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Alkaid - Wikipedia

Coordinates:

13^h 47^m 32.4^s, +49° 18′ 47.8″

From Wikipedia, the free encyclopedia

(Redirected from Eta Ursae Majoris)

Alkaid
Observation data Epoch J2000 Equinox J2000
Location of Alkaid (circled)
Constellation	Ursa Major
Right ascension	13^h 47^m 32.43776^s^[1]
Declination	+49° 18′ 47.7602″^[1]
Apparent magnitude (V)	+1.86^[2]
Characteristics
Spectral type	B3 V^[3]
U−B color index	−0.68^[2]
B−V color index	−0.19^[2]
Astrometry

Radial velocity (R_v)	−10.9^[4] km/s
Proper motion (μ)	RA: −121.17^[1] mas/yr Dec.: −14.91^[1] mas/yr
Parallax (π)	31.38 ± 0.24 mas^[1]
Distance	103.9 ± 0.8 ly (31.9 ± 0.2 pc)
Absolute magnitude (M_V)	−0.67^[5]

Details

Mass	6.1±0.1^[6] `M`_☉
Radius	3.4±0.5^[7] `R`_☉
Luminosity	594±31^[7] `L`_☉
Surface gravity (log g)	3.78^[7] cgs
Temperature	15,540±1,157^[7] K
Rotational velocity (v sin i)	150^[8] km/s
Age	10.0±2.6^[6] Myr

Other designations
Alkaid, Benetnash, Benetnasch,^[9] Elkeid, η UMa, 85 UMa, BD+50°2027, FK5 509, GC 18643, HD 120315, HIP 67301, HR 5191, PPM 53742, SAO 44752.
Database references
SIMBAD	data

Alkaid /ælˈkeɪd/, also called Eta Ursae Majoris (Latinised from η Ursae Majoris, abbreviated Eta UMa, η UMa),^[10]^[11] is a star in the constellation of Ursa Major. It is the most eastern (leftmost) star in the Big Dipper (or Plough) asterism. However, unlike most stars of the Big Dipper, it is not a member of the Ursa Major moving group.^[12] With an apparent visual magnitude of +1.86, it is the third-brightest star in the constellation and one of the brightest stars in the night sky.

Physical properties

Alkaid is a 10-million-year-old^[6] B-type main sequence star with a stellar classification of B3 V.^[3] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.^[13] It has six^[6] times the mass; 3.4^[14] times the radius, and is radiating around 594^[7] times as much energy as the Sun. Its outer atmosphere has an effective temperature of about 15,540 K,^[7] giving it the blue-white hue of a B-type star.^[15] This star is an X-ray emitter with a luminosity of 9.3 × 10²⁸ erg s⁻¹.^[16]

Eta Ursae Majoris was listed as a standard star for the spectral type B3 V. It has broadened absorption lines due to its rapid rotation, which is common in stars of this type. However, the lines are very slightly distorted and variable, which may be caused by some emission from a weak disk of material produced by the rapid rotation.^[17]

Alkaid is a relatively nearby and bright star and has been examined closely, but no exoplanets or companion stars have been discovered.^[18]^[19]

Nomenclature

η Ursae Majoris (Latinised to Eta Ursae Majoris) is the star's Bayer designation. The International Astronomical Union has formally chosen the proper name Alkaid for this star.^[20]

It bore the traditional names Alkaid (or Elkeid from the Arabic القايد القائد) and Benetnasch /ˈbɛnɛtnæʃ/.^[10] Alkaid derives from the Arabic phrase meaning "The leader of the daughters of the bier" (قائد بنات نعش qā'id bināt naʿsh). The daughters of the bier, i.e. the mourning maidens, are the three stars of the handle of the Big Dipper, Alkaid, Mizar, and Alioth; while the four stars of the bowl, Megrez, Phecda, Merak, and Dubhe, are the bier.

It is known as Běidǒuqī (北斗七 - the Seventh Star of the Northern Dipper) or Yáoguāng (瑤光 - the Star of Twinkling Brilliance) in Chinese.

The Hindus knew this star as Marīci, one of the Seven Rishis.^[21]

In Japan and Korea, Alkaid is known as Hagunsei and Mukokseong respectively ("the military breaking star" or "most corner star"). Both meanings come from ancient China's influence in both countries.

