29 replies to this topic

[stefan822]

Here is an image of a 14° large emission nebula in the constellation Gemini:


(Click on the image to go to may homepage)

This image is a false color composite where [OIII] is mapped to red, H-alpha is mapped to green, and [SII] is mapped to blue. Stars are partially subtracted.

Most of the large arc-shaped object that extends across the entire image is only visible in [OIII] light (red). A smaller part, about 3° in diameter, is also bright in H-alpha and [SII] light (cyan).
Some fainter filaments (red and bluish) on the left side are visible in all three wavelengths and are probably related to the large arc.

Does anyone know this object? (SIMBAD doesn't.) It is hard to imagine that such a large object has been overlooked until now.

If I had to guess, I would say it is a supernova remnant.

Right of the arc, below the center of the image, there is a tiny nebula that is also not listed by SIMBAD. This nebula is not visible in [SII] light and is probably a planetary nebula.

The bright object at the lower right is SH2-274. Also note that there are a lot of weakly ionized background nebulae (HII and SII, green to cyan).

Edited by stefan822, 11 June 2024 - 12:15 PM.

[afd33]

It is hard to imagine that such a large object has been overlooked until now.

Andromeda’s Oiii arc wasn’t discovered until a couple years ago, so you never know.

[smiller]

180 hours total , wow!   Very cool equipment setup and project!

[auroraTDunn]

The Medusa nebula is pretty well known and imagined often. But I have not, that I can think of, seen anything like this in conjunction with it. I just looked in "The Astrophotography Atlas" and it shows nothing there (not the end all be all source but a good one). Doing some image crawling almost all images of the Medussa is tight on to it and the few wider images are far to short to see anything.

So a quick guess is Congrats!!!

[SNH]

Very interesting image. Your main arc (visible in O III you say) runs from Kappa Gem down towards 11 CMi. I've never really researched it, but it could be part of the Sivan catalog? That's the only catalog I know of that has huge nebula in it and is from something like the 1980s.

 

Scott H.

[j.gardavsky]

Hello Stefan,

 

the nebula close to 16h 00m +7° 43' is the StDr140 planetary nebula, also known as the Loris Nebula.

 

This is OIII band with the HII filaments is a surprizing discovery, you are here presenting.

 

Thank you so much for sharing,

JG

[stefan822]

I've never really researched it, but it could be part of the Sivan catalog? That's the only catalog I know of that has huge nebula in it and is from something like the 1980s.

The Sivian catalog (from 1974) is contained SIMBAD, see https://ui.adsabs.ha...A&AS...16..163S. In the photos, which cover the region (l=200°, b=20°), I can't see anything.

This is no surprise, because these wide-field catalogs/atlases (Courtes, Sivian, Dubout-Crillon) show H-alpha objects.
  

the nebula close to 16h 00m +7° 43' is the StDr140 planetary nebula, also known as the Loris Nebula.

Thanks for the info. The strange thing is that the surface brightness of this small (already discovered) planetary nebula does not seem to be much higher than that of the large arc.

[xSky_watcher]

Hi Stefan, 

 

You stumbled upon a part of the Monogem SNR, also known as the Monogem ring! The full SNR is 29° in diameter and forms a pretty much full loop. Known structure, especially in radio - but no public full optical image of it yet. 

My team the NHZ is currently working on a full image (one already exists, but from another astrophotographer who didn't make it public) - next year we publish a research paper about the full monogem SNR. 

We also photographed one SNR that sits inside of it recently: https://www.astrobin.com/hblt90/ - the description might be interesting for you. 

 

I hope this helps. 

 

And congrats on the nice find and image!

 

CS, 
Tim

[lucam]

That's a very interesting structure. Following Tim's lead, there is quite a bit written on the Monogem ring in the soft X-ray spectrum but not much in optical. I look forward to seeing more about this intriguing object!

 

Luca

[auroraTDunn]

Hi Stefan, 

 

You stumbled upon a part of the Monogem SNR, also known as the Monogem ring! The full SNR is 29° in diameter and forms a pretty much full loop. Known structure, especially in radio - but no public full optical image of it yet. 

My team the NHZ is currently working on a full image (one already exists, but from another astrophotographer who didn't make it public) - next year we publish a research paper about the full monogem SNR. 

