Talk:Seyfert galaxy

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Expansion of article by Careless Torque[edit]

Major edits that have been made so far:

  • deleted photo of M106 because I believe it is not a Seyfert galaxy
  • created a section on History; I am thinking on re-naming it "Discovery" as it seems more appropriate since it is about the discovery of Seyferts
  • added more information in the classification section

I am thinking of structuring the article like this:

Introduction
1. Active Galactic Nuclei
2. Discovery
3. Classification
3.1 Type I
3.2 Type II
3.3 Type 1.5, 1.8, 1.9
4. Evolution
5. Astrophysics (section about what can be determined from observing them)
6. Current research projects
7. Examples
8. See also
9. References
10.External links

I based this on the structure of the article on Binary stars, which is one of the featured articles about astronomy. Careless Torque (talk) 13:18, 11 October 2013 (UTC)

Thanks for your work on the article. Regarding your restructuring, what would you suggest to go into the "Evolution" section? The e.g., Hopkins model of AGN evolution? Same with "Current research projects": the field is still evolving, so it'd probably be best to stick with review articles. "Astrophysics" would probably heavily reference Peterson's and Osterbrock's books? - Parejkoj (talk) 03:15, 13 October 2013 (UTC)
Thanks for your message, Parejkoj, it was useful and it gave me some good ideas. The evolution section was going to be based on the model on AGN evolution as well as the theories suggesting Type I and Type II are esentially the same etc. For current research projects I was going to go through and review the most recent articles. Of course, as you mentioned, the field is still evolving so I would mention current projects as well, even if they are not finished yet. For the "astrophysics" section I haven't decided yet, but yes, it will probably heavily reference Osterbrock.
Again, thanks for the message and please drop back and check the article as I'm working on it. The work I'm doing is part of my Honours project and any help would be highly appreciated. Careless Torque (talk) 12:25, 15 October 2013 (UTC)

Hi Careless Torque, Just seen some of the new changes, the subheadings in the "Types" category is a nice touch.
The article looks like it's progressing nicely, I look forward to seeing how you develop things from here.
IndianFace (talk) 15:48, 16 October 2013 (UTC)

Hi IndianFace,
Thank you. The plan is to work on the Active Galactic Nuclei section, it doesn't look right where it is now and I can't find a way to include it somewhere else (well, not yet). Will also be working more on characteristics. Careless Torque (talk) 22:35, 16 October 2013 (UTC)
Hi Careless Torque, I've made some edits to this talk page hoping to improve readability a little bit, hope you don't mind. If you disagree with them, please feel free to revert back to the previous form. Regards and thanks for taking the time to improve the article. Gaba (talk) 12:55, 23 October 2013 (UTC)
Hi Gaba_p Thanks for the edits, it is much easier to read now. Please keep checking on the article. Careless Torque (talk) 21:56, 23 October 2013 (UTC)

Hi Careless Torque, maybe adding some notable examples - e.g. Circinus Galaxy is the closest (?) Cas Liber (talk · contribs) 18:46, 23 October 2013 (UTC)

Hi Casliber, I will add a table with examples of Seyfert galaxies soon, still working on the template for the table. Thanks for your message. Careless Torque (talk) 21:56, 23 October 2013 (UTC)

Hi Careless Torque,
My one suggestion would be to do something with the "Active Galactic Nuclei" section, either move it or fold it in somewhere else. It feels a little weird to go from Seyfert Galaxies to Active Galactic Nuclei then back to Seyfert Galaxies.
I would suggest going straight into your "Discovery" section after the introduction, as it fits in nicely with common Wikipedia styling of a historical section following first after the introduction.
Just a suggestion, hope it's of use to you.
IndianFace (talk) 21:15, 23 October 2013 (UTC)

Hi IndianFace, trying to make that section look less out of place gave me nightmares for the past few days. Still working on figuring out something, but I'll take your advice into account. Thank you. Careless Torque (talk) 21:34, 23 October 2013 (UTC)

A note for Careless Torque: you wrote "8 inches in diameter" in one of your edits. Double quotes (") are used to denote arcseconds in astronomy, not inches. I've changed the wording to give the emission region size at the position of the galaxy (8"/206265("/radian)*47x10^6ly), since that size would be more useful to readers than the projected size. - Parejkoj (talk) 16:47, 5 November 2013 (UTC)

re: deVancouleurs1968, I think we need a more recent reference there. Seyferts (all types) make up 2-4% of all galaxies, and up to 8% of spirals. A better modern reference would be Schawinski 2010, particularly the end of section 3.2 and figure 6. It's a color, mass, morphology-dependent relationship. - Parejkoj (talk) 20:22, 7 November 2013 (UTC)

