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APOD spectrum of Nova Del 2013 at maximum

David Benn's picture
David Benn
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A friend pointed me to this Astronomy Picture of the Day of Nova Del 2013's spectrum at maximum showing bands of emission. Very nice.

David

Not just emission bands. 
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SNE
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Not just emission bands.  Each one of those bright bands has a dark (absorption) band on the blueward side!  Very cool.

Neil 

Spectrum evolution
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Have a look at this lovely animation of Nova Del spectrum evolving over the first six days,  obtained by amateur Paolo Beradi -  resolution of ~2.5A using a LHIRES Littrow spectograph

 http://quasar.teoth.it/html/spectra/novadel_15_21.gif

Robin Leadbeater originally posted this link on the BAA forum.

Gary [PYG]

Analysis
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David Benn
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I forgot to mention the absorption lines in the APOD spectrum. :)

That animation is fantastic!

It'd be great to see some analysis of both of these spectra. Is it perhaps worth pointing to this topic from the Spectroscopy forum in the Nova Del topic?

David 

Amateur Spectra of Nova Del 2013
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Hi David,

There is an ongoing detailed commentary by amateur Francois Teyssier and professional Steve Shore published here 

 http://www.astrosurf.com/aras/novae/Nova2013Del.html

They are working with amateur spectroscopists around the globe covering this  object. Spectra  of this event currently total 388 at a wide range of resolutions and wavelengths, coordinated by the ARAS group

  http://www.astrosurf.com/aras/Aras_DataBase/Novae/Nova-Del-2013.htm

Presentation and discussions of  new spectra as they come in are ongoing in the ARAS forum

 http://www.spectro-aras.com/forum/viewtopic.php?f=5&t=682

 

Cheers

Robin

emission/absorption
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SNE wrote:

Not just emission bands.  Each one of those bright bands has a dark (absorption) band on the blueward side!  Very cool.

Hi Neil,

This combination of emission and absorption is  known as a P Cygni profile (after the archetype showing this sort of spectrum feature)  and signifies an outward flow of cooler material from a hot object (From the Nova explosion in this case or from stellar winds in the case of P Cygni)  The hot central region excites the expanding region of cooler gas causing it to emit in all directions eg here most obviously at the Hydrogen Balmer line wavelengths. The emission component of the line mainly comes from the material which is thrown out sideways  and therefore has no relative velocity in our direction.  We see a net absorption however in the material comming directly towards us which is illuminated from behind by the hot central region. This is blue shifted due to its velocity in our direction and produces the absorption component on the blue edge of the line. The velocity of the material can be estimated from the blue shift.

Cheers

Robin 

Thanks for the excellent
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David Benn
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Thanks for the excellent pointers Robin!

David

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