We also photographed one SNR that sits inside of it recently: https://www.astrobin.com/hblt90/ - the description might be interesting for you. 

 

I hope this helps. 

 

And congrats on the nice find and image!

 

CS, 
Tim

Holy flippen moo cows batman that image is magnificent!!! I have never seen that before but I think I may be putting this on my Big project list!

But honestly which do I love more the full widefield or stefan822's closeup of part of the ring? I honestly don't know!

[j.gardavsky]

Hi Stefan, 

 

You stumbled upon a part of the Monogem SNR, also known as the Monogem ring! The full SNR is 29° in diameter and forms a pretty much full loop. Known structure, especially in radio - but no public full optical image of it yet. 

My team the NHZ is currently working on a full image (one already exists, but from another astrophotographer who didn't make it public) - next year we publish a research paper about the full monogem SNR. 

We also photographed one SNR that sits inside of it recently: https://www.astrobin.com/hblt90/ - the description might be interesting for you. 

 

I hope this helps. 

 

And congrats on the nice find and image!

 

CS, 
Tim

Hello Tim,

 

and thank you very much for your added information.

 

With my best regards,

JG

[stefan822]

Hi Tim,
 

You stumbled upon a part of the Monogem SNR, also known as the Monogem ring! The full SNR is 29° in diameter and forms a pretty much full loop. Known structure, especially in radio - but no public full optical image of it yet. 
My team the NHZ is currently working on a full image (one already exists, but from another astrophotographer who didn't make it public) - next year we publish a research paper about the full monogem SNR.

Thanks for the info.

I plotted the the Monogem ring into the JavaScript presentation. You have to copy the following link into browser address bar (hope this works, the forum software doses not support such long URL's):
 

http://www.simg.de/nebulae3/gem-01-ohs.vhtml?nav=0&tbl=1&uo=~3"K1a"%2C115.9862%2C18.6391%2C857.354%2C146.401%2C175%2C"Large%20~114°%20×%202.5°~2%20arc%20with%20dominant%20~3OIII~4%20emission%20lines.%20In%20a%20small%20region%20~1about%203°%2C%20denoted%20as%20“K1b”~2%2C%20H-alpha%20and%20~3SII~4%20are%20dominant.%20Probably%20a%20supernova%20remnant."~4%2C~3"K1b"%2C115.6653%2C21.0673%2C183.859%2C120.001%2C173%2C"Part%20of%20K1a%20dominant%20H-alpha%20and%20~3SII~4%20emission%20lines."~4%2C~3"K1c"%2C119.4090%2C17.4503%2C441.843%2C133.132%2C1%2C"Faint%20filaments%20that%20probably%20belong%20to%20K1a%2Fb%20and%20emit%20light%20at%20all%20three%20wavelengths."~4%2C~3"Monogem%20ring"%2C104.9508%2C14.2387%2C1740.000%2C"Supernova%20remnant%20with%20a%20diameter%20of%2029°%20around%20pulsar%20PSR%20B0656%2B14"~4

The arc does not perfectly lie on the perimeter of the ring. But IMHO it is very unlikely that the arc is a separate object.

Thus, not a new discovery, just the first (public) optical picture of a part of the Monogem ring.

BTW, in H-alpha, the Monogem ring is completely invisible as a ring. The region K1b (in the JavaScript presentation) may be the only H-alpha structure that is a part of the ring.

[xSky_watcher]

Hi Tim,
 

Thanks for the info.

I plotted the the Monogem ring into the JavaScript presentation. You have to copy the following link into browser address bar (hope this works, the forum software doses not support such long URL's):
 