As I said on my talk page, the section summarises how Seyferts were discovered and previous research on the topic. Which is why mentions that in 1968 this was believed. Once I get to more recent papers/research I will add that in as well. But as long as I talk about history, I think it is needed I do say what was done before, even if now we know it to not be accurate. — Preceding unsigned comment added by Careless Torque (talkcontribs) 20:47, 7 November 2013 (UTC)
In that case, it needs to be worded as such. As it stands, that paragraph on surveys sounds like the final say. Maybe start it with "Early surveys to identify and catalog...", and phrase conclusions such that they aren't obviously the last word. - Parejkoj (talk) 15:30, 8 November 2013 (UTC)

Hi Careless Torque,
I noticed in the classifications that you keep switching between using I,II and 1,2 when listing the types. In the interests of continuity it would probably be best to select one of these notations to use. I don't know if one notation is more correct than the other however.
IndianFace (talk) 23:49, 18 November 2013 (UTC)

Hi IndianFace, thanks for pointing it out. I think I was using the notation used in the references, and books and papers seem to switch between the two. Most seem to use II instead of 2, so I will change them all.

Careless Torque (talk) 00:36, 19 November 2013 (UTC)

LINER is not a Seyfert subtype[edit]

LINERs are very much distinct from Seyferts. Their observed emission is different, the host galaxies are different (mass, stellar age, environment), and they are likely caused by quite different emission mechanisms. We could say something about LINERs have some properties similar to Seyferts (forbidden emission lines, x-ray and radio emission, possibly driven by black hole accretion), but they shouldn't be described as an other type of Seyfert. - Parejkoj (talk) 17:46, 19 November 2013 (UTC)

You still have phrased that paragraph as "can be considered as subclasses of Seyferts". That's just not true for LINERs. Also, your phrasing about NLSy1s needs to be reworked to explain how they are different from both Sy1 and Sy2: They have strong broad lines, but not as broad as "ordinary" Sy1. - Parejkoj (talk) 21:05, 20 November 2013 (UTC)
Hi Parejkoj. The references I was using classified Seyfert galaxies as galaxies showing forbidden lines. LINERs show forbidden lines, therefore they were classified as Seyferts. There are papers written about some galaxies being LINER Seyferts. But I understand your point, and I rephrased the section now to say they are very similar,but they do show some differences. Hope it is ok now. Careless Torque (talk) 16:16, 21 November 2013 (UTC)
I think you've misunderstood your references. Seyferts are not classified as such because they show forbidden lines, but that they show those lines in particular ratios. HII regions in galaxies show forbidden lines, but they've got nothing to do with the energy production in Seyferts. To clarify this (for both you, and the article), you should probably include a BPT (aka AGN diagnostic) diagram, from e.g. Kewley et al. 2006, and some discussion thereof, and also an example Seyfert II spectrum. Actually, that might be worth an article itself, considering its importance in classifying emission line galaxies. Your comment about host galaxies of Seyferts and LINERs being indistinguishable is incorrect: see e.g. Kewley et al. 2006, Constantin & Vogeley 2006, Schawinski et al. 2007.
Also, section 5 really needs to be rewritten: the luminosity evolution of AGN over the last 13 billion years is an active area of research, and your summary doesn't really get it right. See Figure 10 of Croom et al. 2006 for a nice demonstration of "cosmic downsizing". Please ask if you have questions: it's a confusing idea, and it'll be tricky to explain it properly here.
Separately, please rework the references to point to the NASA ADS records, with the article DOIs. Some of the refs point to other websites (e.g. IPAC), which makes it harder to find the original paper. Where is the sandbox you are using for this? I feel like it might be better if I could comment there. - Parejkoj (talk) 18:41, 22 November 2013 (UTC)

Some corrections[edit]

Hi Careless Torque, below I'll list a couple of corrections I think are necessary:

