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An oft-visited target I am sure, but this was my first first look at this star over several nights (mainly in August). I am still amazed how stellar dynamics can be seen from your backyard… details in the attached file.
Kevin
Hi Kevin
The spectra are dynamic like you say, are the strong emission lines early on due to mass transfer from the red dwarf onto an accretion disk around the white dwarf, causing disk instability and increase in light. Or does matter impinge onto the surface of the white dwarf increasing the systems light output, or is it a bit of both. Probably am i right in saying its a little more complicated than that. Anyway nice piece of work
Peter
Hi Kevin,
In quiescence, during your first 3 spectra, SS Cyg has a relatively stable accretion disc which is being fed from the secondary star and is in turn transferring this hydrogen-rich material onto the surface of the white dwarf. This process produces the Balmer emission lines you see in the quiescent spectrum. When the star goes into outburst, the temperature of the disc increases elevating the blue end of the continuum, singly ionised helium HeII lines appear, and the opacity of the disc increases which absorbs some of the emerging light generating the absorption component of the spectral lines and reducing their emission component. This is a rather simplified description but conveys the general picture.
If you want to see how you can accurately flux calibrate your spectra using a V magnitude, have a look at my workshop slides in the spectroscopy section of the E&T website.
David
Hi Kevin,
There are a couple of people on the AAVSO forum looking at SS Cyg using Star Analysers with some success. I have been pointing them to yours (and others), spectra in the BAA database 🙂
Cheers
Robin
I have used the Method outlined by David in his slides and spectro-aras posting…
See attached for results.
Kevin
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