Query : 2001A&A...376..154C

2001A&A...376..154C - Astronomy and Astrophysics, volume 376, 154-157 (2001/9-2)

What can HST-GHRS Fe II observations of α Orionis (M2 Iab) tell us about short-period heating?


Abstract (from CDS):

Cuntz (1997A&A...325..709C) 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, 1997ApJ...479..970C), 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.

Abstract Copyright:

Journal keyword(s): hydrodynamics - waves - stars: chromospheres - stars: individual: α Ori - stars: supergiants

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 * alf Tau LP? 04 35 55.23907 +16 30 33.4885 4.32 2.40 0.86 -0.37 -1.31 K5+III 1234 1
2 * zet Aur EB* 05 02 28.6873880 +41 04 33.019985 5.35 4.97 3.75 2.62 1.75 K5II+B7V 451 0
3 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1608 0

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