Astronomy roundup

Over on twitter, @VirtualAstro (the artist formerly known as @NewburyAS) has been compiling a list of astronomy related music. Any further suggestions? I could trawl through youtube for them all if anyone wants to see an enormous unloadable post…

The ‘Jodcast’ (astronomy podcast or internet radio show from Jodrell Bank Observatory) has an ask an astronomer series going.

A member of the Society for Popular Astronomy carefully recorded the brightness variations of Mars as it rotated over a long period of time and used the information to build up a map of light and dark on the Red Planet.

Close to a year ago, I blogged about a new type of Supernova, rich in calcium, that had appeared in a paper on ArXiV. Now more papers on the event and others like it have broken out, as reports in Discovery and Astronomy Now testify.

Another old favourite breaking back into the news is the exoplanet WASP-12b, known for being very close to its host star and as a result, very bloated. Computer models of the atmosphere had suggested that the heating of the planet was sufficient for the outer atmosphere to expand beyond the point at which gravity could keep hold of it. There’s always a bit of atmosphere leaking away from a planet, but this one was losing quite a bit if ideas on its evolution were correct. Now observations by the Hubble Space Telescope using the new Cosmic Origins Spectrograph have proven the ideas to be right, WASP-12b could be as little as ten million years from complete destruction. Reports are available in Skymania, Discovery and Astronomy Now.

Professor Brian Cox has discussed the influence on his life of Carl Sagan, on the Radio 4 show ‘Great Lives’ with Matthew Parris. Listen to this and previous editions of the show here.

The galaxy M83 has seen its layers of dust stripped away to reveal the underlying stars. The observations, by the High-Acuity Wide-field K-band Imager, or HAWK-I instrument of ESO‘s Very Large Telescope, show the 40,000 light year wide, 15 million light year distant galaxy in the constellation of Hydra in quite literally a new light – this one infrared.

And finally, an eclipsing binary star system has been found composed of white dwarf stars. White dwarfs are the bare nuclei of dead smaller mass stars, compressed into a size similar to the Earth. In the pair seen in orbit of one another here, it seems one white dwarf formed in the normal way, leaving a carbon/oxygen core, while another lost most of its mass through leeching by the first one, leaving a rarer helium dominated core. Astronomers who first looked at the pair thought they were seeing a single star that may just be pulsating due to unusual internal processes. They put a student onto the job to carefully measure the light curve of the event – a graph of brightness with time – and the result was the revelation of a system of two compact, heavy cores in orbit of one another every 5.6 hours, eclipsing each other with a 3 minute or so period. The discovery leads to the possibility of using Kepler’s laws to determine the mass of the pair and also the light curve to determine their sizes directly. The helium dwarf has a mass of 0.15 times that of the Sun, and a size of 4.4 times that of the Earth. The more ordinary carbon-oxygen dwarf has a mass of 0.7 Suns and a size of 1.1 Earths. The pair, which are predicted to be losing orbital energy due to gravitational waves, a prediction of General Relativity, are likely to spiral into one another in 6-10 billion years time.

Set the clock.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s