  • Intro
  1. They have a quasar-like nucleus, but unlike quasars, the host galaxy is clearly detectable, what is a "quasar-like nucleus"? Could it be briefly explained? If not perhaps this sentence would be better suited down in Characteristics.
  2. The accretion disk is believed to be the source of the observed ultraviolet radiation, while ultraviolet emission.., difference between "ultraviolet radiation" and "ultraviolet emission"? Are not these the same thing? The "while" is a bit confusing.
  3. Seen in ordinary light, what is "ordinary light"?
  • Discovery
  1. so light-travel-time arguments cannot always be used, not clear.
  2. with Peterson improving the positions, Peterson who?
  3. The two last paragraphs in "Discovery" start the same and should perhaps be merged
  • Characteristics
  1. The two first paragraphs should be revised since I merged a small section into this one.
  2. What are F_rad, F_grav, sigma, m_p, M_solar and L_eddington? Explain this in the section.
  • Classification
  1. include both allowed lines, like H I, He I or He II and narrower forbidden lines, what are allowed and forbidden lines? Can this be explained a bit more in detail?
  2. In 1981, Osterbrook introduced, Osterbrook who? Is it Donald Edward Osterbrock? Please add full name with a wikilink if it is.

If I find some more, I'll add them here. Regards. Gaba (talk) 12:25, 26 November 2013 (UTC)


Hi Gaba , I made a few corrections to the article, as suggested by you.
  • Intro
  1. I added in brackets a small explanation of what I meant by a quasar like nucleus
  2. I did not mean ultraviolet emission = ultraviolet radiation, what I meant by using the term radiation was the electromagnetic radiation of ultraviolet wavelengths, and ultraviolet emission was used when talking about lines ("ultraviolet emission and absorption lines"). I hope this makes sense. I did split the phrase into 2 different sentences, to eliminate possible confusion.
  3. By ordinary light I meant visible light. I changed the term now.
  • Discovery
  1. I meant arguments using distance = speed * time and the fact that the speed of light is constant. I rephrased the sentence now.
  2. I was talking about S. D. Peterson, whose references I used, but I couldn't find his full name or any details, and there is no Wikipedia page about him. I changed the sentence so it doesn't include his name now
  3. I merged the last two paragraphs
  • Characteristics
  1. Made small changes to the first two paragraphs.
  2. I think I just forgot to say what those terms are when I said about the other ones. I corrected this now.
  • Classification
  1. Added a small explanation about what forbidden lines are and included link to the wiki article about the forbidden mechanism
  2. Yes, I did mean D. E. Osterbock. I added his full name and the link to the wiki article about him now.
Thank you for your previous edits and for the comments. If there is anything else please let me know.
Careless Torque (talk) 09:04, 27 November 2013 (UTC)
Thank you for the edits Careless Torque. I've made some minor corrections, most importantly re-arranged the first paragraph in the lead a bit so have a look at it to see what you think. There's only a tag left in the Examples section that should be taken care of and I'd say that's about it for now. I'll go ahead and upgrade the article to B-class and then I'll leave a note at the WikiAstronomy project so other editors know about this and have the chance to chime in if they feel like. Thank you for the hard work! Regards. Gaba (talk) 12:27, 27 November 2013 (UTC)

On the Eddington limit in accretion discs[edit]

To Careless Torque:

Please read the referenced paper, which is available in full. I will not engage in edit warring with you. However, please note that the Eddington limit was originally derived for spherical stars, not black holes, and the math presented in the article is the math which is applicable to stars.

On the Eddington limit in accretion discs, by D. Heinzeller and W. J. Duschl
Although the Eddington limit has originally been derived for stars, recently its relevance for the evolution of accretion discs has been realized. We discuss the question whether the classical Eddington limit – which has been applied globally for almost all calculations on accretion discs – is a good approximation if applied locally in the disc. For this purpose, a critical accretion rate corresponding to this type of modified classical Eddington limit is calculated from thin α-disc models and slim disc models. We account for the non-spherical symmetry of the disc models by computing the local upper limits on the accretion rate from vertical and radial force equilibria separately.
It is shown that the results can differ considerably from the classical (global) value: The vertical radiation force limits the maximum accretion rate in the inner disc region to much less than the classical Eddington value in thin α-discs, while it allows for significantly higher accretion rates in slim discs. We discuss the implications of these results for the evolution of accretion discs and their central objects.

Since November 30, under a variety of IP addresses, I have diligently copy-edited the article and clarified important points that were unclear. On Dec. 6, I blundered in using the word "disc." Since you will not allow me to correct my own mistake, I am afraid that my assistance is at an end.

