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Chi2 Orionis

{{Short description|Star in the constellation Orion}}

{{DISPLAYTITLE:Chi2 Orionis}}

{{other stars by Bayer designation|Chi Orionis{{!}}χ Orionis}}

{{Starbox begin

| name = χ2 Orionis

}}

{{Starbox image

| image=

{{Location mark

|image=Gemini constellation map.svg|alt=|float=center|width=280

|label=|position=right

|mark=Red circle.svg|mark_width=10|mark_link=χ2 Ori|x=862|y=426

}}

|caption=Location of χ2 Orionis (circled)

}}

{{Starbox observe

| epoch = J2000.0

| equinox = J2000.0 (ICRS)

| constell = Orion

| ra = {{RA|06|03|55.18437}}

| dec = {{DEC|+20|08|18.4281}}

| appmag_v=4.63

}}

{{Starbox character

| class = B2Ia

| u-b = −0.68

| b-v = +0.28

| r-i = +0.22

| variable = α Cyg

|type=Blue supergiant}}

{{Starbox astrometry

| radial_v = {{val|16.8|0.9}}

| prop_mo_ra = 2.679

| prop_mo_dec = −2.500

| parallax = 0.7636

| p_error = 0.1219

| parallax_footnote =

| absmag_v = −7.6

}}

{{Starbox detail

| rotational_velocity = 72

| radius = 61.9

| luminosity = 446,000

| mass = {{val|42.3|1.0}}

| gravity = 2.35

| temperature = 19,000

| age_myr = {{val|5|0.6}}

}}

{{Starbox catalog

| names=χ2 Ori, Chi2 Orionis, Chi2 Ori, 62 Orionis, 62 Ori, BD+20 1233, GC 7675, HD 41117, HIP 28716, HR 2135, PPM 95316, SAO 77911

}}

{{Starbox reference

| Simbad=chi2+ori

}}

{{Starbox end}}

Chi2 Orionis (Chi2 Ori / χ2 Orionis / χ2 Ori) {{IPAc-en|k|aɪ|.|t|u:|'|ɒ|r|aɪ}} is a B-type blue supergiant star in the constellation of Orion. It has an apparent visual magnitude of 4.63 but being quite distant, and heavily extinguished it burns with the greatest absolute visual light magnitude among stars in Orion within the near reaches of the galaxy, 0.9 of a magnitude brighter than Rigel.{{cn|date=August 2022}} Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It is considered to be a member of the Gemini OB1 association.

In apparent brightness it ranks, within Orion, admitting the higher published mean brightness of much more variable stars ranked above it, 35th.{{cn|date=August 2022}}

Chi1 Orionis is an unrelated, yellow, main sequence star over two degrees away and far closer to the Sun.

Spectrum

χ2 Orionis has a B2 bright supergiant spectrum and is one of the standard B2 Ia stars. It has been reported as having unusually narrow absorption lines and some weak emission lines and was included as one of the original Be stars. It is no longer treated as a Be star since many supergiants show some emission features at high resolution and Be stars is usually defined to exclude supergiants.

Variability

File:Chi2OriLightCurve.png for Chi2 Orionis, plotted from Hipparcos data]]

χ2 Orionis was listed as having likely small amplitude variability in photometry for the Third Catalogue of Stars measured in the Geneva Observatory Photometric System, specifically varying by 22 thousandths of a magnitude. It was included in the General Catalogue of Variable Stars based on Hipparcos satellite photometry with a magnitude range (in the Hipparchos photometric system) of 4.68 - 4.72 and a period of 2.8 days. A detailed study of the Hipparcos photometry confirmed the star as an α Cyg variable and gave the amplitude of variation as 0.057 magnitudes.

