Pi1 Ursae Majoris
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Observation data Epoch J2000 Equinox J2000 |
|
---|---|
Constellation | Ursa Major |
Right ascension | 08h 39m 11.70440s[1] |
Declination | +65° 01′ 15.2667″[1] |
Apparent magnitude (V) | 5.63 |
Characteristics | |
Spectral type | G1.5Vb[2] |
U−B color index | +0.07[3] |
B−V color index | +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[1] mas |
Distance | 46.8 ± 0.2 ly (14.36 ± 0.08 pc) |
Absolute magnitude (MV) | 4.86 |
Details | |
Mass | 0.90[5] M☉ |
Luminosity | 0.97[6] L☉ |
Surface gravity (log g) | 4.48[7] cgs |
Temperature | 5,884 ± 6.8[8] K |
Metallicity [Fe/H] | –0.04[7] dex |
Rotation | 5 days[9] |
Rotational velocity (v sin i) | 14.27[4] km/s |
Age | 200[10] Myr |
Other designations | |
Database references | |
SIMBAD | data |
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.[10] 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.[11] 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.[6][9]
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.[12]
References
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