| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 16m 09.9294s |
| Declination | +51° 22′ 02.033″ |
| Apparent magnitude (V) | 4.75 |
| Characteristics | |
| Spectral type | A9V |
| U−B color index | 0.06 |
| B−V color index | 0.2 |
| R−I color index | 0.09 |
| Variable type | Delta Scuti variable |
| Astrometry | |
| Radial velocity (Rv) | -18.7 km/s |
| Proper motion (μ) | RA: -149.98 mas/yr Dec.: 89.42 mas/yr |
| Parallax (π) | 33.54 ± 0.56 mas |
| Distance | 97 ± 2 ly (29.8 ± 0.5 pc) |
| Absolute magnitude (MV) | 4.96 |
| Details | |
| Mass | 3.1 M☉ |
| Radius | 2.1 R☉ |
| Luminosity | 40 L☉ |
| Temperature | 7,500–10,000 K |
| Rotation | 137 km/s 0,00212755 Year |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
|
| Database references | |
| SIMBAD | data |
Iota Boötis (ι Boo, ι Boötis) is a star system in the constellation Boötes. It has the traditional name Asellus Secundus (Latin for "second donkey colt")[1] and the Flamsteed designation 21 Boötis.
This star, along with the other Asselus (θ Boo and κ Boo) and λ Boo, were Al Aulād al Dhiʼbah (ألعولد ألذعب - al aulād al dhiʼb), "the Whelps of the Hyenas".[2].
In Chinese, 梗河 (Tiān Qiāng), meaning Celestial Spear, refers to an asterism consisting of ι Boötis, κ2 Boötis and θ Boötis.[3] Consequently, ι Boötis itself is known as 天槍三 (Tiān Qiāng èr, English: the Second Star of Celestial Spear.)[4]
Iota Boötis is a double star, with components at an angular distance of 38.6 arcseconds, easily separated with binoculars. It is approximately 97 light years from Earth.
The primary component, Iota Boötis A, a spectroscopic binary, is a white A-type main sequence dwarf with a mean apparent magnitude of +4.75. It is classified as a Delta Scuti type variable star and its brightness varies from magnitude +4.73 to +4.78. The companion, Iota Boötis B, is a magnitude +8.27 star belonging to spectral class A2.
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