Mu Orionis

{{Short description|Quadruple star system in the constellation Orion}}

{{Starbox begin

| name=μ Orionis

}}

{{Starbox image

| image=

{{Location mark

|image=Orion constellation map.svg

|float=center

|alt=

|label=

|position=right

|width=300

|mark=Red circle.svg

|mark_width=12

|mark_link=μ Orionis

|x=399|y=249

}}

|caption=Location of μ Ori (circled)

}}

{{Starbox observe 2s

| epoch=J2000

| constell=Orion

| component1=μ Ori A

| ra1={{RA|06|02|22.997}}{{cite journal|bibcode=2002A&A...384..180F|title=The Tycho double star catalogue|journal=Astronomy and Astrophysics|volume=384|pages=180–189|last1=Fabricius|first1=C.|last2=Høg|first2=E.|last3=Makarov|first3=V. V.|last4=Mason|first4=B. D.|last5=Wycoff|first5=G. L.|last6=Urban|first6=S. E.|year=2002|doi=10.1051/0004-6361:20011822|doi-access=free}}

| dec1={{DEC|+09|38|50.24}}

| appmag_v1=4.30{{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920|doi-access=free}}

| component2=μ Ori B

| ra2={{RA|06|02|23.009}}{{cite journal|bibcode=2002A&A...384..180F|title=The Tycho double star catalogue|journal=Astronomy and Astrophysics|volume=384|pages=180–189|last1=Fabricius|first1=C.|last2=Høg|first2=E.|last3=Makarov|first3=V. V.|last4=Mason|first4=B. D.|last5=Wycoff|first5=G. L.|last6=Urban|first6=S. E.|year=2002|doi=10.1051/0004-6361:20011822|doi-access=free}}

| dec2={{DEC|+09|38|50.52}}

| appmag_v2=6.27

}}

{{Starbox character

| component1=μ Ori A

| class=A1 Vm

| b-v=+0.14

| u-b=+0.11

| variable=

| component2=μ Ori B

| class2=F2 V

| b-v2=+0.43{{cite journal|bibcode=2002AJ....123.1723F|title=The Quadruple System μ Orionis: Three-dimensional Orbit and Physical Parameters|journal=The Astronomical Journal|volume=123|issue=3|pages=1723|last1=Fekel|first1=Francis C.|last2=Scarfe|first2=C. D.|last3=Barlow|first3=D. J.|last4=Hartkopf|first4=William I.|last5=Mason|first5=Brian D.|last6=McAlister|first6=Harold A.|year=2002|doi=10.1086/339184|doi-access=free}}

| u-b2=+0.00

| variable2=

}}

{{Starbox astrometry

| radial_v = 0.00{{cite journal|bibcode=2004A&A...424..727P|title=SB9: The ninth catalogue of spectroscopic binary orbits|journal=Astronomy and Astrophysics|volume=424|issue=2|pages=727–732|last1=Pourbaix|first1=D.|last2=Tokovinin|first2=A. A.|last3=Batten|first3=A. H.|last4=Fekel|first4=F. C.|last5=Hartkopf|first5=W. I.|last6=Levato|first6=H.|last7=Morrell|first7=N. I.|last8=Torres|first8=G.|last9=Udry|first9=S.|year=2004|doi=10.1051/0004-6361:20041213|arxiv = astro-ph/0406573 |s2cid=119387088}}

