Mu Orionis

μ Orionis

Location of μ Ori (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Orion
A
Right ascension	06^h 02^m 22.997^s[1]
Declination	+09° 38′ 50.24″[1]
Apparent magnitude (V)	4.30[2]
B
Right ascension	06^h 02^m 23.009^s[1]
Declination	+09° 38′ 50.52″[1]
Apparent magnitude (V)	6.27[2]
Characteristics
A
Spectral type	A1 Vm
U−B color index	+0.11[3]
B−V color index	+0.14[3]
B
Spectral type	F2 V
U−B color index	+0.00[3]
B−V color index	+0.43[3]
Astrometry
Radial velocity (Rv)	0.00[4] km/s
Proper motion (μ)	RA: 10.43[5] mas/yr Dec.: −39.09[5] mas/yr
Parallax (π)	21.05 ± 0.68[5] mas
Absolute magnitude (MV)	Aa: 0.93 Ba: 3.53 Bb: 3.53[3]
Orbit[6]
Primary	A
Companion	B
Period (P)	6,813.8 ± 1.2 days
Semi-major axis (a)	273.7 ± 2.1" (12.620 ± 0.057 AU)
Eccentricity (e)	0.7410 ± 0.0011
Inclination (i)	96.028 ± 0.028°
Orbit[6]
Primary	Aa
Companion	Ab
Period (P)	4.4475849 days
Semi-major axis (a)	1.661 ± 0.013" (0.07659 ± 0.00058 AU)
Eccentricity (e)	0.0037 ± 0.0014
Inclination (i)	47.1 ± 9.0°
Semi-amplitude (K1) (primary)	1.03 ± 0.26 km/s
Semi-amplitude (K2) (secondary)	> 4.58 km/s
Orbit[6]
Primary	Ba
Companion	Bb
Period (P)	4.7835349 days
Semi-major axis (a)	1.688 ± 0.013" (0.07659 ± 0.00036 AU)
Eccentricity (e)	0.0016 ± 0.0014
Inclination (i)	110.71 ± 0.73°
Semi-amplitude (K1) (primary)	1.72 ± 0.26 km/s
Semi-amplitude (K2) (secondary)	2.02 ± 0.26 km/s
Details^[6][3]
Aa
Mass	2.38 M☉
Radius	2.85 R☉
Luminosity	32.2 L☉
Temperature	8,300 K
Rotational velocity (v sin i)	10[7] km/s
Ab
Mass	0.652 M☉
Ba
Mass	1.389 M☉
Radius	1.33 R☉
Luminosity	3.0 L☉
Temperature	6,600 K
Bb
Mass	1.356 M☉
Radius	1.33 R☉
Luminosity	3.0 L☉
Temperature	6,600 K
Other designations
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
Database references
SIMBAD	μ Ori data
SIMBAD	μ Ori A data
SIMBAD	μ Ori B data

Mu Orionis is a quadruple star system^[6] 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. All four components are spectroscopic, with A and B systems only several tenths of an arcsec apart. The entire system is located approximately 155 Light Years from the Sun.

Mu Orionis Aa is an A5V dwarf and metallic line star, of effective temperature 8350 Kelvin, and apparent magnitude of +4.31. Mu Orionis Aa has 2.1 solar masses, and a radius of 2.9 solar radii and a luminosity 32x that of the Sun.

Mu Orionis Ab is a G5V dwarf orbiting Aa at a distance of 0.077 AU, .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 eacu other by 0.078 AU.

μ Orionis falls just outside an unrelated planetary nebula Abell 12. The bright star makes detecting the faint nebula difficult and it has been nicknamed The Hidden.

References

1. Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics 384: 180. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
2. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
3. Fekel, Francis C.; Scarfe, C. D.; Barlow, D. J.; Hartkopf, William I.; Mason, Brian D.; McAlister, Harold A. (2002). "The Quadruple System μ Orionis: Three-dimensional Orbit and Physical Parameters". The Astronomical Journal 123 (3): 1723. Bibcode:2002AJ....123.1723F. doi:10.1086/339184.
4. Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics 424 (2): 727. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213.
5. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
6. Muterspaugh, Matthew W.; et al. (2008). "Masses, Luminosities, and Orbital Coplanarities of the μ Orionis Quadruple-Star System from Phases Differential Astrometry". The Astronomical Journal 135 (3): 766–776. arXiv:0710.2126. Bibcode:2008AJ....135..766M. doi:10.1088/0004-6256/135/3/766.
7. Fekel, Francis C. (2003). "Rotational Velocities of B, A, and Early-F Narrow-lined Stars". The Publications of the Astronomical Society of the Pacific 115 (809): 807. Bibcode:2003PASP..115..807F. doi:10.1086/376393.

External Links

http://stars.astro.illinois.edu/sow/muori.html