Pickering triangle, veil + a question on an object

[Erquy]

Hi,

A short one as the nights are getting short up in scandinavia. 6*10 m each Ha and O, and HaOO combination. One thing that strikes me is on the upper right, it looks like a planetary nebula and not a star (or simply an artefact). Any ideas?

On Ha, it just looks like a star, but Oiii definitively not.

David

O filter:

Ha filter:

Edited June 1, 2023 by Erquy

[Erquy]

found it in the simbad database. It looks like a Mira type of stars (interesting, some 7000 known).

Very interesting type of stars https://en.wikipedia.org/wiki/Mira_variable

Such stars would turn into planetary nebula, so I was not far! Or has it turned into such planetary nebula now?? 

regards

 

David

[Ratlet]

What filters are you using?

I did a bit of a deep dive on this because I'm curious.  No definitive answer, but it could be an IR leak in the filter.  ie the OIII filter is letting through some IR light which is causing a halo.  Apparently that star is a bright IR source.

This thread on cloudynights has a good discussion. 

https://www.cloudynights.com/topic/845883-rs-cygni-identification-of-unusual-structurenebula-in-oiii-by-ngc-6888-crescent-nebula/

So it has been observed before but only in the last year or so and those who have seen it are still trying to nail down the cause.  My camera has a UV/IR cut filter on it and I do have a dual band filter.  I'm slightly futher north than you but might be able to pop out and try imaging it to see if I see anything.

[Erquy]

Thank you for your comments and link to cloudynight threads reporting similar. As additional comments:

- Camera is SX694 mono and I use Ha and O baader narrowband filter. I have been using this for more than 10 years, and I never had issues of halos apart on extremely bright stars on my O filter, but not the kind anyhow I report above (the Ha is clearly "round" star like, while the O is a very little dot with a faint spread around).

- This specific star is reported on magnitude 10 or 12 for what I have seen, so not that "bright" for giving halo from my experience. If it was a halo/filter issue, one would see similar behavior on the other 3 simialr brigthness star on the crop picture,  or? I am strucked by the huge difference in intensity of this particular one (Ha vs O) if you compare to the neighboring ones of similar magnitude.

- the B&W cropped are from 1 single sub and without processing apart visual stretch, this is not from some processing and no AI (as reported by Cloud night thread as hypothesis for such artefacts)

[Ratlet]

From the cloudy nights thread that particular star is bright in IR.  The hypothesis put forward on the cloudy nights thread is that some filters have a drop off in the IR range blocking which means that the sensor can then see light with that filter.  Applying it to your images the o3 filter would have a drop off in o3 doing but the h-alpha does not.  

If only this star is bright in IR compared to the others then the other stars would not exhibit this phenomena.

To disprove this, imaging with a uv/it cut filter in the train should remove the ring.

Personally I don't know the answer, however this seems an exciting opportunity to so some international science collaboration!  So (clear skies pending) I'm going to setup my 130pda with dual band filter, uv/ir cut window on a 533 sensor and see if I can see it too. 

I'm hoping very much that I can since this would eliminate the IR theory as well as chromatic aberration as I'm using a Newtonian.

We're pretty far from astro-dark up here but you are at a similar latitude so it gives me hope that I'll see something.

[Erquy]

thanks. Indeed interesting and always exciting to find out some new things whstsoever 'stellar' or optical artefacts!. I will give it a try with stacking my L uv/ir cut on top of the Oiii to check up on this same star ( if weather allows...). Curious to check also on other such mira stars.

I will give it short Ha sub to see (many strong  ha part of planetary nebula are almost totally blown up at 10 min)

I have never seen that behavior before ( some 10 years using same equipment). Even if this is a halo effect/IR leak effect on the O filter, i am still amazed by such big difference on such star between the 2 signals (if one take away the halo on the O filter, then it has a very little tiny dot as compared to the blown big Ha star)

[Erquy]

just a post to add a bit better comparison of the Ha and O than my previous crop on single sub (here as the stack, unprocessed apart STF autostretch in PI) Ha left and O right.

Also forgot to mention I think, that was taken with SCT C8 and starizona FR, so about 1430 mm FL calculated back from measured image scale by astrometry.

 

 

Edited June 1, 2023 by Erquy

[Ratlet]

Very exciting this!  I'm looking forward to seeing what we see.

I found this data which aside from nicely showing the various photmetric magnitudes.

It's impressive how much brighter it is in the IR! ( pink dots) although those observations are 20 years old now.  Details of the wavelength of the dots below:

I wish I hadn't found that AAVSO website.  I feel a dangerously deep rabbit hole opening up.

[Erquy]

unfortunately I cannot check my Oiii filter IR leak topic by stacking my L IR/UV cut... it won´t fit in my FW to stack (and I have no kind of adapter to get my 2 filter stack (small one) and using same set with my SCT/FR.... a bit stuck to check up...

 

Nervertheless, my Oiii filter is of that kind in case it would be known for IR leakage: Baader 8.5nm (claimed "IR blocked"). on normal stars of strong magnitude, i have not noticed over years halos  (note there has been a bad serie of this filter known giving extremely strong halo, but that´s not my case).

Here is a crop of 5.65 mag star I find with strong magnitude star example, all rest is same set up 

using same filter/camera/10 min Oiii with other scope (FMA 180) and on stronger star, no issue at all with Menkib (3.95): 

 

And referring to the link above, I took just few weeks back the RS Cygni with my WOGT81 and no issues neither (10 min Oiii) while reported as well strong IR carbon star type if I understand the CN thread (and its overall magnitude is lower than V AM Cygn -but the latter may be then way stronger in IR as you mention)

 

I looked at quite my Oiii files and cannot find any halos, but I have no image with magnitude below menkid or can think of other example than RS Cygni above

 

Edited June 1, 2023 by Erquy

[Erquy]

Hi,

 

so it looks like my filter leak the IR. I imaged it again, placing it on the bottow left corner of my frame, and one can see it is different (a shorter sub, clouds were coming in). So indeed huge IR on this star!