Monday, March 31, 2008

Transient Events in Nearby Galaxies

Transient events are bursts of energy from stars which last anywhere from a couple of seconds to a month. These events are difficult to observe because they happen very quickly and are impossible to predict!

The students in Group 6 on the University of Southampton's Design in Gamma Ray Astronomy course in Tenerife are looking for bursts of energy in galaxies outside the Milky way. There are about 40 galaxies in our local group, one of the farthest away in the group being Andromeda, which is about 2.5 million light years away (a light year is the distance that light travels in a year). Group 6 want to study bursts of energy caused by X-Ray binary systems and magnetars in galaxies in and past Andromeda.

A magnetar is a rapidly rotating neutron star with an enormous magnetic field. Magnetars eject energy which can only been seen in the X-ray and gamma-ray regions in beams from their magnetic poles. If there was a magnetar located half-way between the earth and moon, it would strip off all the magnetic data from our credit cards!

Magnetic fields cause powerful emissions from the star and it's these emissions that the students want to study. Students in Group 6 will be able to detect what elements are in the stars that they are looking at - eg. they should be able to spot titanium, iron and hydrogen in the neutron stars.

In order to observe very distant objects, Group 6 need to design a gamma-ray focusing telescope which includes a large diffracting 'lens' (a new technology called a Laue-lens) with a focal length of around 100 meters. Instead of having a very large satellite -which wouldn't fit in a rocket- Group 6 will fly two satellites in formation 100 metres apart. Light will be directed by one satellite onto a detector on the other satellite, in a similar fashion to the satellites shown in the illustration.

Group 6: Judit Bakos, Yazmin Padilla Michel, Carolina Berucci, Anastasia-Eleni Tsitali, Benedict Woods and Aron Kisdi.


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