Astronomy:HD 148937

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Short description: Binary star in the constellation Norma
HD 148937
Observation data
Equinox J2000.0]] (ICRS)
Constellation Norma
Right ascension  16h 33m 52.387s[1]
Declination −48° 06′ 40.48″[1]
Apparent magnitude (V) 6.73[2]
Characteristics
Spectral type O6f?p[3]
B−V color index 0.316±0.003[2]
Astrometry
Radial velocity (Rv)−53.9±3.0[2] km/s
Proper motion (μ) RA: +0.741[1] mas/yr
Dec.: −3.404[1] mas/yr
Parallax (π)0.8417 ± 0.0223[1] mas
Distance3,900 ± 100 ly
(1,190 ± 30 pc)
Orbit[4]
Period (P)9,390±300 days
Semi-major axis (a)33.45±0.73 astronomical unit|AU
Eccentricity (e)0.7782±0.0051
Inclination (i)84.07±0.10°
Longitude of the node (Ω)277.27±0.26°
Periastron epoch (T)56,958.2±2.8 MJD
Argument of periastron (ω)
(secondary)		340.10±0.41°
Semi-amplitude (K1)
(primary)		28.4+3.2−3.6 km/s
Semi-amplitude (K2)
(secondary)		31.9+3.7−3.4 km/s
Details
A
Mass29.9+3.4−3.1[4] M☉
Luminosity191,000+28,300−24,600[4] L☉
Surface gravity (log g)4.00±0.09[4] cgs
Temperature37,200+900−400[4] K
Rotational velocity (v sin i)165±20 km/s
Age5[5] Myr
B
Mass26.6+3.0−3.4[4] M☉
Luminosity155,000+27,000−23,000[4] L☉
Surface gravity (log g)3.61+0.05−0.09[4] cgs
Temperature35,000+300−900[4] K
Rotational velocity (v sin i)67±15[4] km/s
Other designations
BD−47°10855, GC 22246, HD 148937, HIP 81100, SAO 226891, PPM 321879, WDS J16339-4807A[6]
Database references
SIMBADdata

HD 148937 is a likely binary star[7] system in the southern constellation of Norma. It has a combined apparent visual magnitude of 6.73,[2] a brightness that is below the limit for being readily visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 3,900 light years from Sun,[1] but is drifting closer with a radial velocity of about −54 km/s.[2] The star is located in the hourglass-shaped emission nebula NGC 6164/65, which it generated through episodes of mass ejection.[8][9]

Observations

In 1955, C. S. Gum identified HD 148937 and possibly 15 Sagittarii as responsible for the emission from the region of NGC 6164/65.[10] In 1959, K. G. Heinze catalogued NGC 6164/65 as a planetary nebula and placed HD 148937 at its center,[11] with the two nebulae and the star being co-linear.[12] However, the apparent brightness of HD 148937 is brighter than any other nucleus for a nebula of this class, and the spectra of the star raised questions about their evolutionary status.[11] B. E. Westerlund classified the star as class O6fp in 1960,[13] with the 'O' meaning an O-type star, 'f' indicating emission from ionized helium and nitrogen, and the 'p' meaning an unspecified peculiarity.[12] He found a series of symmetrical nebular shells surrounding the star at angular separations of 3′, 4′, and 44′–64′.[13]

The nebulae surrounding HD 148937

In 1970, R. M. Catchpole and M. W. Feast showed that the radial velocities for the two nebulae are consistent with them being ejecta expanding away from the central star.[12] A very luminous absolute visual magnitude of −6 was confirmed for the central star in 1972, which demonstrated that the surroundings are not a planetary nebula.[13] This star lies within an H II region spanning 2°, which is surrounded by a thin dust shell.[5] In 1980, the star showed a mass loss rate of 2×10−7 M☉·yr−1, similar to other O-type main-sequence stars.[14]

An abundance analysis of the surrounding nebulae in 1987 demonstrated a strong overabundance of nitrogen, which most likely comes from stellar processing. This indicates the star is evolved, rather than being in a pre-main-sequence phase. The estimated mass of the NGC 6164/6165 nebulae is twice the mass of the Sun, and it shows a kinetic age of 3×103 yr. The surrounding stellar wind bubble is much older at 2×105 yr.[15]

In 2008, a magnetic field with a longitudinal strength of −276±88 G was detected in the star.[16] It shows spectroscopic variability with a period of 7.031±0.003 d, and has a nitrogen enhancement of about four times that in the Sun. Based on variations in the magnetic field strength, the seven day variance is interpreted as the stellar rotation period.[17] X-ray emission has been detected and is interpreted as originating in hot plasma about one stellar radius from the photosphere.[18]