199.46.199.232 (talk) 22:55, 8 December 2013 (UTC) (96.226.185.101, 173.57.52.219)

Eddington limit was originally derived for spherical stars. Correct. However, the article doesn't talk about spherical stars, talks about Seyfert galaxies. In the context of Seyfert galaxies, the derivation doesn't involve spherical stars, it involves accretion discs. I used the word "disc", which is correct, and the other user kept changing it to "sphere", which is wrong. It was never a case of me not letting him correct his mistake. In fact, I was trying to correct his mistakes, which he kept undoing.

Careless Torque (talk) 23:33, 8 December 2013 (UTC)

I am in agreement with 199.46.199.232 on this point. The mathematics presented is correct for stars and incorrect for accretion discs. It is applicable to Seyfert galaxies only when carefully qualified with appropriate caveats, which you have removed. Stigmatella aurantiaca (talk) 23:39, 8 December 2013 (UTC)
Stigmatella and the IP editor are correct here: the Eddington limit for accretion disks is derived assuming spherical accretion, just as it is for stars. This is a known approximation, but it is widely used and does serve a useful purpose. The nature of this approximation must be made clear in the article. - Parejkoj (talk) 00:26, 9 December 2013 (UTC)

I would suggest that Careless Torque use the "Main article" template for the Eddington luminosity. In this instance they clearly state the assumption of a simplified model and it is the editors duty to write with relevance to the topic at hand, which is Seyferts. So the use of disc and the approximation would be correct in this context, and as Parejkoj pointed out it is an approximation widely used. However it is not the place to go into detail beyond the requirements of the article as we end up repeating ourselves all over Wikipedia. It would be the duty of the "Main article" template to expand on the simplification here. I think this would be a solution to satisfy both sides of the discussion. - IndianFace (talk) 05:15, 9 December 2013 (UTC)

Given that Torque has added the main template, I've pruned away all details of the derivation and re-added the IP editor's caveat. Hopefully everybody will be appeased. Stigmatella aurantiaca (talk) 12:11, 9 December 2013 (UTC)

I think that since we can't reach a common ground, both opinions should be included. I feel the derivation as it was before is an integral part of the Seyfert galaxy article, but I also understand people saying the derivation is for spherical stars. So I think we should have the derivation back, but make sure we keep the IP editor's caveat and include a few more words about how the Eddington luminosity is derived, without going into the detail the main article goes into. Careless Torque (talk) 12:18, 9 December 2013 (UTC)