http://www.simg.de/nebulae3/gem-01-ohs.vhtml?nav=0&tbl=1&uo=~3"K1a"%2C115.9862%2C18.6391%2C857.354%2C146.401%2C175%2C"Large%20~114°%20×%202.5°~2%20arc%20with%20dominant%20~3OIII~4%20emission%20lines.%20In%20a%20small%20region%20~1about%203°%2C%20denoted%20as%20“K1b”~2%2C%20H-alpha%20and%20~3SII~4%20are%20dominant.%20Probably%20a%20supernova%20remnant."~4%2C~3"K1b"%2C115.6653%2C21.0673%2C183.859%2C120.001%2C173%2C"Part%20of%20K1a%20dominant%20H-alpha%20and%20~3SII~4%20emission%20lines."~4%2C~3"K1c"%2C119.4090%2C17.4503%2C441.843%2C133.132%2C1%2C"Faint%20filaments%20that%20probably%20belong%20to%20K1a%2Fb%20and%20emit%20light%20at%20all%20three%20wavelengths."~4%2C~3"Monogem%20ring"%2C104.9508%2C14.2387%2C1740.000%2C"Supernova%20remnant%20with%20a%20diameter%20of%2029°%20around%20pulsar%20PSR%20B0656%2B14"~4

The arc does not perfectly lie on the perimeter of the ring. But IMHO it is very unlikely that the arc is a separate object.

Thus, not a new discovery, just the first (public) optical picture of a part of the Monogem ring.

BTW, in H-alpha, the Monogem ring is completely invisible as a ring. The region K1b (in the JavaScript presentation) may be the only H-alpha structure that is a part of the ring.

 

Hi Stefan, 

 

Really cool representation! 

Yea, the SNR is not a perfect Bubble, it's more like this: https://www.astrobin.com/lhhcr5/ - kinda "squary". I do have access to a full picture of the Monogem SNR and so can confirm that it all is one big structure, but has "holes" in it.

 

Exactly! Pretty exciting. Some other people also caught glimpses of the SNR; take this one for example: https://www.astrobin.com/vowsu0/ - you'll see Oiii creeping in in various regions (also note Hu6).

 

I can also confirm that this on not the case. The whole ring is surrounded by a Ha filament. Note that at those sizes (29°) the Ha front is immensly thin and hence you'll not find it on high FWHM surveys available to us. Your best shot might be the mdw survey - data all accessible, tho a hustle to find the filaments as they are so fine. Additionally, we (or I) currently believe that it also has Ha filaments inside - one of which we probably caught in our HU6 image I shared earlier (see the filament extending from lower left to middle?). But difficult to say at this stage - our full image will be more revealing. Again, parallels to Bray's image above and many other big SNRs (https://www.astrobin.com/mxea8z/). If you look at images of well known targets below the Rosette nebula you'll also see parts of the Ha filament. 

Note that the image I have access to is shot at a sampling size of 6arcsec so I also do not know more about the exact distribution of the Ha filaments for the time being, just that there is a full ring and likely inside filaments. Will know in ~1year. 

Also note that the main, obvious emissions are in Oiii, so that's how I know about the morphology of the full structure. 

Edit: you actually have some data on the regions the SNR expands into - so you should roughly know where it lies. I believe with more careful processing you'll see it better.

 

Hope this helps. 

 

Best, Tim

Edited by xSky_watcher, 12 June 2024 - 05:55 PM.

[xSky_watcher]

Holy flippen moo cows batman that image is magnificent!!! I have never seen that before but I think I may be putting this on my Big project list!

But honestly which do I love more the full widefield or stefan822's closeup of part of the ring? I honestly don't know!

Go for it! It's pretty faint tho, so needs a lot of patience and ideally dark skies. 

[stefan822]

Hi Tim,

I can also confirm that this on not the case. The whole ring is surrounded by a Ha filament.

You wrote it: The Monogem ring is surrounded by H-alpha nebulosity.

The entire region is full of faint H-alpha structures, diffuse ones and filaments which seem to be part of different structures (i.e. oriented in different directions, many of them parallel to the galactic plane). But I see no (part of a) ring.

You may "see" more if you know where the OIII structures are, i.e. some of filaments probably can associated to OIII structures which are more complex than just a ring.

Regards, Stefan

[xSky_watcher]

Hi Tim,


You wrote it: The Monogem ring is surrounded by H-alpha nebulosity.

The entire region is full of faint H-alpha structures, diffuse ones and filaments which seem to be part of different structures (i.e. oriented in different directions, many of them parallel to the galactic plane). But I see no (part of a) ring.

You may "see" more if you know where the OIII structures are, i.e. some of filaments probably can associated to OIII structures which are more complex than just a ring.

