Height and dynamics of the quiet solar chromosphere at the limb

¹ Astrophysikalisches Institut Potsdam, Telegrafenberg, 14473 Potsdam, Germany
² Kiepenheuer Institut für Sonnenphysik, Schöneckstraße 6, 79104 Freiburg, Germany

Corresponding author: K. Muglach, kmuglach@aip.de

Received: 8 June 2001
Accepted: 6 September 2001

Abstract

In this paper we present observations of He I 1083.0 nm, He D₃ 587.6 nm and Hβ 486.1 nm taken at various positions at the solar limb. We determine and compare the emission of the lines in terms of line-parameters. The height of the chromosphere as seen in the helium lines varies in space and time and reaches values between 1100 and 1800 km above the continuum and is the same for both helium lines within the errors of the measurement. From a time-sequence of slit-spectra of about 23 min we study the oscillation signature of the chromosphere near the solar limb. We find velocity oscillations in He I 1083.0 nm that do not drop to zero near the limb as would be expected of vertically oriented oscillations, we even get horizontal oscillations in the off-limb emission data of both helium lines.