Post-common-envelope binary

{{Short description|Binary system consisting of a white dwarf and a main sequence star or a brown dwarf}} [[File:HD 101584.jpg|thumb|HD 101584 is a suspected post-common envelope binary. The engulfed companion triggered an outflow of gas, creating the nebula seen by ALMA.]] [[File:Common envelope phase - ejection or merger.svg|thumb|Key stages in a common envelope phase. Top: A star fills its Roche lobe. Middle: The companion is engulfed; the core and companion spiral towards one another inside a common envelope. Bottom: The envelope is ejected and forms a PCEB or the two stars merge.]]

A '''post-common-envelope binary''' ('''PCEB''') or '''pre-cataclysmic variable''' is a binary system consisting of a white dwarf or hot subdwarf and a main-sequence star or a brown dwarf.<ref name=":0">{{Cite journal|last1=Casewell|first1=S. L.|last2=Braker|first2=I. P.|last3=Parsons|first3=S. G.|last4=Hermes|first4=J. J.|last5=Burleigh|first5=M. R.|last6=Belardi|first6=C.|last7=Chaushev|first7=A.|last8=Finch|first8=N. L.|last9=Roy|first9=M.|last10=Littlefair|first10=S. P.|last11=Goad|first11=M.|date=2018-05-01|title=The first sub-70 minute non-interacting WD-BD system: EPIC212235321|journal=Monthly Notices of the Royal Astronomical Society|volume=476|issue=1|pages=1405–1411|doi=10.1093/mnras/sty245|doi-access=free |issn=0035-8711|arxiv=1801.07773|bibcode=2018MNRAS.476.1405C|s2cid=55776991}}</ref> The star or brown dwarf shared a common envelope with the white dwarf progenitor in the red-giant phase. In this scenario, the star or brown dwarf loses angular momentum as it orbits within the envelope, eventually leaving a main-sequence star and white dwarf in a short-period orbit. A PCEB will continue to lose angular momentum via magnetic braking and gravitational waves and will eventually begin mass transfer, resulting in a cataclysmic variable. While there are thousands of PCEBs known, there are only a few eclipsing PCEBs, also called ePCEBs.<ref name=":1">{{Cite journal|last1=Muirhead|first1=Philip S.|last2=Vanderburg|first2=Andrew|last3=Shporer|first3=Avi|last4=Becker|first4=Juliette|last5=Swift|first5=Jonathan J.|last6=Lloyd|first6=James P.|last7=Fuller|first7=Jim|last8=Zhao|first8=Ming|last9=Hinkley|first9=Sasha|last10=Pineda|first10=J. Sebastian|last11=Bottom|first11=Michael|date=2013-04-02|title=Characterizing the Cool KOIs. V. KOI-256: A Mutually Eclipsing Post-Common Envelope Binary|journal=The Astrophysical Journal|volume=767|issue=2|pages=111|doi=10.1088/0004-637X/767/2/111|issn=0004-637X|arxiv=1304.1165|bibcode=2013ApJ...767..111M|s2cid=30368826}}</ref> Even more rare are PCEBs with a brown dwarf as the secondary.<ref name=":0" /> A brown dwarf with a mass lower than 20 {{Jupiter mass|link=true}} might evaporate during the common-envelope phase, so the secondary is supposed to have a mass higher than 20 {{Jupiter mass}}.<ref>{{Cite web|url=https://www.eso.org/public/news/eso0628/|title=A Sub-Stellar Jonah – Brown Dwarf Survives Being Swallowed|last=|website=www.eso.org|language=en|access-date=2020-02-02}}</ref>

