Description |
The ionised interstellar medium (IISM) is an extremely thin gas, composed mostly of independent electrons and protons, that occupies the space between the stars in the Galaxy, making it not quite a perfect vacuum. With the Parkes radio telescope, we regularly observe pulsars. These are tiny rotating dead stars that flash a radio beam once per rotation, like lighthouses. The radio beam from these pulsars changes in strength over time, in a process called "scintillation"; the same process that also causes normal stars to "twinkle". The way a pulsar scintillates depends on the structure in the IISM that the line-of-sight to the pulsar passes through. One pulsar, J1603-7202, shows an extreme scattering event (ESE), which is a very compact "blob" of electrons in the IISM that has moved across our line-of-sight. While trying to study this ESE in detail, we found that we could learn something about the pulsar’s system, as it orbits another dead star. We are monitoring this pulsar to learn more about the ongoing ESE, and to discover what type of dead star the pulsar is orbiting – is it a heavy white dwarf star, or a neutron star (like the pulsar, but not flashing)?
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