Delta Boötis

δ Boötis

Location of δ Boötis, left of center
Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Right ascension	15h 15m 30.163s
Declination	+33° 18′ 53.401″
Apparent magnitude (V)	3.47
Characteristics
Spectral type	G8IIIFe-1
U−B color index	0.66
B−V color index	0.95
R−I color index	0.51
Variable type	Variable star
Astrometry
Radial velocity (Rv)	-12.3 km/s
Proper motion (μ)	RA: 84.84 mas/yr Dec.: -110.57 mas/yr
Parallax (π)	27.94 ± 0.61 mas
Distance	117 ± 3 ly (35.8 ± 0.8 pc)
Absolute magnitude (MV)	4.42
Details
Mass	1.1 M☉
Radius	1.1 R☉
Luminosity	1.2 L☉
Temperature	5,000–6,000 K
Rotation	< 19 km/s
Other designations
49 Boötis, HR 5681, HD 135722, BD+33°2561, FK5 563, HIP 74666, SAO 64589.
Database references
SIMBAD	data
Data sources:
Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.)
Database references
SIMBAD	data

Delta Boötis (δ Boo, δ Boötis) is a binary star in the constellation Boötes. It is approximately 117 light years from Earth. The primary component is a yellow G-type giant with an apparent magnitude of +3.46. Its companion is a yellow G-type main sequence dwarf with an apparent magnitude of +8.7.

Sometimes, this star is called by the name Princeps, meaning prince or prime in Latin^[1].

In Chinese, 七公 (Qī Gōng), meaning Seven Excellencies, refers to an asterism consisting of δ Boötis, 42 Herculis, τ Herculis, φ Herculis, χ Herculis, ν¹ Boötis and μ¹ Boötis.^[2] Consequently, δ Boötis itself is known as 七公七 (Qī Gōng qī, English: the Seventh Star of Seven Excellencies.)^[3]

Delta Boötis

About 3800 AU apart, the two take about 120,000 years to orbit each other.

References

• HR 5681
• CCDM J15156+3319
• Image Delta Boötis

1. ^ Constellations of Word - Boötes (Princeps)
2. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
3. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 26 日