Thursday 3 September at 3pm

Ted von Hippel - Gemini

"Direct Detection of Intergalactic Stars in the Virgo Cluster"

ABSTRACT:"It has been suspected for nearly 50 years that clusters of galaxies should contain a population of intergalactic stars, ripped from galaxies during interactions or by the mean gravitational shear of the cluster. I will discuss our recent direct detection of ~600 isolated red giant branch tip and asymptotic giant branch stars in the Virgo cluster with the Hubble Space Telescope. While detailed studies of the population will require further observations, the available data already constrains the fraction of the total stellar mass of the cluster present in the diffuse component, and provides a test of the distance to the Virgo Cluster that is free from uncertainties in membership of any individual galaxy."