31 Orionis

{{Starbox image

| image =

{{Location mark

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

|label=|position=right

|mark=Red circle.svg|mark_width=10|mark_link=31 Orionis

|x=624|y=546

}}

| caption = Location of 31 Orionis (circled)

}}

{{Starbox observe

| epoch = J2000

| constell = Orion

| ra = {{RA|05|29|43.98147}}

| dec = {{DEC|-01|05|32.0582}}

| appmag_v = 4.71 + 10.2

}}

{{Starbox character

| type =

| class = K5III + F7V

| b-v = +1.58

| u-b = +1.91

| variable = SR?

}}

{{Starbox astrometry

| radial_v = {{Val|+6.02|0.15}}

| prop_mo_ra = +1.242

| prop_mo_dec = −25.476

| parallax = 6.6135

| p_error = 0.2293

| parallax_footnote =

| absmag_v = −1.23

}}

{{Starbox detail

| component1 = 31 Ori A

| mass = 5.2

| radius = 62

| temperature = 4,610

| luminosity = 1,361

| rotational_velocity = 2.7

| gravity = 0.92

| metal_fe = −0.21

| age_gyr =

| component2 = 31 Ori B

| mass2 = 1.1

| radius2 = 1.2

| temperature2 = 6,111

| luminosity2 = 1.9

| rotational_velocity2 =

| gravity2 = 4.24

| metal_fe2 = −0.23

| age_gyr2 = 3.9

}}

{{Starbox catalog

| names = {{odlist | F=31 Ori | V=CI Ori | BD=−01°913 | GC=6792 | HD=36167 | HIP=25737 | HR=1834 | SAO=132176 | WDS=J05297-0106A | CCDM=J05297-0106A }}

}}

{{Starbox reference

| Simbad = 31+Orionis

}}

31 Orionis is a binary star system in the equatorial constellation of Orion, located near the bright star Mintaka. It is visible to the naked eye as a faint, orange-hued point of light with a baseline apparent visual magnitude of 4.71. The distance to this system is approximately 490 light years away based on parallax, and it is drifting further away with a mean radial velocity of +6 km/s.

File:CIOriLightCurve.png for CI Orionis, plotted from Hipparcos data]]

As of 2008, the pair had an angular separation of {{Val|12.7|ul=arcsecond}}. The brighter member, designated component A, is an aging giant star with a stellar classification of K5III. It is reported as a semi-regular variable with magnitude ranging from 4.68 to 4.72 over 141 days, although the General Catalogue of Variable Stars describes this as unconfirmed by subsequent observations. It has the variable star designation CI Orionis, while 31 Orionis is the Flamsteed designation. The magnitude 10.2 companion star, component B, is an F-type main-sequence star with a class of F7V.

References

{{reflist|refs=

{{cite web

| url=https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats

| website=Centre de Données astronomiques de Strasbourg | title=/ftp/cats/more/HIP/cdroms/cats

| publisher=Strasbourg astronomical Data Center |access-date=15 October 2022}}

{{cite journal

| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971

| title=XHIP: An extended hipparcos compilation

| journal=Astronomy Letters

| volume=38 | issue=5 | pages=331 | year=2012

| last1=Anderson | first1=E. | last2=Francis | first2=Ch.

| s2cid=119257644 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=V/137D/XHIP&HIP=25737 Vizier catalog entry]

{{cite journal

| title=VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)

| journal=VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H

| volume=5050 | year=1995 | bibcode=1995yCat.5050....0H

| last1=Hoffleit | first1=D. | last2=Warren | first2=W. H. }}

{{cite journal

| bibcode=2006yCat.2168....0M

| title=Homogeneous Means in the UBV System (Mermilliod 1991)

| journal=VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie

| volume=2168 | last1=Mermilliod | first1=J. C. | year=2006

}}[http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=II/168/ubvmeans&LID=%2B100036167 Vizier catalog entry]

{{cite journal

| bibcode=2014A&A...561A.126D | doi=10.1051/0004-6361/201220762 | arxiv=1312.3474

| title=A catalog of rotational and radial velocities for evolved stars

| journal=Astronomy & Astrophysics

| volume=561 | pages=A126 | year=2014

| last1=De Medeiros | first1=J. R. | last2=Alves | first2=S.

| last3=Udry | first3=S. | last4=Andersen | first4=J.

| last5=Nordström | first5=B. | last6=Mayor | first6=M.

| s2cid=54046583 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/A%2bA/561/A126/table1&HD=36167 Vizier catalog entry]

{{cite web

| title=CI Ori

| url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=23173|

website=The International Variable Star

| publisher=AAVSO – American Association of Variable Star Observers

| access-date=6 August 2016

}}

{{cite journal

| bibcode=2009yCat....102025S

| title=General Catalogue of Variable Stars (Samus+ 2007-2013)

| journal=VizieR On-line Data Catalog: B/gcvs

| volume=1 | year=2009 | display-authors=etal

| last1=Samus | first1=N. N. | last2=Durlevich | first2=O. V. }}

{{cite journal

| bibcode=2008MNRAS.389..869E | doi=10.1111/j.1365-2966.2008.13596.x | arxiv=0806.2878

| title=A catalogue of multiplicity among bright stellar systems

| journal=Monthly Notices of the Royal Astronomical Society

| volume=389 | issue=2 | pages=869 | year=2008

| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.

| doi-access=free | s2cid=14878976 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/MNRAS/389/869/table1&mHR=1834 Vizier catalog entry]

}}

Category:K-type giants

Category:K-type main-sequence stars

Category:Binary stars

Category:Orion (constellation)