Volume 376, Number 1, September II 2001
|Page(s)||154 - 157|
|Section||Interstellar and circumstellar matter|
|Published online||15 September 2001|
Research Note: What can HST-GHRS Fe II observations of Orionis (M2 Iab) tell us about short-period heating? *
Department of Physics, University of Texas at Arlington, Arlington, TX 76019-0059, USA
2 Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA e-mail: email@example.com; firstname.lastname@example.org
3 Department of Astronomy and Physics, Saint Mary's University, Halifax, N.S. B3H 3C3, Canada e-mail: email@example.com
Corresponding author: M. Cuntz, firstname.lastname@example.org
Accepted: 21 May 2001
Cuntz ([CITE]) suggested that apparent velocity shifts in Fe II emission lines observed in Betelgeuse (α Orionis: M2 Iab) indicate that non-magnetic wave modes are relevant for the heating and dynamics of α Ori's chromosphere. This claim was based on the similarity of computed stochastic velocities in 1-D short-period acoustic wave models and velocity shifts in profile fits to Fe II emission lines (Carpenter & Robinson [CITE]), which is now identified as coincidental. While acoustic waves may indeed be important for the heating and dynamics of α Ori's chromosphere, the interpretation of the Fe II emission line profiles does not provide evidence for this possibility. The line formation of optically thick scattering lines in an extended outflow makes Fe II emission lines poorly suited as a diagnostic for small-scale structure in hydrodynamical models. Better diagnostics include electron density sensitive, low opacity lines such as C II] . In the view of these findings, we discuss directions of future research.
Key words: hydrodynamics / waves / stars: chromospheres / stars: individual: α Ori / stars: supergiants
© ESO, 2001
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.