Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ursa Major |
Right ascension | 11h 41m 03.01594s [1] |
Declination | +34° 12′ 05.8824″ [1] |
Apparent magnitude (V) | 5.35 [2] |
Characteristics | |
Evolutionary stage | Main sequence [3] |
Spectral type | G8V [4] |
U−B color index | +0.27 [5] |
B−V color index | +0.69 [5] |
Variable type | Suspected |
Astrometry | |
Radial velocity (Rv) | −5.18±0.08 [6] km/s |
Proper motion (μ) |
RA: −12.247
[1]
mas/
yr Dec.: −381.257 [1] mas/ yr |
Parallax (π) | 104.3904 ± 0.1287 mas [1] |
Distance | 31.24 ± 0.04
ly (9.58 ± 0.01 pc) |
Absolute magnitude (MV) | 5.53±0.006 [7] |
Details | |
Mass | 0.93±0.02 [8] M☉ |
Radius | 0.86±0.02 [9] R☉ |
Luminosity | 0.609±0.009 [10] L☉ |
Surface gravity (log g) | 4.43±0.06 [3] cgs |
Temperature | 5,488±44 [3] K |
Metallicity [Fe/H] | −0.03±0.03 [3] dex |
Rotation | 17.1 days [11] |
Rotational velocity (v sin i) | 3.3 [3] km/s |
Age | 2.1±1.7 [8] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
61 Ursae Majoris, abbreviated 61 UMa, is a single [13] star in the northern circumpolar constellation of Ursa Major. It has a yellow-orange hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.35. [2] The distance to this star is 31.2 light years based on parallax, [1] and it is drifting closer with a radial velocity of −5.2 km/s. [6] The star has a relatively high proper motion traversing the sky at the rate of 0.381 ″ yr−1. [14]
The stellar classification of 61 UMa is G8V, [4] matching a late G-type main-sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. [15] It is considered a solar-type star, having physical properties that make it similar to the Sun. [16] The star has 93% [8] of the mass of the Sun and 86% [9] of the Sun's radius. It is roughly two [8] billion years old and is spinning with a projected rotational velocity of 3.3 km/s, [3] for a period of 17.1 days. [11] The metallicity, or abundance of elements with higher atomic number than helium, appears about the same as in the Sun. [3] The star is radiating 61% [10] of the luminosity of the Sun from its photosphere at an effective temperature of 5,488K. [3]
During the 1950s, Karl Pilowski reported that photographic plates taken of the star appeared to show a variability of 0.2 in magnitude. Follow-up studies initially failed to confirm this variability, and it was found not to be an eclipsing binary based on radial velocity measurements. [17] The star's photosphere is rotating differentially, and the rotation period, typically in the range of 16-18 days, shows a larger difference between different latitudes than for most other stars. [18] It has an active chromosphere that exhibits strong and persistent starspot activity. [9] A flare event was captured in 2013 while the star was being observed by the VATT, [19] and the star has been detected as a source of X-ray emission. [20]
No substellar companions have been observed in orbit around this star, and it appears to lack a dust ring as is found around some comparable stars. A radial velocity survey completed in 2020 has indicated that giant planetary companions are absent. [9] A magnitude 11.35 stellar visual companion was reported by O. Struve in 1850. As of 2015, this star was located at an angular separation of 158.90″ from the brighter star, along a position angle of 86°. [21]
In the science fiction of Larry Niven's Known Space universe, the homeworld of the major race the Kzinti is the third planet in orbit around 61 Ursae Majoris. [22]
In the Star Trek universe, Archer IV is the fourth planet around 61 Ursae Majoris. [23]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ursa Major |
Right ascension | 11h 41m 03.01594s [1] |
Declination | +34° 12′ 05.8824″ [1] |
Apparent magnitude (V) | 5.35 [2] |
Characteristics | |
Evolutionary stage | Main sequence [3] |
Spectral type | G8V [4] |
U−B color index | +0.27 [5] |
B−V color index | +0.69 [5] |
Variable type | Suspected |
Astrometry | |
Radial velocity (Rv) | −5.18±0.08 [6] km/s |
Proper motion (μ) |
RA: −12.247
[1]
mas/
yr Dec.: −381.257 [1] mas/ yr |
Parallax (π) | 104.3904 ± 0.1287 mas [1] |
Distance | 31.24 ± 0.04
ly (9.58 ± 0.01 pc) |
Absolute magnitude (MV) | 5.53±0.006 [7] |
Details | |
Mass | 0.93±0.02 [8] M☉ |
Radius | 0.86±0.02 [9] R☉ |
Luminosity | 0.609±0.009 [10] L☉ |
Surface gravity (log g) | 4.43±0.06 [3] cgs |
Temperature | 5,488±44 [3] K |
Metallicity [Fe/H] | −0.03±0.03 [3] dex |
Rotation | 17.1 days [11] |
Rotational velocity (v sin i) | 3.3 [3] km/s |
Age | 2.1±1.7 [8] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
61 Ursae Majoris, abbreviated 61 UMa, is a single [13] star in the northern circumpolar constellation of Ursa Major. It has a yellow-orange hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.35. [2] The distance to this star is 31.2 light years based on parallax, [1] and it is drifting closer with a radial velocity of −5.2 km/s. [6] The star has a relatively high proper motion traversing the sky at the rate of 0.381 ″ yr−1. [14]
The stellar classification of 61 UMa is G8V, [4] matching a late G-type main-sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. [15] It is considered a solar-type star, having physical properties that make it similar to the Sun. [16] The star has 93% [8] of the mass of the Sun and 86% [9] of the Sun's radius. It is roughly two [8] billion years old and is spinning with a projected rotational velocity of 3.3 km/s, [3] for a period of 17.1 days. [11] The metallicity, or abundance of elements with higher atomic number than helium, appears about the same as in the Sun. [3] The star is radiating 61% [10] of the luminosity of the Sun from its photosphere at an effective temperature of 5,488K. [3]
During the 1950s, Karl Pilowski reported that photographic plates taken of the star appeared to show a variability of 0.2 in magnitude. Follow-up studies initially failed to confirm this variability, and it was found not to be an eclipsing binary based on radial velocity measurements. [17] The star's photosphere is rotating differentially, and the rotation period, typically in the range of 16-18 days, shows a larger difference between different latitudes than for most other stars. [18] It has an active chromosphere that exhibits strong and persistent starspot activity. [9] A flare event was captured in 2013 while the star was being observed by the VATT, [19] and the star has been detected as a source of X-ray emission. [20]
No substellar companions have been observed in orbit around this star, and it appears to lack a dust ring as is found around some comparable stars. A radial velocity survey completed in 2020 has indicated that giant planetary companions are absent. [9] A magnitude 11.35 stellar visual companion was reported by O. Struve in 1850. As of 2015, this star was located at an angular separation of 158.90″ from the brighter star, along a position angle of 86°. [21]
In the science fiction of Larry Niven's Known Space universe, the homeworld of the major race the Kzinti is the third planet in orbit around 61 Ursae Majoris. [22]
In the Star Trek universe, Archer IV is the fourth planet around 61 Ursae Majoris. [23]