Spectral Star Analysis Astrophysics Spectral Star Analysis

Diagram Placements Spectral Analysis ? How do we place them? The process of determining stellar types from observed spectral absorption lines.

Obtaining a Stellar Spectrum

Spectral Key

Spectral Key

Spectral Types “Oh, Be A Fine Guy/Girl, Kiss Me” O B A F G K M Each class is subdivided 0-9 i.e. B0, B1, … B9, A0, … Then further sub divided by Roman Numerals (I – V) And additionally divided alphabetically (a, b, c, d, etc…)

Spectral Types Temperature Variations Color Variations O: hottest, M: coolest Color Variations O, B: Blue A, F, G: Yellow/Orange K, M: Red

Spectral Types O >16 B 2.1 – 16 A 1.4 – 2.1 F 1.04 – 1.4 G Spectral Class Mass (in multiples of the Sun’s mass) O >16 B 2.1 – 16 A 1.4 – 2.1 F 1.04 – 1.4 G 0.8 – 1.04 K 0.45 – 0.8 M 0.08 – 0.45

d Leo b Leo 15_Monocerous

s Leo HD-27808 Rho Auriga

Wein’s Law

Temperature from Wavelength Wien’s Law lmax*T = 0.290 cm K