Epsilon Monocerotis

ε Monocerotis, Latinised as Epsilon Monocerotis, is the Bayer designation of a binary star system in the equatorial constellation Monoceros. Its location is a guide for sky navigation toward the Rosette Nebula.[11]

ε Monocerotis

Location of ε Monocerotis (circled red)
Observation data Epoch J2000      Equinox
Constellation	Monoceros
ε Mon A
Right ascension	06^h 23^m 46.08471^s[1]
Declination	4° 35′ 34.3153″[1]
Apparent magnitude (V)	4.39[2]
ε Mon B
Right ascension	06^h 23^m 46.48292^s[1]
Declination	4° 35′ 45.2307″[1]
Apparent magnitude (V)	6.72[2]
Characteristics
ε Mon A
Spectral type	class = A5 IV[3]
U−B color index	+0.14[4]
B−V color index	+0.20[4]
ε Mon B
Spectral type	F5 V[3]
U−B color index	−0.05[5]
B−V color index	+0.45[5]
Astrometry
ε Mon A
Radial velocity (Rv)	+13.10[6] km/s
Proper motion (μ)	RA: −22.06[1] mas/yr Dec.: +10.91[1] mas/yr
Parallax (π)	26.67 ± 0.90[1] mas
Distance	122 ± 4 ly (37 ± 1 pc)
Absolute magnitude (MV)	1.52[2]
ε Mon B
Radial velocity (Rv)	+12.40[6] km/s
Proper motion (μ)	RA: −21.86[1] mas/yr Dec.: +11.35[1] mas/yr
Parallax (π)	26.95 ± 0.99[1] mas
Distance	121 ± 4 ly (37 ± 1 pc)
Absolute magnitude (MV)	+3.88[2]
Details
ε Mon A
Mass	2.04[7] M☉
Radius	2.5[8] R☉
Luminosity	25[7] L☉
Surface gravity (log g)	3.95[9] cgs
Temperature	7,923[9] K
Metallicity [Fe/H]	−0.11[10] dex
Rotational velocity (v sin i)	149[7] km/s
ε Mon B
Mass	1.16[8] M☉
Radius	1.1[8] R☉
Luminosity	2.39[2] L☉
Surface gravity (log g)	3.95[9] cgs
Temperature	7,923[9] K
Rotational velocity (v sin i)	25[3] km/s
Other designations
ε Mon, 8 Monocerotis, CCDM J06237+0436, WDS J06238+0436
ε Mon A: BD+04° 1236, FK5 244, GC 8240, HD 44769, HIP 30419, HR 2298, SAO 113810
ε Mon B: BD+04° 1237, FK5 244, GC 8241, HD 44770, HIP 30422, HR 2299, SAO 113811
Database references
SIMBAD	data
SIMBAD	data

The white-hued primary component has a stellar classification of A5 IV,[3] suggesting it is an aging subgiant star. Its apparent magnitude is 4.39[2] and it is approximately 122 light years away based on parallax.[1] It is reportedly a spectroscopic binary with a period around 331 days.[12]

The B component, at a separation of around 12.3",[12] is a yellow-white hued F-type main-sequence star of class F5 V[3] and an apparent magnitude of 6.72.[2]

References

1. 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. Vizier catalog entry A Vizier catalog entry B
2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. Vizier catalog entry A Vizier catalog entry B
3. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
4. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
5. Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
6. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
7. Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. Vizier catalog entry
8. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A.
9. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.
10. Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2010). "Coudé-feed stellar spectral library – atmospheric parameters". Astronomy & Astrophysics. 525: A71. arXiv:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014.
11. Kaler, James. "EPS MON (Epsilon Monocerotis)". STARS. University of Illinois. Retrieved 2017-12-23.
12. 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. Vizier catalog entry