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MWC 560

A light curve for MWC 560. The main plot, displaying the ASAS-3 data,[1] shows the long term variability, and the inset plot, adapted from Marchev et al.,[2] shows the intermittent short timescale flickering.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Monoceros
Right ascension 07h 25m 51.284s[3]
Declination −07° 44′ 08.08″[3]
Apparent magnitude (V) 9.70[4] (9.1 to 10.1)[5]
Characteristics
Spectral type M4ep + Beq[6]
B−V color index 0.31[4]
Astrometry
Proper motion (μ) RA: 2.067 mas/yr[3]
Dec.: 0.552 mas/yr[3]
Parallax (π)0.424 ± 0.0352 mas[3]
Distance7,700 ± 600 ly
(2,400 ± 200 pc)
Details
M-type giant
Mass~1[7] M☉
White dwarf
Mass0.9[8] M☉
Radius6,221[8] km
Luminosity200 to 3,000[8] L☉
Temperature7,000–13,000[8] K
Other designations
MWC 560, V694 Mon, IRAS 07233-0737[9]
Database references
SIMBADdata

MWC 560 is a symbiotic binary star system in the equatorial constellation of Monoceros. The identifier comes from the Mount Wilson Calatogue of class O, B and A stars with bright hydrogen lines, published in 1933 by P. W. Merrill and associates.[10] It has the variable star designation V694 Monoceros.[5] This system has a typical apparent visual magnitude of 9.70,[4] which is too dim to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 7,700 light years from the Sun.[3]

Observations

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N. Sanduleak and C. B. Stephenson included this in a list of objects in the southern Milky Way with strong emission lines in 1973. They found bands of TiO in the spectrum and indicators of variable emission lines. A stellar classification of M4ep was found.[11] In 1984, H. E. Bond and associates classified this as a symbiotic binary system consisting of an M-type giant star with an orbiting compact companion. The profiles of absorption lines show changes on a day to day basis. They theorized that matter is being transferred from the M–giant at a higher rate than the companion is able to accrete it, producing a flickering appearance.[12]

In 1990, absorption lines were found to be coming from high velocity components, possibly from a jet-like ejecta nearly along the line of sight.[13] The high velocity aspect was confirmed by the IUE during an outburst, which suggested the ejection of a cool, optically-thick shell from the compact object.[14] Velocities of up to 6,000 km/s were recorded, and during the outburst the brightness increased from magnitude 12.5 up to as high as 9.2. Meanwhile the emission lines showed a stable radial velocity. The high rate of mass transfer inferred that an accretion disk is orbiting the compact object, with a thick envelop hiding the inner disk and compact object from direct sight. This disk is probably perpendicular to the line of sight from Earth, so it is being viewed nearly face-on.[15]

Observation of the system over a ten year period demonstrated a light variation with a period of 1,930 days, which may be explained by precessing of the disk. The system shifted between active and stable states, with outflow much higher during the active stage.[16] Meanwhile, infrared observations in the i band suggested that the M-giant may undergo pulsations with a period of around 5 months.[17] In 2007, this was refined to a period of about 340 days, making this a semiregular variable probably consisting of a thermally pulsing asymptotic giant branch star.[7] X-ray emission was detected from this system in 2009, with the data being consistent with an accreting white dwarf source.[18] It is accreting mass at a rate of (1 to 20)×10−7 M☉·yr−1,[8] with just a few percent of this rate being ejected in the jet.[18]

The optical flickering persisted from 1984 until 2016.[19] After a short pause it resumed until 2018, when it disappeared. At that point the system underwent steady brightness increase with periodicities of 331 and 1860 days.[2] As of 2023, it remains in a non-flickering state,[20] with maximum brightness achieved in October 2021.[2]

