The effect of scattering processes in the continuum on the formation of spectral lines in a static atmosphere with an arbitrary distribution of the internal energy sources is investigated using Ambartsumian's principle of invariance. Spectral line profiles are calculated to illustrate the effect the assumption of the complete redistribution on

We have observed the planetary nebula NGC 2440 in the transitions [O II] λ3727, He II λ4686, [O III] λλ(4363+5007), H I λλ(4861+6563), He I λ5876, [N II] λ6584, [S II] λλ(6717+6731), and [S III] λ9061, as well as in various continuum filters. As a result, we are able to evaluate the excitation structure of the source and determine the projected

Astrophysics is a very recent development in Spain, but its spectacular evolution in itself constitutes a singular phenomenon that has aroused the interest of sociologists and historians of science alike....

The magnetic field observed in the photosphere and at higher levels of the solar atmosphere is generated in the convective envelope that extends along the first 200 000 km below the solar surface (see DYNAMOS: SOLAR AND STELLAR and SOLAR INTERIOR). To properly understand the solar magnetic cycle, it is necessary to explain the processes whereby the

In the diffusion-collision model, the unfolding or backward rates are given by the likelihood of secondary structural cluster dissociation. In this work, we introduce a backward rate calculation modeled from a Kramers-type thermal tunneling through a barrier, which represents the free energy potential well for buried hydrophobic residues. Our