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Star in the constellation Ursa Major
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.
[2] 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.
[2] There are two known
exoplanets orbiting this star.
At various times the star HD 89744 has been assigned a
stellar classification of F7V,
[4]
[14] F7IV-V,
[15] and F8IV,
[5]
[2] 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]
See also
References
^
a
b
c
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arXiv :
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doi :
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S2CID
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Gaia DR3 record for this source at
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^
a
b
c
d
e
f Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters . 38 (5): 331.
arXiv :
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^
a
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doi :
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S2CID
244398875 .
Gaia DR3 record for this source at
VizieR .
^
a
b
c Scholz, R. -D. (March 2016). "Overlooked wide companions of nearby F stars". Astronomy & Astrophysics . 587 : 8.
arXiv :
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^
a
b Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I". The Astronomical Journal . 132 (1): 161–170.
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^
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^
a
b
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arXiv :
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VizieR .
^
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e Metcalfe, Travis S.; Egeland, Ricky (January 2019).
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arXiv :
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S2CID
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^
a
b Morris, Brett M.; et al. (September 2019).
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arXiv :
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S2CID
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^
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c Mugrauer, M.; et al. (2005).
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arXiv :
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^
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^
a
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doi :
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^
a
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^ Lopez‐Santiago, J.; et al. (2006).
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^ Schaefer, G. H.; et al. (2018-05-07).
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^
a
b Wilson, J. C.; et al. (October 2001). "Three Wide-Separation L Dwarf Companions from the Two Micron All Sky Survey: Gliese 337C, Gliese 618.1B, and HD 89744B". The Astronomical Journal . 122 (4): 1989–2000.
arXiv :
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S2CID
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^ Butler, R. P.; et al. (2006).
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^
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b Wittenmyer, Robert A.; et al. (2019). "Truly eccentric – I. Revisiting eight single-eccentric planetary systems". Monthly Notices of the Royal Astronomical Society . 484 (4): 5859–5867.
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