U Scorpii

U Scorpii (U Sco) is a recurrent nova system; one of 10 known recurring novae in the Milky Way galaxy.[5] Located near the northern edge of the constellation Scorpius it normally has a magnitude of 18, but reaches a magnitude of about 8 during outbursts. Outbursts have been observed in 1863, 1906, 1936, 1979, 1987, 1999, 2010, and 2022.[6][7]

Not to be confused with Upsilon Scorpii.
U Scorpii
Location of U Scorpii (circled in red)
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 16h 22m 30.78s[1]
Declination −17° 52′ 42.8″[1]
Apparent magnitude (V) 7.5 Max.
17.6 Min.[2]
Characteristics
Spectral type  ? / White Dwarf
Variable type Recurrent nova[2]
Astrometry
Radial velocity (Rv)65[3] km/s
Proper motion (μ) RA: −0.380±0.202[4] mas/yr
Dec.: −7.591±0.144[4] mas/yr
Parallax (π)−0.0945[4] ± 0.1334[4] mas[4]
Distance19600+21000
−5300[2] pc
Other designations
AAVSO 1616-17, Nova Sco 1863, BD−17 4554, Gaia DR2 6246188565119443072, 2MASS J16223079-1752431[3]
Database references
SIMBADdata

The 2010 outburst was predicted to occur April 2009 ± 1.0 year, based on observations during quiescence following the 1999 outburst.[8] The U Sco 2010 eruption faded by 1 magnitude in 1 day, and by 4 magnitudes in 6 days. By February 6 it was dimmer than magnitude 13. Between February 10–19, it was flickering around magnitude 14. The eruption ended on day 64, which is the fastest observed decline to quiescence of recurring nova. This eruption of U Sco is now the best-observed nova event with 22,000 magnitudes already accumulated. Astronomers have predicted that another eruption of U Sco will occur in 2020±2. This prediction was correct; it brightened to +7.8 magnitude on 6 June 2022.[9]

AAVSO light curve of recurrent nova U Sco from 1 Jan 2010 to 1 Sept 2010. Up is brighter and down is fainter. Day numbers are Julian day. Different colors reflect different bandpasses.

Originally identified in 1863 by English astronomer N.R. Pogson, U Scorpii was the third recurrent nova to be identified, in the years preceding World War II by Helen L. Thomas.[10][11]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Schaefer, Bradley E. (2018). "The distances to Novae as seen by Gaia". Monthly Notices of the Royal Astronomical Society. 481 (3): 3033–3051. arXiv:1809.00180. Bibcode:2018MNRAS.481.3033S. doi:10.1093/mnras/sty2388. S2CID 118925493.
  3. "U Scorpii". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-17.
  4. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  5. Comprehensive Photometric Histories of All Known Galactic Recurrent Novae, B. Schaefer
  6. The 1999 Outburst of the Recurrent Nova U Scorpii, Anupama & Dewangan
  7. Thar She Blows! U Scorpii Erupts as Predicted, A. MacRobert
  8. B. Schaefer; A. Pagnotta; et al. (October 2010). "Discovery of the 2010 Eruption and the Pre-Eruption Light Curve for Recurrent Nova U Scorpii". The Astronomical Journal. 140 (4): 925–932. arXiv:1004.2842. Bibcode:2010AJ....140..925S. doi:10.1088/0004-6256/140/4/925. S2CID 118394042. Retrieved 12 February 2015.
  9. Matthew Templeton (May 6, 2010). "Long-term monitoring of the recurrent nova U Scorpii". AAVSO. Retrieved 2010-11-15.
  10. Templeton, Matthew. "U Scorpii | aavso". www.aavso.org. Retrieved 2022-05-28.
  11. "Eloge: Helen Meriwether Lewis Thomas, 21 August 1905-6 August 1997". Isis. 89 (2): 316–317. 1998-06-01. doi:10.1086/384004. ISSN 0021-1753. S2CID 144636725.
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