View source for RS Ophiuchi

{{Short description|Recurrent nova in the constellation Ophiuchus}}
{{Starbox begin
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{{Starbox image
 | image=
   {{Location mark
     | image=Ophiuchus IAU.svg
     | float=center | width=250 | position=right
     | mark=Red circle.svg | mark_width=10 | mark_link=RS Oph
     | x%=38.7 | y%=42.1
   }}
 | caption=Location of RS Ophiuchi (circled)
}}
{{Starbox observe
| epoch = [[J2000.0]]
| constell = [[Ophiuchus]] 
| ra = {{RA|17|50|13.2}}
| dec = {{DEC|-06|42|28}}
| appmag_v = 9.6{{snd}}13.5 (quiet), < 5 (burst)
}}
{{Starbox character
| class = K5.5/M0IIIe / [[White dwarf]]
| b-v = 
| u-b = 
| variable = [[Recurrent nova]]
}}
{{Starbox astrometry
| radial_v = 
| prop_mo_ra = 
| prop_mo_dec = 
| parallax = 
| p_error = 
| dist_ly = 3,900{{snd}}6,500
| dist_pc = 1,200{{snd}}2,000<ref>{{cite journal |title= On the Distance of RS Ophiuchi |year= 2008 |first1= R. K. |last1= Barry |first2= K. |last2= Mukai |first3= J. L. |last3= Sokoloski |journal= RS Ophiuchi (2006) and the Recurrent Nova Phenomenon |series= ASP Conference Series |volume= 401 |page= 52 |bibcode=2008ASPC..401...52B}}</ref>
| absmag_v = 
}}
{{Starbox catalog
| names = [[Henry Draper Catalogue|HD]] 162214, [[Bonner Durchmusterung|BD]]−06°4661
}}
{{Starbox reference
| Simbad = RS+Oph
}}
{{Starbox end
}}
'''RS Ophiuchi''' (''RS Oph'') is a recurrent [[nova]] system approximately 5,000 [[light-year]]s away in the [[constellation]] [[Ophiuchus]]. In its quiet phase it has an [[apparent magnitude]] of about 12.5. It has been observed to erupt in 1898, 1933, 1958, 1967, 1985, 2006 and 2021 and reached about magnitude 5 on average. A further two eruptions, in 1907 and 1945, have been inferred from archival data. The recurrent nova is produced  by a [[white dwarf]] star and a [[red giant]] in a [[binary system]]. About every 15 years, enough material from the red giant builds up on the surface of the white dwarf to produce a [[thermonuclear explosion]]. The white dwarf orbits close to the red giant, with an [[accretion disc]] concentrating the overflowing atmosphere of the red giant onto the white dwarf.

==Properties==
RS Ophiuchi is a system consisting of a [[white dwarf]] with a [[red giant]] companion. The stars are in a [[binary system]] with an orbital period of around 454 days.<ref>{{cite journal |title= Spectroscopic orbits and variations of RS Ophiuchi |year= 2009 |journal= Astronomy and Astrophysics |volume= 497 |issue= 3 |pages= 815–825 |last1= Brandi |first1= E. |last2= Quiroga |first2= C. |last3= Mikołajewska |first3= J. |doi= 10.1051/0004-6361/200811417 |bibcode=2009A&A...497..815B|arxiv = 0902.2177 |s2cid= 18755152 }}</ref>

==Eruptive history==
The chart below shows when every recorded nova had occurred since the first confirmed one in the year of 1898.

{|class="wikitable sortable"
!Date of<br>eruption
!Years since<br>last eruption
|-
|1898 || –
|-
|1907 || 9
|-
|1933 || 26
|-
|1945 || 12
|-
|1958 || 13
|-
|1967 || 9
|-
|1985 || 18
|-
|2006 || 21
|-
|2021 || 15
|}

=== 1898 ===
[[File:RSOphLightCurve.png|thumb|right|The [[light curve]] of RS Ophiuchi, showing five eruptions. Plotted from [[AAVSO]] visible-band data.]]

The 1898 eruption was, in fact, not discovered until several years after it happened. [[Williamina Fleming]] discovered a nova-like spectrum in the Henry Draper Memorial photographs and announced it as a potential nova in 1904. This diagnosis was affirmed by [[Edward Charles Pickering]] in 1905, after which [[Annie Jump Cannon]] determined that RS Ophiuchi had likely reached maximum in 1898.

