AAVSO news

The American Association of Variable Star Observers has put out a few interesting news bulletins. The first couple are collations of observations of particular variable stars. U Sco is the name of a nova that flared up earlier in the year. Observations so far have revealed a number of interesting things including unexplained flare ups in the light early on in the rise in brightness as well as dips in optical brightness caused by the raised rim of an accretion disc around the flaring white dwarf. The report also analyses various scientific parameters of the eclipse. The second observations report considers a category of objects rather than a single one and is a large observing campaign (ongoing if you wish to join). The campaign looks at a type of star called a Z Cam, which has a characteristic light curve (graph of brightness with time). The campaign hopes to both identify new ones and state whether or not identified ones actually do belong to this group (some are considered dodgy). The report contains light curves for a variety of stars.

The AAVSO runs AAVSOnet, a series of robotic telescopes to monitor the brightness of stars. This MP3 from Slacker Astronomy is an interview on the subject of AAVSOnet. Incidentally, the British Astronomical Association also have a blog post on robotic telescopes fresh from the digital printer.

And finally, if you have an organisation dedicated to measuring changes in the brightness of stars and you’ve noticed there’s a lot of noise in exoplanet circles about exoplanets transiting and therefore changing the brightness of stars, it makes sense to see what you can do about it. This article from the electronic Journal of the AAVSO examines exoplanet observations using standard DSLR cameras, and finds them quite useful. If you don’t think observing already known transiting exoplanets is particularly exciting, then you should be aware of the possibility of using them as probes for other planets in the system. Transit Timing Variations, or TTVs are variations in the time of transit on set caused by gravitational perturbations with other planets in the system. These guys believe they have used the technique to identify a second planet in the WASP 3 system by making careful studies of the transits of the known exoplanet. WASP-3c is believed to be fifteen times the mass of the Earth and was found by careful measurements of the transit times of WASP-3b, which is twice the mass of Jupiter. It is thought that TTV could lead to the discovery of Earth sized planets using present equipment. A similar method, Transit Time Duration, which looks at the gravitational tug on an exoplanet of an orbiting moon, which can alter the orbital velocity as it goes round, also looks towards Earth-mass worlds, this time of the exomoon variety. More on that here.


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