HD 148937
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| 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 mas/yr[1] Dec.: −3.404 mas/yr[1] |
| Parallax (π) | 0.8417 ± 0.0223 mas[1] |
| Distance | 3,900 ± 100 ly (1,190 ± 30 pc) |
| Orbit[4] | |
| Period (P) | 9,390±300 days |
| Semi-major axis (a) | 33.45±0.73 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 | |
| Mass | 29.9+3.4 −3.1[4] M☉ |
| Luminosity | 191,000+28,300 −24,600[4] L☉ |
| Surface gravity (log g) | 4.00±0.09[4] cgs |
| Temperature | 37,200+900 −400[4] K |
| Rotational velocity (v sin i) | 165±20 km/s |
| Age | 5[5] Myr |
| B | |
| Mass | 26.6+3.0 −3.4[4] M☉ |
| Luminosity | 155,000+27,000 −23,000[4] L☉ |
| Surface gravity (log g) | 3.61+0.05 −0.09[4] cgs |
| Temperature | 35,000+300 −900[4] K |
| Rotational velocity (v sin i) | 67±15[4] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
[edit]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]
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
[edit]- ^ a b c d e 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.
- ^ a b c d e 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, S2CID 119257644.
- ^ Sota, A.; et al. (2014), "The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars", The Astrophysical Journal Supplement, 211 (1): 10, arXiv:1312.6222, Bibcode:2014ApJS..211...10S, doi:10.1088/0067-0049/211/1/10, S2CID 118847528.
- ^ a b c d e f g h i j k Frost, A. J.; et al. (April 2024), "A magnetic massive star has experienced a stellar merger", Science, 384 (6692): 214–217, arXiv:2404.10167, Bibcode:2024Sci...384..214F, doi:10.1126/science.adg7700.
- ^ a b 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, Bibcode:1981ApJ...251..126B, doi:10.1086/159446.
- ^ "HD 148937". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-12-04.
- ^ a b 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, arXiv:1811.11153, Bibcode:2019MNRAS.483.2581W, doi:10.1093/mnras/sty3304.
- ^ 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, arXiv:1211.2505, Bibcode:2013MNRAS.431....2F, doi:10.1093/mnras/sts393.
- ^ 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, arXiv:2312.03211, Bibcode:2024ApJ...961...72L, doi:10.3847/1538-4357/ad12c4.
- ^ Gum, Colin S. (1955), "A Survey of Southern HII Regions", Memoirs of the Royal Astronomical Society, 67: 155, Bibcode:1955MmRAS..67..155G.
- ^ a b Henize, Karl G. (1959), "A new planetary nebula NGC 6164-65 (Cederblad 135a, b)", Astronomical Journal, 64: 51, Bibcode:1959AJ.....64S..51H, doi:10.1086/108043.
- ^ a b c Catchpole, R. M.; Feast, M. W. (August 1970), "Nebulosities ejected from the star HD 148937", The Observatory, 90: 136, Bibcode:1970Obs....90..136C.
- ^ a b c Johnson, Hugh M. (September 1972), "The Peculiar O6f Star HD 148937 and the Symmetrically Surrounding Nebulae", The Astrophysical Journal, 176: 645–649, Bibcode:1972ApJ...176..645J, doi:10.1086/151666, hdl:2060/19730002097.
- ^ Dufour, Reginald J.; et al. (April 1988), "Spectrophotometry and Chemical Composition of the Oxygen-poor Bipolar Nebula NGC 6164--5", Astrophysical Journal, 327: 859, Bibcode:1988ApJ...327..859D, doi:10.1086/166244.
- ^ 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.
- ^ 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, arXiv:0808.2039, Bibcode:2008A&A...490..793H, doi:10.1051/0004-6361:200810171.
- ^ 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, arXiv:1108.4847, Bibcode:2012MNRAS.419.2459W, doi:10.1111/j.1365-2966.2011.19897.x.
- ^ 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, arXiv:1111.7186, Bibcode:2012ApJ...746..142N, doi:10.1088/0004-637X/746/2/142.
Further reading
[edit]- 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, Bibcode:2021osvm.confE..24B, doi:10.5281/zenodo.5080062.
- 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, arXiv:1611.07257, Bibcode:2017A&A...599A..61M, doi:10.1051/0004-6361/201629585.
- 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, arXiv:0803.0605, Bibcode:2008AJ....135.1946N, doi:10.1088/0004-6256/135/5/1946.
- 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, vol. 136, Dordrecht: Reidel, p. 209, Bibcode:1987ASSL..136..209L, doi:10.1007/978-94-009-3901-1_15, ISBN 978-94-010-8232-7.
- 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, Bibcode:1977ApJ...215..561C, doi:10.1086/155389.
