# Three-Dimensional Doppler Images of the Disk-like and Stream-like States of U Coronae Borealis - Astrophysics

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Abstract: The 3D Radioastronomical Approach to Doppler tomography has been used tostudy the H$\alpha$ emission sources in U Coronae Borealis. These 3D tomogramsprovide greater resolution than the projected 2D version and highlight thejet-like gas flows in the $V z$ direction transverse to the orbital plane. Inthis paper, the 3D tomograms are compared at two distinct epochs when U CrB wasin the disk-like state 1993 data and the stream-like state 1994 data. Bothstates display a prominent emission source, the circumprimary bulge, which isproduced when the gas stream strikes the photosphere of the mass-gainer. Thissource is detected within $V z$ = $\pm$150 km s{$^{-1}$}, and demonstrates thatthe bulge is not confined to the orbital plane although it achieves maximumstrength near $V z$=0 km s{$^{-1}$}. Other emission sources include thestream-star and stream-disk shocks and a Localized Region LR where thecircling disk material strikes the incoming gas stream. The LR has $V z$velocities of 200 to 500 km s{$^{-1}$} in the disk-like state. The diskemission is seen over a range of $V z$ velocities, and there is evidence thatthe disk is inclined to the orbital plane or may have two arms. The gas streamflows along its predicted trajectory in the stream-like state, and a comparisonwith the disk-like state suggests that the gas stream has a higher density thanthe disk in both states of this binary.

Autor: Michail Agafonov, Olga Sharova, Mercedes Richards

Fuente: https://arxiv.org/