Iota Boötis (ι Boo, ι Boötis) is a member of a binary star system in the constellation Boötes, approximately 96 light-years from Earth. It has the traditional name Asellus Secundus /əˈsɛləs sɪˈkʌndəs/ (Latin for "second donkey colt") and the Flamsteed designation 21 Boötis. The companion is HD 234121, a K0 main sequence star.
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 16m 09.92976s[1] |
| Declination | +51° 22′ 02.0287″[1] |
| Apparent magnitude (V) | 4.75[2] (4.73 – 4.78[3]) |
| Characteristics | |
| Spectral type | A7 V[4] |
| U−B color index | +0.06[5] |
| B−V color index | +0.20[5] |
| R−I color index | +0.09[5] |
| Variable type | Delta Scuti variable[3] |
| Astrometry | |
| Radial velocity (Rv) | −18.7[6] km/s |
| Proper motion (μ) | RA: −149.277[1] mas/yr Dec.: +89.135[1] mas/yr |
| Parallax (π) | 33.8856 ± 0.0820 mas[1] |
| Distance | 96.3 ± 0.2 ly (29.51 ± 0.07 pc) |
| Absolute magnitude (MV) | +2.38[7] |
| Details | |
| Mass | 1.81[4] M☉ |
| Radius | 1.7[1] R☉ |
| Luminosity | 8.8[1] L☉ |
| Surface gravity (log g) | 4.14[1] cgs |
| Temperature | 7,764[1] K |
| Metallicity [Fe/H] | +0.19[8] dex |
| Rotational velocity (v sin i) | 144[9] km/s |
| Age | 785[1] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
Components
Iota Boötis has a companion at an angular distance of 38.6 arcseconds, easily separated with binoculars.
The primary component 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.[7]
The companion, HD 234121, is a magnitude 7.3 main-sequence star belonging to spectral class K0V.[12][13] It is separated from ι Boo by 1,100 AU.[4] HD 234121 has a mass of 0.8 M☉, a luminosity of 0.4 L☉, a temperature of 5,090 K, and a radius of 0.8 R☉.[14]
The Washington Double Star Catalog lists a third component, a 14th-magnitude star at 90 arcseconds,[13] but it is an unrelated background star.[15]
Nomenclature
This star, along with the other Aselli (θ Boo and κ Boo) and λ Boo, were Aulād al Dhiʼbah (أولاد الضّباع - awlād al-ḍibā‘), "the Whelps of the Hyenas".[the transcription does not match the Arabic][16]
In Chinese, 天槍 (Tiān Qiāng), meaning Celestial Spear, refers to an asterism consisting of ι Boötis, κ2 Boötis and θ Boötis.[17] Consequently, the Chinese name for ι Boötis itself is 天槍二 (Tiān Qiāng èr, English: the Second Star of Celestial Spear).[18]
References
External links
Wikiwand in your browser!
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.
