Energy Transport, Overshoot, and Mixing in the Atmospheres of Very Cool Stars
(2003) In Modelling of Stellar Atmospheres ; Proceedings of the 210th Symposium of the International Astronomical Union held at Uppsala University, Uppsala, Sweden, 1721 June, 2002 210. p.113125 Abstract
 We constructed hydrodynamical model atmospheres for mid Mtype main, as well as premainsequence objects. Despite the complex chemistry encountered in such cool atmospheres a reasonably accurate representation of the radiative transfer is possible. The detailed treatment of the interplay between radiation and convection in the hydrodynamical models allows to study processes usually not accessible within the framework conventional model atmospheres. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency expressed in terms of an equivalent mixinglength parameter amounts to values around 2 in the optically thick, and 2.8 in... (More)
 We constructed hydrodynamical model atmospheres for mid Mtype main, as well as premainsequence objects. Despite the complex chemistry encountered in such cool atmospheres a reasonably accurate representation of the radiative transfer is possible. The detailed treatment of the interplay between radiation and convection in the hydrodynamical models allows to study processes usually not accessible within the framework conventional model atmospheres. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency expressed in terms of an equivalent mixinglength parameter amounts to values around 2 in the optically thick, and 2.8 in the optically thin regime. The thermal structure of the formally convectively stable layers is little affected by convective overshoot and wave heating, i.e. stays close to radiative equilibrium. Mixing by convective overshoot shows an exponential decline with geometrical distance from the Schwarzschild stability boundary. The scale height of the decline varies with gravitational acceleration roughly as g(1/2), with 0.5 pressure scale heights at log(g)=5.0. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/528240
 author
 Ludwig, HansGünter ^{LU}
 organization
 publishing date
 2003
 type
 Chapter in Book/Report/Conference proceeding
 publication status
 published
 subject
 in
 Modelling of Stellar Atmospheres ; Proceedings of the 210th Symposium of the International Astronomical Union held at Uppsala University, Uppsala, Sweden, 1721 June, 2002
 editor
 Piskunov, N.; Weiss, W.W. and Gray, D.F.
 volume
 210
 pages
 113  125
 publisher
 Astronomical Society of the Pacific
 external identifiers

 WOS:000243352400011
 ISBN
 1583811605
 language
 English
 LU publication?
 yes
 id
 65092e2a92cd4678aaf1b593b055a186 (old id 528240)
 alternative location
 http://arxiv.org/abs/astroph/0208583
 date added to LUP
 20070921 12:21:06
 date last changed
 20160416 07:34:50
@misc{65092e2a92cd4678aaf1b593b055a186, abstract = {We constructed hydrodynamical model atmospheres for mid Mtype main, as well as premainsequence objects. Despite the complex chemistry encountered in such cool atmospheres a reasonably accurate representation of the radiative transfer is possible. The detailed treatment of the interplay between radiation and convection in the hydrodynamical models allows to study processes usually not accessible within the framework conventional model atmospheres. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency expressed in terms of an equivalent mixinglength parameter amounts to values around 2 in the optically thick, and 2.8 in the optically thin regime. The thermal structure of the formally convectively stable layers is little affected by convective overshoot and wave heating, i.e. stays close to radiative equilibrium. Mixing by convective overshoot shows an exponential decline with geometrical distance from the Schwarzschild stability boundary. The scale height of the decline varies with gravitational acceleration roughly as g(1/2), with 0.5 pressure scale heights at log(g)=5.0.}, author = {Ludwig, HansGünter}, editor = {Piskunov, N. and Weiss, W.W. and Gray, D.F.}, isbn = {1583811605}, language = {eng}, pages = {113125}, publisher = {ARRAY(0xe63aa40)}, series = {Modelling of Stellar Atmospheres ; Proceedings of the 210th Symposium of the International Astronomical Union held at Uppsala University, Uppsala, Sweden, 1721 June, 2002}, title = {Energy Transport, Overshoot, and Mixing in the Atmospheres of Very Cool Stars}, volume = {210}, year = {2003}, }