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Star in the constellation Ursa Major
HR 4072
Observation data
Epoch
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
−0.052± 0.012
[3]
Variable type
α2 CVn
[5]
Astrometry
Radial velocity (Rv ) −2.6± 4.2
[3] 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 (104 ± 2
pc )
Absolute magnitude (MV ) −0.15
[3]
Orbit
[6]
Period (P) 11.57907± 0.00019 d
Eccentricity (e) 0.26± 0.04
Periastron
epoch (T) 2,418,468.175± 0.051
JD
Argument of periastron (ω) (secondary) 171.0± 1.6 °
Semi-amplitude (K1 ) (primary) 38.9± 0.5 km/sSemi-amplitude (K2 ) (secondary)64.8 km/s
Details A
Luminosity 138.84
[3]
L ☉
Surface gravity (log g ) 3.89
[7]
cgs
Temperature 10,307
[7]
K
Metallicity [Fe/H]+0.39
[7]
dex
Rotational velocity (v sin i ) 4.5
[7] km/s
Other designations
ET UMa ,
BD +66 664 ,
GJ 9327,
HD 89822,
HIP 50933,
HR 4072,
SAO 15163,
PPM 17427,
PLX 2433,
TYC 4150-1302-1 ,
IRAS 10205+6549 ,
2MASS J10240782+6533590
[8]
Database references
SIMBAD
data
HR 4072 is a
binary star
[9] system in the northern
circumpolar constellation of
Ursa Major . It has the
variable star designation ET Ursae Majoris , abbreviated ET Uma,
[5] while HR 4072 is the system's designation from the
Bright Star Catalogue . It has a white hue and is faintly visible to the naked eye with an
apparent visual magnitude that fluctuates around 4.94.
[3] The system is located at a distance of approximately 339
light years from the
Sun based on
parallax measurements.
[2] The
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] star system with an
orbital period of 11.6 days and an
eccentricity of 0.26. The orbit for this star was first determined by
R. H. Baker in 1912, then later revised.
[6]
The primary, designated component A, is an
Ap type
chemically-peculiar star
[10]
[11]
[12] with a
stellar classification of A1:VpSiSrHg,
[4] although it has also been considered to be a
mercury-manganese star .
[13] The suffix notation indicates abundance anomalies of silicon, strontium, and mercury in the
spectrum . It is an
α2 Canum Venaticorum variable with an amplitude of 0.05 magnitude in the
B (blue) band .
[5] The star is rotating slowly with a
projected rotational velocity of 4.5 km/s.
[7] It is radiating 139
[3] times the
luminosity of the Sun from its
photosphere at an
effective temperature of 10,307 K.
[7]
The secondary component has been reported to have characteristics of an
Am star .
[11]
References
^
"MAST: Barbara A. Mikulski Archive for Space Telescopes" . Space Telescope Science Institute. Retrieved 8 December 2021 .
^
a
b
c
d
e
f
Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018).
"Gaia Data Release 2: Summary of the contents and survey properties" .
Astronomy & Astrophysics . 616 . A1.
arXiv :
1804.09365 .
Bibcode :
2018A&A...616A...1G .
doi :
10.1051/0004-6361/201833051 .
Gaia DR2 record for this source at
VizieR .
^
a
b
c
d
e
f
g
h Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters . 38 (5): 331.
arXiv :
1108.4971 .
Bibcode :
2012AstL...38..331A .
doi :
10.1134/S1063773712050015 .
S2CID
119257644 .
^
a
b Abt, Helmut A.; Morrell, Nidia I. (1995).
"The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars" . Astrophysical Journal Supplement . 99 : 135.
Bibcode :
1995ApJS...99..135A .
doi :
10.1086/192182 .
^
a
b
c Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports . 5.1. 61 (1): 80–88.
Bibcode :
2017ARep...61...80S .
doi :
10.1134/S1063772917010085 .
S2CID
125853869 .
^
a
b Nariai, K. (1970). "Orbit of the Double-Line Spectroscopic Binary HR4072(Ap)". Publications of the Astronomical Society of Japan . 22 : 113.
Bibcode :
1970PASJ...22..113N .
^
a
b
c
d
e
f
g Takeda, Yoichi; et al. (October 2018). "Photospheric carbon, nitrogen, and oxygen abundances of A-type main-sequence stars*". Publications of the Astronomical Society of Japan . 70 (5): 91.
arXiv :
1807.06265 .
Bibcode :
2018PASJ...70...91T .
doi :
10.1093/pasj/psy091 .
S2CID
119258233 . 91.
^
"ET UMa" .
SIMBAD .
Centre de données astronomiques de Strasbourg . Retrieved 2019-12-06 .
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society . 389 (2): 869–879.
arXiv :
0806.2878 .
Bibcode :
2008MNRAS.389..869E .
doi :
10.1111/j.1365-2966.2008.13596.x .
S2CID
14878976 .
^ Renson, P.; Manfroid, J. (2009).
"Catalogue of Ap, HGMN and Am stars" . Astronomy and Astrophysics . 498 (3): 961.
Bibcode :
2009A&A...498..961R .
doi :
10.1051/0004-6361/200810788 .
^
a
b Popper, Daniel M. (1971).
"Some Double-Lined Eclipsing Binaries with Metallic-Line Spectra" . The Astrophysical Journal . 169 : 549.
Bibcode :
1971ApJ...169..549P .
doi :
10.1086/151173 .
^ Chen, P. S.; Liu, J. Y.; Shan, H. G. (2017).
"A New Photometric Study of Ap and Am Stars in the Infrared" . The Astronomical Journal . 153 (5): 218.
Bibcode :
2017AJ....153..218C .
doi :
10.3847/1538-3881/aa679a .
^ Ghazaryan, S.; Alecian, G. (2016).
"Statistical analysis from recent abundance determinations in Hg Mn stars" . Monthly Notices of the Royal Astronomical Society . 460 (2): 1912.
Bibcode :
2016MNRAS.460.1912G .
doi :
10.1093/mnras/stw911 .