Bellatrix
{{Short description|Star in the constellation Orion}}
{{other uses}}
{{Starbox begin}}
{{Starbox image
| image =
{{Location mark
|image=Orion IAU.svg
|float=center
|alt=
|label=
|position=right
|width=250
|mark=Red circle.svg
|mark_width=12
|mark_link=Bellatrix
|x=522|y=552
}}
| caption = Location of γ Orionis (circled)
}}
{{Starbox observe
| epoch = J2000
| constell = Orion
| pronounce = {{IPAc-en|ˈ|b|ɛ|l|ə|t|r|ɪ|k|s}} {{IPAc-en|b|E|'|l|ei|t|r|I|k|s}}
| dec = {{DEC|+06|20|58.9318}}
| appmag_v = 1.64 {{nowrap|(1.59 - 1.64)}}
}}
{{Starbox character
| class = B2III or B2V
}}
{{Starbox astrometry
| parallax = 12.92
| p_error = 0.52
}}
{{Starbox detail
| temperature = {{val|22339|602|fmt=commas}}
}}
{{Starbox catalog
| names = {{odlist| name=Bellatrix | B=γ Orionis, Gamma Ori, γ Ori | name2=BenAnna{{cite web |url=https://www.kjopenstjerne.no/starregistry/IPC-4UV-9QY-QE5 |title=Starling Star Registry}} |name4=Amazon Star | F=24 Ori | name3=Al Najīd | HR=1790 | BD=+06°919 | HD=35468 | SAO=112740 | FK5=201 | HIP=25336 | NSV=1972 }}
}}
{{Starbox reference
| Simbad = Bellatrix
}}
{{Starbox end}}
Bellatrix is the third-brightest star and a candidate binary star in the constellation of Orion, positioned 5° west of the red supergiant Betelgeuse (Alpha Orionis). It has the Bayer designation γ Orionis, which is Latinized to Gamma Orionis. With a slightly variable magnitude of around 1.6, it is typically the 25th-brightest star in the night sky. According to parallax measurements by the Hipparcos spacecraft, Bellatrix is located at a distance of 250{{±|10}} light-years.
Nomenclature
The traditional name Bellatrix is from the Latin bellātrix "female warrior". It first appeared in the works of Abu Ma'shar al-Balkhi and Johannes Hispalensis, where it originally referred to Capella, but was transferred to Gamma Orionis by the Vienna school of astronomers in the 15th century, and appeared in contemporary reprints of the Alfonsine tables. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Bellatrix for this star. It is now so entered in the IAU Catalog of Star Names. The designation of Bellatrix as γ Orionis (Latinized to Gamma Orionis) was made by Johann Bayer in 1603. The "gamma" designation is commonly given to the third-brightest star in each constellation.
Standard star
Bellatrix has been used as both a photometric and spectral standard star, but both characteristics have been shown to be unreliable.
In 1963, Bellatrix was included with a set of bright stars used to define the UBV magnitude system. These are used for comparison with other stars to check for variability, and so by definition, the apparent magnitude of Bellatrix was set to 1.64. However, when an all-sky photometry survey was carried out in 1988, this star was suspected to be variable. It was measured ranging in apparent magnitude from 1.59 to 1.64, and appears to be a low amplitude, possibly irregular variable.
Physical properties
File:1e9m comparison Gamma Orionis, Algol B, the Sun, and smaller - antialiased no transparency.png]]
The spectral types for O and early B stars were defined more rigorously in 1971 and Bellatrix was used as a standard for the B2 III type. The expected brightness of Bellatrix from this spectral type is about one magnitude brighter than calculated from its apparent magnitude and Hipparcos distance. Analysis of the observed characteristics of the star indicate that it should be a B2 main sequence star, not the giant that it appears from its spectral type. Close analysis of high resolution spectra suggest that it is a spectroscopic binary composed of two similar stars less luminous than a B2 giant.
Bellatrix is a massive star with about 8.6 times the mass and 6.4 times the radius of the Sun. As a massive star, this star will evolve faster than the Sun, currently it has an estimated age of approximately 25 million years. The hydrogen should be exhausted in seven million years, after that Bellatrix will expand and cool. It may end its life in a supernova. The effective temperature of the outer envelope of this star is {{val|22000|u=K|fmt=commas}}, which is considerably hotter than the 5,772 K on the Sun. This high temperature gives this star the blue-white hue that occurs with B-type stars. It shows a projected rotational velocity of around 52 km/s.
Companions
Bellatrix was thought to belong to the Orion OB1 association of stars that share a common motion through space, along with the stars of Orion's Belt: Alnitak (Zeta Orionis), Alnilam (Epsilon Orionis), and Mintaka (Delta Orionis). However, this is no longer believed to be the case, as Bellatrix is now known to be much closer than the rest of the group. It is not known to have a stellar companion, although researchers Maria-Fernanda Nieva and Norbert Przybilla raised the possibility it might be a spectroscopic binary. A 2011 search for nearby companions failed to conclusively find any objects that share a proper motion with Bellatrix. Three nearby candidates were all found to be background stars.
Some researchers suspected that Bellatrix was a member of the 32 Orionis group. They proposed that the 32 Ori group should instead be termed the Bellatrix Cluster on the basis that the sky position and distance of Bellatrix are similar to those of the 32 Ori group. The proper motion of Bellatrix deviates significantly from the mean motion of the group, leaving its membership in question. However, it may be possible to reconcile membership if the divergent velocity is the result of an unseen companion. For example, a face-on orbit with a black hole companion orbiting {{val|100|ul=AU|p=~}} from the star with a period measured in centuries could account for the discrepancy.
