MONET/South joins international microlensing campaign

12 May 2016 - Frederic Hessman

With most of our technical problems solved, MONET/South is finally actively participating in an international campaign to find planets around very distant stars near the center of our galaxy.  

As part of the MiNDTSTEp collaboration lead by the Niels Bohr Institute/DK and the Univ. of St. Andrews/UK, we are intensively following the short-lived increases in the light of distant stars caused by the gravity of an intervening but otherwise invisible star: the curvature of space-time around the star acts like a giant lens, magnifying the light of the background star.  Because the effect is small, we can’t resolve the (terrible!) image of the lensed star, but we can see the increase in brightness - the effect is thus called “micro-lensing”.  If the lensing star has a planetary system, the planets can also add to the effects, albeit very weakly.  Thus, it is important that the measurements are very carefully made.  

Dr. Markus Hundertmark in Copenhagen, a former student of ours and an expert in this field, has taken over the difficult task of analysing the MONET/South images and extracting very accurate lightcurves.  Here’s a plot of one of our initial targets showing that the first MONET points (black; the yellow points are from our polish colleagues from OGLE) are a real contribution due to their accuracy!

QOB160086 light curve

The current campaign is being made in collaboration with a large team which includes the use of NASA’s Kepler and Spitzer satellites, so we are devoting a LOT of time to these targets.  Please be patient if MONET/South’s attention to your projects is temporarily decreased - the Galactic Bulge region being imaged will eventually become unobservable and we can return to business-as-usual!