Ou 5, also known as IPHASXJ211420.0+434136, is a

planetary nebula A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to ...

in the constellation of Cygnus. It was discovered by the

IPHAS The INT Photometric H-Alpha Survey (IPHAS) is an astronomical survey of the northern plane of our Galaxy, the Milky Way, as visible from the Isaac Newton Telescope (INT) in the Canary Islands, Spain. The survey uses two broad-band filters and a ...

project in data taken on August 1, 2010, and independently by the French amateur astronomer Nicolas Outters in September 2012. Located two degrees east of the North American Nebula, it is an unusual planetary nebula because its central star is a short period

eclipsing binary A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

. Ou 5 showed signs of variability during the three occasions when IPHAS observed it. Because of that, members of the IPHAS team made follow-up photometric observations of the nebula during October and November 2013, using the 80 cm IAC80 telescope at the

Teide Observatory Teide Observatory ( es, Observatorio del Teide), IAU code 954, is an astronomical observatory on Mount Teide at , located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It becam ...

. The derived light curve showed that the central star was an eclipsing binary, and the short orbital period (8.7 hours) implies that during the

red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...

phase which preceded the formation of the planetary nebula, the stars must have formed a

common envelope In astronomy, a common envelope (CE) is gas that contains a binary star system. The gas does not rotate at the same rate as the embedded binary system. A system with such a configuration is said to be in a common envelope phase or undergoing commo ...

binary. Passing through a common envelope stage is often invoked as an explanation for the bipolar shape seen in many planetary nebulae, and Ou 5 does have bipolar features. The structure of the barrel-shaped nebula suggests that there may have been multiple mass ejection events during the common envelope phase. The eclipses of the compact primary star in Ou 5 allow spectra of the fainter secondary star to be obtained. They indicate that the secondary star is a late K or early M-type star. The masses of the hot primary and cool secondary stars are estimated to be , and respectively.

References

{{reflist, refs= {{cite journal , last1=Corradi , first1=R. L. M. , last2=Rodríguez-Gil , first2=P. , last3=Jones , first3=D. , last4=García-Rojas , first4=J. , last5=Mampaso , first5=A. , last6=García-Alvarez , first6=D. , last7=Pursimo , first7=T. , last8=Eenmae , first8=T. , last9=Liimets , first9=T. , last10=Miszalski , first10=B. , title=The planetary nebula IPHASXJ211420.0+434136 (Ou5): insights into common-envelope dynamical and chemical evolution , journal=Monthly Notices of the Royal Astronomical Society , date=July 2014 , volume=441 , issue=4 , pages=2799–2808 , doi=10.1093/mnras/stu703 , url=https://ui.adsabs.harvard.edu/abs/2014MNRAS.441.2799C , access-date=5 June 2022, arxiv=1406.4309 , bibcode=2014MNRAS.441.2799C {{cite journal , last1=Jones , first1=David , last2=Munday , first2=James , last3=Corradi , first3=Romano L. M. , last4=Rodríguez-Gil , first4=Pablo , last5=Boffin , first5=Henri M. J. , last6=Zak , first6=Jiri , last7=Sowicka , first7=Paulina , last8=Parsons , first8=Steven G. , last9=Dhillon , first9=Vik S. , last10=Littlefair , first10=S. P. , last11=Marsh , first11=T. R. , last12=Reindl , first12=Nicole , last13=Garcia-Rojas , first13=Jorge , title=The post-common-envelope binary central star of the planetary nebula Ou 5: a doubly-eclipsing post-red-giant-branch system , journal=Monthly Notices of the Royal Astronomical Society , date=February 2022 , volume=510 , issue=2 , pages=3102–3110 , doi=10.1093/mnras/stab3736 , bibcode=2022MNRAS.510.3102J , doi-access=free {{Citation , title=NAME PN Ou 5, date=June 5, 2022 , publisher=

SIMBAD SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data) is an astronomical database of objects beyond the Solar System. It is maintained by the Centre de données astronomiques de Strasbourg (CDS), France. SIMBA ...

Centre de données astronomiques de Strasbourg Center or centre may refer to: Mathematics *Center (geometry), the middle of an object * Center (algebra), used in various contexts ** Center (group theory) ** Center (ring theory) * Graph center, the set of all vertices of minimum eccentricity ...

, url=http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=PN+Ou+5 {{cite journal , last1=Acker , first1=A. , last2=Le Du , first2=P. , title=Nebuleuses Planetaires: Joyaux de L'Astrophotographie , journal=L'Astronomie , date=January 2014 , url=http://www.cielocean.fr/uploads/images/FichiersPDF/L-Astronomie-_Janvier2014.pdfomie-_Janvier2014.pdf , access-date=5 June 2022 {{cite web , title=The IPHAS DR2 Source Catalogue , url=http://www.iphas.org/dr2/ , website=IPHAS , publisher=University of Hertfordshire, UK , access-date=5 June 2022 {{cite web , last1=Outters , first1=Nicolas , title=Summary of my discoveries , url=http://outters.fr/wp/?page_id=1707 , publisher=Nicolas Outters , access-date=5 June 2022 {{cite journal , last1=Ondratschek , first1=Patrick A. , last2=Röpke , first2=Friedrich K. , last3=Schneider , first3=Fabian R. N. , last4=Fendt , first4=Christian , last5=Sand , first5=Christian , last6=Ohlmann , first6=Sebastian T. , last7=Pakmor , first7=Rüdiger , last8=Springel , first8=Volker , title=Bipolar planetary nebulae from common-envelope evolution of binary stars , journal=Astronomy & Astrophysics, date=April 2022 , volume=660 , page=L8 , doi=10.1051/0004-6361/202142478 , arxiv=2110.13177 , bibcode=2022A&A...660L...8O , s2cid=239885314 , url=https://www.aanda.org/articles/aa/pdf/2022/04/aa42478-21.pdf , access-date=5 June 2022

External links

Image of Ou 5 (object on the left)
Planetary nebulae Cygnus (constellation)