Regards, Stefan

The full ring of Ha filament around the SNR is known and associated. There's also other Ha emissions of course, yes. You see no part of a ring because you don't see the full picture and probably don't know what is SNR and what is galactic.

[Robin]

Hi Stefan,

 

Beautiful image of this large SNR!

 

 

- next year we publish a research paper about the full monogem SNR. 

 

Tim, please let us know here in this forum when your paper will have been published!

Clear skies

Robin

 

[stefan822]

Hi,

Since it is difficult to discuss secret/unpublished things, I have collected the [OIII] data I already have for this region. It turned out that the coverage is already complete, but quality is still bad and there are many artifacts..

Here is the star-subtracted result:


Image is centered to pulsar PSR B0656+14, the origin of the Monogem ring. Width and height of the image is 31°.

Click on this link (or on the image above) to go to a redirection to JavaScript presentation.

An X-Ray image of the Monogem ring can be found in Fig. 1 in Thorsett et al., PSR B0656+14 and Monogem Ring.

Here are my thoughts:

•  With a ring diameter of 18.4° (not 29°) some filaments near the galactic plane are an approximate fit
• The arc from the initial post is in a region outside the ring which is interpreted as western blowout in the publication above
• If the arc is completed to a circle, its center lies at a totally different position the the center of the Monogem Ring

[xSky_watcher]

Hi,

Since it is difficult to discuss secret/unpublished things, I have collected the [OIII] data I already have for this region. It turned out that the coverage is already complete, but quality is still bad and there are many artifacts..

Here is the star-subtracted result:


Image is centered to pulsar PSR B0656+14, the origin of the Monogem ring. Width and height of the image is 31°.

Click on this link (or on the image above) to go to a redirection to JavaScript presentation.

An X-Ray image of the Monogem ring can be found in Fig. 1 in Thorsett et al., PSR B0656+14 and Monogem Ring.

Here are my thoughts:

•  With a ring diameter of 18.4° (not 29°) some filaments near the galactic plane are an approximate fit
• The arc from the initial post is in a region outside the ring which is interpreted as western blowout in the publication above
• If the arc is completed to a circle, its center lies at a totally different position the the center of the Monogem Ring

 

Ah well there you go, that's about the same framing I know. 

 

Ring diameter is 25°... not 18° and not 29° (29° was the FOV we capture and also 29° at longest point).

Not every SNR is a perfect circle, as the paper says it's a blowout and hence what we see is the full thing.

[Robin]

I can't find the Monogem Ring in D.A. Green's catalog of supernova remnants: https://www.mrao.cam.../snrs.data.html

 

But I found this paper that links the Gemini H-alpha ring with the Monogem X-Ray ring:

https://ui.adsabs.ha....4414K/abstract

 

So it seems as if material (emitted by a former supernova?) is ionized by some massive O and B stars and swept up by their powerful stellar winds.

Should it be called supershell/superbubble rather than supernova remnant?

 

Anyway, this is fascinating stuff!
 

Clear skies,

Robin

[stefan822]

Here are a few more considerations:

• The ring diameter of 18.4° is the diameter of the "primary ring structure" as shown in Fig. 1 of https://iopscience.i...77682/fulltext/. This "primary ring structure"  is an approximate match with the OIII filaments which we see at galactic plane, see my previous post. The size of 25° (in east-west direction and mentioned it the abstract of the paper) is the size of the SNR including the western blowout.
• The Monogem ring lies in a distance of about 300 pc. The Orion-Eridanus superbubble extends within a distance of approximately 150pc to 400pc. IMHO it is plausible to consider the Monogem ring as part of the Orion-Eridanus superbubble.
• If the arc is completed to a circle its center lies far away from PSR B0656+14, the origin of the SNR, and its diameter is about 60°. The distorted shape of the Monogem SNR is explained by interaction with interstellar matter (ISM). To be flattened that much, the SNR would have to collide with something like a wall of ISM. This, in turn, would explain the strong emissions there.
• If the arc is completed to a circle, several H-alpha filaments lie close to the perimeter of such a ring. To check this, visit the JavaScript presentation linked in my last post, switch to navigation mode by pressing the 'N'-key or 'n'-button, and browse to H-alpha views after clicking within the yellow frames.  This is probably random and such a large structure is probably not spherical.  But it is not totally unlikely that the arc belongs to another structure which then probably belongs to the Orion-Eridanus superbubble.
• Two years ago I identified 3 possible H-alpha rings in that region: FA1 is the Gemini H-alpha mentioned in Robins post, FA2 is similar to the 18.4° Ring, but shifted southwards and a little bit smaller, and FA3 is another ring. (To make them visible in the Javscript viewer, toggle the plots on and off using the '2'-key)

