Sakurai's Object

Sakurai's Object

Sakurai's Object (photo by ESO)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 17h 52m 32.69s[1]
Declination −17° 41′ 08.0″[1]
Apparent magnitude (V) 10.90 - 21[2]
Characteristics
Spectral type variable
Apparent magnitude (J) 11.555 ± 0.022[1]
U−B color index +0.27[3]
B−V color index +0.81[3]
V−R color index +0.57[3]
Astrometry
Radial velocity (Rv)−170 ± 30[4] km/s
Distance1800-5000[5] pc
Details
Mass0.6[6] M☉
Luminosity~10,000[7] L☉
Other designations
V4334 Sgr, V4334 Sagittarii, 2MASS J17523269-1741080, DPV 1, Sakurai's variable, PN G010.4+04.4, GSC2 S2202011182877, Sakurai's Object, AAVSO 1746-17
Database references
SIMBADdata

Sakurai's Object (V4334 Sagittarii) is a star in the constellation of Sagittarius. It is thought to have previously been a white dwarf that, as a result of a very late thermal pulse, swelled and became a red giant. It is located at the center of a planetary nebula and is believed to currently be in thermal instability and within its final shell helium flash phase.

At the time of its discovery, astronomers believed Sakurai's Object to be a slow nova. Later spectroscopic analysis suggested that the star was not a nova, but had instead undergone a very late thermal pulse similar to that of V605 Aquilae, causing it to vastly expand. V605 Aquilae, which was discovered in 1919, is the only other star known to have been observed during the high luminosity phase of a very late thermal pulse, and models predict that Sakurai's Object, over the next few decades, will follow a similar life cycle.

Sakurai's Object and other similar stars are expected to end up as helium-rich white dwarfs after retracing their evolution track from the "born-again" giant phase back to the white dwarf cooling track. There are few other suspected "born-again" objects, one example being FG Sagittae. Having erupted in 1995, it is expected that Sakurai's Object's final helium flash will be the first well-observed one.[8]

  1. ^ a b c Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  2. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. ^ a b c Arkhipova, V. P.; Noskova, R. I. (1997). "UBV photometry of Sakurai's object in 1996 and remarks about its evolutionary status". Astronomy Letters. 23 (5): 623. Bibcode:1997AstL...23..623A.
  4. ^ Eyres, S. P. S.; Geballe, T. R.; Tyne, V. H.; Evans, A.; Smalley, B.; Worters, H. L. (May 2004). "Warm high-velocity CO in the wind of Sakurai's Object (= V4334 Sgr)". Monthly Notices of the Royal Astronomical Society. 350 (1): L9–L12. arXiv:astro-ph/0403439. Bibcode:2004MNRAS.350L...9E. doi:10.1111/j.1365-2966.2004.07808.x. S2CID 18500269.
  5. ^ van Hoof, P. A. M.; Hajduk, M. (2007). "The onset of photoionization in Sakurai's Object (V4334 Sagittarii)". Astronomy & Astrophysics. 471 (1): L9–L12. arXiv:0706.3857. Bibcode:2007A&A...471L...9V. doi:10.1051/0004-6361:20077932. S2CID 119324745.
  6. ^ Herwig, Falk (2011). "Convective-reactive proton-12C combustion in Sakurai's Object (V4334 Sagittarii) and implications for the evolution and yields from the first generations of stars". The Astrophysical Journal. 727 (2): 89. arXiv:1002.2241. Bibcode:2011ApJ...727...89H. doi:10.1088/0004-637X/727/2/89. S2CID 51428014.
  7. ^ Cite error: The named reference hajduk was invoked but never defined (see the help page).
  8. ^ Duerbeck, Hilmar W.; Benetti, Stefano (10 September 1996). "Sakurai's Object—A Possible Final Helium Flash in a Planetary Nebula Nucleus". The Astrophysical Journal. 468 (2): L111–L114. Bibcode:1996ApJ...468L.111D. doi:10.1086/310241. S2CID 121491943.