The material ejected from the common envelope forms a planetary nebula. One in five planetary nebulae are thought to be ejected from common envelopes, but this might be an underestimate. A planetary nebula formed by a common-envelope system usually shows a bipolar structure.<ref>{{Cite journal|last1=De Marco|first1=Orsola|author1-link=Orsola De Marco|last2=Reichardt|first2=T.|last3=Iaconi|first3=R.|last4=Hillwig|first4=T.|last5=Jacoby|first5=G. H.|last6=Keller|first6=D.|last7=Izzard|first7=R. G.|last8=Nordhaus|first8=J.|last9=Blackman|first9=E. G.|date=October 2017|title=Post-common envelope PN, fundamental or irrelevant?|journal= Proceedings of the International Astronomical Union|language=en|volume=323|pages=213–217|doi=10.1017/S1743921317002149|arxiv=1612.03515|bibcode=2017IAUS..323..213D|s2cid=119069917|issn=1743-9221}}</ref>

The suspected PCEB HD 101584 is surrounded by a complex nebula. During the common-envelope phase, the red-giant phase of the primary was terminated prematurely, avoiding a stellar merger. The remaining hydrogen envelope of HD 101584 was ejected during the interaction between the red giant and the companion, and it now forms the circumstellar medium around the binary.<ref name="Olofsson et al"/>

Many eclipsing post-common-envelope binaries show variations in the timing of eclipses, the cause of which is uncertain. While orbiting exoplanets are often proposed as the causes of these variations, planetary models often fail to predict subsequent changes in eclipse timing. Other proposed causes, such as the Applegate mechanism, often cannot fully explain the observed eclipse timing variations either.<ref name="Pulley2022"/>