Another strange observation: In the arc the OIII structures are less detailed than the HII and SII structures. This is unusual for SNR's and does not correspond with the SNR structures at the Galactic plane (in the OIII image of my last post). For other nebulae, this is not unusual, because OIII glows in the fully ionized region (which does not have a sharp boundary) and SII glows in the weakly ionized regions at the (sharp) boundaries of the nebula. HII glows in both regions.
 
To make it even stranger, here we have a nebula with a weakly ionized center (SII, HII) with many fine structures, and a fully ionized outer region, which looks diffuse and which is not surrounded by weakly ionized HII or SII. This can only be explained by the absence of Hydrogen and Sulfur.

BTW, I plan to consider the arc shaped emission nebula form the initial post as a new discovery because:

• To my best knowledge it was not published anywhere that there is such an emission nebula. So I couldn't have known this nebula and had to discover it myself.
• It does not matter whether whether the nebula belongs to another super-structure. (All nebulae belong to a super structure ...)

[yuzameh]

First of all, why [OIII] is in red and not Halpha and [OIII] in green I'll never understand why images do what they do, but that's me.

 

Second, you've discovered nothing new as it is part of a known object.

 

HOWEVER, you have imaged and revealed [OIII] in this region of the monogem ring.

 

Third, you may not have discovered the presence of oxygen though, you need to read the monogem specific xray and spectral sampling papers to see if they have discovered this [OIII] presence before.

 

However, that does not stop the fact that you seem to have been first to show [OIII] optical nebulosity.  Private stuff is private, I've seen that argument before, "oh, we did that years ago, we just haven't pubilshed it yet", and ignored it in at least one of my own publications.  I've more than once been told over the internet, after publishing, in the past "oh, yeh, I did that a while back".  How's any bugger to know if no one tells 'em?

 

Fourth  GALEX FUV (far ultraviolet images) show the details of your image details for [OIII] (your red stuff) to match perfectly with its images in FUV, positionally and structurally.  Other than already mentioned xray information I can't find any indication of any other imaged detection in any other region of the electromagnetic spectrum.  From cursory glances it appears the FUV is the region of the electromagnetic spectrum where highly ionised oxygen shows up (at negligible red shift, anyway), specifically OVI and OVIII.  Now, as there are eight electrons in an atom of neutral oxygen, ie OI, you can't get much more ionised than that (lose the last eighth electron and you've no electron shells left to give emission lines, only an oxygen nucleus).

 

Fifth, these species in highly tenuous gas/plasma OVI and OVIII have been used to show warm interstellar/intergalactic matter caused by shock fronts, which fits well this object being an SNR.

 

Whatever the case without careful precision spectra of your detected [OIII] nebulosity you can't say it is associated or unassociated with the monogem snr.  Radial velocity measures would be needed.  Circumstantial evidence is strong that it is connected and not mere coincidental line of sight, however the large nebulosity apparently adjacent to M31 shows coincidence can occur.  Compare also Galactic Halo Cirrus and the fields of M81 and M82.

 

Sixth, there is no sixth.

 

Seventh, if you search on Knies and monogem ring you will find a 2022 thesis paper which gives a comprehensive overview of this ring using data from eROSITA AND the SUBARU Telescope.  I think it was suburu...  An initial websearch may suggest that it is written in German but only part of the abstract is (there's bilingual abstracts but the paper is in English).  There are other objects mentioned in the thesis but section 4 is about this object.  It seems he prime authored a somewhat similar paper in 2018.

 

Eight, yeah, a well matured and old enough nearby SNR doesn't have to be a perfect circular because ISM density varies markedly, and when stuff is relatively near things you normally wouldn't notice crop up, sometimes only due to projection effects.