In culture

USS Alkaid (AK-114) was a United States Navy Crater class cargo ship named after the star.^[22]

Alkaid is one of the Behenian fixed stars, used in Alchemy.

The fossil starfish Alkaidia is named after Alkaid.^[23]

References

^ ^a ^b ^c ^d ^e van Leeuwen, Floor (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752v1. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Note: see VizieR catalogue I/311.
^ ^a ^b ^c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
^ ^a ^b Morgan, W. W.; Keenan, P. C. (1973). "Spectral Classification". Annual Review of Astronomy and Astrophysics. 11: 29. Bibcode:1973ARA&A..11...29M. doi:10.1146/annurev.aa.11.090173.000333.
^ Wielen, R.; et al. (1999). "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions". Veröff. Astron. Rechen-Inst. Heidelb. 35 (35): 1. Bibcode:1999VeARI..35....1W.
^ 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 ^c ^d Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
^ ^a ^b ^c ^d ^e ^f Baines, E.; Schmitt, H. R.; Zavala, R. T.; Hutter, D.; van Belle, G. T. (2017). "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer". The Astronomical Journal. 155 (1): 30. arXiv:1712.08109. Bibcode:2018AJ....155...30B. doi:10.3847/1538-3881/aa9d8b. S2CID 119427037.
^ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002). "Rotational Velocities of B Stars". The Astrophysical Journal. 573 (1): 359–365. Bibcode:2002ApJ...573..359A. doi:10.1086/340590.
^ Rumrill, H. B. (1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. 48 (283): 139. Bibcode:1936PASP...48..139R. doi:10.1086/124681. S2CID 120743052.
^ ^a ^b Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
^ Motz, Lloyd; Nathanson, Carol (1988). The Constellations: An Enthusiast's Guide To The Night Sky. Doubleday. p. 39. ISBN 978-0385176002.
^ Garrison, R. F. (December 1993). "Anchor Points for the MK System of Spectral Classification". Bulletin of the American Astronomical Society. 25: 1319. Bibcode:1993AAS...183.1710G. Archived from the original on 2019-06-25. Retrieved 2012-02-04.
^ Underhill, A. B.; et al. (November 1979). "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars". Monthly Notices of the Royal Astronomical Society. 189 (3): 601–605. Bibcode:1979MNRAS.189..601U. doi:10.1093/mnras/189.3.601.
^ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2012-03-18. Retrieved 2012-01-16.
^ Cassinelli, J. P.; et al. (February 1994). "X-ray emission from near-main-sequence B stars". Astrophysical Journal, Part 1. 421 (2): 705–717. Bibcode:1994ApJ...421..705C. doi:10.1086/173683.
^ Bopp, B. W; Caplinger, J. R; Crosby, N. A; Mahoney, D. F; O'Brien, S. P; Dempsey, R. C (1989). "Is the MK Standard eta UMa an Incipient be Star?". Information Bulletin on Variable Stars. 3347: 1. Bibcode:1989IBVS.3347....1B.
^ Howard, Andrew W; Fulton, Benjamin J (2016). "Limits on Planetary Companions from Doppler Surveys of Nearby Stars". Publications of the Astronomical Society of the Pacific. 128 (969): 114401. arXiv:1606.03134. Bibcode:2016PASP..128k4401H. doi:10.1088/1538-3873/128/969/114401. S2CID 118503912.
^ Roberts, Lewis C; Turner, Nils H; Ten Brummelaar, Theo A (2007). "Adaptive Optics Photometry and Astrometry of Binary Stars. II. A Multiplicity Survey of B Stars". The Astronomical Journal. 133 (2): 545. Bibcode:2007AJ....133..545R. CiteSeerX 10.1.1.549.4623. doi:10.1086/510335.
^ "Naming Stars". International Astronomical Union. Retrieved 18 July 2023.
^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 438. ISBN 978-0-486-21079-7. Retrieved 2012-09-04.
^ "Alkaid (AK-114)". Naval History and Heritage Command. 11 December 2016. Retrieved 31 December 2019.
^ Blake, Daniel B.; Reid, Robert (1998). "Some Albian (Cretaceous) asteroids (Echinodermata) from Texas and their paleobiological implications". Journal of Paleontology. 72 (3): 512–532. Bibcode:1998JPal...72..512B. doi:10.1017/S002233600002429X. ISSN 0022-3360.

