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).[11] This object has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.73.[2] The distance to this star has been measured using the patallax method, which locates it 126 light years from the Sun. It is drifting closer with a radial velocity of −4.4 km/s.[2] There are two known exoplanets orbiting this star.

At various times the star HD 89744 has been assigned a stellar classification of F7V,[3][12] F7IV-V,[13] and F8IV,[4][2] suggesting it is an F-type main-sequence star that is evolving onto the subgiant branch. It is ~8.4[7] billion years old with an inactive chromosphere[13] and is spinning with a projected rotational velocity of 9.3 km/s.[8] The star is 2.16[1] times the size of the Sun with 1.4[6] 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[7] times the luminosity of the Sun from its photosphere at an effective temperature of 6,381 K.[6]

In 2001, a faint co-moving companion was identified at an angular separation of 63.1″ from the primary.[14] This is equivalent to a linear projected separation of 2,456 AU (0.04 ly).[9] The companion, designated component B, is an L-class (~L0.5)[3] brown dwarf[14] with a mass of ~0.076 M_☉.[9]

Planetary system

In April 2000, a planet was discovered using radial velocity measurements taken at Fred Lawrence Whipple Observatory and Lick Observatory.[12] The orbital parameters were updated in 2006 and 2007 using additional measurements.[15][16] A second planet with a much longer period was discovered in 2019.[17]

See also

• List of extrasolar planets

References

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