1,071 research outputs found
The discrepancy between solar abundances and helioseismology
There have been recent downward revisions of the solar photospheric
abundances of Oxygen and other heavy elements. These revised abundances along
with OPAL opacities are not consistent with seismic constraints. In this work
we show that the recently released OP opacity tables cannot resolve this
discrepancy either. While the revision in opacities does not seem to resolve
this conflict, an upward revision of Neon abundance in solar photosphere offers
a possible solution to this problem.Comment: To appear in ApJ Letter
Temporal variations of the rotation rate in the solar interior
The temporal variations of the rotation rate in the solar interior are
studied using frequency splittings from Global Oscillations Network Group
(GONG) data obtained during the period 1995-99. We find alternating latitudinal
bands of faster and slower rotation which appear to move towards the equator
with time - similar to the torsional oscillations seen at the solar surface.
This flow pattern appears to persist to a depth of about 0.1R_sun and in this
region its magnitude is well correlated with solar activity indices. We do not
find any periodic or systematic changes in the rotation rate near the base of
the convection zone.Comment: To appear in Ap
Determining solar abundances using helioseismology
The recent downward revision of solar photospheric abundances of Oxygen and
other heavy elements has resulted in serious discrepancies between solar models
and solar structure as determined through helioseismology. In this work we
investigate the possibility of determining the solar heavy-element abundance
without reference to spectroscopy by using helioseismic data. Using the
dimensionless sound-speed derivative in the solar convection zone, we find that
the heavy element abundance, Z, of 0.0172 +/- 0.002, which is closer to the
older, higher value of the abundances.Comment: To appear in Ap
Changes in the subsurface stratification of the Sun with the 11-year activity cycle
We report on the changes of the Sun's subsurface stratification inferred from
helioseismology data. Using SOHO/MDI (SOlar and Heliospheric
Observatory/Michelson Doppler Imager) data for the last 9 years and, more
precisely, the temporal variation of f-mode frequencies, we have computed the
variation of the radius of subsurface layers of the Sun by applying
helioseismic inversions. We have found a variability of the ``helioseismic''
radius in antiphase with the solar activity, with the strongest variations of
the stratification being just below the surface around 0.995.
Besides, the radius of the deeper layers of the Sun, between 0.975
and 0.99 changes in phase with the 11-year cycle.Comment: 14 pages, 7 figures, accepted in ApJ
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