An essential feature of substellar dwarfs compared with the Sun and stars is the formation of dust in their photospheres (not in the outer envelope). It appears that the observed data could be understood if the dust exists in a form of thin cloud deep in the photosphere rather than in the cooler surface region. Recent observations also show that the dust column densities in the observable photo...

Solar observations with the Hinode space observatory led to the discovery of strong horizontal magnetic fields in the photosphere of quiet internetwork regions. Here we investigate realistic numerical simulations of the surface layers of the Sun with respect to horizontal magnetic fields and compute the corresponding responses in the Fe I 630 nm line pair. We analyze two simulation runs with gr...

Calculations of the statistical equilibrium of magnesium in the solar photosphere have shown that NLTE populations hardly affect Mg line formation in the Sun. However, in metal-poor dwarfs and giants the influence of electron collisions is reduced, and the ultraviolet radiation field, enhanced due to reduced background line opacity, results in more pronounced NLTE effects. In the photosphere of...

We self-consistently derive the magnetic energy and relative magnetic helicity budgets of a three-dimensional linear force-free magnetic structure rooted in a lower boundary plane. For the potential magnetic energy we derive a general expression that gives results practically equivalent to those of the magnetic Virial theorem. All magnetic energy and helicity budgets are formulated in terms of ...

The umbral regions of sunspots and pores in the solar photosphere are generally dominated by $3$~mHz oscillations, which due to $p$-modes penetrating magnetic region. In these locations, wave power is also significantly reduced with respect quiet Sun. However, here we study a pore where oscillations umbra not only comparable, or even larger than that Sun, but main dominant frequency as expected...

Recent helioseismic observations (Duvall et al.) have demonstrated how new data analysis techniques can determine local changes in the acoustic properties beneath the photosphere. The recent results provide compelling evidence of a latitudinal sound speed variation. Using results from numerical simulations, we show here how this acoustic variation has the correct form and amplitude needed to ac...

A historical summary of observations since 1960 raises questions about the standard solar model (SSM). The SSM ascribes luminosity to hydrogen fusion in the solar core. It assumes the Sun formed suddenly without mass accretion so its interior had the same composition as its surface. The lightest element, hydrogen, accounts for over 90 percent of the atoms in the Sun’s atmosphere. The next light...

The Chinese Hα Solar Explorer (CHASE), dubbed “Xihe”—Goddess of the Sun, was launched on October 14, 2021 as first solar space mission China National Space Administration (CNSA). CHASE is designed to test a newly developed satellite platform and acquire spectroscopic observations in waveband. Imaging Spectrograph (HIS) scientific payload satellite. It consists two observational modes: raster sc...