Pi1 Ursae Majoris

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Pi1 Ursae Majoris
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Location of π¹ Ursae Majoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 5.63
Characteristics
Spectral type G1.5Vb[2]
U−B Template:Engvar +0.07[3]
B−V Template:Engvar +0.62[3]
Variable type BY Draconis
Astrometry
Radial velocity (Rv)–13.88 ± 0.47[4] km/s
Proper motion (μ) RA: -27.44 ± 0.31[1] mas/yr
Dec.: +88.13 ± 0.26[1] mas/yr
Parallax (π)69.66±0.37 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)4.86[5]
Details
Mass0.90[6] Template:Solar mass
Luminosity0.97[7] Template:Solar luminosity
Surface gravity (log g)4.48[8] cgs
Temperature5,884 ± 6.8[9] K
Metallicity [Fe/H]–0.04[8] dex
Rotation5 days[10]
Rotational velocity (v sin i)14.27[4] km/s
Age200[11] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[12]
Database references
SIMBADdata

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File:Pi1UMaLightCurve.png
A light curve for pi1 Ursae Majoris, plotted from TESS data.[13] The main plot shows the variation over several weeks, and the inset plot shows the same data folded, assuming a 4.9 day period,[14] and averaged into 250 phase bins.

Pi1 Ursae Majoris (Pi1 UMa, π¹ Ursae Majoris, π¹ UMa) is a yellow G-type main sequence dwarf with a mean apparent magnitude of +5.63. It is approximately 46.8 light years from Earth,[1] and is a relatively young star with an age of about 200 million years.[11] It is classified as a BY Draconis type variable star and its brightness varies by 0.08 magnitudes. In 1986, it became the first solar-type star to have the emission from an X-ray flare observed.[15] Based upon its space velocity components, this star is a member of the Ursa Major moving group of stars that share a common motion through space.[7][10]

An excess of infrared radiation has been detected from this system, which suggests the presence of a debris disk. The best fit to the data indicates that there is a ring of fine debris out to a radius of about 0.4 AU, consisting of 0.25 μm grains of amorphous silicates or crystalline forsterite. There may also be a wider ring of larger (10 μm) grains out to a distance of 16 AU.[16]

Naming and etymology

With π2, σ1, σ2, ρ, A and d, it composed the Arabic asterism Al Ṭhibā᾽, the Gazelle.[17] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Ṭhibā were the title for seven stars : A as Althiba I, this star (π1) as Althiba II, π2 as Althiba III, ρ as Althiba IV, σ1 as Althiba V, σ2 as Althiba VI, and d as Althiba VII.[18]

References

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External links

Template:Stars of Ursa Major

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