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Groombridge 1830


Dec 15, 2021

Groombridge 1830 (also known as 1830 Groombridge or Argelander’s Star)[11] is a star in the constellationUrsa Major.

Star in the constellation Ursa Major

Groombridge 1830

The red dot shows the location of Groombridge 1830 in Ursa Major.

Detailed position of HR 4550 ( = Groombridge 1830; bottom-left edge) related to Chi UMa and Psi UMa.
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 11h 52m 58.7675s[1]
Declination +37° 43 07.2553[1]
Apparent magnitude (V) 6.44[2]
Spectral type G8VIp[3]
U−B color index +0.16[2]
B−V color index +0.75[2]
Variable type Suspected[4]
Radial velocity(Rv) –98.0[5] km/s
Proper motion(μ) RA: 4002.567±0.070[1] mas/yr
Dec.: −5817.856±0.056[1] mas/yr
Parallax(π) 108.9551 ± 0.0490[1] mas
Distance 29.93 ± 0.01 ly
(9.178 ± 0.004 pc)
Absolute magnitude (MV) 6.64[6]
Mass 0.661[7] M
Radius 0.681 ± 0.006[8] R
Luminosity 0.212 ± 0.002[8] L
Surface gravity(log g) 4.68[9] cgs
Temperature 4,759 ± 20[8] K
Metallicity [Fe/H] –1.33[9] dex
Age 4.7–5.3[10] Gyr
Other designations
BD+38 2285, FK5 1307, GCTP 2745.00, GJ 451, HIP 57939, HR 4550, HD 103095, LHS 44, LTT 13276, SAO 62738, 1830 Groombridge, Argelander’s Star
Database references

. . . Groombridge 1830 . . .

It is a yellow-hued class G8subdwarf catalogued by British astronomer Stephen Groombridge with the Groombridge Transit Circle between 1806 and the 1830s and published posthumously in his star catalog, Catalogue of Circumpolar Stars (1838). Its high proper motion was noted by Friedrich Wilhelm Argelander in 1842.

It is 29.9 light-years (9.2 parsecs) from the Sun as measured by the Gaia spacecraft,[1] which, as the distance is nearly 10 parsecs, means its absolute magnitude is almost equal to its apparent magnitude. It is a member of the galactic halo; such stars account for only 0.1 to 0.2 percent of the stars near the Sun. Like most halo stars, it has a low abundance of elements other than hydrogen and helium—what astronomers term a metal-poor star.[12]

Once suspected of being a binary star with a period of 175 days, current consensus is that it is single. Previous suspected observations of a stellar companion were probably “superflares”—analogous to the Sun’s solar flares, but hundreds to millions of times more energetic.[12][13] It had one of the first nine identified superflares.

. . . Groombridge 1830 . . .

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. . . Groombridge 1830 . . .