U Scorpii

{{short description|Recurrent nova system first seen in 1863}}{{confuse|Upsilon Scorpii}}

{{Starbox begin

| name = U Scorpii

}}

{{Starbox image

| image=

{{Location mark

|image=UScoLocation.png|alt=|width=280

}}

|caption=Location of U Scorpii (circled in red)

}}

{{Starbox observe

| epoch = J2000

| constell = Scorpius

| ra = {{RA|16|22|30.78}}

| dec = {{DEC|-17|52|42.8}}

| appmag_v = 7.5 Max.
17.6 Min.

}}

{{Starbox character

| class = ? / White Dwarf

| b-v =

| u-b =

| variable = Recurrent nova

}}

{{Starbox astrometry

| radial_v = 65

| prop_mo_ra = {{val|-0.380|0.202}}

| prop_mo_dec = {{val|-7.591|0.144}}

| parallax = −0.0945

| p_error = 0.1334

| parallax_footnote =

| dist_pc = {{val|19600|21000|5300}}

| absmag_v =

}}

{{Starbox catalog

| names = {{odlist | name=AAVSO 1616-17 | name2=Nova Sco 1863 | 2MASS=J16223079-1752431 | BD=−17 4554 | Gaia DR2=6246188565119443072 }}

}}

{{Starbox reference

| Simbad = U+Sco

}}

{{Starbox end}}

U Scorpii (U Sco) is a recurrent nova system, one of 10 known recurring novae in the Milky Way galaxy.[https://arxiv.org/abs/0912.4426 Comprehensive Photometric Histories of All Known Galactic Recurrent Novae, B. Schaefer] 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,[http://www.iop.org/EJ/article/1538-3881/119/3/1359/990310.html The 1999 Outburst of the Recurrent Nova U Scorpii, Anupama & Dewangan] 2010,[https://skyandtelescope.org/astronomy-news/thar-she-blows-u-scorpii-erupts-as-predicted/ Thar She Blows! U Scorpii Erupts as Predicted, A. MacRobert] and 2022.

The 2010 outburst was predicted to occur April 2009 ± 1.0 year, based on observations during quiescence following the 1999 outburst.{{cite journal |journal= The Astronomical Journal |author= B. Schaefer |author2= A. Pagnotta |display-authors= et al |title= Discovery of the 2010 Eruption and the Pre-Eruption Light Curve for Recurrent Nova U Scorpii |url= http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1004.2842 |arxiv= 1004.2842 |date= October 2010 |volume= 140 |issue= 4 |pages= 925–932 |doi= 10.1088/0004-6256/140/4/925 |access-date= 12 February 2015|bibcode = 2010AJ....140..925S |s2cid= 118394042 }} 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 a recurring nova.{{cite web |author=Matthew Templeton |date=May 6, 2010 |title=Long-term monitoring of the recurrent nova U Scorpii |url=http://www.aavso.org/long-term-monitoring-recurrent-nova-u-scorpii |access-date=2010-11-15 |publisher=AAVSO}} This eruption of U Sco became the best-observed nova event to its day, with 22,000 magnitudes accumulated. Astronomers then predicted that another eruption of U Sco would occur in 2020±2. This prediction was correct: it brightened to +7.8 magnitude on 6 June 2022.{{Cn|date=December 2024}}

File:U-Sco-2010-Lightcurve-AAVSO.png 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 as a nova in 1863 by English astronomer N.R. Pogson, U Scorpii was the third nova to be identified as recurrent, by American astronomer and historian of science Helen L. Thomas, in the years preceding World War II.{{Cite web |last=Templeton |first=Matthew |title=U Scorpii {{!}} aavso |url=https://www.aavso.org/vsots_usco |access-date=2022-05-28 |website=www.aavso.org}}{{Cite journal |date=1998-06-01 |title=Eloge: Helen Meriwether Lewis Thomas, 21 August 1905-6 August 1997 |url=https://www.journals.uchicago.edu/doi/abs/10.1086/384004 |journal=Isis |volume=89 |issue=2 |pages=316–317 |doi=10.1086/384004 |s2cid=144636725 |issn=0021-1753|url-access=subscription }}