Abstract
WE have previously presented1 spectral results for Her X-1 in the energy range 20 to 100 keV and have set an upper limit of about 40% for the pulsating component. We have recently made further observations on this source with a telescope of much larger area and have obtained a longer exposure during its bright phase in the binary cycle (phase = 0.25) and almost in the middle of its βonβ period in the 35-d cycle (phase = 0.45 to 0.55). The new observations set an upper limit of 10% for the pulsating component in the energy range 20 to 45 keV which has important consequences on the models proposed for the X-ray emission features of Her X-1.
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IYENGAR, V., MANCHANDA, R., DURGAPRASAD, N. et al. Near absence of hard X-ray pulsations in Her X-1. Nature 251, 292β294 (1974). https://doi.org/10.1038/251292a0
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DOI: https://doi.org/10.1038/251292a0
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