HD 199579

HD 199579
Location of HD 199579 (circled) in the North America Nebula
Observation data
Epoch J2000      Equinox ICRS
Constellation Cygnus
Right ascension 20h 56m 34.77791s
Declination +44° 55′ 29.0009″
Apparent magnitude (V) 5.96
Characteristics
Spectral type O6V((f)) + B1-2V
B−V color index 0.020
Astrometry
Radial velocity (Rv)−6.4±0.4 km/s
Proper motion (μ) RA: +0.464 mas/yr
Dec.: −2.129 mas/yr
Parallax (π)1.1507±0.0348 mas
Distance2,830 ± 90 ly
(870 ± 30 pc)
Absolute magnitude (MV)−5.2 / −2.7
Orbit
Period (P)48.5216±0.0015 d
Eccentricity (e)0.065±0.011
Inclination (i)64±11°
Periastron epoch (T)HJD 2422944.8±0.14
Argument of periastron (ω)
(secondary)		94±12°
Semi-amplitude (K1)
(primary)		40.4±0.6 km/s
Details
A
Mass33.10±0.42 M☉
Temperature39,360±110 K
B
Mass~8 M☉
Other designations
Toronto star, BD+44 3639, HD 199579, HIP 103371, HR 8023, SAO 50263
Database references
SIMBADdata

HD 199579, nicknamed the Toronto star, is a binary star in the constellation Cygnus, within the North America Nebula. It is approximately 2,800 light-years (870 parsecs) from Earth. With an apparent magnitude of 5.96, it is faintly visible to the naked eye under ideal viewing conditions. Its nickname, first used in 2022, refers to the city of Toronto in reference to its position in the North America Nebula.

This is a spectroscopic binary; its orbit was first determined by John Stanley Plaskett in 1922. The primary component is an O-type main-sequence star with a stellar classification of O6V((f)), and the secondary is a B-type main-sequence star classified as B1V or B2V. The pair complete an orbit around each other in 48.5 days. The primary is a candidate magnetic O-type star.

HD 199579 is one of two O-type stars in the region of the North America and Pelican Nebulae; the other is the Bajamar Star, which is the main ionizing star of the nebula complex. HD 199579 had been proposed as the ionizing star in the 1950s, but was found not to be. Both the Bajamar and Toronto stars are rapidly escaping in different directions from a group of stars which has been dubbed the Bermuda cluster. They appear to have been ejected from the cluster around 1.5 million years ago.

References

  1. 1 2 3 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. XHIP record for this object at VizieR.
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 5 Williams, A. M.; Gies, D. R.; et al. (February 2001). "Detection of the Faint Companion in the Massive Binary HD 199579". The Astrophysical Journal. 548 (1): 425–428. Bibcode:2001ApJ...548..425W. doi:10.1086/318688. ISSN 0004-637X.
  4. 1 2 3 4 5 6 Maíz Apellániz, J.; Pantaleoni González, M.; et al. (January 2022). "Escape from the Bermuda cluster: Orphanization by multiple stellar ejections". Astronomy & Astrophysics. 657: A72. arXiv:2110.01484. Bibcode:2022A&A...657A..72M. doi:10.1051/0004-6361/202142366. ISSN 0004-6361.
  5. ↑ "HD 199579". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 10 June 2026.
  6. ↑ Grunhut, J. H.; Wade, G. A.; et al. (February 2017). "The MiMeS survey of Magnetism in Massive Stars: magnetic analysis of the O-type stars". Monthly Notices of the Royal Astronomical Society. 465 (2): 2432–2470. arXiv:1610.07895. Bibcode:2017MNRAS.465.2432G. doi:10.1093/mnras/stw2743. ISSN 0035-8711.
  7. ↑ Kuhn, Michael A.; Hillenbrand, Lynne A.; et al. (August 2020). "The Formation of a Stellar Association in the NGC 7000/IC 5070 Complex: Results from Kinematic Analysis of Stars and Gas". The Astrophysical Journal. 899 (2): 128. arXiv:2006.08622. Bibcode:2020ApJ...899..128K. doi:10.3847/1538-4357/aba19a. ISSN 0004-637X.
  8. ↑ Comerón, F.; Pasquali, A. (February 2005). "The ionizing star of the North America and Pelican nebulae". Astronomy & Astrophysics. 430 (2): 541–548. Bibcode:2005A&A...430..541C. doi:10.1051/0004-6361:20041788. ISSN 0004-6361.