5 research outputs found
Detection of periodic signatures in the solar power spectrum. On the track of l=1 gravity modes
In the present work we show robust indications of the existence of g modes in
the Sun using 10 years of GOLF data. The present analysis is based on the
exploitation of the collective properties of the predicted low-frequency (25 to
140 microHz) g modes: their asymptotic nature, which implies a quasi
equidistant separation of their periods for a given angular degree (l). The
Power Spectrum (PS) of the Power Spectrum Density (PSD), reveals a significant
structure indicating the presence of features (peaks) in the PSD with near
equidistant periods corresponding to l=1 modes in the range n=-4 to n=-26. The
study of its statistical significance of this feature was fully undertaken and
complemented with Monte Carlo simulations. This structure has a confidence
level better than 99.86% not to be due to pure noise. Furthermore, a detailed
study of this structure suggests that the gravity modes have a much more
complex structure than the one initially expected (line-widths, magnetic
splittings...). Compared to the latest solar models, the obtained results tend
to favor a solar core rotating significantly faster than the rest of the
radiative zone. In the framework of the Phoebus group, we have also applied the
same methodology to other helioseismology instruments on board SoHO and ground
based networks.Comment: Proceedings of the SOHO-18/GONG2006/HELAS I: Beyond the spherical Su
Detecting individual gravity modes in the Sun: Chimera or reality?
Over the past 15 years, our knowledge of the interior of the Sun has
tremendously progressed by the use of helioseismic measurements. However, to go
further in our understanding of the solar core, we need to measure gravity (g)
modes. Thanks to the high quality of the Doppler-velocity signal measured by
GOLF/SoHO, it has been possible to unveil the signature of the asymptotic
properties of the solar g modes, thus obtaining a hint of the rotation rate in
the core. However, the quest for the detection of individual g modes is not yet
over. In this work, we apply the latest theoretical developments to guide our
research using GOLF velocity time series. In contrary to what was thought till
now, we are maybe starting to identify individual low-frequency g modes...Comment: Highlight of Astronomy (HoA) proceedings of the JD-11, IAU 2009. 2
pages, 1 figur
Prospects for studying the solar CNO cycle by means of a lithium neutrino detector
Lithium detectors have a high sensitivity to CNO neutrinos from the Sun. The
present experimental data and prospects for future experiments on the detection
of CNO neutrinos are discussed. A nonstationary case is considered when the
flux of 13N neutrinos is higher than the standard solar model predicts due to
the influx of fresh material from the peripheral layers to the solar core.Comment: 12 pages, 5 figures, a thoroughly revised version, reported at
International Symposium "Physics of Massive Neutrinos" at MILOS (Greece)
19-23 May 200