TY  - JOUR
A1  - Kurfürst, P.
A1  - Feldmeier, Achim
A1  - Krticka, Jiri
T1  - Two-dimensional modeling of density and thermal structure of dense circumstellar outflowing disks
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Evolution of massive stars is affected by a significant loss of mass either via (nearly) spherically symmetric stellar winds or by aspherical mass-loss mechanisms, namely the outflowing equatorial disks. However, the scenario that leads to the formation of a disk or rings of gas and dust around massive stars is still under debate. It is also unclear how various forming physical mechanisms of the circumstellar environment affect its shape and density, as well as its kinematic and thermal structure. Results. Our models show the geometric distribution and contribution of viscous heating that begins to dominate in the central part of the disk for mass-loss rates higher than (M) over dot greater than or similar to 10(-10) M-circle dot yr(-1). In the models of dense viscous disks with (M) over dot > 10(-8) M-circle dot yr(-1), the viscosity increases the central temperature up to several tens of thousands of Kelvins, however the temperature rapidly drops with radius and with distance from the disk midplane. The high mass-loss rates and high viscosity lead to instabilities with significant waves or bumps in density and temperature in the very inner disk region. Conclusions. The two-dimensional radial-vertical models of dense outflowing disks including the full Navier-Stokes viscosity terms show very high temperatures that are however limited to only the central disk cores inside the optically thick area, while near the edge of the optically thick region the temperature may be low enough for the existence of neutral hydrogen, for example.
KW  - stars: massive
KW  - stars: mass-loss
KW  - stars: winds, outflows
KW  - stars: evolution
KW  - stars: rotation
KW  - hydrodynamics
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201731300
SN  - 1432-0746
VL  - 613
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - GEN
A1  - Kurfürst, P.
A1  - Feldmeier, Achim
A1  - Krtička, Jiri
T1  - Modeling sgB[e] Circumstellar Disks
T2  - The B(e) Phenomenon: Forty Years of Studies : proceedings of a conference held at Charles University, Prague, Czech Republic, 27 June-1 July 2016
N2  - During their evolution, massive stars are characterized by a significant loss of mass either via spherically symmetric stellar winds or by aspherical mass-loss mechanisms, namely outflowing equatorial disks. However, the scenario that leads to the formation of a disk or rings of gas and dust around these objects is still under debate. Is it a viscous disk or an ouftlowing disk-forming wind or some other mechanism? It is also unclear how various physical mechanisms that act on the circumstellar environment of the stars affect its shape, density, kinematic, and thermal structure. We assume that the disk-forming mechanism is a viscous transport within an equatorial outflowing disk of a rapidly or even critically rotating star. We study the hydrodynamic and thermal structure of optically thick dense parts of outflowing circumstellar disks that may form around,e.g., Be stars, sgB[e] stars, or Pop m stars. We calculate self-consistent time dependent models of the inner dense region of the disk that is strongly affected either by irradiation from the central star and by contributions of viscous heating effects. We also simulate the dynamic effects of collision between expanding ejecta of supernovae and circumstellar disks that may be form in sgB[e] stars and, e.g., LBVs or Pop in stars.
Y1  - 2017
UR  - https://www.physics.muni.cz/~petrk/presentation.pdf
SN  - 978-1-58381-900-5
SN  - 978-1-58381-901-2
VL  - 508
SP  - 17
EP  - 22
PB  - Astronomical Scoeity of the Pacific
CY  - San Fransisco
ER  -