Transition probabilities and oscillator strengths of 382 lines with astrophysical interest arising from 5d96s26p, 5d106snl, 5d106s2, 5d106p2, 5d106p7s and 5d106p6d configurations and some levels radiative lifetimes of Pb iii have been calculated. These values were obtained in intermediate coupling (IC) and using relativistic Hartree–Fock calculations including core‐polarization effects. We use for the IC calculations the standard method of least‐square fitting from experimental energy levels by means of Cowan computer code. The inclusion in these calculations of the 5d106p7s and 5d106p6d configurations has facilitated us a complete assignment of the levels of energy in the Pb iii. Transition probabilities, oscillator strengths and radiative lifetimes obtained are generally in good agreement with the experimental data.

Transitional pulsars provide us with a unique laboratory to study the physics of accretion onto a magnetic neutron star. PSR J1023+0038 (J1023) is the best studied of this class. We investigate the X-ray spectral properties of J1023 in the framework of a working radio pulsar during the active state. We modelled the X-ray spectra in three modes (low, high, and flare) as well as in quiescence, to constrain the emission mechanism and source parameters. The emission model, formed by an assumed pulsar emission (thermal and magnetospheric) plus a shock component, can account for the data only adding a hot dense absorber covering~30% of the emitting source in high mode. The covering fraction is similar in flaring mode, thus excluding total enshrouding, and decreases in the low mode despite large uncertainties. This provides support to the recently advanced idea of a mini-pulsar wind nebula (PWN), where X-ray and optical pulsations arise via synchrotron shock emission in a very close (∼ 100 km, comparable to a light cylinder), PWN-like region that is associated with this hot absorber. In low mode, this region may expand, pulsations become undetectable, and the covering fraction decreases.

We report on an optical photometric and polarimetric campaign on the accreting millisecond X-ray pulsar (AMXP) SAX J1808.4–3658 during its 2019 outburst. The emergence of a low-frequency excess in the spectral energy distribution in the form of a red excess above the disk spectrum (seen most prominently in the z, i, and R bands) is observed as the outburst evolves. This is indicative of optically thin synchrotron emission due to a jet, as seen previously in this source and in other AMXPs during outburst. At the end of the outburst decay, the source enters a reflaring state. The low-frequency excess is still observed during the reflares. Our optical (BVRI) polarimetric campaign shows variable linear polarization (LP) throughout the outburst. We show that this is intrinsic to the source, with low-level but significant detections (0.2%–2%) in all bands. The LP spectrum is red during both the main outburst and the reflaring state, favoring a jet origin for this variable polarization over other interpretations, such as Thomson scattering with free electrons from the disk or the propelled matter. During the reflaring state, a few episodes with stronger LP levels (1%–2%) are observed. The low-level, variable LP is suggestive of strongly tangled magnetic fields near the base of the jet. These results clearly demonstrate how polarimetry is a powerful tool for probing the magnetic field structure in X-ray binary jets, as for active galactic nuclei jets.

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