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UY Volantis - Wikipedia

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(Redirected from EXO 0748-676)

UY Volantis
Observation data Epoch J2000 Equinox J2000
A red band light curve for UY Volantis, adapted from Hynes and Jones (2009)^[1]
Constellation	Volans
Right ascension	07^h 48^m 33.71^s^[2]
Declination	−67° 45′ 07.70″^[2]
Apparent magnitude (V)	16.9^[3]
Characteristics
Apparent magnitude (U)	16.10^[3]
Apparent magnitude (B)	17^[3]
Apparent magnitude (R)	16.7^[2]
Astrometry

Radial velocity (R_v)	20^[4] km/s
Distance	6,800 - 9,100^[5] pc

Other designations
EXO 0748-676
Database references
SIMBAD	data

UY Volantis, also known as EXO 0748-676, is a low mass X-ray binary^[6] system located in the constellation Volans. With an apparent magnitude of 16.9, it requires a powerful telescope to see. With a radial velocity of 20 km/s, it is drifting away from the Solar System, and is currently located 26,000 light years away.

Properties

The properties of the two system components are uncertain and contradictory. One component is almost certain to be a neutron star, which has a fairly strict upper mass limit. The other component is a low mass star, but its properties are affected by the close neutron star. The two components orbit each other every 3.82 hours.^[7]

The system undergoes x-ray eclipses which can be used to constrain the properties of the orbit and of the component stars. The orbital inclination must be high and is thought to be about 76°.^[8] The mass ratio of the components is relatively well-known and shows the neutron star to be about four times as massive as its partner. This implies either an unusually low-mass star or an unusually high-mass neutron star. Simple models produce neutron star masses above 3 M_☉ which is theoretically impossible.^[9] More complex models of the system produced by measuring the eclipses still produce an unexpectedly high neutron star mass of about 2 M_☉ which would make it one of the highest known.^[8] A more expected neutron star mass of around 1.4 M_☉ can be deduced by making certain assumptions about the origin of the spectral lines or an unusually low-mass companion.^[10]^[8]

References

^ Hynes, Robert I.; Jones, Erica D. (2009). "The Quiescent Optical and Infrared Counterpart to EXO 0748-676 = UY Vol". The Astrophysical Journal. 697 (1): L14–L17. arXiv:0903.4164. Bibcode:2009ApJ...697L..14H. doi:10.1088/0004-637X/697/1/L14. S2CID 19003541.
^ ^a ^b ^c Monet, David G.; et al. (February 2003). "The USNO-B Catalog". The Astronomical Journal. 125 (2): 984–993. arXiv:astro-ph/0210694. Bibcode:2003AJ....125..984M. doi:10.1086/345888. eISSN 1538-3881. ISSN 0004-6256.
^ ^a ^b ^c Liu, Q. Z.; van Paradijs, J.; van den Heuvel, E. P. J. (11 April 2007). "A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)". Astronomy & Astrophysics. 469 (2): 807–810. arXiv:0707.0544. Bibcode:2007A&A...469..807L. doi:10.1051/0004-6361:20077303. eISSN 1432-0746. ISSN 0004-6361.
^ Duflot, M.; Figon, P.; Meyssonnier, N. (1995-12-01). "Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue". Astronomy and Astrophysics Supplement Series. 114: 269. Bibcode:1995A&AS..114..269D. ISSN 0365-0138.
^ Jonker, P. G.; Nelemans, G. (October 2004). "The distances to Galactic low-mass X-ray binaries: consequences for black hole luminosities and kicks". Monthly Notices of the Royal Astronomical Society. 354 (2): 355–366. arXiv:astro-ph/0407168. Bibcode:2004MNRAS.354..355J. doi:10.1111/j.1365-2966.2004.08193.x. eISSN 1365-2966. ISSN 0035-8711.
^ Baumgartner, W. H.; Tueller, J.; Markwardt, C. B.; Skinner, G. K.; Barthelmy, S.; Mushotzky, R. F.; Evans, P. A.; Gehrels, N. (5 July 2013). "THE 70 Month SWIFT--BAT All-sky Hard X-Ray Survey". The Astrophysical Journal Supplement Series. 207 (2): 19. arXiv:1212.3336. Bibcode:2013ApJS..207...19B. doi:10.1088/0067-0049/207/2/19. eISSN 1538-4365. hdl:2381/18987. ISSN 0067-0049.
^ Ritter, H.; Kolb, U. (2003-06-01). "Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)". Astronomy and Astrophysics. 404: 301–303. arXiv:astro-ph/0301444. Bibcode:2003A&A...404..301R. doi:10.1051/0004-6361:20030330. ISSN 0004-6361.
^ ^a ^b ^c Knight, Amy H.; Ingram, Adam; Middleton, Matthew; Drake, Jeremy (2022). "Eclipse mapping of EXO 0748-676: Evidence for a massive neutron star". Monthly Notices of the Royal Astronomical Society. 510 (4): 4736. arXiv:2201.02188. Bibcode:2022MNRAS.510.4736K. doi:10.1093/mnras/stab3722.
^ Ratti, E. M.; Steeghs, D. T. H.; Jonker, P. G.; Torres, M. A. P.; Bassa, C. G.; Verbunt, F. (2012). "Optical spectroscopy of the quiescent counterpart to EXO 0748-676: A black widow scenario?". Monthly Notices of the Royal Astronomical Society. 420 (1): 75. arXiv:1110.3963. Bibcode:2012MNRAS.420...75R. doi:10.1111/j.1365-2966.2011.19999.x.
^ Mikles, Valerie J.; Hynes, Robert I. (2012). "Gemini Multi-Object Spectrograph Spectroscopy of EXO 0748-676 (=UY Vol) in Outburst". The Astrophysical Journal. 750 (2): 132. arXiv:1203.0782. Bibcode:2012ApJ...750..132M. doi:10.1088/0004-637X/750/2/132. S2CID 117376389.

Constellation of Volans

Stars

Bayer	α β γ δ ε ζ η θ ι κ
Variable	R S UY
HR	2505 2531 2536 2662 2712 2888 2979 2980 3036 3038 3081 3171 3280 3346 3370 3417 3491 3495 3537 3544 3610
HD	59640 68402 74423 76700
Other	L 98-59 L 97-12 WD 0806−661 WISE 0734−7157

Exoplanets	HD 68402 b HD 76700 b L 98-59 b

Galaxies

NGC	2305 2397 2442 2443 2466
Other	AM 0644-741

Galaxy clusters	SMACS J0723.3–7327