44 Boötis

This article is about i Boötis and is not to be confused with ι Boötis.

44 Boötis, also known as i Boötis, is a triple star system in the constellation Boötes. It is approximately 41.6 light years from Earth.

44 Boötis

A light curve for 44 Boötis plotted from TESS data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Right ascension	15h 03m 47.29565s[2]
Declination	+47° 39′ 14.6228″[2]
Apparent magnitude (V)	4.70 - 4.84[3] (5.136 / 6.004)[4]
Characteristics
Spectral type	G0Vnv[5] + (K0V + K4V)[6]
U−B color index	0.09[7]
B−V color index	0.65[7]
Variable type	W UMa[3]
Astrometry
Radial velocity (Rv)	−17.89[8] km/s
Proper motion (μ)	RA: −445.84[2] mas/yr Dec.: 19.86[2] mas/yr
Parallax (π)	78.39±1.03 mas[9]
Distance	41.6 ± 0.5 ly (12.8 ± 0.2 pc)
Absolute magnitude (MV)	+2.211[9] / +5.38[10]
Orbit[11]
Primary	44 Boo A
Companion	44 Boo B
Period (P)	209.8±3.3 yr
Semi-major axis (a)	3.666±0.021″
Eccentricity (e)	0.5111±0.0065
Inclination (i)	83.55±0.05°
Longitude of the node (Ω)	57.14±0.06°
Periastron epoch (T)	B 2012.04±0.26
Argument of periastron (ω) (secondary)	39.86±0.68°
Orbit[10]
Primary	44 Boo Ba
Companion	44 Boo Bb
Period (P)	0.267818 days
Semi-major axis (a)	2.015 R☉
Eccentricity (e)	0.0
Inclination (i)	72.8°
Semi-amplitude (K1) (primary)	231.31 km/s
Semi-amplitude (K2) (secondary)	112.70 km/s
Details
44 Boo A
Mass	1.04±0.10[11] M☉
Luminosity	1.552[4] L☉
Surface gravity (log g)	4.33[12] cgs
Temperature	5,877[12] K
Metallicity [Fe/H]	−0.24[12] dex
Age	1.4–1.5[13] Gyr
44 Boo Ba
Mass	0.98[14] M☉
Radius	0.87[14] R☉
Luminosity	0.51[14] L☉
Temperature	5,300[14] K
44 Boo Bb
Mass	0.55[14] M☉
Radius	0.66[14] R☉
Luminosity	0.24[14] L☉
Temperature	5,035[14] K
Other designations
Quadrans, i Boötis, 40 Boo, BD+48°2259, FK5 3182, GJ 575, HD 133640, HIP 73695, HR 5618, SAO 45357, ADS 9494, CCDM 15038+4739[15]
Database references
SIMBAD	data
	A
	B

44 Boötis can be resolved into two stars, of 5th and 6th magnitudes respectively. They were separated by 1.5″ when the pair were confirmed in 1819, but were only 0.2″ by 2020 as the two orbit every 210 years.^[16][11]

The primary component, 44 Boötis A, also named Quadrans,^[17] is a yellow-white G-type main sequence star with a mean apparent magnitude of +4.83. The companion component, 44 Boötis B, is a W Ursae Majoris variable spectroscopic binary. The variability of this star system was discovered by English astronomer William Herschel.^[18] The brightness of the eclipsing binary varies from magnitude +5.8 to +6.40 with a period of 6.43 hours.^[19] The two eclipsing components of the system are close enough to allow their stellar envelopes to overlap, or at least nearly so.^[10] In 1948, flare behavior was measured from this system based on data from O. J. Eggen.^[20]

44 Boötis appears to have an infrared excess, implying the existence of a dust disk that absorbs visible light and re-emits it as infrared light. The dust would have a blackbody temperature of about 23 K, situated up to 182 au from the parent star.^[4]

This star was a member of the obsolete constellation Quadrans Muralis. The IAU Working Group on Star Names approved the name Quadrans for component A on 17 February 2025, after the obsolete constellation, and it is now so entered in the IAU Catalog of Star Names.^[17]