Determining the Temperature of a Star Through Stellar Spectroscopy Sanil K. Rajput COSMOS Cluster 4 Spectrographs separate the different forms of light Elements absorbs photons of specific frequencies Absorption results in black vertical lines Measure temperature of stars outer atmosphere Find chemical composition of stars outer layers Heat detected as electromagnetic radiation known as infrared Increasing temperature leads to shorter peak wavelengths Wiens Law uses peak wavelength to calculate temperature Wiens Displacement Constant= (26)10 3 m K Wavelength inversely proportional to temperature = 1.Extract a 1D spectrum from the 2D spectrum 2.Combine spectra from all exposures 3.Solve for wavelength scale from Angstrom to pixels 4.Calibrate the data set 5.Divide by the resampled data Blackbodies come with easily identified signatures Once the blackbody curve is matched, the temperature is all but identified Represents electromagnetic radiation emitted by blackbody in thermal equilibrium Star 1 = Antares Calculated Temperature = 3500 K Actual Temperature = K Star 4 = Alkaid Calculated Temperature = 8500 K Actual Temperature = K Data Reduction Beta Cygnus Albireo A and B The smaller, bluer one is hotter Part of Cygnus the Swan