HD 89744

HD 89744 is a star in the northern circumpolar constellation of Ursa Major, positioned about 0.4° due south of the bright star Tania Australis (μ UMa).^[13] This object has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.73.^[1] The distance to this star has been measured using the parallax method, which locates it 126 light years from the Sun. It is drifting closer with a radial velocity of −4.4 km/s.^[1] There are two known exoplanets orbiting this star.

HD 89744

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Ursa Major[1]
A
Right ascension	10h 22m 10.5619s[2]
Declination	+41° 13′ 46.310″[2]
Apparent magnitude (V)	5.73[1]
B
Right ascension	10h 22m 14.8721s[3]
Declination	+41° 14′ 26.514″[3]
Characteristics
Evolutionary stage	Main sequence
Spectral type	F7V[4] or F8IV[5]
B−V color index	0.531±0.003[1]
Astrometry
A
Radial velocity (Rv)	−4.35±0.12[1] km/s
Proper motion (μ)	RA: −120.285(42) mas/yr[2] Dec.: −138.171(50) mas/yr[2]
Parallax (π)	25.9334±0.0436 mas[2]
Distance	125.8 ± 0.2 ly (38.56 ± 0.06 pc)
Absolute magnitude (MV)	2.83[6]
B
Proper motion (μ)	RA: −119.215(647) mas/yr[3] Dec.: −140.390(457) mas/yr[3]
Parallax (π)	26.0070±0.4713 mas[3]
Distance	125 ± 2 ly (38.5 ± 0.7 pc)
Details
A
Mass	1.37±0.09[7] M☉
Radius	2.16+0.06 −0.01[8] R☉
Luminosity	6.38±0.02[9] L☉
Surface gravity (log g)	4.27±0.05[7] cgs
Temperature	6,381±43[7] K
Metallicity [Fe/H]	0.30±0.03[7] dex
Rotation	~9 days[9]
Rotational velocity (v sin i)	9.3[10] km/s
Age	8.4[9] Gyr
B
Mass	0.076[11] M☉
Other designations
BD+41°2076, GJ 9326, HD 89744, HIP 50786, HR 4067, WDS J10222+4114[12]
A: HD 89744A
B: Gaia DR3 804745827531820288, HD 89744B, 2MASS J10221489+4114266
Database references
A
SIMBAD	data
Exoplanet Archive	data
ARICNS	data
B
SIMBAD	data

At various times the star HD 89744 has been assigned a stellar classification of F7V,^[4][14] F7IV-V,^[15] and F8IV,^[5][1] suggesting it is an F-type main-sequence star that is evolving onto the subgiant branch. It is ~8.4^[9] billion years old with an inactive chromosphere^[15] and is spinning with a projected rotational velocity of 9.3 km/s.^[10] The star is 2.16^[8] times the size of the Sun with 1.4^[7] times the Sun's radius. It is a high metallicity star, showing a greater abundance of heavier elements than in the Sun. The star is radiating 6.4^[9] times the luminosity of the Sun from its photosphere at an effective temperature of 6,381 K.^[7]

This star was identified as a member of the AB Doradus moving group by J. López-Santiago and collaborators in 2006.^[16] It was later shown that its evolutionary state is incompatible with membership.^[17]

In 2001, a faint co-moving companion was identified at an angular separation of 63.1″ from the primary.^[18] This is equivalent to a linear projected separation of 2,456 AU (0.04 ly).^[11] The companion, designated component B, is an L-class (~L0.5)^[4] brown dwarf^[18] with a mass of ~0.076 M_☉.^[11]

Planetary system

In April 2000, a planet was discovered using radial velocity measurements taken at Fred Lawrence Whipple Observatory and Lick Observatory.^[14] The orbital parameters were updated in 2006 and 2007 using additional measurements.^[19][20] A second planet with a much longer period was discovered in 2019.^[21]

The HD 89744 planetary system^[21]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	>8.35±0.18 MJ	0.917±0.009	256.78±0.02	0.677±0.003	—	—
c (unconfirmed)	>5.36±4.57 MJ	8.3±1.8	6,974±2,161	0.29±0.12	—	—

See also

• List of exoplanets discovered before 2000 - HD 89744 b