CEN 16

❧

Wikipedia

CEN 16

2MASS image of CEN 16
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension 18h 20m 22.70s[1]
Declination −16° 08′ 34.17″[1]
Apparent magnitude (V) 13.69[1]
Characteristics
Evolutionary stage Main sequence[2]
Spectral type O8.5V[2]
Apparent magnitude (K) 8.884[2]
Astrometry
Parallax (π)0.7051±0.0226 mas[1]
Distance4,600 ± 100 ly
(1,420 ± 50 pc)
Details
Mass20.4+7.9
−7.3[3] M☉
Radius10.9[4] R☉
Luminosity125000±37000[4] L☉
Surface gravity (log g)4.24+0.16
−0.22[3] cgs
Temperature34000±1000[4] K
Rotational velocity (v sin i)30+15
−25[3] km/s
Age4[3] Myr
Other designations
NGC 6618 258, ALS 19608, B311, SLS 165
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.[1] The star is located in the center of the Omega Nebula, roughly 4600±100 light years (or 1420±50 parsecs) away.[1] The star has an apparent visual magnitude of 13.69.[1] The star was discovered in March 1976 in a survey of stars in the Omega Nebula.[5]

Characteristics

CEN 16 is a massive, young late O-type main sequence star in the Omega Nebula.[1] 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.[2] The star is also believed to very massive with a spectroscopic-derived stellar mass of 20.4+7.9
−7.3 M☉.[3] The star has a rotational velocity of 30+15
−25 km/s.[3] The star is predicted to be extremely young with an age of only four million years.[3] The star has an estimated radius of 10.9 R☉.[4] The diameter was found using a stellar luminosity of 125000±37000 L☉, and an effective temperature of 34000±1000 K.[4][a]

Substellar Companion

In November 2024, it was discovered that a potential brown dwarf companion may orbit CEN 16.[6] The unconfirmed brown dwarf companion has a radius of 7.5 RJ and a mass of 70 MJ.[6][7] The candidate brown dwarf companion has a calculated temperature of 2,884 K, and a luminosity of 0.033 L☉.[6][7] CEN 16 B has a semi-major axis of 883.5 astronomical units.[7] CEN 16 B is notable because substellar objects orbiting O-type main sequence stars are exceptionally rare.[8] According to the Extrasolar Planets Encyclopaedia, CEN 16 B is the only substellar object found around a O-type main sequence star.[9]

The CEN 16 planetary system[6][7]
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:
    .

References

  1. 1 2 3 4 5 6 7 8 "SIMBAD Results for CEN 16". SIMBAD. Retrieved 2026-01-27.
  2. 1 2 3 4 Ramírez-Tannus, M. C. (2017). "Massive pre-main-sequence stars in M17". NASA Ads. 604: A78. arXiv:1704.08216. Bibcode:2017A&A...604A..78R. doi:10.1051/0004-6361/201629503. Retrieved 2026-01-27.
  3. 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". NASA Ads. 690. arXiv:2408.11713. Bibcode:2024A&A...690A.113B. doi:10.1051/0004-6361/202450494. Retrieved 2026-01-27.
  4. 1 2 3 4 5 Patten, Nikhil (2025). "Fundamental Parameters for Central Stars of 103 Infrared Bow Shock Nebulae". NASA Ads. 988 (2): 183. arXiv:2506.07904. Bibcode:2025ApJ...988..183P. doi:10.3847/1538-4357/ade22f.
  5. ↑ Ogura, K. (1976). "UBV Photometry of the Stars in the Fields of Emission Nebulae. II. M 17". NASA Ads. 28 (1): 35. Bibcode:1976PASJ...28...35O. doi:10.1093/pasj/28.1.35. Retrieved 2026-01-27.
  6. 1 2 3 4 Pauwels, Tinne (2024). "Low-mass Stellar and Substellar Candidate Companions around Massive Stars in Sco OB1 and M17". NASA Ads. 168 (5): 209. arXiv:2409.16212. Bibcode:2024AJ....168..209P. doi:10.3847/1538-3881/ad6f06.
  7. 1 2 3 4 "EPE Results for CEN 16 b". Extrasolar Planets Encyclopaedia. Retrieved 2026-01-27.
  8. ↑ Veras, Dimitri (2020). "Constraining planet formation around 6-8 M⊙ stars". NASA Ads. 493 (1): 765. arXiv:2001.08757. Bibcode:2020MNRAS.493..765V. doi:10.1093/mnras/staa241.
  9. ↑ "EPE Catalog". Extrasolar Planets Encyclopaedia. 1995. Retrieved 2026-01-27.