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High S/N Spectroscopy of Pre-Main Sequence Stars I

Published online by Cambridge University Press:  19 July 2016

I. Appenzeller
I. Appenzeller*
Affiliation:
Landessternwarte, Königstuhl, D 6900 Heidelberg, Federal Republic of Germany

Abstract

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The spectra of PMS stars usually are superpositions of contributions from a relatively normal photosphere, an often strongly enhanced chromosphere, and of circumstellar matter related to stellar winds, accreation flows, jets, and cool circumstellar disks. Only high S/N data allows a reliable separation of these different contributions. Because of the high optical depths of PMS chromospheres, the PMS photospheres often can be observed in the very weak spectral lines only, which are undectable on low S/N spectrograms. Finally, magnetic fields are assumed to play a particularly important role for the appearance and evolution of PMS objects. Their spectroscopic measurement requires very high S/N data.

Type
II. Pre-Main-Sequence Stars
Information
Symposium - International Astronomical Union , Volume 132: The Impact of Veryhigh S/N Spectroscopy on Stellar Physics , 1988 , pp. 87 - 93
Copyright
Copyright © Kluwer 1988 

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