| prop_mo_ra = 10.43

| prop_mo_dec = −39.09

| parallax = 21.69

| p_error = 0.13

| parallax_footnote =

| dist_ly =

| dist_pc =

| absmag_v = Aa: 0.93
Ba: 3.53
Bb: 3.53

}}

{{Starbox orbit

| reference=

| primary=μ Ori A

| name=μ Ori B

| period_unitless={{val|6813.8|1.2|u=days|fmt=commas}}

| axis={{val|0.2737|0.0021}}

| axis_unitless={{val|12.620|0.057|u=AU}}

| inclination={{val|96.028|0.028}}

| eccentricity={{val|0.7410|0.0011}}

| k1=

| k2=

}}

{{Starbox orbit

| reference=

| primary=μ Ori Aa

| name=μ Ori Ab

| period=

| period_unitless=4.4475849 days

| axis={{val|0.001661|0.000013}}

| axis_unitless={{val|0.07659|0.00058|u=AU}}

| inclination={{val|47.1|9.0}}

| eccentricity={{val|0.0037|0.0014}}

| k1={{val|1.03|0.26}}

| k2=> 4.58

}}

{{Starbox orbit

| reference=

| primary=μ Ori Ba

| name=μ Ori Bb

| period=

| period_unitless=4.7835349 days

| axis={{val|0.001688|0.000013}}

| axis_unitless={{val|0.07659|0.00036|u=AU}}

| inclination={{val|110.71|0.73}}

| eccentricity={{val|0.0016|0.0014}}

| k1={{val|1.72|0.26}}

| k2={{val|2.02|0.26}}

}}

{{Starbox detail

| source=

| component1=μ Ori Aa

| mass=2.38

| temperature=8,300

| radius=2.85

| luminosity=32.2

| rotational_velocity=10{{cite journal|bibcode=2003PASP..115..807F|title=Rotational Velocities of B, A, and Early-F Narrow-lined Stars|journal=The Publications of the Astronomical Society of the Pacific|volume=115|issue=809|pages=807–810|last1=Fekel|first1=Francis C.|year=2003|doi=10.1086/376393|doi-access=free}}

| gravity=

| age_myr=282

| component2=μ Ori Ab

| mass2=0.652

| temperature2=

| radius2=

| luminosity2=

| rotational_velocity2=

| gravity2=

| age2=

}}

{{Starbox detail|no_heading=y

| component1=μ Ori Ba

| mass=1.389

| temperature=6,600

| radius=1.33

| luminosity=3.0

| rotational_velocity=

| gravity=

| age=

| component2=μ Ori Bb

| mass2=1.356

| temperature2=6,600

| radius2=1.33

| luminosity2=3.0

| rotational_velocity2=

| gravity2=

| age2=

}}

{{Starbox catalog

| names=Mu Orionis, Mu Ori, μ Orionis, μ Ori, 61 Orionis, 61 Ori, HR 2124, HD 40932, HIP 28614, BD+09°1064, ADS 4617, WDS J06024+0939, 2MASS J05351889-0516140

}}

{{Starbox reference

| Simbad=HR+2124| name=μ Ori

| Simbad2=HD+40932A| name2=μ Ori A

| Simbad3=HD+40932B| name3=μ Ori B

}}

{{Starbox end}}

μ Orionis (Latinised to Mu Orionis, abbreviated to μ Ori or Mu Ori) is a quadruple star system in the constellation Orion, similar to Mizar and Epsilon Lyrae with combined visual magnitude of 4.13. The four stars are known as Mu Orionis Aa, Mu Orionis Ab, Mu Orionis Ba, and Mu Orionis Bb. The A and B systems are several tenths of an arcsecond apart. The entire system is located approximately 150 light years from the Sun.

Mu Orionis Aa is an A5V dwarf and metallic line star, of effective temperature {{val|8350|ul=Kelvin|fmt=commas}}, and apparent magnitude of +4.31. Mu Orionis Aa has 2.1 solar masses, and a radius of {{solar radius|2.9|link=y}} and a luminosity 32 times that of the Sun.

Mu Orionis Ab is a G5V dwarf orbiting Aa at a distance of {{val|0.077|u=AU}}, 0.2x the orbit of Mercury.

Mu Orionis Ba and Bb are F5V dwarfs with 1.4 solar masses and apparent magnitudes of 6.91. They are separated from each other by {{val|0.078|u=AU}}.

μ Orionis is very close in the sky to the faint planetary nebula Abell 12. The star's relative brightness makes detecting the nebula difficult and it has been nicknamed The Hidden Nebula as a result.{{cn|date=April 2022}}