In Search of More Massive Protostars Physics TSP 2005 Lisa Torlina

Collective Properties & The Hertzsprung-Russell Diagram Plot of luminosity vs temperature of star’s photosphere Certain regions filled preferentially stars sharing certain structure cluster together Immensely useful: Following stellar evolution (tracks on diagram) Inference of mass & age

HR with a Twist Photospheres of stars: blackbodies Single clearly defined temperature Protostars: Buried deep inside gas/dust clouds No well-defined photosphere Range of temperatures; spectrum broader & cooler than central source; non-constant efficiency Protostars form deep inside dusty gas clouds such as this one

HR with a Twist The Solution: Assign number representative of spectral distribution & temperature Average out complexity, Study protostars statistically  Mean frequency & Bolometric temperature! Plot of Tbol vs luminosity (BLT): close relative of HR Diagram

More Massive Protostars & Evolution on the BLT Diagram Done for low mass stars Our project: where do medium & high mass protostars fit in? Theoretically predict: Protostars evolve from low to high Tbol (heat up, blow away gas & dust) Luminosity: function of mass (bigger  more gPE  greater energy output) Expect: pattern of evolution shifted up Similar spread? Accelerated evolution – can’t detect? Evolutionary Tracks for low mass protostars

Medium Mass Protostars: Source Selection & Data Analysis Different regions of Milky way Based on colour-colour diagram (medium mass) IR image of source 27 IRAS, MXS, 1.2mm infrared data Calculate bolometric temperature & luminosity (piecewise integration) Plot BLT diagram

The Results!

The Results! My Medium Mass Sources George’s Eta Carinae Sources

Conclusions & the Future Selection process & mean frequency analysis successful Occupy region just above low mass protostars – as predicted! These objects are out there The future? Plot more sources, analyse statistically – further patterns may emerge Develop theoretical models