== List of post-common envelope binaries == {{Expand list|date=February 2020}}Sorted by increasing orbital period. {| class="wikitable" |+ !Name !Period !Secondary !Note |- |SDSS J1205-0242 |71.2 minutes<ref>{{Cite journal|last1=Rappaport|first1=S.|last2=Vanderburg|first2=A.|last3=Nelson|first3=L.|last4=Gary|first4=B. L.|last5=Kaye|first5=T. G.|last6=Kalomeni|first6=B.|last7=Howell|first7=S. B.|last8=Thorstensen|first8=J. R.|last9=Lachapelle|first9=F.-R.|last10=Lundy|first10=M.|last11=St-Antoine|first11=J.|date=October 2017|title=WD 1202-024: the shortest-period pre-cataclysmic variable|journal= Monthly Notices of the Royal Astronomical Society|language=en|volume=471|issue=1|pages=948–961|doi=10.1093/mnras/stx1611|doi-access=free |issn=0035-8711|bibcode=2017MNRAS.471..948R|arxiv=1705.05863|s2cid=119349942}}</ref> |low-mass star or brown dwarf |shortest period PCEB (as of 2017) |- |WD 0137−349 |116 minutes |brown dwarf |first confirmed PCEB with a brown dwarf as a companion |- |CSS21055 |121.73 minutes<ref>{{Cite journal|last1=Beuermann|first1=K.|last2=Dreizler|first2=S.|last3=Hessman|first3=F. V.|last4=Backhaus|first4=U.|last5=Boesch|first5=A.|last6=Husser|first6=T.-O.|last7=Nortmann|first7=L.|last8=Schmelev|first8=A.|last9=Springer|first9=R.|date=October 2013|title=The eclipsing post-common envelope binary CSS21055: a white dwarf with a probable brown-dwarf companion|journal=Astronomy & Astrophysics|language=en|volume=558|pages=A96|doi=10.1051/0004-6361/201322241|issn=0004-6361|bibcode=2013A&A...558A..96B|arxiv=1312.5088|s2cid=54497208}}</ref> |brown dwarf |eclipsing binary |- |SDSS 1557 |2.27 hours<ref>{{Cite journal|last1=Farihi|first1=J.|last2=Parsons|first2=S. G.|last3=Gänsicke|first3=B. T.|date=March 2017|title=A circumbinary debris disk in a polluted white dwarf system|journal= Nature Astronomy|language=en|volume=1|issue=3|pages=0032|doi=10.1038/s41550-016-0032|issn=2397-3366|bibcode=2017NatAs...1E..32F|arxiv=1612.05259|s2cid=54742816}}</ref> |brown dwarf |circumbinary debris disk with a polluted white dwarf |- |V470 Camelopardalis<br/>(HS0705+6700) |{{convert|0.096|d|h|disp=out|abbr=off}}<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |NY Virginis |{{convert|0.101|d|h|disp=out|abbr=off}}<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |NSVS 14256825 |{{convert|0.110|d|h|disp=out|abbr=off}}<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |HW Virginis |{{convert|0.117|d|h|disp=out|abbr=off}}<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |NN Serpentis |3.12 hours<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |WD 0837+185 |4.2 hours<ref>{{Cite journal|last1=Casewell|first1=S. L.|last2=Burleigh|first2=M. R.|last3=Wynn|first3=G. A.|last4=Alexander|first4=R. D.|last5=Napiwotzki|first5=R.|last6=Lawrie|first6=K. A.|last7=Dobbie|first7=P. D.|last8=Jameson|first8=R. F.|last9=Hodgkin|first9=S. T.|date=November 2012|title=WD0837+185: The Formation and Evolution of an Extreme Mass-ratio White-dwarf-Brown-dwarf Binary in Praesepe|journal= The Astrophysical Journal|language=en|volume=759|issue=2|pages=L34|doi=10.1088/2041-8205/759/2/L34|arxiv=1210.0446|issn=0004-637X|bibcode=2012ApJ...759L..34C|s2cid=53545021}}</ref> |brown dwarf |extreme mass ratio of the progenitor, with the primary having a mass of 3.5-3.7 {{Solar mass}} and the secondary 25-30 {{Jupiter mass}} |- |RR Caeli |{{convert|0.304|d|h|disp=out|abbr=off}}<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |DE Canum Venaticorum |{{convert|0.364|d|h|disp=out|abbr=off}}<ref name="Pulley2022"/> |red dwarf |eclipsing binary |- |central source of Hen 2-11 |14.616 hours<ref>{{Cite journal|last1=Jones|first1=D.|last2=Boffin|first2=H. M. J.|last3=Miszalski|first3=B.|last4=Wesson|first4=R.|last5=Corradi|first5=R. L. M.|last6=Tyndall|first6=A. A.|date=February 2014|title=The post-common-envelope, binary central star of the planetary nebula Hen 2–11|journal= Astronomy & Astrophysics|language=en|volume=562|pages=A89|doi=10.1051/0004-6361/201322797|arxiv=1401.1358|bibcode=2014A&A...562A..89J|s2cid=59437439|issn=0004-6361}}</ref> |K-type main sequence star |planetary nebula and eclipsing binary |- |K 1-2 |16.2192 hours<ref>{{Cite journal|last1=Ritter|first1=H.|last2=Kolb|first2=U.|date=June 2003|title=Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)|journal=Astronomy & Astrophysics|language=en|volume=404|pages=301–303|doi=10.1051/0004-6361:20030330|issn=0004-6361|bibcode=2003A&A...404..301R|arxiv=astro-ph/0301444|s2cid=61117701}}</ref> | |planetary nebula |- |central source of Fleming 1 |1.1953 days<ref>{{Cite journal|last1=Boffin|first1=Henri M. J.|last2=Miszalski|first2=Brent|last3=Rauch|first3=Thomas|last4=Jones|first4=David|last5=Corradi|first5=Romano L. M.|last6=Napiwotzki|first6=Ralf|last7=Day-Jones|first7=Avril C.|last8=Köppen|first8=Joachim|date=November 2012|title=An Interacting Binary System Powers Precessing Outflows of an Evolved Star|journal= Science|language=en|volume=338|issue=6108|pages=773–5|doi=10.1126/science.1225386|pmid=23139326|arxiv=1211.2200|bibcode=2012Sci...338..773B|s2cid=206542812|issn=0036-8075}}</ref> |white dwarf |planetary nebula |- |KOI-256 |1.37865 days<ref name=":1" /> |red dwarf |eclipsing binary |- |central source of NGC 2392 |1.9 days<ref>{{Cite journal|last1=Miszalski|first1=Brent|last2=Manick|first2=Rajeev|last3=Van Winckel|first3=Hans|last4=Escorza|first4=Ana|date=May 2019|title=The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392|journal= Publications of the Astronomical Society of Australia|language=en|volume=36|article-number=e018|doi=10.1017/pasa.2019.11|arxiv=1903.07264|bibcode=2019PASA...36...18M|s2cid=119400616|issn=1323-3580}}</ref> |hot white dwarf |planetary nebula and x-ray binary |- |central source of NGC 5189 |4.04 days<ref>{{Cite journal|last1=Manick|first1=Rajeev|last2=Miszalski|first2=Brent|last3=McBride|first3=Vanessa|date=April 2015|title=A radial velocity survey for post-common-envelope Wolf-Rayet central stars of planetary nebulae: first results and discovery of the close binary nucleus of NGC 5189|journal= Monthly Notices of the Royal Astronomical Society|language=en|volume=448|issue=2|pages=1789–1806|doi=10.1093/mnras/stv074|doi-access=free |arxiv=1501.03373|bibcode=2015MNRAS.448.1789M|s2cid=118600965|issn=0035-8711}}</ref> |massive white dwarf |planetary nebula; primary is a low-mass Wolf-Rayet star |- |central source of NGC 2346 |16 days<ref>{{Cite journal|last1=Brown|first1=Alex J.|last2=Jones|first2=David|last3=Boffin|first3=Henri M. J.|last4=Van Winckel|first4=Hans|date=February 2019|title=On the post-common-envelope central star of the planetary nebula NGC 2346|journal= Monthly Notices of the Royal Astronomical Society|language=en|volume=482|issue=4|pages=4951–4955|doi=10.1093/mnras/sty2986|doi-access=free |arxiv=1810.09764|bibcode=2019MNRAS.482.4951B|s2cid=119070983|issn=0035-8711}}</ref> |>3.5 {{Solar mass}} sub-giant |planetary nebula; one of the longest period PCEB which could host the most massive secondary |- |HD 101584 |150–200 days<ref name="Olofsson et al"/> |red dwarf or white dwarf |the engulfment of the companion probably triggered gas to outflow, creating the nebula, seen with Hubble and ALMA; primary is a post-RGB star |}

