SPOT AND CHROMOSPHERIC ACTIVITY ON THE RS CVN STAR DM URSAE MAJORIS

被引:42
作者
HATZES, AP
机构
[1] McDonald Observatory, University of Texas at Austin, Austin
关键词
D O I
10.1086/117280
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A Doppler image of the spot distribution on the RS CVn star DM UMa for the epoch 1993.10 is presented. This distribution is characterized by a polar spot with appendages extending down to low latitudes and at least two isolated spots near the equator. This distribution is typical of what has been seen on other RS CVn stars. Data were simultaneously acquired on the chromospheric activity indicators provided by Hα and He I D3 5876 Å. The Hα emission and He I absorption significantly increase at phase 0.59, near the time when an equatorial spot is in the line of sight. Possibly, this spot represents a newly emerged magnetic flux region. Such regions on the Sun are accompanied by large scale mass motions, flare activity, and increased x-ray emission and a similar region on DM UMa may account for the increased Hα emission and He I absorption. The Hα emission profile was found to be asymmetrical and with broad (200-300 km s-1) wings at the continuum. This profile becomes more symmetrical after subtracting the underlying Hα absorption using a rotationally broadened spectrum of α Boo. The Hα profile was parametrized using a narrow and a broad component. The large changes in the strength of the Hα emission occur primarily in the broad component. The origin of this component is unknown, but it could result from large-scale mass motions or winds in the chromosphere.
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页码:350 / 358
页数:9
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