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Astron. Astrophys. 328, 695-701


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The lithium abundance in sunspots

S. Ritzenhoff, E.H. Schröter, and W. Schmidt

Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg, Germany

Received 30 September 1996 / Accepted 21 July 1997

Abstract

The solar lithium abundance was determined using an empirical model for an observed sunspot umbra. The atmospheric model is deduced from a number of spectral lines. In addition to the lithium (I) line doublets from ${\rm Li^6}$ and ${\rm Li^7}$ at 670.8 nm eight different line profiles were observed with high spectrographic resolution. A magnetically sensitive line was included in order to determine the magnetic field strength. An estimation for the influence of molecular blends caused by CN and TiO was taken into account.

Under the assumption of LTE a lithium abundance of $\epsilon_{\rm Li}=1.02
\pm0.12$1 was derived.

Some evidence for the existence of a small but notable amount of ${\rm Li^6}$ is found, however only an upper limit of ${\rm Li^6/Li^7}\le 0.03$ can be derived. A more precise determination of the isotopic ratio is hampered by the uncertainties induced by the presence of TiO blends.

Key words: abundances, atmospheres, Sun

1On the logarithmic scale, where the abundance of hydrogen is $\epsilon_{\rm H}=12$

Send offprint requests to: W. Schmidt


© European Southern Observatory (ESO) 1997

Online publication: November 24, 1997
Last change: March 26, 1998
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