Mass-luminosity relation and space-based interferometry: from Hubble Space Telescope to the space interferometry mission

Abstract

With a white-light interferometer (Fine Guidance Sensor 3) on the Hubble Space Telescope (HST) we have secured fringe scanning and fringe tracking observations to measure distances, orbits, and, hence, masses, for several nearby low-mass stars. We have made progress towards a more precise Mass-Luminosity Relation (MLR) for the lower Main Sequence. However, the MLR is a map whose low mass region is complicated by relative and absolute age and whose high-mass end is very poorly determined. To begin to disentangle these effects, and to obtain high-precision mass determinations throughout the Main Sequence, we will participate in the Space Interferometry Mission (SIM) to observe binary stars of all masses in five star clusters with a large range of well-known ages and chemical compositions. We will also observe a sample of stars throughout the Main Sequence. The unparalleled angular resolution and limiting magnitude of SIM will allow us to obtain masses precise to 1%.