An interesting one, for sure!!
I'm assuming the large peak in Hb....
What happens to the Ha?????? None in this type of star?
I'll have a go at the spectrum later today. Keep you posted.
The above reference was the only one I've come across which shows the spectra of a CV from 450nm through to 740nm. This one is IY UMa, but I would have expected some similarities.
Figure 14 Shows the Hb emission with a central trough ( also the Ha),
HeI absorptions at 4921, 5015, 5876, 6678, 7065
and another (?) emission at 5861.
Trying to match any of these to the OY Car spectra is very difficult.
If we assume the large hump shown at around 4750 is Hbeta(4861) , then the next two emission "bumps" seem to match the IY UMa data (??) and the hump at 6710 is Halpha (6563). Based on the Balmer series the strength of the Ha should be twice the Hb so it doesn't look right???
I think we need a higher resolution spectra to be able to go much further.
An excellent example to "practise" with!!!! Well done.
I had another go at imaging OY Car last night. This image is better as I took 3 exposures of 5 mins and this has increased the SN ratio. Unfortunately I cant increase the resolution until a spacer that I have ordered arrives (hopefully next week).
The lines are very similar. I angled the camera slightly differently so any background stars different. I'm still not sure what the lines are. I have attached a ".dat" file if you wan't to open it in Vspec.(it is zipped as the forum won't accept ".dat" files)
cheers
terry,
Did you normalise the spectra using a calibrated camera resonse curve?
For some reason I'm still surprised with the lack of Ha.
I'll punch it into Vspec and see if I can find anything for you.
terry,
Did you normalise the spectra using a calibrated camera resonse curve?
For some reason I'm still surprised with the lack of Ha.
I'll punch it into Vspec and see if I can find anything for you.
Terry,
No luck so far.
I've tried Ha,Hb, Hgama etc in emission and also in absorption; He and Fe, can't find much to latch onto. Unfortunately looks like higher resolution is required?
Sorry mate.
I had the chance to try out the DSI3 on sat night, and got a number of spectra OK. These are the only 2 processed so for. I'm getting just a fraction over 11 Ang/px with the current setup. Trying to better it as there's enough room on the ccd for a longer spectra.
The images show quite a bit of fishtailing at the blue end (problem with using an achromatic refractor ). The ccd seems to be providing some reasonable response below 400nm, probably good to 350nm.
Good stuff, Mark. The DSI3 must have a bigger sensor than the DMK21 to get down into IR at that dispersion. The images don't look that dissimilar to what I get off the DMK in the blue/violet range but your camera response correction seems to bring out the detail better than I've achieved so far.
Jeff,
beta grus is an M5 class so it's a relatively cool star and the absorption lines you've recorded are mainly molecular groups. TiO among others. That does make it a bit harder to work out calibration lines, as they also tend to be broader.
I used the Sirius curve to recheck my new system. As an A class, the lines are fairly well seen, reasonably thin, and they are basically just Hydrogen.
You didn't happen to get a spectra of alpha grus (B class) did you as that one would be great!
Can you post the actual spectra image? What system did you use to capture the image? CCD, scope etc....
I'll have a look tonight (unless someone answers your questions before hand)
Al,
it's a 1.4mega pixel chip, 6.45 x 6.45 micron, Sony ICX285AL. I deliberately got the b+w version so the bayer filter was not a problem. It can also do 2x2 binning, which is probably of limited use in spectra images.
cheers
Mark
Quote:
Originally Posted by sheeny
Good stuff, Mark. The DSI3 must have a bigger sensor than the DMK21 to get down into IR at that dispersion. The images don't look that dissimilar to what I get off the DMK in the blue/violet range but your camera response correction seems to bring out the detail better than I've achieved so far.
You may have a Hb (hydrogen beta) line (the one just before the red line), however you'll have to check it against an A star (like Mark said), to calibrate it. Cool classes like M tend to be a nest of spectral lines, especially in the red region where you're getting "44 million" molecular lines showing up!!.
Can you post the actual spectra image? What system did you use to capture the image? CCD, scope etc....
I use a 12" f5 reflector GSO, and a ST7e camera. Grating on the filter-wheel. Not sure of the grating/imager distance.
I will try for A-Grus tonight, if not then another A1-2.
). The ccd seems to be providing some reasonable response below 400nm, probably good to 350nm.
