Misplaced Pages

S Monocerotis

S Monocerotis lies in NGC 2264 at the very northern edge of Monoceros.
Observation data Epoch J2000      Equinox J2000
Constellation	Monoceros
A
Right ascension	06 40 58.656
Declination	+09° 53′ 44.71″
Apparent magnitude (V)	4.66 (4.62 - 4.68) + 5.90
B
Right ascension	06 40 58.566
Declination	+09° 53′ 42.20″
Apparent magnitude (V)	7.830
Characteristics
Spectral type	O7V((f))zvar + O9.5Vn + B2V
U−B color index	−1.034
B−V color index	−0.261
Variable type	Ia
Astrometry
A
Radial velocity (Rv)	22.00 km/s
Proper motion (μ)	RA: −2.61 mas/yr Dec.: −1.61 mas/yr
Parallax (π)	3.55 ± 0.50 mas
Distance	720 pc
Absolute magnitude (MV)	−5.21
B
Proper motion (μ)	RA: −1.971 mas/yr Dec.: −4.225 mas/yr
Parallax (π)	1.4019 ± 0.0984 mas
Distance	2,300 ± 200 ly (710 ± 50 pc)
C
Proper motion (μ)	RA: −1.464 mas/yr Dec.: −2.746 mas/yr
Parallax (π)	1.5438 ± 0.0394 mas
Distance	2,110 ± 50 ly (650 ± 20 pc)
Orbit
Primary	Aa
Companion	Ab
Period (P)	108±12 yr
Semi-major axis (a)	112.5±6 mas
Eccentricity (e)	0.770+0.023 −0.030
Inclination (i)	47±2°
Longitude of the node (Ω)	60±3°
Periastron epoch (T)	B 1996.05+0.15 −0.10
Argument of periastron (ω) (secondary)	63±4°
Details
Aa
Mass	29.1 M☉
Radius	9.9 R☉
Luminosity	214,000 L☉
Surface gravity (log g)	4.5 cgs
Temperature	38,500 K
Rotational velocity (v sin i)	120 km/s
Ab
Mass	21.3 M☉
Age	3.1 Myr
Other designations
15 Monocerotis, HD 47839, HIP 31978, HR 2456, SAO 114258, BD+10°1220
Database references
SIMBAD	data
ARICNS	data

S Monocerotis, also known as 15 Monocerotis, is a massive multiple and variable star system located in the constellation Monoceros. It is the brightest star in the Christmas Tree open cluster in the area catalogued as NGC 2264.

S Monocerotis is found within an open cluster and the Washington Double Star Catalog lists many companion stars. The closest and brightest is S Mon B, magnitude 7.8 and 3 arcseconds away. It is classified as B2 main sequence star with a mass of 7.31 M_☉. Designated component C is an 11th-magnitude B8V star. The cluster contains another dozen or so 9th and 10th magnitude stars and many fainter stars.

S Monocerotis A is a spectroscopic binary system with an eccentric orbit of about 112 years. Since 1943, the spectrum of this star has served as the MK standard for O7 by which other stars are classified. It is also an irregular variable star with a range of less than a tenth of a magnitude. The orbital parameters can be used to derive the masses of the two stars, giving 31 M_☉ and 11 M_☉.

The distance to S Monocerotis and NGC 2264 has been derived in various ways, including dynamical parallax and isochrone fitting. These consistently give estimates of 700 - 900 parsecs, although this is double the likely distance derived from the Hipparcos parallax measurements. Gaia Early Data Release 3 contains parallaxes for the companions components B and C of 1.4 mas and 1.5 mas respectively, consistent with the expected distance to the cluster.

