Bibcode
DOI
Jiménez, A.
Bibliographical reference
The Astrophysical Journal, Volume 646, Issue 2, pp. 1398-1404.
Advertised on:
8
2006
Journal
Citations
22
Refereed citations
18
Description
The acoustic cutoff frequency (νac) is an important
atmospheric parameter whose estimation has in the past been based on the
study of power spectra that have yielded a wide range of values between
5300 and 5700 μHz. The discovery of a solar signal well beyond the
acoustic cutoff frequency (pseudomodes) might lead one to think that the
determination of νac would be even more complicated
because, for example, looking for a sudden drop in the power density
signal could no be longer used. Contrary to what might be thought at
first sight, the existence of pseudomodes helps to provide a good
estimation of νac, because the frequency pattern of
pseudomodes is shifted with respect to that of p-modes. In this study a
bivariate analysis (coherence and phase shift) between the intensity
signals of VIRGO and the velocity signal of GOLF (both instruments on
board the SOHO probe) is carried out over the frequency range of p-modes
and pseudomodes. The results shows clear evidence that the acoustic
cutoff frequency of the Sun is close to the theoretical value of 5300
μHz specifically, a value around 5100 μHz is found in this
research.