Western Australia's Astronomy & Space Science Community
The Probing Lensing Anomalies NETwork (PLANET) has
been looking for variations in microlensing events.
Microlensing is an optical effect which occurs when
a large mass (usually a star) passes in front of a
background star and gravity “bends” the
light towards the observer. When the foreground object
is directly between the observer and the background
star the light from the background star is uniformly “bent” by
gravity and redirected towards the observer in the
form of a ring around the foreground object. As the
foreground object moves away from the centre the ring
separates into two images of the background star. Often
the ring and dual images are not resolvable, but are
recorded as an increase in the brightness of the star.
Previous microlensing surveys were conducted obtained
well defined light curves (a record of the variances
in the brightness) on a scale of 10s or 100s of days.
However, these curves are generally poorly defined
at the time scales needed to observe small-scale variances.
These small-scale variances are what give astronomers
clues to the structure of the foreground (or lensing)
object. PLANET uses smaller time-scale surveys of potential
microlensing events to get finer detail of any variances
in the microlensing events.
Variances can be caused by a large range of reasons,
all with different geometries and lensing properties.
These include: double lenses, double background stars,
background and foreground light mixing, or even planetary
systems around lenses.
PLANET uses four telescopes; all located in the
Southern Hemisphere, in three different countries (2
in Australia; Perth and Mt Canopus) to conduct its
observing campaigns. PLANET has 32 members in 18 institutions
across 10 countries.
To learn more about PLANET or microlensing, please
visit their website.