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Abstract:

Low-radio-frequency observations played a remarkable role in the early days of radio astronomy; however, in the subsequent three or four decades their usefulness has largely been in terms of the finding-frequency of surveys. Recent technical innovation at the VLA has meant that spatially well-resolved imaging at low frequencies is now possible. Such imaging is essential to understanding the relationship between the hotspot and lobe emission in classical double radio sources, for example. We here present new images of 3C radio sources at 74 MHz and 330 MHz and discuss their implications.

Abstract:

We present near TR spectra (0.8-2.5 μm) of the two candidate B[e]/X-ray binary systems CI Cam/XTE J0421+560 and HD34921/1H 0521+37. The spectra of both systems show evidence for a more complex circumstellar environment than those seen in classical Be/X-ray binaries. Strong H I and He I emission is seen, confirming the presence of a dense circumstellar wind; O I, Fe II and [Fe II] emission in CI Cam points to recombination of this wind. He II emission, presumably due to excitation by the compact companion is observed in CI Cam. Finally, emission is seen from Na I and CO, which implies regions of the circumstellar environment with much lower excitation temperatures and higher densities, shielded from direct stellar radiation. Both systems show evidence for continuum emission from circumstellar dust. Neither of these two features has previously been observed in any other classical Be/X-ray binary system. Adopting the classification criteria of Lamers et al. (1998) we suggest identifications of unclB[e] and sgB[e] for HD34921 and CI Cam respectively, making them the first High Mass X-ray Binaries with primaries showing the B[e] phenomenon known.