Etymology and cultural significance
Bellatrix was also called the Amazon Star, which Richard Hinckley Allen proposed came from a loose translation of the Arabic name Al Najīd, the Conqueror. A c.1275 Arabic celestial globe records the name as المرزم "the lion". Bellatrix is one of the four navigational stars in Orion that are used for celestial navigation.
In the 17th century catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Menkib al Jauza al Aisr, which was translated into Latin as Humerus Sinister Gigantis (The Left Shoulder of the Giant).
The Wardaman people of northern Australia know Bellatrix as Banjan, the sparkling pigment used in ceremonies conducted by Rigel the Red Kangaroo Leader in a songline when Orion is high in the sky. The other stars of Orion are his ceremonial tools and entourage. Betelgeuse is Ya-jungin "Owl Eyes Flicking", watching the ceremonies.
To the Inuit, the appearance of Betelgeuse and Bellatrix high in the southern sky after sunset marked the beginning of spring and lengthening days in late February and early March. The two stars were known as Akuttujuuk "those (two) placed far apart", referring to the distance between them, mainly to people from North Baffin Island and Melville Peninsula.
See also
References
{{reflist|refs=
{{cite book | last1=Allen | first1=Richard H. | author-link=Richard Hinckley Allen | date=1963 | title=Star Names: Their Lore and Meaning | edition=reprint | publisher=Dover Publications Inc. | location=New York, NY | isbn=0-486-21079-0 | page=[https://archive.org/details/bub_gb_5xQuAAAAIAAJ/page/n259 237] | url=https://archive.org/details/bub_gb_5xQuAAAAIAAJ }}
| title=Cosmography of OB stars in the solar neighbourhood
| last1=Bouy | first1=H. | last2=Alves | first2=J.
| journal=Astronomy & Astrophysics
| volume=584 | pages=A26 | date=December 2015
| bibcode=2015A&A...584A..26B | doi=10.1051/0004-6361/201527058
| issn=0004-6361 | s2cid=123265789 | doi-access=free }}
| title=A stellar census of the nearby, young 32 Orionis group
| display-authors=1 | last1=Bell | first1=Cameron P. M.
| last2=Murphy | first2=Simon J. | last3=Mamajek | first3=Eric E.
| journal=Monthly Notices of the Royal Astronomical Society
| volume=468 | issue=1 | pages=1198–1220 | date=June 2017
| doi=10.1093/mnras/stx535 | doi-access=free | arxiv=1703.00015
| bibcode=2017MNRAS.468.1198B }}
| title=The IACOB project. I. Rotational velocities in northern Galactic O- and early B-type stars revisited. The impact of other sources of line-broadening
| last1=Simón-Díaz | first1=S. |last2=Herrero | first2=A.
| journal=Astronomy & Astrophysics
| volume=562 | pages= A135 | year=2014
| doi=10.1051/0004-6361/201322758 | arxiv=1311.3360
| bibcode=2014A&A...562A.135S | s2cid=119278062}}
| title=Further Photometry of alpha Ori and gamma Ori
| last=Krisciunas | first=K.
| journal=Information Bulletin on Variable Stars
| volume=4028 | page=1 | date=May 1994
| bibcode=1994IBVS.4028....1K }}
|last1=Kunitzsch |first1=Paul
|last2=Smart |first2=Tim
|date = 2006 |edition = 2nd rev.
|title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
|publisher = Sky Pub |location = Cambridge, Massachusetts
|isbn = 978-1-931559-44-7
}}
| last = Dorn
| first = Bernhard
| date = July 1830
| title = Description of the Celestial Globe belonging to Major-General Sir John Malcolm, G.C.B., K.L.S., &c. &c., deposited in the Museum of the Royal Asiatic Society of Great Britain and Ireland
| journal = Transactions of the Royal Asiatic Society of Great Britain and Ireland
| volume = 2
| issue = 2
| pages = 371–392
| doi = 10.1017/S0950473700000513
| url = https://zenodo.org/record/1807366
}}
| last=Knobel | first=E. B.
| title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket
| journal=Monthly Notices of the Royal Astronomical Society
| volume=55 | issue=8
| page=429 |date=June 1895
| bibcode=1895MNRAS..55..429K | doi=10.1093/mnras/55.8.429| doi-access=free}}
{{cite book | last1 = Harney | first1 = Bill Yidumduma | last2 = Cairns | first2 = Hugh C. | title = Dark Sparklers | publisher = Hugh C. Cairns | location = Merimbula, New South Wales | pages=139–40 | date = 2004 | orig-year = 2003 | edition = Revised | isbn = 0-9750908-0-1}}
{{cite book |title = The Arctic sky: Inuit astronomy, star lore, and legend |url = https://archive.org/details/arcticskyinuitas0000macd/page/52 |url-access = registration |last = MacDonald |first = John |publisher =Royal Ontario Museum/Nunavut Research Institute |location = Toronto, Ontario/Iqaluit, NWT |date = 1998 |isbn = 9780888544278 |pages = [https://archive.org/details/arcticskyinuitas0000macd/page/52 52–54, 119] }}
}}
External links
{{wiktionary|bellatrix}}
- [https://sl.voxastro.org/library/UVES-POP/details/?star=Bellatrix Spectrum of Bellatrix]
- Navigational Stars
{{Stars of Orion}}
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Category:Orion (constellation)