Spectroscopic Atlas for Amateur Astronomers 1 Spectroscopic Atlas for Amateur Astronomers A Guide to the Stellar Spectral Classes Richard Walker Version 4.0 04/2013 Spectroscopic Atlas for Amateur Astronomers 2 Table of Content 1 Introduction .................................................................................................................... 11 2 Selection, Preparation and Presentation of the Spectra ........................................ 13 2.1 Selection of Spectra ............................................................................................................................. 13 2.2 Recording and Resolution of the Spectra ........................................................................................ 13 2.3 The Processing of the Spectra ........................................................................................................... 14 2.4 Calibration of the Wavelength ........................................................................................................... 14 2.5 Normalisation of the Intensity ............................................................................................................ 15 2.6 Line Identification ................................................................................................................................. 15 2.7 Presentation .......................................................................................................................................... 15 3 Terms, Definitions and Abbreviations........................................................................ 16 3.1 Parameters and Identification of the Stars ...................................................................................... 16 3.2 Galactic Nebulae and Star Clusters .................................................................................................. 16 3.3 Extragalactic Objects ........................................................................................................................... 16 3.4 "Early" and "Late" Spectral Types ...................................................................................................... 16 3.5 Abbreviations and Units ...................................................................................................................... 16 3.6 Identifiying of the Elements and Ions ............................................................................................... 17 3.7 The Metal Abundance Z (Metallicity) ................................................................................................ 17 4 The Fraunhofer Lines .................................................................................................... 18 5 Overview and Characteristics of Stellar Spectral Classes ..................................... 19 5.1 The Temperature Sequence ............................................................................................................... 19 5.2 The Luminosity Classes ....................................................................................................................... 22 5.3 Suffixes, Prefixes, and Special Classes ............................................................................................ 22 6 Appearance of Elements and Molecules in the Spectra......................................... 24 7 Spectral Class O ............................................................................................................ 25 7.1 Overview ................................................................................................................................................ 25 7.2 Parameters of the Early to Late O-Class Stars ................................................................................ 26 7.3 Spectral Characteristics of the O-Class............................................................................................ 26 7.4 General Remarks to the Classification of O-Stars .......................................................................... 26 7.5 Commented Spectra ............................................................................................................................ 27 8 Wolf Rayet Stars ............................................................................................................ 32 9 Spectral Class B............................................................................................................. 38 9.1 Overview ................................................................................................................................................ 38 9.2 Parameters of the Early to Late B-Class Stars ................................................................................. 38 9.3 Spectral Characteristics of the B-Class ............................................................................................ 38 9.4 Commented Spectra ............................................................................................................................ 39 10 LBV Stars......................................................................................................................... 45 11 Be Stars ........................................................................................................................... 49 12 Be Shell Stars ................................................................................................................. 52 Spectroscopic Atlas for Amateur Astronomers 3 13 PMS Protostars .............................................................................................................. 54 13.1 Overview ................................................................................................................................................ 54 13.2 Herbig Ae/Be and T Tauri Stars ......................................................................................................... 54 13.3 Spectral Characteristics of PMS Stars .............................................................................................. 54 13.4 The FU Orionis Phenomenon .............................................................................................................. 55 13.5 Commented Spectra ............................................................................................................................ 55 14 Spectral Class A............................................................................................................. 60 14.1 Overview ................................................................................................................................................ 60 14.2 Parameters of the Early to Late A-Class Stars ................................................................................. 60 14.3 Spectral Characteristics of the A-Class ............................................................................................ 60 14.4 Commented Spectra ............................................................................................................................ 61 15 Spectral Class F ............................................................................................................. 67 15.1 Overview ................................................................................................................................................ 67 15.2 Parameters of the Early to Late F-Class Stars ................................................................................. 67 15.3 Spectral Characteristics of the F-Class ............................................................................................ 67 15.4 Commented Spectra ............................................................................................................................ 68 16 Spectral Class G ............................................................................................................ 72 16.1 Overview ................................................................................................................................................ 72 16.2 Parameters of the Early to Late G-Class Stars ................................................................................ 72 16.3 Spectral Characteristics of the G-Class ............................................................................................ 72 16.4 Commented Spectra ............................................................................................................................ 73 17 Spectral Class K............................................................................................................. 77 17.1 Overview ................................................................................................................................................ 77 17.2 Parameters of the Early to Late K-Class Stars ................................................................................. 77 17.3 Spectral Characteristics of the K-Class ............................................................................................ 77 17.4 Commented Spectra ............................................................................................................................ 78 18 Spectral Class M............................................................................................................ 85 18.1 Overview ................................................................................................................................................ 85 18.2 Parameters