 and it is now so included in the List of IAU-approved Star Names. [15]
The term ra's al-jaθiyy or Ras al Djathi appeared in the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, which was translated into Latin as Caput Ingeniculi. [16]
In Chinese astronomy, Alpha Herculis is called 帝座, Pinyin: Dìzuò, meaning 'Emperor's Seat'. The star is seen as marking itself, and stands alone in the center of the Emperor's Seat asterism, Heavenly Market enclosure (see: Chinese constellations). [17] 帝座 (Dìzuò) was westernized into Ti Tso by R.H. Allen, with the same meaning [18]
Alpha Herculis A and B are more than 500 AU apart, with an estimated orbital period of approximately 3600 years.[ citation needed] A presents as a relatively massive red bright giant, but radial velocity measurements suggest a companion with a period of the order of a decade. [11] B's two components are a primary yellow giant star and a secondary, yellow-white dwarf star in a 51.578 day orbit. [20]
Alpha Herculis A is an asymptotic giant branch (AGB) star, a luminous red giant that has both hydrogen and helium shells around a degenerate carbon-oxygen core. It is the second nearest AGB star to the Sun. Its radius pulsates between 264 and 303 solar radii. At its minimum, the effective temperature is of 3,155 K (2,882 °C) and the luminosity is of 7,200 solar luminosities, while at its maximum the temperature is of 3,365 K (3,092 °C) and the luminosity is of 9,330 solar luminosities. [3] If Alpha Herculis were at the center of the Solar System its radius would extend past the orbit of Earth at 1.23 – 1.4 AU but not quite as far as the orbit of Mars or the asteroid belt. The red giant is estimated to have started its life with about 2.175-3.250 M☉. [3]
The primary has been specified as a standard star for the spectral class M5 Ib-II. [3] Like most type M stars near the end of their lives, Alpha Herculis is experiencing a high degree of stellar mass loss creating a sparse, gaseous envelope that extends at least 930 AU. [20] It is a semiregular variable with complex changes in brightness with periods ranging from a few weeks to many years. The most noticeable variations occur at timescales of 80–140 days and at 1,000 - 3,000 days. The strongest detectable period is 128 days. [21] The full range in brightness is from magnitude 2.7 to 4.0, [2] but it usually varies over a much smaller range of around 0.6 magnitudes. [21]
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 | |
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 | |
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 |
Ba | |
Mass | ~2.5 [3] M☉ |
Luminosity | 126 [3] L☉ |
Temperature | 4,900 [3] K |
Bb | |
Mass | ~2 [3] M☉ |
Luminosity | 26 [3] L☉ |
Temperature | 7,350 [3] K |
Age | 0.41–1.25 [3] Gyr |
Other designations | |
A: HD 156014, HR 6406, SAO 102680 | |
B: HD 156015, HR 6407, SAO 102681 | |
Database references | |
SIMBAD | α Her |
A | |
B |
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.
Alpha Herculis is a triple star system. The primary (brightest) of the three stars, designated α1 Herculis or α Herculis A, is a pulsating variable star on the asymptotic giant branch (AGB). The primary star forms a visual binary pair with a second star, which is itself a spectroscopic binary. [3]
Alpha Herculis also forms the A and B components of a wider system designated WDS J17146+1423, with two additional faint visual companions designated WDS J17146+1423C and D. [11] The two fainter stars are far more distant than the triple system. [12]
α Herculis ( Latinised to Alpha Herculis) is the system's Bayer designation; α1 and α2 Herculis, those of its two visible components. 64 Herculis is the system's Flamsteed designation. WDS J17146+1423 is the wider system's designation in the Washington Double Star Catalog. The designations of Alpha Herculis' main components as Alpha Herculis A and B and the wider system's four components as WDS J17146+1423A, B, C and D, together with the spectroscopic pair - Alpha Herculis Ba and Bb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). [13]
Alpha Herculis bore the traditional name Rasalgethi or Ras Algethi ( Arabic: رأس الجاثي ra‘is al-jāthī 'Head of the Kneeler'). [14] 'Head' comes from the fact that in antiquity Hercules was depicted upside down on maps of the constellation. In 2016, the IAU organized a Working Group on Star Names (WGSN) [15] to catalog and standardize proper names for stars. The WGSN approved the name Rasalgethi for the component Alpha Herculis A (α1) on 30 June 2016 and it is now so included in the List of IAU-approved Star Names. [15]
The term ra's al-jaθiyy or Ras al Djathi appeared in the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, which was translated into Latin as Caput Ingeniculi. [16]
In Chinese astronomy, Alpha Herculis is called 帝座, Pinyin: Dìzuò, meaning 'Emperor's Seat'. The star is seen as marking itself, and stands alone in the center of the Emperor's Seat asterism, Heavenly Market enclosure (see: Chinese constellations). [17] 帝座 (Dìzuò) was westernized into Ti Tso by R.H. Allen, with the same meaning [18]
Alpha Herculis A and B are more than 500 AU apart, with an estimated orbital period of approximately 3600 years.[ citation needed] A presents as a relatively massive red bright giant, but radial velocity measurements suggest a companion with a period of the order of a decade. [11] B's two components are a primary yellow giant star and a secondary, yellow-white dwarf star in a 51.578 day orbit. [20]
Alpha Herculis A is an asymptotic giant branch (AGB) star, a luminous red giant that has both hydrogen and helium shells around a degenerate carbon-oxygen core. It is the second nearest AGB star to the Sun. Its radius pulsates between 264 and 303 solar radii. At its minimum, the effective temperature is of 3,155 K (2,882 °C) and the luminosity is of 7,200 solar luminosities, while at its maximum the temperature is of 3,365 K (3,092 °C) and the luminosity is of 9,330 solar luminosities. [3] If Alpha Herculis were at the center of the Solar System its radius would extend past the orbit of Earth at 1.23 – 1.4 AU but not quite as far as the orbit of Mars or the asteroid belt. The red giant is estimated to have started its life with about 2.175-3.250 M☉. [3]
The primary has been specified as a standard star for the spectral class M5 Ib-II. [3] Like most type M stars near the end of their lives, Alpha Herculis is experiencing a high degree of stellar mass loss creating a sparse, gaseous envelope that extends at least 930 AU. [20] It is a semiregular variable with complex changes in brightness with periods ranging from a few weeks to many years. The most noticeable variations occur at timescales of 80–140 days and at 1,000 - 3,000 days. The strongest detectable period is 128 days. [21] The full range in brightness is from magnitude 2.7 to 4.0, [2] but it usually varies over a much smaller range of around 0.6 magnitudes. [21]