Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Ursa Major |
Right ascension | 11h 29m 48.489s [2] |
Declination | +30° 04′ 02.38″ [2] |
Apparent magnitude (V) | 10.03 [3] (9.26 to 10.24) [4] |
Characteristics | |
Spectral type | kA2hA9.5 (phase 0.03) kF0hF7.5 (phase 0.56) [5] |
B−V color index | 0.355±0.034 [3] |
Variable type | RRab [4] |
Astrometry | |
Radial velocity (Rv) | 98.50±2.1 [6] km/s |
Proper motion (μ) |
RA: −69.141
mas/
yr
[2] Dec.: −53.426 mas/ yr [2] |
Parallax (π) | 1.5641 ± 0.0252 mas [2] |
Distance | 2,090 ± 30
ly (640 ± 10 pc) |
Absolute magnitude (MV) | 0.66 [7] |
Details | |
Mass | 0.55 [8] M☉ |
Radius | 4.93 [9] R☉ |
Luminosity | 44.7 [7] L☉ |
Surface gravity (log g) | 2.10±0.15 [10] cgs |
Temperature | 6,200±65 [10] K |
Metallicity [Fe/H] | −1.31 [10] dex |
Rotational velocity (v sin i) | 12.76 [11] km/s |
Other designations | |
Database references | |
SIMBAD | data |
TU Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major. It is classified as a Bailey-type 'ab' RR Lyrae variable with a period of 0.557648 days [13] that ranges in brightness from apparent visual magnitude of 9.26 down to 10.24. [4] The distance to this star is approximately 2,090 light years based on parallax measurements. [9] It is located near the north galactic pole at a distance that indicates this is a member of the galactic halo. [14]
The periodic variability of this star was discovered by P. Guthnick and R. Prager in 1929. [15] [8] Its relative brightness has made this star the subject of regular observation since its discovery, [16] both photographically and then photoelectrically starting in 1957. [17] It was initially classed as a Bailey-type "a" RR Lyrae variable. The variations were found to be somewhat similar to RR Lyrae, with the periodicity of TU UMa differing by less than 1% of a day. [16] However, no evidence of a long-period modulation, known as the Blazhko effect, was found in this star. [17]
In 1990, A. Saha and R. E. White found variations in radial velocity over time that suggested this is a binary system. [14] However, confirmation of this proved difficult because of the distance and the pulsational behavior of the variable. [8] The system shows significant evidence of proper motion acceleration from a binary interaction. [18] Analysis of long-term oscillatory variations suggests an orbital period of 23.3 years and an eccentricity of 0.79, [19] with the secondary having at least 33% of the mass of the Sun. [8]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Ursa Major |
Right ascension | 11h 29m 48.489s [2] |
Declination | +30° 04′ 02.38″ [2] |
Apparent magnitude (V) | 10.03 [3] (9.26 to 10.24) [4] |
Characteristics | |
Spectral type | kA2hA9.5 (phase 0.03) kF0hF7.5 (phase 0.56) [5] |
B−V color index | 0.355±0.034 [3] |
Variable type | RRab [4] |
Astrometry | |
Radial velocity (Rv) | 98.50±2.1 [6] km/s |
Proper motion (μ) |
RA: −69.141
mas/
yr
[2] Dec.: −53.426 mas/ yr [2] |
Parallax (π) | 1.5641 ± 0.0252 mas [2] |
Distance | 2,090 ± 30
ly (640 ± 10 pc) |
Absolute magnitude (MV) | 0.66 [7] |
Details | |
Mass | 0.55 [8] M☉ |
Radius | 4.93 [9] R☉ |
Luminosity | 44.7 [7] L☉ |
Surface gravity (log g) | 2.10±0.15 [10] cgs |
Temperature | 6,200±65 [10] K |
Metallicity [Fe/H] | −1.31 [10] dex |
Rotational velocity (v sin i) | 12.76 [11] km/s |
Other designations | |
Database references | |
SIMBAD | data |
TU Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major. It is classified as a Bailey-type 'ab' RR Lyrae variable with a period of 0.557648 days [13] that ranges in brightness from apparent visual magnitude of 9.26 down to 10.24. [4] The distance to this star is approximately 2,090 light years based on parallax measurements. [9] It is located near the north galactic pole at a distance that indicates this is a member of the galactic halo. [14]
The periodic variability of this star was discovered by P. Guthnick and R. Prager in 1929. [15] [8] Its relative brightness has made this star the subject of regular observation since its discovery, [16] both photographically and then photoelectrically starting in 1957. [17] It was initially classed as a Bailey-type "a" RR Lyrae variable. The variations were found to be somewhat similar to RR Lyrae, with the periodicity of TU UMa differing by less than 1% of a day. [16] However, no evidence of a long-period modulation, known as the Blazhko effect, was found in this star. [17]
In 1990, A. Saha and R. E. White found variations in radial velocity over time that suggested this is a binary system. [14] However, confirmation of this proved difficult because of the distance and the pulsational behavior of the variable. [8] The system shows significant evidence of proper motion acceleration from a binary interaction. [18] Analysis of long-term oscillatory variations suggests an orbital period of 23.3 years and an eccentricity of 0.79, [19] with the secondary having at least 33% of the mass of the Sun. [8]