===1907===
[[Image:Recurrent nova RS Ophiuchi as seen 23 FEB 2006 from Mt Laguna, Calif.jpg|thumb|Recurrent nova RS Ophiuchi in eruption of February 2006]]

Though the 1907 eruption was not observed during outburst, measurements of a dip in brightness from archival observations suggests that RS Oph underwent an eruption in early 1907 during a time when it was obscured by the sun.<ref>{{cite journal |last= Schaefer |first= B. E. |journal= IAU Circular |volume=8396 |date= August 2004 |url= http://www.cbat.eps.harvard.edu/iauc/08300/08396.html#Item2 |title= RS Ophiuchi |access-date= 24 May 2015}}</ref><ref>{{harvnb|Schaefer|2010|p=312}}</ref>

===1933===
The 1933 outburst was first detected by [[Eppe Loreta]], from [[Bologna]], [[Italy]].  Loreta had been observing [[Y Ophiuchi]] when he serendipitously noticed a bright object about 50 arcminutes southwest of Y Oph.  The detection of this luminous star resulted in the second recorded outburst of RS Oph.  An independent discovery of this activity was made several days later by [[Leslie Peltier]] (P) while making his routine check of the variable.

===1945===
The 1945 eruption was also inferred from archival data after the outburst as a result of obscuration from the sun during the peak brightness. This eruption is more certain than that in 1907, as the tail of the eruption was also observed.<ref>{{harvnb|Schaefer|2010|p=313}}</ref>

===1958===
The 1958 outburst was detected by [[Cyrus Fernald]], located in [[Longwood, Florida]].  Fernald's monthly report for July 1958, containing 345 observations, displays a note in which he comments ''"Not too good of a month outside of the RS Oph observations (19 in total). It was interesting to watch the change in color as the star faded. It was reddish-yellow the first night, then yellowish-red, and so on. The last observation was the reddest star that I have ever seen."'' The crimson color of which Fernald speaks is indicative of the strong H-alpha emission displayed in the several days following the outburst.

[[Image:AAVSO light curve of RS Oph 2005 outburst in various bandpasses.png|thumb|right|[[AAVSO]] [[light curve]] of RS Oph's 2006 outburst. Different colors reflect different [[Photometric system|bandpasses]].]]

[[Image:RS Oph 2021.jpg|thumb|right|Image of RS Oph in 2021 outburst from [[Nakhodka]]]]

===1967===
The 1967 outburst was again detected by Cyrus Fernald (FE), however, Fernald was not given credit for the earliest observation of maximum.  For on the same evening, Dr. Max Beyer (BY), located in Hamburg, Germany, observed the variable at 6th magnitude. Due to the 6-hour difference in time zones, Dr. Beyer was credited with the first report.

===1985===
In January 1985, [[Warren Morrison]] of [[Peterborough, Ontario|Peterborough]], [[Canada]] discovered RS Oph to again be in outburst, reaching a maximum brightness of magnitude 5.4.

===2006===
On 12 February 2006 a new outburst occurred, reaching magnitude 4.5. The opportunity was taken to observe it at different wavelengths.
It was notably observed with the VLTI by [[Olivier Chesneau]], who discovered an elongated fireball as early as 5.5 days after the explosion (see the figure below).<ref>{{cite journal | url=http://www.iop.org/EJ/article/0004-637X/652/1/629/65145.html | author=Bode | title=Swift Observations of the 2006 Outburst of the Recurrent Nova RS Ophiuchi. I. Early X-Ray Emission from the Shocked Ejecta and Red Giant Wind  | journal=The Astrophysical Journal | volume=652 | issue=1 | date=2006 | pages=629–635 | doi=10.1086/507980 | last2=O’brien | first2=T. J. | last3=Osborne | first3=J. P. | last4=Page | first4=K. L. | last5=Senziani | first5=F. | last6=Skinner | first6=G. K. | last7=Starrfield | first7=S. | last8=Ness | first8=J.-U. | last9=Drake | first9=J. J. | bibcode=2006ApJ...652..629B|arxiv = astro-ph/0604618 | hdl=2381/18811 | s2cid=18465274 | display-authors=1 }}</ref><ref>{{cite journal | url=http://www.iop.org/EJ/article/1538-4357/647/2/L127/20762.html | author=Monnier | title=No Expanding Fireball: Resolving the Recurrent Nova RS Ophiuchi with Infrared Interferometry | journal=The Astrophysical Journal Letters | volume=647 | issue=2 | date=2006 | pages=L127–L130 | doi=10.1086/507584 | last2=Barry | first2=R. K. | last3=Traub | first3=W. A. | last4=Lane | first4=B. F. | last5=Akeson | first5=R. L. | last6=Ragland | first6=S. | last7=Schuller | first7=P. A. | last8=Le Coroller | first8=H. | last9=Berger | first9=J.-P. | bibcode=2006ApJ...647L.127M|arxiv = astro-ph/0607399 | s2cid=1822816 | display-authors=1 }}</ref><ref>{{cite journal | author=Chesneau | title=AMBER/VLTI interferometric observations of the recurrent Nova RS Ophiuchii 5.5 days after outburst  | journal=[[Astronomy & Astrophysics]] | volume=464 | issue=1 | date=2007 | pages=119–126 | doi=10.1051/0004-6361:20066609 | bibcode=2007A&A...464..119C|arxiv = astro-ph/0611602 | s2cid=15269066 | url=https://hal.archives-ouvertes.fr/hal-00114847/document }}</ref> Silicate dust and [[Silicon monoxide|SiO]] emissions were observed after eruptuon.<ref name=Rushton2022>{{cite journal|arxiv=2209.12626|last1=Rushton |first1=M. T. |last2=Woodward |first2=C. E. |last3=Gehrz |first3=R. D. |last4=Evans |first4=A. |last5=Kaminsky |first5=B. |last6=Pavlenko |first6=Ya. V. |last7=Eyres |first7=S. P. S. |title=Rise and fall of silicate dust in RS Ophiuchi following the 2006 eruption |journal=Monthly Notices of the Royal Astronomical Society |year=2022 |volume=517 |issue=2 |pages=2526–2533 |doi=10.1093/mnras/stac2771 |doi-access=free }}</ref>

