Solar Pulsations

Abstract

Oscillations of the Sun with the period of 160 first observed in Crimea in 1974 and described in a set of papers by Kotov, Severny and Tsap (Severny et al. 1976Kotov et al. 1978) were observed also by Brookes et al. (1976) and have been afterwards observed during the last three years in Stanford (Scherrer et al. 1979) and Kitt Peak (Snider et al. 1978). This fact excludes possible instrumental origin of the effect. Moreover, the phase coherence (after elimination of integer number of 160 -periods) between these four observatories makes the assumption of Earth atmospheric origin of the oscillations (Fossat and Grec 1978) very unlikely. Besides that, (1) the dependence of amplitude of oscillations on the phase of solar rotation and (2) slow, synchronous (at Crimea and Stanford) drift of the phase of maximum from year to year, pointing to a true period slightly higher 160 (160 0.1), make the "telluric hypothesis" of the effect completely inconsistent. In Figure 2 we see the dependence of amplitude of the oscillations versus the phase of solar rotation. Figure 3 shows the yearly drift of phase of the velocity maximum according to our (C) and Stanford (S) observations. The regression line on this graph leads to the period P = 160 m .010. This period is too long for purely radial pulsations of a standard model adopted at the present time. It would be in good agreement with the period of such pulsations for an almost homogeneous sphere (polytrope n ~ 0.5), but such a model would not produce the observed luminosity and would possess Rayleigh-Taylor instability. It is well known, as was pointed out by Cowling, that quadrupole oscillation described by spherical harmonics % = 2 in the case of a fluid sphere has a period 186 . Christensen-Dalsgaard, Dilke and Gough showed that 453

The measurement of solar magnetic fields

“…T h e measurements discussed above relate only to the longitudinal component of the magnetic field. Although many attempts have been made to record transverse magnetic fields (Stepanov and Severny 1962, Severny 1965, Bruckner 1968, Wiehr 1969, Kotov 1970, Rayrole andSemel 1970), the determinations of the transverse field have not been very reliable for various reasons.…”

The Thermal and Magnetic Structure of Umbral Dots from the Inversion of High‐Resolution Full Stokes Observations

“…The cluster (also known as spaghetti) model was proposed by Severny (1965) and Parker (1979) and assumes that a sunspot is actually made up of a bunch of magnetic flux ropes bundled together. According to this model, UDs are a manifestation of the field-free hot gas that surrounds the flux ropes.…”

A flare-associated mechanism for solar surges

“…The magnitude of each of the filamentary currents may amount to 101~ (e.g. see Severny, 1965Severny, , 1969Moreton and Severny, 1968). In order for these currents to be reasonably steady in the chromosphere and corona they must there flow in nearly force-free structures with the current almost parallel to the magnetic field.…”