PHYS 183 Chapter Notes - Chapter 16: Accretion Disk, Radiation, Main Sequence
Document Summary
Youngest star clusters always associated with dark clouds of gas & dust birthplace of stars. Dark patches in the milky way are interstellar gas clouds interstellar medium: the gas & dust that fill the spaces between stars within a galaxy; consists of. 70% h, 25% he & 2% heavier elements: virtually all has the same chemical composition but can look very different place to place based on differences in temperature & density. Detect reddening from doppler shift since it doesn"t change wavelength of stars spectral lines so determine amount of reddening by comparing observed colour to colour expected of that spectral type. Amount of reddening tells how much dusty gas lies between earth & star. Molecular clouds are the only places in space that the force of gravity overcomes the form of pressure. Pressure depends on density & temperature thermal pressure: temperature dependant pressure: can resist gravity in most interstellar gas clouds due to low gas densities keeping gravity weak.