External links

Alkaid at Jim Kaler's Stars website

Constellation of Ursa Major

Stars

Bayer	α (Dubhe) β (Merak) γ (Phecda) δ (Megrez) ε (Alioth) ζ (Mizar) η (Alkaid) θ ι (Talitha) κ (Alkaphrah) λ (Tania Borealis) μ (Tania Australis) ν (Alula Borealis) ξ (Alula Australis) ο (Muscida) π¹ π² ρ σ¹ σ² τ υ φ χ (Taiyangshou) ψ ω
Flamsteed	2 (A) 5 (b) 6 15 (f) 16 (c) 17 18 (e) 19 20 21 22 23 (h) 24 (d) 26 27 28 31 32 35 36 37 38 39 40 41 42 43 44 46 47 (Chalawan) 49 51 55 56 57 58 59 60 61 62 65 66 67 68 70 71 72 73 74 75 76 78 80 (Alcor) 81 82 83 84 86 55 Cam 56 Cam 57 Cam 1 CVn 14 LMi 15 LMi 25 LMi 47 LMi 37 Lyn 39 Lyn 41 Lyn (Intercrus)
Variable	R T U W Z RV ST SU SW SX TU TX TY UX UY VV VX VY XY ZZ AA AB AE AN AR AW BC BE BM BZ CG CH CO CQ CY DH DI DM DV DW EE EG EI EK EN EP ER ET EU EV EZ IY KS
HR	3922 4067 4098 4132 4867 5148
HD	68988 (Násti) 74389 80606 80607 84406 98618 99706 118203 (Liesma) 233731
Other	ADS 7251 Feige 55 G 196-3 Gliese 338 Gliese 412 Gliese 414 GJ 3512 Groombridge 1618 Groombridge 1830 HAT-P-3 (Dombay) HAT-P-13 HAT-P-21 (Mazaalai) HIP 57050 HIP 57274 1SWASP J093010.78+533859.5 KELT-24 Lalande 21185 M82 X-1 M82 X-2 Qatar-8 Sidus Ludoviciana SN H0pe UGC 5497 US 708 Winnecke 4 WISE 1405+5534 XTE J1118+480

Exoplanets	47 Ursae Majoris b (Taphao Thong) c (Taphao Kaew) d ο Ursae Majoris b 41 Lyncis b (Arkas) Gliese 414 Ab c HAT-P-3b (Teberda) HD 80606 b HD 89744 b KELT-24b

Nebulae	Owl Nebula

Galaxies

Messier	81 (Bode's Galaxy) 82 (Cigar Galaxy) 101 (Pinwheel Galaxy) 108 109
NGC	2603 2606 2681 2685 2688 2768 2787 2800 2805 2814 2841 2857 2950 2959 2976 2985 2998 3005 3006 3008 3009 3073 3077 3079 3184 3191 3198 3206 3259 3310 3319 3353 3359 3435 3445 3448 3516 3539 3545B 3550 3552 3553 3554 3358 3561 3583 3610 3613 3619 3631 3642 3656 3665 3669 3675 3690 3718 3726 3729 3738 3741 3786 3794 3877 3893 3898 3921 3928 3938 3941 3945 3949 3953 3972 3982 3985 3994 3995 3998 4013 4026 4036 4041 4051 4088 4096 4100 4102 4144 4157 4194 4500 4605 5001 5164 5201 5204 5256 5278 5279 5308 5322 5422 5473 5474 5477 5486 5502 5585
Other	2MASX J10222849+5006200 3C 219 3C 244.1 3C 268.3 CEERS-2112 Haro 2 Holmberg IX I Zwicky 18 IC 923 IC 2574 IRAS F11119+3257 Markarian 231 Markarian 273 Markarian 421 Mayall's Object SBS 0953+549 SDSS J1148+5251 UGC 4879 UGC 5101 UGC 6945 UGC 8335 UGC 8508 Ursa Major III