Mu1 Boötis

For other stars with this Bayer designation, see Mu Boötis.

Mu¹ Boötis is a binary star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from μ¹ Boötis, and abbreviated Mu¹ Boo or μ¹ Boo. This system had the traditional name Alkalurops, pronounced /ælkəˈljʊərɒps/.^[8] Based on parallax measurements, the system is located at a distance of 123 light-years.

Mu¹ Boötis

Location of μ1 Boötis (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Right ascension	15h 24m 29.43147s[1]
Declination	+37° 22′ 37.7613″[1]
Apparent magnitude (V)	4.31[2]
Characteristics
Spectral type	F2IV[3]
U−B color index	+0.06[4]
B−V color index	+0.31[4]
R−I color index	0.15
Astrometry
Radial velocity (Rv)	−8.60±0.3[5] km/s
Proper motion (μ)	RA: −149.928[1] mas/yr Dec.: +89.573[1] mas/yr
Parallax (π)	26.5759±0.7871 mas[1]
Distance	123 ± 4 ly (38 ± 1 pc)
Absolute magnitude (MV)	1.47[6]
Orbit[3]
Primary	Aa
Companion	Ab
Period (P)	3.75 years
Semi-major axis (a)	0.099″
Eccentricity (e)	0.270
Inclination (i)	129.7°
Longitude of the node (Ω)	129.4°
Periastron epoch (T)	1006.33
Argument of periastron (ω) (secondary)	43.5°
Details
Aa
Mass	1.6[3] M☉
Radius	1.9[2] R☉
Luminosity	20[7] L☉
Surface gravity (log g)	3.4[3] cgs
Temperature	7,000[3] K
Rotational velocity (v sin i)	89[3] km/s
Ab
Mass	1.5[3] M☉
Surface gravity (log g)	3.6[3] cgs
Temperature	7,000[3] K
Rotational velocity (v sin i)	40[3] km/s
Other designations
Alkalurops, Inkalunis, Icalurus, Clava, Venabulum, μ Boo, 51 Boötis A, BD+37°2636, FK5 568, GC 20724, GJ 3903, HD 137391, HIP 75411, HR 5733, SAO 64686, ADS 9626, CCDM 15245+3722
Database references
SIMBAD	data

The components of the system have an angular separation of 0.10″.^[9] They form a spectroscopic binary system with an orbital period of 3.75 years.^[3] The visible component is a yellow-white F-type subgiant with an apparent magnitude of +4.31.

The system μ² Boötis, separated by 109", makes an optical double with μ¹, and even has a similar distance from Earth and comparable proper motions, but has a substantially different metallicity, and therefore is not a gravitationally bound companion.^[3]

Nomenclature

μ¹ Boötis (Latinised to Mu¹ Boötis) is the star's Bayer designation.

The system's traditional name Alkalurops is from the Greek καλαύροψ kalaurops "a herdsman's crook or staff", with the Arabic prefix attached.^[10] It has also been known as Inkalunis (from the Alfonsine tables), Clava (Latin 'the club') and Venabulum (Latin 'a hunting spear').^[11] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)^[12] to catalogue and standardize proper names for stars. The WGSN approved the name Alkalurops for μ¹ Boötis on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.^[8]

It is known as 七公六, Qī Gōng liù (the Sixth Star of the Seven Excellencies) in Chinese.^[13]

Gallery

• 
  Mu Bootis (Alkalurops) as seen in a small telescope
• 
  Illustration of Mu^1,2 Boötis