References

1. ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 0333750888.
2. ^ Cvetkovc, Zorica; Vince, Istvan; Ninkovic, Slobodan (2008). "Orbit of Binary 15 Monocerotis". arXiv:0804.0698 .
3. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
4. Sota, A.; Maíz Apellániz, J.; Walborn, N. R.; Alfaro, E. J.; Barbá, R. H.; Morrell, N. I.; Gamen, R. C.; Arias, J. I. (2011). "The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-violet at R ~ 2500". The Astrophysical Journal Supplement. 193 (2): 24. arXiv:1101.4002. Bibcode:2011ApJS..193...24S. doi:10.1088/0067-0049/193/2/24. S2CID 119248206.
5. ^ Cvetković, Z.; Vince, I.; Ninković, S. (2010). "A new orbit of binary 15 Monocerotis". New Astronomy. 15 (3): 302–306. Bibcode:2010NewA...15..302C. doi:10.1016/j.newast.2009.09.002.
6. ^ Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
7. ^ Oja, T. (August 1985). "Photoelectric photometry of stars near the north Galactic pole. II". Astronomy and Astrophysics Supplement Series. 61: 331–339. Bibcode:1985A&AS...61..331O.
8. 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): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
9. ^ Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
10. Feinstein, A.; Vazquez, R. A.; Benvenuto, O. G. (1986). "Of-stars in young open clusters". Astronomy and Astrophysics. 159: 223. Bibcode:1986A&A...159..223F.
11. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
12. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
13. ^ Maíz Apellániz, J. (2019). "Gaia DR2 distances to Collinder 419 and NGC 2264 and new astrometric orbits for HD 193 322 Aa,Ab and 15 Mon Aa,Ab". Astronomy and Astrophysics. 630: A119. arXiv:1908.02040. Bibcode:2019A&A...630A.119M. doi:10.1051/0004-6361/201935885. S2CID 247759810.
14. ^ Herrero, A.; Kudritzki, R. P.; Vilchez, J. M.; Kunze, D.; Butler, K.; Haser, S. (1992). "Intrinsic parameters of galactic luminous OB stars". Astronomy and Astrophysics. 261: 209. Bibcode:1992A&A...261..209H.
15. Sung, Hwankyung; Stauffer, John R.; Bessell, Michael S. (2009). "A Spitzer View of the Young Open Cluster NGC 2264". The Astronomical Journal. 138 (4): 1116–1136. arXiv:0906.3072. Bibcode:2009AJ....138.1116S. doi:10.1088/0004-6256/138/4/1116. S2CID 5272305.
16. Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1): 1. Bibcode:1970CoAsi.239....1B.
17. Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten. 331 (4): 349–360. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. S2CID 111387483.
18. Worley, C. E.; Douglass, G. G. (1997). "The Washington Double Star Catalog (WDS, 1996.0)". Astronomy and Astrophysics Supplement Series. 125 (3): 523. Bibcode:1997A&AS..125..523W. doi:10.1051/aas:1997239.
19. Garrison, R. F. (December 1993). "Anchor Points for the MK System of Spectral Classification". Bulletin of the American Astronomical Society. 25: 1319. Bibcode:1993AAS...183.1710G. Archived from the original on 2019-06-25. Retrieved 2012-02-04.

External links

• S Monocerotis by James B. Kaler

v t e Constellation of Monoceros
List of stars in Monoceros Monoceros in Chinese astronomy Monocerotids Monoceros Ring
Stars	Bayer α β γ δ ε ζ Flamsteed 1 2 3 6 7 9 10 12 13 14 16 17 18 19 20 21 23 24 25 27 28 77 Ori 78 Ori Variable R S (15) T U V RU RW SV TU UX VV VY AO AR AU AX BE BN BT BX CL CS CV CW DD FU GI IM PZ V372 V396 V474 V505 V569 V577 V578 V582 V588 V589 V590 V592 V614 V616 V638 V640 V641 V644 V653 V682 V684 V689 V694 V695 V696 V700 V715 V721 V723 V728 V731 V739 V743 V750 V753 V827 V838 V926 HR 2150 2154 2179 2205 2224 2234 2237 2267 2270 2280 2292 2300 2313 2317 2321 2324 2325 2328 2333 2342 2347 2355 2367 2370 2375 2378 2381 2386 2395 2406 2409 2418 2426 2430 2440 2458 2461 2467 2469 2474 2479 2502 2508 2514 2521 2530 2543 2551 2555 2570 2572 2577 2582 2584 2589 2599 2606 2610 2613 2624 2627 2636 2639 2647 2655 2656 2663 2676 2694 2731 2732 2739 2752 2765 2806 2807 2811 2833 2865 2866 2867 2876 2883 2920 2958 3014 3047 3054 3072 3150 3172 3174 3189 HD 42132 44179 44219 45090 45166 45215 45652 (Lusitânia) 46149 46150 46202 46223 46375 46966 48099 50064 50138 50281 52265 (Citalá) 65938 66428 Other A0620-00 AFGL 961 CoRoT-1 CoRoT-4 CoRoT-5 CoRoT-7 CoRoT-12 CoRoT-13 CoRoT-14 CoRoT-15 CoRoT-18 CoRoT-19 CoRoT-20 CoRoT-21 CoRoT-24 Gliese 282 Monoceros R2 IRS 3 NGC 2264 IRS 1 Ross 614 Scholz's SCR 0640−0552 UGPS J0652+0324 UGPS J0722−0540
Exoplanets CoRoT-1b CoRoT-4b CoRoT-5b CoRoT-7b CoRoT-7c CoRoT-7d CoRoT-12b CoRoT-13b CoRoT-14b CoRoT-15b CoRoT-18b CoRoT-19b CoRoT-20b CoRoT-20c CoRoT-21b CoRoT-24b CoRoT-24c HD 44219 b HD 45652 b (Viriato) HD 46375 b HD 52265 b (Cayahuanca)
Star clusters	NGC 2232 2244 2264 2301 2349 2353 2506 Other Messier 50 Christmas Tree Cluster Snowflake Cluster
Nebulae	NGC 2170 2261 2264 2346 Other Cone Nebula Fox Fur Nebula IC 447 IC 2177 Red Rectangle Nebula Rosette Nebula
Galaxies	NGC 2494 Other PKS 0805-07
Category

• Monoceros
• Flamsteed objects
• Irregular variables
• Objects with variable star designations
• Durchmusterung objects
• Bright Star Catalogue objects
• Henry Draper Catalogue objects
• Hipparcos objects
• O-type main-sequence stars
• B-type main-sequence stars
• Emission-line stars
• Multiple star systems
• NGC 2264