Studies of 'nearby' molecular clouds - within a distance of a few 100 pc and with the Orion Molecular Cloud as the most prominent example - have revealed the physics of star formation in exquisite detail - ranging from density profiles of clouds from dust extinction mapping to accurate star formation rates from counting young stellar objects. Larger samples of clouds are needed to place these local results in a more complete context. The arguably best way to obtain a large reference sample of clouds would be to observe resolved individual molecular clouds in the Andromeda Galaxy (M31), as the most nearby large spiral galaxy with close to Galactic metallicity - importantly using dust rather than gas as the primary tracer, just as for the local clouds, enabling a direct comparison. Fortunately, with wideband continuum radio interferometers, this is now becoming possible. I will present first results of a large program targeting M31 with the Submillimeter Array (SMA). Using the SMA's wideband capabilities, we have not only demonstrated that direct detection of resolved continuum emission from individual clouds is now possible on scales of 10-15 pc in M31, but we can even concurrently measure CO within the same observational setup. This ensures identical calibration and spatial filtering of dust and gas measurements, providing unique constraints on cloud identification and the CO 'X' factor for a large number of molecular clouds. Given the meaningful overlap in physical resolution with measurements of local clouds, this experiment will truly enable us to compare the local molecular clouds with a significant fraction of the cloud population of the Andromeda Galaxy. The main goals of the project include a cloud-scale assessment of star formation laws as well as of cloud properties as described by Larson's relations.
Local organisation: Maud Galametz