 

You need to read papers in full before making decisions about what is and what is not known.  Granted the Veil Nebula has different NGC numbers for different bits of the ring, but that ended up being discovered a few weeks ago now.

 

You are, of course, free decide whatever you desire.

 

As, of course, is also the case for everyone else.

 

Besides that, very nice image, shame about the colour scheme reversal thing going on with it.

[stefan822]

Hi,
 

First of all, why [OIII] is in red and not Halpha and [OIII] in green I'll never understand why images do what they do, but that's me.

Because

1. Eye is most sensitive in green and H-alpha typically has the highest signal-noise-ratio / contains most information
2. H-alpha glows in highly and weekly ionized regions. It therefore looks better if is "between" SII and OIII. (Same for the star colors)

 

Second, you've discovered nothing new as it is part of a known object.

I did not claimed that I discovered a new object. I claimed that I discovered an emission nebula and learned and pointed out, that it is probably a part of a known structure.

Is it known (and published) that there is an object that emits light in visible wavelengths? If not, I discovered that.
 

Third, you may not have discovered the presence of oxygen though, you need to read the monogem specific xray and spectral sampling papers to see if they have discovered this [OIII] presence before.

Is there such a paper?

According to my search, there is no publication of this structure in visible wavelengths.
 

Whatever the case without careful precision spectra of your detected [OIII] nebulosity you can't say it is associated or unassociated with the monogem snr.  Radial velocity measures would be needed.  Circumstantial evidence is strong that it is connected and not mere coincidental line of sight, however the large nebulosity apparently adjacent to M31 shows coincidence can occur.  Compare also Galactic Halo Cirrus and the fields of M81 and M82.

Who is "you"? I have never claimed anything like that or the opposite with certainty. (Because I can't be sure, I use terms like "probably" an "likely")
 

Seventh, if you search on Knies and monogem ring you will find a 2022 thesis paper which gives a comprehensive overview of this ring using data from eROSITA AND the SUBARU Telescope.  I think it was suburu...  An initial websearch may suggest that it is written in German but only part of the abstract is (there's bilingual abstracts but the paper is in English).  There are other objects mentioned in the thesis but section 4 is about this object.  It seems he prime authored a somewhat similar paper in 2018.

Above you write: "you can't say it is associated or unassociated with the monogem snr".

 

You need to read papers in full before making decisions about what is and what is not known.

You need to read posts more carefully.

Again, who is "you"?

I never decided what it is -- I speculated what it could be.

Regards Stefan

[j.gardavsky]

Not sure,

if this has been already linked, discussed or mentioned above,

here is a brand new paper by Knies et al., suggesting an answer for the eastern offset filament, as imaged by Stefan,

 

https://arxiv.org/html/2401.17289v2

("A new understanding of the Gemini-Monoceros X-ray enhancement from discoveries with eROSITA")

 

Happy reading, even if it is about the X-rays and not OIII,

JG

[yuzameh]

"you" is less pretentious than "one", but I might as well have said that.

 

you, as in you, not one, should not take what people write so personally.  There are many different speakers of English with difference idioms and styles, and things when written can oft times sound far worse than they are meant.

 

However, you did state that as far as you were concerned you found a new nebula, or implied such in your last wording.

 

Whatever the case, my view is my view, and yours is yours.

 

But when the words 'discovery' and 'new' are bandied about you have to do a massive deep dive into literature.

 

One fortunate side is we know have the internet and papers are mostly accessible.

 

Incidentally, the literature links are in simbad, it just turns out if you are doing a coordinate search you have to use the centre of the monogem ring position, not the edge.

 

However, you can search on ID and input monogem.

 

AJ, ApJ and A&A papers, and often MNRAS too, are open access nowadays, meanwhile astro-ph, part of arxiv.org, will often have the preprint even it not open access.

 

It's an impressive image, it's an interesting find.

 

But personally I'll never be able to stand green things being shown as red, but that's my personal viewpoint.

 

Critique is not the same as criticism and has no inherent obligation within it to be taken note of by anyone.

 

As far as I can tell there's no mention of [OIII] in that part of the ring/snr, or in the whole thing either for that matter, however I have not read every single paper in depth.  The couple that I did find mentioning optical filaments were rather old, probably early CCD days, and only covered a small region of the whole.