Common Envelope Jets Supernova (November 2017)

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In a new paper Avishai Gilkis and I proposed a common envelope jets supernova scenario for the enigmatic supernova iPTF14hls where a neutron star that spirals-in inside the envelope of a massive giant star accretes mass and launches jets that power the ejection of the circumstellar shell and a few weeks later the explosion itself.

Live poster (July 2017)

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In the meeting The IMPACT of BINARIES on STELLAR EVOLUTION (ESO Garching, July 3-7, 2017), I presented a live poster. I updated it twice a day, referring to many talks and posters. 

Click on an image to enlarge it and you can read the poster on the far right. 

Core collapse supernova remnants with ears (November 2016)

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In a new paper Aldana Grichener and I study the morphologies of core collapse supernova remnantzfigcs (CCSNRs) and find that about third of CCSNRs have two opposite `ears’ protruding from their main shell, and that the typical energy that is required to inflate these ears is about 10 percents of the explosion kinetic energy. We argue that these properties are most compatible with the expectation from the explosion jet feedback mechanism (JFM). This study further supports the call for a paradigm shift from neutrino-driven to jet-driven core-collapse supernova mechanisms.

A popular summary of our research is in New Scientist.

Simulating the Grazing envelope evolution (July 2016)

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In a new paper Sagiv Shiber, Amit Kashi, and I, presented the first simulations of the grazing envelope evolution (GEE).  In the GEE jets launched by the secondary star efficiently remove the outer part of the giant envelope, while the secondary star grazes the surface of the primary giant star and spirals-in. 

Simulations: A secondary main sequence star enters the envelope of an asymptotic giant branch star of 3.4 solar mass. We assume that the secondary star launches two opposite jets perpendicular to the orbital plane.  There are three segments, each 1.5 years: (i) Density in the orbital plane; (ii) 3D image of jet material (blue) and ejected gas from the envelope of the giant primary star (red); (iii) Temperature in the equatorial plane.   GEE_ref6

The jet feedback mechanism (May 2016)

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I posted a review paper on the operation of jets in a negative feedback mechanism in stars, galaxies, and clusters of galaxies. I argue that jets are more common that what is usually thought, and that they play an important role in powering many different kind of astrophysical objects.  (paper posted to the arXiv.)


Launching jets from accretion belts (January 2016a)

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Ron Schreier and I proposed that sub-Keplerian accretion belts around stars might launch jets. Our speculative belt-launched jets model has implications to a rich variety of astrophysical objects, from the removal of common envelopes to the explosion of core collapse supernovae by jittering jets. (paper posted to the arXiv)

Astrophysical Naturalness (October 2015)

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I suggest that stars introduce mass and density scales that lead to `naturalness’ in the Universe (paper posted to the arXiv).  The combination of the stellar mass scale with the Planck mass and the Chandrasekhar mass leads to a ratio of order unity.  In the pure fundamental particles domain there is no naturalness; either naturalness does not exist or there is a need for a new physics or new particles. The `Astrophysical Naturalness’ offers a third possibility: stars introduce the combinations of, or relations among, known fundamental quantities that lead to naturalness.