Star in the constellation Ursa Major
HR 4072
Observation dataEpoch J2000 Equinox J2000
Constellation Ursa Major
Right ascension 10h 24m 07.84801s [ 2]
Declination +65° 33′ 59.1239″ [ 2]
Apparent magnitude (V)4.94[ 3]
Characteristics
Spectral type A1:VpSiSrHg[ 4]
B−V color index
± 0.012[ 3]
Variable type α2 CVn [ 5]
Astrometry Radial velocity (Rv )± 0.03[ 6] km/s Proper motion (μ) RA: −9.427[ 2] mas /yr Dec.: −20.994[ 2] mas /yr Parallax (π)9.61± 0.20 mas [ 2] Distance 339 ± 7 ly pc ) Absolute magnitude (MV )−0.15[ 3] Orbit [ 6] Period (P)± 0.000010 dSemi-major axis (a)± 0.001 mas Eccentricity (e)± 0.0009Longitude of the node (Ω)± 0.13° Periastron epoch (T)± 0.005 JD Argument of periastron (ω)± 0.20° Semi-amplitude 1 )± 0.04 km/sSemi-amplitude (K2 )± 0.09 km/sDetails[ 6] A Mass ± 0.153 M ☉ Radius ± 0.11 R ☉ Luminosity ± 8 L ☉ Surface gravity (log g )± 0.05 cgs Temperature ± 100 K Metallicity
[
M
/
H
]
{\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}}
= ± 0.04Metallicity [Fe/H] +0.39[ 7] dex Rotational velocity (v sin i )≤4.2 km/s B Mass ± 0.094 M ☉ Radius ± 0.06 R ☉ Luminosity ± 1.0 L ☉ Surface gravity (log g )± 0.05 cgs Temperature ± 140 K Metallicity
[
M
/
H
]
{\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}}
= ± 0.07Rotational velocity (v sin i )± 2.1 km/sOther designations ET UMa , BD +66 664GJ 9327HD 89822HIP 50933HR 4072SAO 15163PPM 17427PLX 2433TYC 4150-1302-1IRAS 10205+65492MASS J10240782+6533590[ 8] Database references SIMBAD data
HR 4072 is a binary star [ 9] circumpolar constellation of Ursa Major . It has the variable star designation ET Ursae Majoris , abbreviated ET UMa,[ 5] HR 4072 is the system's designation from the Bright Star Catalogue naked eye with an apparent visual magnitude that fluctuates around 4.94.[ 3] light years from the Sun based on parallax measurements.[ 2] radial velocity measurement is poorly constrained, but it appears to be drifting closer to the Sun at the rate of around −3 km/s.[ 3]
This is a double-lined spectroscopic binary [ 7] orbital period of 11.58 days and an eccentricity of 0.29.[ 6] R. H. Baker in 1912, then later revised.[ 10] [ 6]
The primary, designated component A, is an Ap type chemically-peculiar star [ 11] [ 12] [ 13] stellar classification of A1:VpSiSrHg,[ 4] mercury-manganese star .[ 14] spectrum . It is an α2 Canum Venaticorum variable with an amplitude of 0.05 magnitude in the B (blue) band .[ 5] projected rotational velocity of 4.5 km/s.[ 7] effective temperature of K [ 6]
The secondary component has been reported to have characteristics of an Am star .[ 12] F-type star with 1.73 times the size of the Sun and 1.71 times its mass. Its luminosity is about 10 times that of the Sun, or one-tenth of that of the primary, and it has an effective temperature of K [ 6]
![{\displaystyle {\begin{smallmatrix}\left[{\mathrm {M} }/{\mathrm {H} }\right]\end{smallmatrix}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d9a106d03666c72cc54c1dff07a5637d3adda9a1)
