Jump to content

SkySurveyBanner.jpg.21855908fce40597655603b6c9af720d.jpg

Recommended Posts

Hello,

Last night I added a focal reducer to the MX916. This is the first test with it included as an extra spacer, next time i will put it at the front of the star analyser so I can compare the two and decide which is the better arrangement.

Attached is my image of Regulus, which I knew was a B class star so was very amazed to see a spectra which looked so much like an A class star.

post-1883-0-09285800-1365002650_thumb.jp

I also looked at a couple of HIP stars around regulus as i was trying to work out the extent of magnitude I could easily image. One of them HIP 55262 is near M65 and M66 which I ended up with a spectra of. Can I calibrate these as I would a star or do they need different treatment? Is there anything in particular element wise, I should be seeing?

Kate

Link to comment
Share on other sites

Hi Kate,

Nice Regulus spectrum. Hydrogen lines can be seen in B, A and F stars and their intensity peaks around the low A (eg Vega at A0) B8 at the top end of the B range is very similoar in temperature so the Balmer lines are also strong here. (As the temperature increases they become weaker and He lines appear. At the other end metal linesappear as the Balmer lines decrease but they are still visible for example in G stars like the sun. Here is a graphic showing roughly at what temperature various lines can be seen in the spectrum

https://www.courses.psu.edu/astro/astro001_pjm25/tempco5.jpg

Galaxies show spectra similar to a combination of all stellar types plus H alpha emission from star forming areas but they are extended objects and any spectrum features tend to be smeared out in slitless spectra. Slit spectra show features well though. An exception are galaxies with active nuclei (material falling into a black hole producing H alpha emission. Quasars and Seyfert galaxies are examples of these and provided the nucleus is sufficiently compact can be recorded using the Star Analyser. Here is an example of a Star Analyser spectrum of a Seyfert galaxy

http://www.threehillsobservatory.co.uk/astro/spectra_21.htm

They are processed in the same way as stellar spectra, though it can be potentially useful to try and subtract the diffuse galactic spectrum from that of the nucleus.

M65 and M66 are both classed as active galaxies so you may be able to pick up H alpha emission

Cheers

Robin

Link to comment
Share on other sites

Thanks for the information Robin. I will have a go at the two galaxies and see what I get. They were dimmer than the HIP star so may not end up too good, just really impressed that I caught them so I could recognise them on screen.

Will have a look at Seyfert Galxies visible at home and see which ones are in my viewing window to image.

Kate

Link to comment
Share on other sites

Neother of the galaxies worked really well. I have put regulus in the background as it calibrated well and shows the hydrogen lines well.

post-1883-0-39712700-1365074809_thumb.jp

post-1883-0-69472400-1365074843_thumb.jp

A little too much noise in the images, despite using darks. Will try again though.

Kate

Link to comment
Share on other sites

Hi Kate,

Actually if we take the results at face value they already appear to show some rather interesting features:

The M65 spectrum appears to show a sharp feature at around the Na D line wavelength. This could be from sodium in the galaxy or in the interstellar medium in our own galaxy or anywhere in between (Lines from interstellar clouds of sodium are often seen in stellar spectra. You can see them here fore example in this medium resolution spectrum of WR140 http://www.threehillsobservatory.co.uk/astro/spectra_41.htm ).

The M66 spectrum is rather red with very little light in the blue. This may be due to interstellar extinction caused by dust, again either in our galaxy or in M66

Cheers

Robin

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.