References

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  1. ^ "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 4 December 2024.
  2. ^ a b c Marchev, Dragomir; et al. (November 2022), "For optical flickering in symbiotic star MWC 560", Acta Scientifica Naturalis, 9 (3): 1–9, arXiv:2212.05604, Bibcode:2022AcSN....9c...1M, doi:10.2478/asn-2022-0017.
  3. ^ 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.
  4. ^ a b c Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862.
  5. ^ a b Samus, N. N.; et al. (January 2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  6. ^ Bidelman, W. P.; MacConnel, D. J. (October 1973), "The brighter stars of astrophysical interest in the southern sky", The Astronomical Journal, 78: 687, Bibcode:1973AJ.....78..687B, doi:10.1086/111475, ISSN 0004-6256.
  7. ^ a b Gromadzki, M.; et al. (February 2007), "On the nature of the cool component of MWC 560", Astronomy and Astrophysics, 463 (2): 703–706, arXiv:astro-ph/0611815, Bibcode:2007A&A...463..703G, doi:10.1051/0004-6361:20066538.
  8. ^ a b c d e Marchev, V. D.; Zamanov, R. K. (February 2024), "Mass accretion rate in the jet-driving symbiotic binary MWC 560", Bulgarian Astronomical Journal, 40: 85, arXiv:2312.04208, Bibcode:2024BlgAJ..40...85M.
  9. ^ "MWC 560". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-12-01.
  10. ^ Merrill, Paul W.; Burwell, Cora G. (September 1933), "Catalogue and Bibliography of Stars of Classes B and A whose Spectra have Bright Hydrogen Lines", Astrophysical Journal, 78: 87, Bibcode:1933ApJ....78...87M, doi:10.1086/143490.
  11. ^ Sanduleak, N.; Stephenson, C. B. (November 1973), "Low-dispersion spectra and galactic distribution of various interesting strong-emission-line objects in the southern Milky Way", Astrophysical Journal, 185: 899–913, Bibcode:1973ApJ...185..899S, doi:10.1086/152464.
  12. ^ Bond, H. E.; et al. (March 1984), "The Extraordinary Symbiotic-Like Variable MWC 560", Bulletin of the American Astronomical Society, 16: 516, Bibcode:1984BAAS...16..516B.
  13. ^ Tomov, T. (January 1990), Marsden, B. G. (ed.), "MWC 560", IAU Circular, 4955: 1, Bibcode:1990IAUC.4955....1T.
  14. ^ Michalitsianos, A. G.; et al. (April 1991), "Observations of the Peculiar Object MWC 560 in Outburst", Astrophysical Journal, 371: 761, Bibcode:1991ApJ...371..761M, doi:10.1086/169940.
  15. ^ Tomov, T.; et al. (September 1992), "MWC 560: jets or optically thick expanding envelope?", Monthly Notices of the Royal Astronomical Society, 258: 23–35, Bibcode:1992MNRAS.258...23T, doi:10.1093/mnras/258.1.23.
  16. ^ Iijima, T. (August 2002), "MWC 560: An SS 433 type object with a white dwarf", Astronomy and Astrophysics, 391 (2): 617–623, Bibcode:2002A&A...391..617I, doi:10.1051/0004-6361:20020816.
  17. ^ Frckowiak, S. M.; et al. (2003), Corradi, R. L. M.; et al. (eds.), "Possible Pulsations of the M Giant in MWC 560", Symbiotic Stars Probing Stellar Evolution, ASP Conference Proceedings, Vol. 303. Held 27-31 May 2002 at Isaac Newton Group of Telescopes, La Palma, Spain, vol. 303, San Francisco: Astronomical Society of the Pacific, p. 120, Bibcode:2003ASPC..303..120F, ISBN 1-58381-152-4.
  18. ^ a b Stute, M.; Sahai, R. (April 2009), "Detection of X-rays from the jet-driving symbiotic star MWC 560", Astronomy and Astrophysics, 498 (1): 209–215, arXiv:0902.1526, Bibcode:2009A&A...498..209S, doi:10.1051/0004-6361/200811176.
  19. ^ Munari, U.; et al. (November 2016), "The 2016 outburst of the unique symbiotic star MWC 560 (= V694 Mon), its long-term BVRI evolution and a marked 331 days periodicity", New Astronomy, 49: 43–49, arXiv:1607.06309, Bibcode:2016NewA...49...43M, doi:10.1016/j.newast.2016.06.004.
  20. ^ Marchev, D.; et al. (February 2023), "MWC 560 remains in high state", The Astronomer's Telegram, 15906: 1, Bibcode:2023ATel15906....1M.

Further reading

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