==See also== * Cataclysmic variable * Second generation planet

==References== {{Reflist|refs=

<ref name="Olofsson et al">{{Cite journal|last1=Olofsson|first1=H.|last2=Khouri|first2=T.|last3=Maercker|first3=M.|last4=Bergman|first4=P.|last5=Doan|first5=L.|last6=Tafoya|first6=D.|last7=Vlemmings|first7=W. H. T.|last8=Humphreys|first8=E. M. L.|last9=Lindqvist|first9=M.|last10=Nyman|first10=L.|last11=Ramstedt|first11=S.|date=March 2019|title=HD 101584: circumstellar characteristics and evolutionary status|journal= Astronomy & Astrophysics|language=en|volume=623|pages=A153|doi=10.1051/0004-6361/201834897|arxiv=1902.02153|bibcode=2019A&A...623A.153O|s2cid=102480818|issn=0004-6361}}</ref>

<ref name="Pulley2022">{{cite journal |last1=Pulley |first1=D. |last2=Sharp |first2=I. D. |last3=Mallett |first3=J. |last4=von Harrach |first4=S. |date=August 2022 |title=Eclipse timing variations in post-common envelope binaries: Are they a reliable indicator of circumbinary companions? |journal=Monthly Notices of the Royal Astronomical Society |volume=514 |issue=4 |pages=5725–5738 |doi=10.1093/mnras/stac1676 |doi-access=free |arxiv=2206.06919 |bibcode=2022MNRAS.514.5725P}}</ref>

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Category:Binary stars Category:White dwarfs Category:Stellar phenomena