Transcript Slide 1
by Claudia Knez Outline • What is star formation? • Why study the star formation using infrared radiation and not visible light? • Why SOFIA is important for our observations? Star Formation • Large clouds of cold, dense gas (molecular clouds) collapse to form stars. • Cold gas means temperature T~10–50 K 0 oC = 273 K • Stars of different masses form in these regions. • Massive stars do not form in isolation. • As the clouds collapse and stars begin to form, the temperature of the gas and dust rises. From Stars to Planets • Chemical studies in star forming regions reveal the composition of the gas. • Planets form from gas around stars. • Comets have similar composition as the interstellar medium. • Are organic molecules common in star forming regions? Dust • At low temperatures, the gas freezes onto dust grains. • Chemical reactions occurs on the surface of grains. • As gas is heated by protostars, the ice is evaporated from the dust grains. Gas • Newly evaporated molecules such as acetylene, C2H2, and methane, CH4, are observed. • These and other complex organic molecules are seen towards protostars. • The molecules necessary for life seem to be COMMON! Why Study Protostars in the Infrared? • Gas around forming stars is dense and it traps light from protostars. • The gas and dust heat up and re-emit the light at longer wavelength (infrared and radio). • Molecules along the line of sight absorb the light and create an absorption spectrum. • Visible light does not get through the cloud! Absorption Spectrum Continuum spectrum Absorption spectrum Emission spectrum Challenge of Infrared Astronomy EARTH’S ATMOSPHERE ! ! Infrared Water Vapor Image Hurricane in Infrared Fish at Depth Earth’s atmosphere at 16.7 microns Earth’s Atmosphere at 11.9 microns Absorbers in Atmosphere • Main absorbers in the atmosphere are: – Water – Carbon dioxide – Ozone • Other absorbers include: – Methane Space Observatory SOFIA Ground telescope SOFIA • SOFIA will fly above most of the troposphere • Absorption by most atmospheric molecules will be decreased. • The study of molecules such as water and methane will be possible! Telescope