I begin with the deep mysteries and awe striking beauty that is of course Keith Cooper. Astronomy Now has a set of photos on facebook, which includes their intrepid reporters and editor. Plus a photo of a staircase.
Most the talk at NAM seemed to be about volcanic ash (which had shut down the airports, rather unhelpfully for those getting to and from the meeting, and which might’ve provided a nice sunset up there). But there were a few on stellar remnants too.
Neutron stars are the crushed cores of massive stars that have exploded in supernovae. One known star is Cassiopeia A, the youngest neutron star in the galaxy, which exploded sometime in the 17th century. At the point of explosion, these things are expected to be billions of degrees in temperature, but observations of the remnant in x-ray emissions using the Chandra x-ray space telescope, have shown it to have cooled to two million degrees. A campaign of observations over two years then showed the temperature drop by three percent. It is believed that nuclear processes are producing neutrinos that then carry away energy from the system, causing the cooling.
The star V838 Monocerotis, which became extremely luminous during an outburst in 2002 captured by the Hubble Space Telescope has become extremely cold for a star (indeed as cool as a brown dwarf, the object between planetary and stellar masses). It is believed, eight years of observations later, that the outburst and cooling are both due to a violent merger between two stars. Gravitational interactions would’ve torn away the outer layers, and the expansion would’ve both cooled them and made their surface area and therefore total luminosity far larger. Now indications from the Chandra x-ray space telescope are that things have settled down and the photosphere is coming back together in one big, hot object.
Finally, it would be remiss of me to have an Astronomy Now heavy post with no mention of Nick Howes and his latest splitting comet (following Siding Spring), McNaught. Images from their youtube channel are below: