Rock and ice at NAM2010

The National Astronomy Meeting 2010 at Glasgow University has been hearing from those interested in water in the universe, according to the Astronomy Now magazine’s NAM2010 blog.

The big story (covered in Discovery as well as Astronomy Now) is on the emergence of pollutants in the atmospheres of White Dwarfs. Now there’s no reason for these to be there as the atmospheres of these things tend to be pretty clean. However, observations show 3-20% have some level of pollutants (the level to which the survey was sensitive to was the mass of a 150km asteroid). Previously, people thought this may be due to stuff lying about between the stars and the telescope in interstellar space, but the analysis of this survey refutes that, suggesting the material comes from the remains of rocky material around the star. In addition the signature of water was detected far and wide, suggesting there are a lot more wet planets out there than thought as well as a lot more rocky ones.

…and the water didn’t stop there. A new class of objects known as Main Belt Comets were presented which were comets residing in the asteroid belt. Now we know comets are closer to frosted blocks of rock than dirty ice, we also know that ice can remain trapped in them for a very long time even part way into the inner solar system. This allows us to look for the signatures of bodies with no frost on the outside that are nevertheless emitting small amounts of ice from pockets below the surface, possibly exposed due to impacts or fragmentation. About a half dozen MBCs have been seen.

A most certainly non MBC was Comet McNaught, which put on a huge show in 2007 with a tail stretching across the horizon. Now results from the Ulysses spacecraft suggest that the extent of the ionised comet was even greater. The spacecraft measured the wake of the comet in the solar wind from a distance more than one and a half times the Earth Sun distance away. It took the spacecraft eighteen days to cross the wake, compared with 2.5 days for Comet Hyakutake. Of course, things like the increased width of the wake with distance and the strength of the solar wind encountered do need to be taken into account, but measurements from other spacecraft such as Giotto, which encountered the tails of Grigg-Skjellerup and Halley, each taking a matter of hours to cross, seem to confirm the immensity of McNaught’s plasma presence.

Another thing revealed in that session was water in lots of exoplanetary atmospheres. In other sessions, more exoplanets popped up – nine new ones to be exact. The nine new planets included some with backward orbits and strange inclinations. The suggestion from these is that they didn’t simply migrate inwards of their own accord after forming from the protoplanetary disc, but were kicked in by gravitational interactions with say a nearby brown or red dwarf. The bad news is for Earth like planets in the vicinity, migration is something that can be coped with, huge planets bouncing round like deranged comets looking for a fight is not. Earths in this situation are either destroyed or depart the planetary system, looking to be alone.

Astronomy Now also recorded a few interviews at NAM2010 and stuck them on their youtube channel:

Meanwhile, UCL released a mini-lecture by one of its PhD students on the science her group is doing on the moons of Saturn.


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