The problem with the classical Eddington luminosity is a lot more than just geometric effects. For example, Eddington only considered electron scattering, but in actuality, other radiation processes are involved (Bremsstrahlung). Eddington only considered a hydrogen atmosphere; in actuality the limit depends on chemical composition. For black holes in particular, energy can be lost across the event horizon, which changes things quite a bit. In other words, this is a pretty complex subject, and the details are best left to the main article. The present verbal description gives a pretty good intuitive idea of the basics. Re-adding the derivation would give a false sense of rigor. Stigmatella aurantiaca (talk) 13:00, 9 December 2013 (UTC)
Also, if one presents a derivation, the beginning part of the derivation presents the basic assumptions that will be used. Starting off with the statement "Assume that a black hole is surrounded by a disc of luminous gas" and following with equations that assume spherical symmetry is totally unacceptable. It is better not to present any derivation at all than to present a confused sequence of non sequiturs. Stigmatella aurantiaca (talk) 16:15, 9 December 2013 (UTC)
I agree with both being included, but there should be mention to the fact that we are deriving the force same as we would for a star either before or during the derivation, this would prevent a false sense of rigor where currently it feels that there is a lack of rigor. It would also provide a manner in which to write the caveat in a more context driven manner, as currently I would say there are issues with both the wording and placement of the caveat. - IndianFace (talk) 17:05, 10 December 2013 (UTC)
The easiest way would be to replace the word "disc" with "sphere", providing the abbreviated calculation, then mentioning that a rigorous calculation would take into account the actual geometry, etc.Face-smile.svg Stigmatella aurantiaca (talk) 17:41, 10 December 2013 (UTC)
You can't replace "disc" with "sphere" in the context of an accretion disk. That is just wrong. I will work through a more thorough derivation however and make sure I include all caveats, and also mention all the things that the derivation doesn't take into account but occur in accretion discs, and how the answers would be different. Careless Torque (talk) 18:52, 10 December 2013 (UTC)
You can't replace "sphere" with "disc" in the context of the derivation. That is totally unacceptable. The whole point of the Main template is to avoid going "into detail beyond the requirements of the article as we end up repeating ourselves all over Wikipedia." Stigmatella aurantiaca (talk) 20:38, 10 December 2013 (UTC)
Actually, yes, you can include the derivation and say it's an approximation which is derived using a sphere, but in this context it is applied to a disc. I admit I didn't phrase this properly in the original version of the article. Of course accretion discs aren't spherical and they are subject to other phenomena, like turbulences and magnetic fields, which the Eddington limit doesn't take into account. Which is why the discs are usually brighten than the Eddington limit (super Eddington luminosities). And no, the point of the main template is not to give users a reason to delete others' work without trying to first rephrase it or improve it, just because it points to another article, which by the way, doesn't really give much detail about the Eddington limit as applied to accretion discs. So all that happened is that work was deleted and it isn't in the main article. So we're not repeating ourselves all over Wikipeidia, we're not saying these details on Wikipedia at all at the moment. The way the article is at the moment (after your edit) throws a formula pretty much out of context, after talking about forces that are never given a formula, and just throws a badly worded and written "caveat" at the end, which again, doesn't make sense in the current formulation of the article. Doing this "is totally unacceptable", to quote you. How about we try to actually work on a good derivation and include all the points that need mention instead of just removing pieces of work and leaving fragments out of context? Careless Torque (talk) 21:23, 10 December 2013 (UTC)
As was said previously by another user "The nature of this approximation must be made clear in the article". My point about using the Main template was that going into an extended explanation about stars is unnecessary and the focus should be kept on black holes and Seyferts. I think the original derivation should still be included, and little more than a line saying something akin to "we derive the Eddington luminosity the same as we do for a star", or even before Frad "we assume spherical..." etc etc, would be sufficient. I would advise Careless Torque to be careful with their planned reworking not to go into too much detail. While the complexities of the Eddington luminosity in regard to accretion discs may not yet be in the main article, you should treat it as if the details would exist there as the intention would be that at some point someone will rewrite the Eddington luminosity article to that of an encyclopedic quality. - IndianFace (talk) 23:07, 10 December 2013 (UTC)

OK. Here is a version to work on. Please make edits directly to the text and we can discuss below. Stigmatella aurantiaca (talk) 02:27, 11 December 2013 (UTC)

Eddington luminosity - this talk section no longer needed[edit]

With IndianFace's latest edit pushing the derivation into a note, this section is no longer needed, so I am blanking it. Stigmatella aurantiaca (talk) 17:30, 14 December 2013 (UTC)

References[edit]

Discussion on the above proposed text[edit]

As written, the above section will be one of the largest in the entire article. My feeling is that this could possibly be an undue emphasis on a secondary point. I prefer offloading the derivation to the Eddington luminosity article. Stigmatella aurantiaca (talk) 02:50, 11 December 2013 (UTC)

Eddington luminosity applies to AGN in general, not just Seyferts. There are actually several sections of this article that would almost be better placed in the Active galactic nucleus article, but this is definitely one of them, since it applies to all accretion-driven AGN. - Parejkoj (talk) 16:55, 11 December 2013 (UTC)
Yes, agree that this mostly belongs in the AGN article. In this article, this maybe deserves a paragraph or so, to summarize the main points. StringTheory11 (t • c) 02:56, 13 December 2013 (UTC)

Apparent consensus that the proposed section is too long[edit]

Parejkoj, StringTheory11 and I have thus far all argued that the current version of the above proposed text is too long. Stigmatella aurantiaca (talk) 10:23, 13 December 2013 (UTC)

Continuing discussion using Eddington luminosity - revision 1[edit]

I have hence replaced the proposed section with the version from the current text in article space, calling it "Revision 1." It seems to me that StringTheory11 is arguing that even this abbreviated version would be too much. He spoke of maybe including only "a paragraph or so, to summarize the main points." Comments? Stigmatella aurantiaca (talk) 10:36, 13 December 2013 (UTC)

