J. Ventura

Deep optical observations of G 65.3+5.7

We present the rst CCD mosaic of the supernova remnant G 65.3+5.7 in the optical emission lines of (O ii )a nd (Oiii). The new images reveal several diuse and lamentary structures both inside and outside the extent of the remnant as dened by its X{ray and radio emission. The medium ionization line of (O iii)5007 A provides the sharpest view to the system, while the remnant appears less lamentary in the emission line of (O ii). There are signicant morphological dierences between the two images strongly suggesting the presence of incomplete shock structures. Deep long{slit spectra were taken at several dierent positions of G 65.3+5.7. All spectra originate from shock heated gas, while the majority of them is characterized by large (O iii)/H ratios. The sulfur line ratios indicate electron densities below200 cm 3 , while estimates of the shock velocities lie in the range of 90{140 km s 1 . Finally, the observed variations of the H/H ratios may reflect the presence of

Elementary Processes in Strong Magnetic Fields

The magnetic constriction of electronic orbits in strong magnetic fields (SMF) drastically modifies the properties of electronic matter, while SMF will even modify the properties of electromagnetic radiation in vacuum through such processes as polarization, pair creation, and photon splitting. We review the bulk properties of matter in SMF with emphasis on radiative opacities and transport in external magnetic fields appropriate for application to pulsars and magnetars. SMF changes in atomic matter and condensed matter at the surface layers of neutron stars are also touched upon.

Hydrogen-Like Ions Moving in a Strong Magnetic Field

Generally, the dependences of the binding energies on N for the hydrogen-like ion are similar to the corresponding dependences for the hydrogen atom on K 1 2 , the square of the (continuous) eigenvalue of the transverse generalized momentum (cf. Vincke et al., 1992; Potekhin, 1994). Similar to the case of neutral atom, the ion’s motion across the magnetic field changes the selection rules so that transitions forbidden in the limit of infinite nucleus mass become permitted. Moreover, since the transverse motion of the charged two-body system is quantized, a fine structure of the ion spectral lines and photoionization edges should appear when the fine structure components are narrower than the spacing between them. We expect these results to be important for modeling of atmospheres of neutron stars with strong magnetic fields, B ∼ 1012 − 1013 G.

Ionization Equilibrium and Equation of State of Hydrogen Plasmas in Strong Magnetic Fields

We study hydrogen plasmas at magnetic fields B ∼ 1012 – 1013 G, densities pH ∼ 10−3 – 103 g cm−3 and temperatures T ∼ 105.5 –106.5 K, typical of photospheres of middle-aged cooling neutron stars. We construct an analytical free energy model of the partially ionized plasma, including into consideration the decentred atomic states, which arise due to the thermal motion across the strong field. We show that these states, neglected in previous studies, may contribute appreciably into thermodynamics of the outer atmospheric layers at pH ≲ 1 g cm−3 and typical B and T. We take into account Coulomb non-ideality of the ionized component of the plasma affected by intense magnetic field. Ionization degree, occupancies and equation of state are calculated, and their dependences on the temperature, density and magnetic field are studied.