{{clear left}}

References

{{reflist|30em|refs=

{{cite Gaia DR3|3374836252947269888}}

{{cite web

| title=Light Curve |url=https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve

| website=Hipparcos ESA |publisher=ESA |access-date=11 August 2022}}

{{cite journal|bibcode=1994A&AS..103..135A|title=A study of Be stars in the wavelength region around Paschen 7|journal=Astronomy and Astrophysics Supplement Series |volume=103|last1=Andrillat|first1=Y.|last2=Jaschek|first2=M.|last3=Jaschek|first3=C.|year=1994|page=135 }}

{{cite journal|bibcode=1982A&AS...48..503R|title=List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry|journal=Astronomy and Astrophysics Supplement Series|volume=48|pages=503|last1=Rufener|first1=F.|last2=Bartholdi|first2=P.|year=1982}}

{{cite journal|bibcode=1999IBVS.4659....1K|title=The 74th Special Name-list of Variable Stars|journal=Information Bulletin on Variable Stars|volume=4659|pages=1|last1=Kazarovets|first1=E. V.|last2=Samus|first2=N. N.|last3=Durlevich|first3=O. V.|last4=Frolov|first4=M. S.|last5=Antipin|first5=S. V.|last6=Kireeva|first6=N. N.|last7=Pastukhova|first7=E. N.|year=1999}}

{{cite journal|bibcode=2009A&A...507.1141L|title=A systematic study of variability among OB-stars based on HIPPARCOS photometry|journal=Astronomy and Astrophysics|volume=507|issue=2|pages=1141|last1=Lefèvre|first1=L.|last2=Marchenko|first2=S. V.|last3=Moffat|first3=A. F. J.|last4=Acker|first4=A.|year=2009|doi=10.1051/0004-6361/200912304|doi-access=free}}

{{cite journal|bibcode=1925ApJ....61..389M|title=Discovery and Observations of Stars of Class Be|journal=Astrophysical Journal|volume=61|pages=389|last1=Merrill|first1=P. W.|last2=Humason|first2=M. L.|last3=Burwell|first3=C. G.|year=1925|doi=10.1086/142899|doi-access=free}}

khi 2 Ori, database entry, [http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/iii.dat The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars] {{Webarchive|url=https://web.archive.org/web/20170620004609/http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/iii.dat |date=2017-06-20 }}, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line January 14, 2011.

[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=2135 HR 2135], database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID [http://vizier.u-strasbg.fr/viz-bin/Cat?V/50 V/50]. Accessed on line January 14, 2011.

{{citation | last1=Garrison | first1=R. F. | title=Anchor Points for the MK System of Spectral Classification | journal=Bulletin of the American Astronomical Society | volume=25 | page=1319 | date=December 1993 | bibcode=1993AAS...183.1710G | url=http://www.astro.utoronto.ca/~garrison/mkstds.html | accessdate=2012-02-04 | archive-date=2019-06-25 | archive-url=https://web.archive.org/web/20190625094716/http://www.astro.utoronto.ca/~garrison/mkstds.html | url-status=dead }}

{{cite journal |bibcode=1953GCRV..C......0W|title=General catalogue of stellar radial velocities|publisher=Carnegie Institution of Washington|last1=Wilson|first1=Ralph Elmer|journal=Carnegie Institute Washington D.C. Publication |year=1953}}

{{Cite journal | last1 = Tetzlaff | first1 = N. | last2 = Neuhäuser | first2 = R. | last3 = Hohle | first3 = M. M. | title = A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | doi = 10.1111/j.1365-2966.2010.17434.x | journal = Monthly Notices of the Royal Astronomical Society | volume = 410 | pages = 190–200 | year = 2011 | issue = 1 | doi-access = free |arxiv = 1007.4883 |bibcode = 2011MNRAS.410..190T | s2cid = 118629873 }}

{{Cite journal | last1 = Crowther | first1 = P. A. | last2 = Lennon | first2 = D. J. | last3 = Walborn | first3 = N. R. | title = Physical parameters and wind properties of galactic early B supergiants | doi = 10.1051/0004-6361:20053685 | journal = Astronomy and Astrophysics | volume = 446 | pages = 279–293 | year = 2006 | issue = 1 |arxiv = astro-ph/0509436 |bibcode = 2006A&A...446..279C | s2cid = 18815761 }}

}}

{{Stars of Orion}}

{{DEFAULTSORT:Chi2 Orionis}}

Category:Orion (constellation)

Category:B-type supergiants

Orionis, 62

Orionis, Chi2

041117

028716

Category:Alpha Cygni variables

2135

BD+20 1233