Stellar nova V1405 Cas (low resolution spectrum) (Remco Kemperman)

Stellar nova V1405 Cas (low resolution spectrum)

Stellar Nova V1405 in Cassiopeia is still going strong. It is even brightening a bit further to 6th magnitude again lately.This is my 2nd time taking a spectrum of it. This time with more resolution by moving the diffraction grating about 4 times as far from the camera sensor. That requires more exposure time, but it turns out that it gives a much nicer result 🙂.What you can clearly see are hydrogen and helium emission lines (peaks). Normal stars don't have that, those have absorption lines (dips).Due to the improved resolution I can now see and measure the P-Cygni profiles much more clearly. P-Cygni profiles are emission peaks with a dip in front. This is because the gas shell whiche is moving towards us absorbs some of the light. The speed towards us causes that absorption dip is shifted towards the blue and causes that absorption dip to move to the left.By measuring the difference in wavelength between the peak and the dip, you can see how fast the gas shell is moving away from the star, towards us.I averaged it at 1260 km/s (with a considerable margin of uncertainty of course 🙂)The earlier recording from March 2021 also contained a few P-Cygni profiles that were visible. If you compare it with that of July, it is noticeable that the blue shift in March seemed to be slightly larger. In other words, the gas shell has slowed down a bit.Recorded with 6 inch skywatcher 150/750 newton, QHY 294 Mono camera and staranalyzer diffraction grating.BTW: The emmission line at 5166 angstrom with the question marks. I identified that later as Fe ii (ionized iron). This nova started showing iron emission lines after a while.

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