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Dissecting Light: Stellar Spectroscopy with Harry Roberts, ASNSW

Friday 9 March 2012 - 8:00pm
Topic: Dissecting Light: Stellar Spectroscopy
Speaker: Harry Roberts, ASNSW
Venue: Epping Creative Centre - 26 Stanley Road, Epping
Abstract: Spectra always fascinate. A basic spectroscope shows many dark lines crossing the solar spectrum, and some in the spectra of many naked-eye stars. These are absorption lines that reveal the presence of elements and molecules in the stars chromospheres. More extreme stars show bright emission bands in their spectra.

My first solar spectroscope was made in high school days, with a prism from a science supplier and various lenses. It gave a ‘high rez’ solar spectrum, with hundreds of lines. A photo from that time shows nice details in the violet region (as well as the poor quality of colour film then). Assuming you can locate a prism or a diffraction grating a tabletop solar spectroscope is easy to build, but remember never view the sun through any optics that are not protected by a certified solar filter. A basic stellar spectroscope is even easier to build or buy.

In this talk we review the basic Draper spectral types, and locate examples in the night sky. As well, here in the south, we have some spectral rarities – that give glimpses of extreme astrophysics. However, this is not a talk on physics, and the HR diagram and luminosity classes are barely mentioned.

Star spectra are both informative and beautiful – and well suited to small ‘scopes in urban settings. We will also take a look at the spectra of two famous nebulae.

And finally, we’ll find out what was the highlight – the moment of supreme revelation - in the long career of astrophysicist Cecila Payne-Gaposchkin - and why it mattered!

 

Event Date: 
Friday, 9 March, 2012 - 20:00

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