Hi, I do agree that the version you posted above is too long. I am currently working on a shorter version that still includes all the main points and I should hopefully have a draft soon. As you know, this is part of my project and I've been tasked with including at least parts of the derivation in the Seyfert galaxy article, which is why I'm trying to find a way to make it more suitable. I have no problem with including the full derivation in the Eddington luminosity article (and a few words should be included in the AGN article as well), but at the moments I am focusing on my project. Once the project is done I can work on a version we can include in the other articles mentioned as well. Careless Torque (talk) 10:41, 13 December 2013 (UTC)
You might consider pushing the derivation into a Notes section, using hypertext markup instead of <math>LaTeX markup<math>. To see what I mean, in Michelson–Morley experiment, User:D.H and I used notes to include extensive commentary that would have been cluttering and distracting if included in the main article space. Note how it is perfectly OK to simultaneously include grouped and ungrouped notes. The notes can be grouped so that you have note references of form [N 1], [N 2] etc. while the bulk of the references can remain ungrouped. In Fizeau experiment, User:D.H carefully distinguished between primary and secondary sources. Stigmatella aurantiaca (talk) 11:03, 13 December 2013 (UTC)
Thanks for the idea, I didn't know how to use notes actually :) I'll have a look at that. Careless Torque (talk) 12:45, 13 December 2013 (UTC)
As it seems there is a consensus on pushing the derivation to a note, I have updated the article as such. One of the lines of math is not contained very well in the pop-up window, some people may find issue with this, I'll leave it open to consensus as to whether this is changed. I think it would be best at present to focus on as StringTheory11 put it "a paragraph or so, to summarize the main points", we could do this by looking to the existing paragraph for expansion or rewriting. - IndianFace (talk) 17:00, 14 December 2013 (UTC)
I broke up the long line of math so that it could wrap. Stigmatella aurantiaca (talk) 17:11, 14 December 2013 (UTC)
Thanks for that Stigmatella aurantiaca, I hadn't thought of closing it into separate math statements to make it run onto the next line. Do you know if there is a way to change the width of the pop-up window when you hover over a note link? - IndianFace (talk) 18:56, 14 December 2013 (UTC)
Unfortunately, no. If there is a way, it would probably be defined in some CSS style sheet somewhere to which we wouldn't have access. Maybe there is a forum somewhere where I could raise a technical assistance question. Stigmatella aurantiaca (talk) 23:12, 14 December 2013 (UTC)
I've placed my question at Wikipedia:Help_desk#Adjusting_the_width_of_tooltips.3F. Let's see if somebody there can offer some help. Stigmatella aurantiaca (talk) 05:29, 15 December 2013 (UTC)
Got a response from User:ColinFine. It wasn't very encouraging. Stigmatella aurantiaca (talk) 13:58, 15 December 2013 (UTC)

Examples section[edit]

Much thanks to Johndric Valdez for adding a genuinely useful and interesting list to the Examples section.

On the other hand, the long-standing table of "representative Seyfert galaxies from the Markarian catalog" below his list seems totally random to me. There is nothing to indicate why these galaxies and no others from Markarian have been highlighted with detailed information. Are any of them especially close or bright? Do any of the ones with NGC designations have separate Wikipedia articles devoted to them? Does the table provide links to related articles in the scientific literature?

No, no, and no.

I propose to delete this table, and that we should do what we can to expand Johndric's list. Stigmatella aurantiaca (talk) 08:52, 12 February 2014 (UTC)

The examples in the table were really just randomly picked to try include as wide a range from the Markarian catalogue as possible. I agree that the new list is better so if you want to remove the table (or add different galaxies etc) go ahead. I do however think that at least a mention of the Markarian catalogue should be kept, even if the table is deleted. Careless Torque (talk) 11:21, 12 February 2014 (UTC)
Also, while the new list is really good, I don't see any references in it. I think we should first try and find some references for each of the galaxies mentioned and the comments about them. Careless Torque (talk) 11:24, 12 February 2014 (UTC)
Deleted table. Please check that my comment about the Markarian catalog is appropriate. Also, I'm starting to research references. It is evident that some of the comments will need to be revised. Stigmatella aurantiaca (talk) 12:17, 12 February 2014 (UTC)

Brightest Seyfert galaxy?[edit]

