Observation data Epoch J2000 Equinox J2000 |
|
---|---|
Constellation | Boötes |
Right ascension | 14h 16m 09.92995s |
Declination | +51° 22′ 02.0267″ |
Apparent magnitude (V) | 4.75(4.73 - 4.78) |
Characteristics | |
Spectral type | A7 V |
U−B color index | +0.06 |
B−V color index | +0.20 |
R−I color index | +0.09 |
Variable type | Delta Scuti variable |
Astrometry | |
Radial velocity (Rv) | −18.7 km/s |
Proper motion (μ) |
RA: -149.39 mas/yr Dec.: +88.72 mas/yr |
Parallax (π) | 34.40 ± 0.19mas |
Distance | 94.8 ± 0.5 ly (29.1 ± 0.2 pc) |
Absolute magnitude (MV) | +2.38 |
Details | |
Mass | 1.81 M☉ |
Radius | 1.6 R☉ |
Luminosity | 9.6 L☉ |
Surface gravity (log g) | 4.3 cgs |
Temperature | 8,000 K |
Metallicity [Fe/H] | +0.19 dex |
Rotational velocity (v sin i) | 144 km/s |
Other designations | |
Database references | |
SIMBAD | data |
Data sources: | |
Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
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") and the Flamsteed designation 21 Boötis. It is approximately 95 light years from Earth.
This star, along with the other Aselli (θ Boo and κ Boo) and λ Boo, were Aulād al Dhiʼbah (أولاد الضّباع - aulād al dhiʼb), "the Whelps of the Hyenas".
In Chinese, 梗河 (Tiān Qiāng), meaning Celestial Spear, refers to an asterism consisting of ι Boötis, κ2 Boötis and θ Boötis. Consequently, ι Boötis itself is known as 天槍二 (Tiān Qiāng èr, English: the Second Star of Celestial Spear.)
Iota Boötis has a companion at an angular distance of 38.6 arcseconds, easily separated with binoculars.
The primary component, Iota Boötis, 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 with a stable period of 38 minutes.
The companion, HD 234121, is a magnitude +8.27 main sequence star belonging to spectral class K0. It is separated from ι Boo by 1,100 AU.