{"id":975,"date":"2023-02-13T08:15:49","date_gmt":"2023-02-13T07:15:49","guid":{"rendered":"http:\/\/utf.mff.cuni.cz\/~pejcha\/?p=975"},"modified":"2023-02-13T08:15:49","modified_gmt":"2023-02-13T07:15:49","slug":"post-dynamical-inspiral-phase-of-common-envelope-evolution-binary-orbit-evolution-and-angular-momentum-transport","status":"publish","type":"post","link":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/2023\/02\/13\/post-dynamical-inspiral-phase-of-common-envelope-evolution-binary-orbit-evolution-and-angular-momentum-transport\/","title":{"rendered":"Post-dynamical inspiral phase of common envelope evolution: binary orbit evolution and angular momentum transport"},"content":{"rendered":"\n<p>In a new paper, Damien Gagnier looks at what happens during late stages of common envelope after the companion plunges in and the two cores orbit in a shared envelope. In the simulations, we mimick the plunge-in by depositing angular momentum in the envelope in a controlled way and study transport of angular momentum by advection, turbulence, gravitational torques, and viscosity. We find that the binary orbit decays on a timescale of 10^3 to 10^5 orbits of the central binary suggesting that the orbit will continue shrinking for a long time. This might help resolving the discrepancy between simulations and observed final binary separations. Although too slow to directly study with multi-d hydro, the evolution is often much faster than the envelope thermal timescale &#8211; perhaps there is no need for any thermal &#8220;self-regulation&#8221; of the late inspiral. This also lends support to the usual energy-conserving alpha formalism. Interestingly, much of the hydrodynamics is very similar to circumbinary disks. For example, the &#8220;lump&#8221; is also seen, but it is more of a 3D phenomenon rather than a well-localized object. 3D simulations were done with Athena++ in spherical coordinates with AMR. By excising a sphere around the binary, the simulations can be run for 100s of orbits of the central binary. The cost was ~4.6 million CPU hours at <a href=\"https:\/\/www.it4i.cz\/\">IT4Innovations<\/a>. The paper is at <a href=\"https:\/\/arxiv.org\/abs\/2302.00691\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/arxiv.org\/abs\/2302.00691<\/a><\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Common envelope - Density\" width=\"840\" height=\"473\" src=\"https:\/\/www.youtube.com\/embed\/c4Swv52leGw?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-4-3 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Common envelope - Surface density about the orbital plane\" width=\"840\" height=\"630\" src=\"https:\/\/www.youtube.com\/embed\/DYx0FuVIEQI?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>In a new paper, Damien Gagnier looks at what happens during late stages of common envelope after the companion plunges in and the two cores orbit in a shared envelope. In the simulations, we mimick the plunge-in by depositing angular momentum in the envelope in a controlled way and study transport of angular momentum by &hellip; <a href=\"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/2023\/02\/13\/post-dynamical-inspiral-phase-of-common-envelope-evolution-binary-orbit-evolution-and-angular-momentum-transport\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Post-dynamical inspiral phase of common envelope evolution: binary orbit evolution and angular momentum transport&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/posts\/975"}],"collection":[{"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/comments?post=975"}],"version-history":[{"count":1,"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/posts\/975\/revisions"}],"predecessor-version":[{"id":976,"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/posts\/975\/revisions\/976"}],"wp:attachment":[{"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/media?parent=975"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/categories?post=975"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/utf.mff.cuni.cz\/~pejcha\/index.php\/wp-json\/wp\/v2\/tags?post=975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}