=== 2021 ===
On 8 August 2021, the Brazilian amateur astronomer [[Alexandre Amorim]], from [[Florianópolis]], [[Brazil]] detected a new outburst of RS Oph at 21:55 UT and sent a notification to [[American Association of Variable Star Observers|AAVSO]].<ref name=":0">{{Cite web|title=RS Ophiuchi {{!}} aavso|url=https://www.aavso.org/rs-ophiuchi|access-date=2021-09-28|website=www.aavso.org}}</ref> The outbust was confirmed by an independent observation of Keith Geary from [[Ireland]] at 22:20 UT.<ref name=":0" /> The [[Fermi Gamma-ray Space Telescope|Fermi Gamma Ray Space Telescope]] corroborated optical observations made by Amorim and Geary of a new outburst associated with RS Oph, with an estimated visual magnitude of 5.0.<ref>{{Cite web|title=[vsnet-alert 26131] Outburst of RS Ophiuchi|url=http://ooruri.kusastro.kyoto-u.ac.jp/mailarchive/vsnet-alert/26131|access-date=2021-08-09|website=ooruri.kusastro.kyoto-u.ac.jp}}</ref><ref>{{Cite web|title=ATel #14834: Fermi-LAT Gamma-ray Detection of the Recurrent Nova RS Oph|url=https://astronomerstelegram.org/?read=14834|access-date=2021-08-09|website=ATel}}</ref> It reached a peak visual magnitude of approximately 4.6 the following day.

==References==
{{Reflist}}

==Bibliography==
[[File:RS Ophiuchi.jpg|thumb|radio profile of RS Ophiuchi, together with the fireball as seen by VLTI 5.5 days after outburst (coloured ellipses).]]
*{{cite journal |last= Schaefer |first= B. E. |title= Comprehensive Photometric Histories of All Known Galactic Recurrent Novae |journal= Astrophysical Journal |volume= 187 |issue= 2 |year= 2010 |doi= 10.1088/0067-0049/187/2/275 |pages=275–373 |bibcode=2010ApJS..187..275S|arxiv = 0912.4426 |s2cid= 119294221 }}

==External links==
{{commons category|RS Ophiuchi}}
* {{cite simbad|title=V* RS Oph}}
* [http://antwrp.gsfc.nasa.gov/apod/ap060726.html Entry at] [[Astronomy Picture of the Day]]
* [http://www.aavso.org/vsx/index.php?view=detail.top&oid=20497 Entry in the Variable Star Index]
* [http://www.aavso.org/vsots_rsoph AAVSO]

{{Stars of Ophiuchus}}

{{DEFAULTSORT:RS Ophiuchi}}
[[Category:Recurrent novae]]
[[Category:Ophiuchus]]
[[Category:M-type giants]]
[[Category:Objects with variable star designations|Ophiuchi, RS]]
[[Category:Henry Draper Catalogue objects|162214]]
[[Category:Durchmusterung objects]]