2D-spectroscopic observations of -band bright structures in the solar photosphere

Kiepenheuer–Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany

Corresponding author: K. Langhans, kai@kis.uni-freiburg.de

Received: 10 June 2002
Accepted: 7 August 2002

Abstract

We took two-dimensional spectra with the filter spectrometer TESOS at the German Vacuum Tower Telescope, Tenerife, of an absorption line of the CH molecule and a Fe II-line in the -band at 430.3 nm. We observed a region, close to disk center of the Sun, that showed a lot of structures with enhanced -band intensity (up to 1.3 times the mean intensity of normal granulation). Our spectroscopic investigation of these structures suggests two classes which differ in their spectroscopic signature: (a) Bright structures caused by significant (up to 40%) weakening of absorption lines of the CH molecule; (b) bright structures only caused by an enhanced continuum intensity. In order to distinguish between those two classes we introduce a Bright Point Index (BPI) defined by the ratio of the normalized line depressions of the Fe II and the CH-line. The bright structures caused by weakening of the CH-lines have high BPI values and are accompanied by downflows. The remaining -band bright structures have low BPI and are related to granules.