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Titolo:
SPECKLE MEASUREMENTS OF THE CENTER-TO-LIMB VARIATION OF THE SOLAR GRANULATION
Autore:
WILKEN V; DEBOER CR; DENKER C; KNEER F;
Indirizzi:
UNIV STERNWARTE,GEISMARLANDSTR 11 D-37083 GOTTINGEN GERMANY MAX PLANCK INST AERON D-37189 KATLENBURG DUHM GERMANY
Titolo Testata:
Astronomy and astrophysics
fascicolo: 2, volume: 325, anno: 1997,
pagine: 819 - 824
SICI:
0004-6361(1997)325:2<819:SMOTCV>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
ATMOSPHERIC-TURBULENCE; HEIGHT DEPENDENCE; MASKING; PHOTOSPHERE; INTERFEROMETRY; RECONSTRUCTION; FLUCTUATIONS; CONVECTION; IMAGES;
Keywords:
SUN, GRANULATION, CENTER-TO-LIMB VARIATION; TECHNIQUES, SPECKLE INTERFEROMETRY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
V. Wilken et al., "SPECKLE MEASUREMENTS OF THE CENTER-TO-LIMB VARIATION OF THE SOLAR GRANULATION", Astronomy and astrophysics, 325(2), 1997, pp. 819-824

Abstract

The Vacuum Tower Telescope (VTT) at the Observatorio del Teide/Tenerife was used to perform speckle observations of photospheric granulation from disc centre to limb at lambda = 550 +/- 5 nm. Images were reconstructed with the spectral ratio technique (von der Luhe 1984) and thespeckle masking method method (Weigelt 1977, Weigelt & Wirnitzer 1983, Lohmann et al. 1983). The granular rms contrast relative to the local average intensity decreases monotonically from 13.5 +/- 1.0% at disccentre to 8-9 % at cos theta = 0.1. The granular images as well as the power spectra of the intensity fluctuations show a fading of the coarse granular pattern towards the limb while smaller structures become more pronounced off the disc centre. We identify these as the bright worm-like structures appearing sometimes at the granular borders (de Boer et al. 1992). This finding supports the result from simulations of granular dynamics by Steffen et al. (1994). There the bright structures are locations of low pressure between the centres of granules and intergranular spaces with penetration of hot gas into the lower photosphere.

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Documento generato il 05/12/20 alle ore 23:57:48