Betelgeuse: Giant convection cells

Gray, DF

Df. Gray, Betelgeuse: Giant convection cells, PUB AST S P, 113(789), 2001, pp. 1378-1385

20

INGLESE

Article

Space Sciences

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC

0004-6280 → ACNP

113

789

2001

1378 - 1385

ISI

0004-6280(200111)113:789<1378:BGCC>2.0.ZU;2-7

Spectroscopic observations of the M supergiant star Betelgeuse were taken a t the Elginfield Observatory over 17 months in the 1999-2000 observing seas ons in order to search for giant convection cells. Although the photospheri c spectral lines show some temporal variations, mainly in their depths (con sistent with a previously study), the Doppler shift distribution inferred f rom them is remarkably stable. The spectral lines show characteristic macro turbulence dispersion similar to 15 km s(-1) and cover a full span of +/-50 -60 km s(-1). The widths of the lines show occasional as well as longer ter m changes of a few percent but no evidence for giant convection cells. Thes e spectroscopic observations are more consistent with a classical picture o f nonthermal photospheric velocities in which large numbers of convection c ells appear on the stellar disk at all times.