CEN 16

CEN 16

2MASS image of CEN 16
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Sagittarius
Right ascension 18h 20m 22.70s
Declination −16° 08′ 34.2″
Apparent magnitude (V) 13.69
Characteristics
Evolutionary stage Main sequence
Spectral type O8.5V
Apparent magnitude (G) 12.61
Apparent magnitude (K) 8.884
Astrometry
Proper motion (μ) RA: 0.339±0.022 mas/yr
Dec.: −1.599±0.015 mas/yr
Parallax (π)0.7051±0.0226 mas
Distance4,600 ± 100 ly
(1,420 ± 50 pc)
Details
Mass20.4+7.9
−7.3 M☉
Radius10.9 R☉
Luminosity125000±37000 L☉
Surface gravity (log g)4.24+0.16
−0.22 cgs
Temperature34000±1000 K
Rotational velocity (v sin i)30+15
−25 km/s
Age4 Myr
Other designations
NGC 6618 258, ALS 19608, B311, SLS 165, Gaia DR2 4098003291268883584, Gaia DR3 4098003291268883584
Database references
SIMBADdata
CEN 16 is part of the Omega Nebula

CEN 16, also known as ALS 19608, is a O-type main sequence star in the constellation of Sagittarius. The star is located in the center of the Omega Nebula, roughly 4600±100 light years (or 1420±50 parsecs) away. The star has an apparent visual magnitude of 13.69. The star was discovered on 25 March 1976 in a survey of stars in the Omega Nebula.

Characteristics

CEN 16 is a massive, young late O-type main sequence star in the Omega Nebula. The star has a spectral type of O8.5V found using data from the Very Large Telescope, meaning it is still in the main-sequence phase. The star is also believed to very massive with a spectroscopic-derived stellar mass of 20.4+7.9
−7.3 M☉. The star has a rotational velocity of 30+15
−25 km/s. The star is predicted to be extremely young with an age of only four million years. The star has an estimated radius of 10.9 R☉. The diameter was found using a stellar luminosity of 125000±37000 L☉, and an effective temperature of 34000±1000 K.

Substellar companion

In November 2024, it was discovered that a potential brown dwarf companion may orbit CEN 16. The unconfirmed brown dwarf companion has a radius of 7.5 RJ and a mass of 70 MJ. The candidate brown dwarf companion has a calculated temperature of 2,884 K, and a luminosity of 0.033 L☉. CEN 16 B has a semi-major axis of 883.5 astronomical units. CEN 16 B is notable because substellar objects orbiting O-type main sequence stars are exceptionally rare. According to the Extrasolar Planets Encyclopaedia, CEN 16 B is the only substellar object found around a O-type main sequence star.

The CEN 16 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(years)		 Eccentricity Inclination
(°)		 Radius
B 70 MJ 883.5 — — — 7.5 RJ

Notes

  1. ↑ Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
    (5,77234,000)4⋅125,000=10.9 R⊙.

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. 1 2 3 4 5 6 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 "SIMBAD Results for CEN 16". SIMBAD. Retrieved 2026-01-27.
  4. 1 2 3 4 Ramírez-Tannus, M. C. (2017). "Massive pre-main-sequence stars in M17". Astronomy & Astrophysics. 604: A78. arXiv:1704.08216. Bibcode:2017A&A...604A..78R. doi:10.1051/0004-6361/201629503.
  5. 1 2 3 4 5 6 7 Backs, F. (2024). "Properties of intermediate- to high-mass stars in the young cluster M17: Characterizing the (pre-)zero-age main sequence". Astronomy and Astrophysics. 690. arXiv:2408.11713. Bibcode:2024A&A...690A.113B. doi:10.1051/0004-6361/202450494.
  6. 1 2 3 4 5 Patten, Nikhil (2025). "Fundamental Parameters for Central Stars of 103 Infrared Bow Shock Nebulae". The Astrophysical Journal. 988 (2): 183. arXiv:2506.07904. Bibcode:2025ApJ...988..183P. doi:10.3847/1538-4357/ade22f.
  7. ↑ Ogura, K. (1976). "UBV Photometry of the Stars in the Fields of Emission Nebulae. II. M 17". Publications of the Astronomical Society of Japan. 28 (1): 35. Bibcode:1976PASJ...28...35O. doi:10.1093/pasj/28.1.35. Retrieved 2026-01-27.
  8. 1 2 3 4 Pauwels, Tinne (2024). "Low-mass Stellar and Substellar Candidate Companions around Massive Stars in Sco OB1 and M17". The Astronomical Journal. 168 (5): 209. arXiv:2409.16212. Bibcode:2024AJ....168..209P. doi:10.3847/1538-3881/ad6f06.
  9. 1 2 3 4 "EPE Results for CEN 16 b". Extrasolar Planets Encyclopaedia. Retrieved 2026-01-27.
  10. ↑ Veras, Dimitri (2020). "Constraining planet formation around 6-8 M⊙ stars". Monthly Notices of the Royal Astronomical Society. 493 (1): 765. arXiv:2001.08757. Bibcode:2020MNRAS.493..765V. doi:10.1093/mnras/staa241.
  11. ↑ "EPE Catalog". Extrasolar Planets Encyclopaedia. 1995. Retrieved 2026-01-27.