It is stated on the Examples section, Messier 77 is stated as the brightest Seyfert galaxy, at apparent magnitude 9.6. However, I've found lots of journals in the Internet claiming the much brighter (apparent magnitude 8.4) and closer Whirlpool Galaxy (Messier 51) as a Seyfert galaxy type 2. Some of the journals are these:

http://arxiv.org/abs/0704.0947 http://www.asiaa.sinica.edu.tw/~satoki/m51multiCO-details.html http://adsabs.harvard.edu/full/2005ASPC..344...90M http://iopscience.iop.org/0004-637X/496/1/210/fulltext/ http://iopscience.iop.org/1538-4357/616/1/L55/fulltext/18265.text.html http://www.johnmurphyastro.info/messier/m51-whirlpool-galaxy

There are strong, and lots of references stating that the Whirlpool galaxy is a Seyfert galaxy. Could we change the information in Messier 77 and put Whirlpool Galaxy as "the brightest Seyfert galaxy in the sky"? Johndric Valdez (talk) 12:45, 18 February 2014 (UTC)

Actually, Messier 81 is listed with an apparent magnitude of 6.94... Stigmatella aurantiaca (talk) 23:56, 18 February 2014 (UTC)
Yes, the source provided for the M77 claim even states that the Total Apparent Magnitude is 10.32, which, while reasonably bright, isn't remotely close to being the brightest. It even mentions that the nuclear absolute magnitude is rather less than the average of other Seyferts. If the source actually says that M77 is the brightest, I'm not seeing it, and for that reason alone it should be removed from the list. I don't think the claim of "brightest Seyfert" should even be made unless a source is found which specifically states as such. Huntster (t @ c) 05:23, 19 February 2014 (UTC)
The 1973 paper by de Vaucouleurs cited NGC 1068 (M77) as being the brightest, but since then, a great many active galaxies with obscured nuclei have become recognized as Seyferts; hence the confusion. I'll try rewording. Stigmatella aurantiaca (talk) 05:36, 19 February 2014 (UTC)
Out of pure curiosity, where in the paper does it mention M77 being brightest? Huntster (t @ c) 06:52, 19 February 2014 (UTC)
First sentence. "The large southern spiral NGC 1566, type SAB(s)bc, is the second brightest Seyfert galaxy, being surpassed only by NGC 1068..." and NGC 1068 = M77. Face-smile.svg Stigmatella aurantiaca (talk) 09:05, 19 February 2014 (UTC)
/me walks away in shame... Huntster (t @ c) 16:34, 19 February 2014 (UTC)

But I've found out that the radio galaxy Centaurus A is also a Seyfert galaxy with an apparent magnitude of 6.84... ==Johndric Valdez (talk) 06:15, 14 April 2014 (UTC)==

About M106[edit]

Careless Torque mentioned above that M106 is not a Seyfert Galaxy. However, the article itself states it and has a reference by Roberta Humphreys et al. I think we need to put a picture of M106 here since it is one of the closest and best known Seyfert galaxies. ==Johndric Valdez (talk) 08:14, 5 April 2014 (UTC)==

Closest Seyfert galaxy?[edit]

It is stated in the article that the Circinus Galaxy is the closest Seyfert galaxy to Earth, distanced 13 million light years. However, I've found out that NGC 4945, distanced 11.7 million light-years to Earth, is a Seyfert galaxy type 2. What's going on? Johndric Valdez (talk) 06:10, 10 April 2014 (UTC)

I've found out even more! A galaxy named NGC 185, distanced 2.08 million light years and is a sattelite galaxy of Andromeda, is a Seyfert galaxy type 2. Now that would pretty get the claim! Johndric Valdez (talk) 04:33, 1 May 2014 (UTC)

It seems that claim may be jumping the gun a bit. See http://arxiv.org/abs/1110.5891; until its status can be clarified, best not include it in the list. I'll work up something for 185's article tomorrow to deal with the discrepancy. Huntster (t @ c) 05:33, 1 May 2014 (UTC)
The status of NGC185 as a Seyfert apparently is in doubt [1]; if it doesn't have an active nucleus, then it isn't a Seyfert, but some other type of galaxy with Seyfert like features. (as claimed by the linked to paper)
The distances for Circinus and 4945 are similar, and the spread in the values reported for those two galaxies span millions of light years. 4945 in [2] says 13 million light years, not your figure of 11.7; so it would depend on what figure you're using for the distance.
This source [3] says NGC4395 is the nearest, at 8Mly
While this source [4] clearly says the Circinus is the closest Type 2 Seyfert.
-- 65.94.171.206 (talk) 00:40, 4 May 2014 (UTC)