The three-dimensional structure of the Large and Small Magellanic Clouds from Red Giant Variables Philip Lah Collaborators: Laszlo Kiss Tim Bedding (University of Sydney)

Red Giant Variables Red Giant Variables - 5 distinct period- luminosity relations - Peter Wood discovered in MACHO data 1999 fairly constant infrared magnitudes – vary the most at blue wavelengths period of variation days (some have multiple periods)

Period-Luminosity Diagram (LMC)

The Project See if one can use the period-luminosity relations as a distance indicator Use to measure variation in the structure of the Large & Small Magellanic Clouds Data - OGLE II micro-lensing observations over 4 years (used to derive periods) - 2MASS K magnitudes of stars

Large Magellanic Cloud

Sky position LMC

Period mag LMC

LMC Line Fitting

LMC Distance Variation

Comparison with Subramaniam Data

LMC 3D

Small Magellanic Cloud

Sky position SMC

Period mag SMC

SMC Line Fitting

SMC Distance Variation

SMC 3D

Conclusions demonstrated that the Red Giant Variables can be use as distance indicators LMC bar inclined and has substructure (warps) SMC found patchy substructure - results less convincing due to larger range in spatial depth of SMC

The End

Light Curve - MACHO

Colour Mag Diagram