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Dying Stars’ Cocoons Might Explain Fast Blue Optical Transients

April 29, 2022

*Text taken from Amanda Morris from Northwestern Now

Fast blue optical transients (FBOTs) have utterly surprised and completely confounded both observational and theoretical astrophysicists since their discovery in 2018. 

So hot that they glow blue, these mysterious objects are the brightest known optical phenomenon in the universe. But with only a few discovered so far, FBOTs’ origins have remained elusive. 

Now a Northwestern University astrophysics team led by Sasha Tchekovskoy, Assistant Professor of Physics and Astronomy, and Ore Gottlieb, Rothschild Fellow in Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)  presents a bold new explanation for the origin of these curious anomalies. Using a new model, the astrophysicists believe FBOTs could result from the actively cooling cocoons that surround jets launched by dying stars. It marks the first astrophysics model that is fully consistent with all observations related to FBOTs.

The research was published April 11 in the Monthly Notices of the Royal Astronomical Society.

As a massive star collapses, it can launch outflows of debris at rates near the speed of light. These outflows, or jets, collide into collapsing layers of the dying star to form a “cocoon” around the jet. The new model shows that as the jet pushes the cocoon outward — away from the core of the collapsing star — it cools, releasing heat as an observed FBOT emission.

Read the full article here

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