V4332 Sagittarii

V4332 Sagittarii is a nova-like event in the constellation of Sagittarius. It was discovered February 24, 1994 at an apparent visual magnitude of 8.9 by Japanese amateur astronomer Minoru Yamamoto from Okazaki, Aichi, then confirmed by K. Hirosawa.[7] Initially designated Nova Sagittarii 1994 #1, it was given the variable star designation V4332 Sgr.[2] A spectra of the event taken March 4 lacked the characteristic features of a classical nova, with the only emission lines being of the Balmer series.[8] Subsequent spectra showed a rapid decline in luminosity and a change of spectral type over a period of five days.[2] By 2003, the object was ~1500 times less luminous than at peak magnitude and showed a spectrum of an M-type star.[9]

V4332 Sagittarii

A visual band light curve for V4332 Sagittarii. The main plot, adapted from Tylenda et al. (2015),[1] shows the long-term variability, and the inset, adapted from Martini et al. (1999),[2] shows the variation during the first weeks of the eruption.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension 18h 50m 36.696s[3]
Declination –21° 23′ 28.93″[3]
Apparent magnitude (V) 8.5[2]
Characteristics
Spectral type K8/M0e[4]
Astrometry
Proper motion (μ) RA: −2.722 mas/yr[3]
Dec.: −5.555 mas/yr[3]
Parallax (π)0.0017 ± 0.2798 mas[3]
Distance(3.71±3.3)×103[5] ly
Other designations
V4332 Sgr, Nova Sgr 1994[6]
Database references
SIMBADdata

The nova-like event V838 Mon and this outburst formed an unusual category of erupting stars. In 2003, N. Soker and R. Tylenda proposed an accretion scenario as an explanation. They noted that a merger of two main sequence stars in a close binary orbit could explain the observed properties,[10] a process now known as a luminous red nova. In this scenario, the decline in brightness and radius of V4332 Sgr was a consequence of the merged stellar envelope undergoing gravitational contraction.[9]

An infrared excess from the object suggests it has a circumstellar disk. The infrared spectrum of this feature showed an absorption band of water ice and a carbon monoxide emission band.[9] By 2010, the stellar component had become concealed by a dusty disk viewed edge-on.[1] This dust includes a significant component of alumina, with growing amounts of magnesia and iron oxide.[11]

See also

References
  1. Tylenda, R.; et al. (June 2015), "VLT/UVES spectroscopy of V4332 Sagittarii in 2005: The best view on a decade-old stellar-merger remnant", Astronomy & Astrophysics, 578: 14, arXiv:1412.7822, Bibcode:2015A&A...578A..75T, doi:10.1051/0004-6361/201425592, S2CID 54789582, A75.
  2. Martini, Paul; et al. (August 1999), "Nova Sagittarii 1994 1 (V4332 Sagittarii): The Discovery and Evolution of an Unusual Luminous Red Variable Star", The Astronomical Journal, 118 (2): 1034–1042, arXiv:astro-ph/9905016, Bibcode:1999AJ....118.1034M, doi:10.1086/300951, S2CID 13862209.
  3. 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. Kimeswenger, S. (January 2006), "V4332 Sgr in 'Quiescence'", Astronomische Nachrichten, 327 (1): 44–52, arXiv:astro-ph/0509844, Bibcode:2006AN....327...44K, doi:10.1002/asna.200510482, S2CID 118936262.
  5. Özdönmez, Aykut; et al. (September 2016), "The distances of the Galactic novae", Monthly Notices of the Royal Astronomical Society, 461 (2): 1177–1201, arXiv:1606.01907, Bibcode:2016MNRAS.461.1177O, doi:10.1093/mnras/stw1362.
  6. "V4332 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-02-05.{{cite web}}: CS1 maint: postscript (link)
  7. Hayashi, S. S.; et al. (February 1994), Marsden, B. G. (ed.), "Nova Sagittarii 1994", IAU Circular, 5942 (1): 1, Bibcode:1994IAUC.5942....1H.
  8. Wagner, R. M.; et al. (March 1994), Marsden, B. G. (ed.), "Nova Sagittarii 1994", IAU Circular, 5944 (1): 1, Bibcode:1994IAUC.5944....1W.
  9. Tylenda, R.; et al. (August 2005), "V4332 Sagittarii revisited", Astronomy and Astrophysics, 439 (2): 651–661, arXiv:astro-ph/0412205, Bibcode:2005A&A...439..651T, doi:10.1051/0004-6361:20041581, S2CID 119410176.
  10. Soker, Noam; Tylenda, Romuald (January 2003), "Main-Sequence Stellar Eruption Model for V838 Monocerotis", The Astrophysical Journal, 582 (2): L105–L108, arXiv:astro-ph/0210463, Bibcode:2003ApJ...582L.105S, doi:10.1086/367759, S2CID 18351411.
  11. Banerjee, Dipankar. P. K.; et al. (December 2015), "Evolution of the Dust in V4332 Sagittarii", The Astrophysical Journal, 814 (2): 9, arXiv:1510.05074, Bibcode:2015ApJ...814..109B, doi:10.1088/0004-637X/814/2/109, S2CID 119299700, 109.{{citation}}: CS1 maint: multiple names: authors list (link)

Further reading
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