Observations of the star made between 2015 and 2019 showed a significant change in the spectrum. Radial velocity measurements made during this period suggest that this is a double-lined spectroscopic binary system of high mass stars. Initial measurements suggest they have an eccentric orbit with a period of about 26 years and an orbital eccentricity of 0.75.[7] Only one member of the pair is magnetic, and it appears younger than the companion. This younger star may have been formed by a merger with a third member of the system, an event that can explain both the magnetic field and the surrounding nebula.[4]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  3. ↑ Sota, A. et al. (2014), "The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars", The Astrophysical Journal Supplement 211 (1): 10, doi:10.1088/0067-0049/211/1/10, Bibcode: 2014ApJS..211...10S. 
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Frost, A. J. et al. (April 2024), "A magnetic massive star has experienced a stellar merger", Science 384 (6692): 214–217, doi:10.1126/science.adg7700, PMID 38603482, Bibcode: 2024Sci...384..214F. 
  5. ↑ 5.0 5.1 Bruhweiler, F. C. et al. (December 1981), "On the nebulosities associated with the extreme Of star HD 148937", The Astrophysical Journal, Part 1 251: 126–132, doi:10.1086/159446, Bibcode: 1981ApJ...251..126B. 
  6. ↑ "HD 148937". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+148937. 
  7. ↑ 7.0 7.1 Wade, G. A. et al. (February 2019), "A remarkable change of the spectrum of the magnetic Of?p star HD 148937 reveals evidence of an eccentric, high-mass binary", Monthly Notices of the Royal Astronomical Society 483 (2): 2581–2591, doi:10.1093/mnras/sty3304, Bibcode: 2019MNRAS.483.2581W. 
  8. ↑ Frew, David J. et al. (May 2013), "A catalogue of integrated Hα fluxes for 1258 Galactic planetary nebulae", Monthly Notices of the Royal Astronomical Society 431 (1): 2–26, doi:10.1093/mnras/sts393, Bibcode: 2013MNRAS.431....2F. 
  9. ↑ Lim, Beomdu et al. (January 2024), "A Morphokinematic Study of the Enigmatic Emission Nebula NGC 6164/5 Surrounding the Magnetic O-type Star HD 148937", The Astrophysical Journal 961 (1): 72, doi:10.3847/1538-4357/ad12c4, Bibcode: 2024ApJ...961...72L. 
  10. ↑ Gum, Colin S. (1955), "A Survey of Southern HII Regions", Memoirs of the Royal Astronomical Society 67: 155, Bibcode: 1955MmRAS..67..155G. 
  11. ↑ 11.0 11.1 Henize, Karl G. (1959), "A new planetary nebula NGC 6164-65 (Cederblad 135a, b)", Astronomical Journal 64: 51, doi:10.1086/108043, Bibcode: 1959AJ.....64S..51H. 
  12. ↑ 12.0 12.1 12.2 Catchpole, R. M.; Feast, M. W. (August 1970), "Nebulosities ejected from the star HD 148937", The Observatory 90: 136, Bibcode: 1970Obs....90..136C. 
  13. ↑ 13.0 13.1 13.2 Johnson, Hugh M. (September 1972), "The Peculiar O6f Star HD 148937 and the Symmetrically Surrounding Nebulae", The Astrophysical Journal 176: 645–649, doi:10.1086/151666, Bibcode: 1972ApJ...176..645J. 
  14. ↑ Dufour, Reginald J. et al. (April 1988), "Spectrophotometry and Chemical Composition of the Oxygen-poor Bipolar Nebula NGC 6164--5", Astrophysical Journal 327: 859, doi:10.1086/166244, Bibcode: 1988ApJ...327..859D. 
  15. ↑ Leitherer, C.; Chavarria-K., C. (March 1987), "The O6.5f?p star HD 148937 and its interstellar environment", Astronomy and Astrophysics 175: 208–218, Bibcode: 1987A&A...175..208L. 
  16. ↑ Hubrig, S. et al. (November 2008), "Magnetic field measurements of O stars with FORS 1 at the VLT", Astronomy and Astrophysics 490 (2): 793–800, doi:10.1051/0004-6361:200810171, Bibcode: 2008A&A...490..793H. 
  17. ↑ Wade, G. A. et al. (January 2012), "The spectral variability and magnetic field characteristics of the Of?p star HD 148937", Monthly Notices of the Royal Astronomical Society 419 (3): 2459–2471, doi:10.1111/j.1365-2966.2011.19897.x, Bibcode: 2012MNRAS.419.2459W. 
  18. ↑ Nazé, Yaël et al. (February 2012), "High-resolution X-Ray Spectroscopy of the Magnetic Of?p Star HD 148937", The Astrophysical Journal 746 (2): 142, doi:10.1088/0004-637X/746/2/142, Bibcode: 2012ApJ...746..142N. 

Further reading

  • Barron, James A. O.; Wade, Gregg A. (April 2021), "TESS photometry of the Of?p stars HD 148937 and LMC 164-2", OBA Stars: Variability and Magnetic Fields. On-line conference, held 26-30 April, 2021: id. 24, doi:10.5281/zenodo.5080062, Bibcode: 2021osvm.confE..24B. 
  • Mahy, L. et al. (March 2017), "Evolutionary status of the Of?p star HD 148937 and of its surrounding nebula NGC 6164/5", Astronomy and Astrophysics 599: id. A61, doi:10.1051/0004-6361/201629585, Bibcode: 2017A&A...599A..61M. 
  • Nazé, Yaël et al. (May 2008), "HD 148937: A Multiwavelength Study of the Third Galactic Member of the Of?p Class", The Astronomical Journal 135 (5): 1946–1957, doi:10.1088/0004-6256/135/5/1946, Bibcode: 2008AJ....135.1946N. 
  • Leitherer, C.; Chavarria-K, C. (1987), Lamers, Henny J. G.; De Loore, C. W. H., eds., "The unstable of 06.5f?p star HD 148937 and its interstellar environment", Instabilities in Luminous Early Type Stars, Proceedings of a Workshop in honour of Professor Cees de Jager on the occasion of his 65th birthday, held in Lunteren, The Netherlands, April 21-24, 1986, Astrophysics and Space Science Library (Dordrecht: Reidel) 136: p. 209, doi:10.1007/978-94-009-3901-1_15, ISBN 978-94-010-8232-7, Bibcode: 1987ASSL..136..209L. 
  • Conti, P. S. et al. (July 1977), "Radial velocities of three Of stars: HD 148937, HD 151804, and HD 152408", The Astrophysical Journal 215: 561–567, doi:10.1086/155389, Bibcode: 1977ApJ...215..561C. 



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