Page 41 of 97 FirstFirst ... 3139404142435191 ... LastLast
Results 1,201 to 1,230 of 2890

Thread: More from Arp et al.

  1. #1201
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by Cougar
    Refresh my memory. What "signs of interaction" were noted other than the fact that it is an HII galaxy in the same line of sight as NGC 1232?
    The HII galaxy has an interaction tail curving toward the spiral arm. It has dwarf galaxy morphology consistent with it being a small companion galaxy. The galaxy shows no sign of reddening. Given that the galaxy sits at the edge of a spiral arm that is somewhat surprising.

  2. #1202
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by turbo-1
    There is certainly a lot of observational work left to be done, and many of the AM galaxies seem almost "invisible" to Google searches. I found that AM 0550-342 had been followed up spectroscopically by C. J. Donzelli and M. G. Pastoriza:

    http://www.journals.uchicago.edu/cgi...791695394Guest

    AM 0550-342 is a face-on M-51 type galaxy with a compact luminous companion connected to the end of a very distorted, tidally-stripped spiral arm. Predictably, the authors call this an "apparent" association because the smaller companion is redshifted WRT to the host.
    There are quite a few examples in that paper that have sizeable differences. That will be worth looking at more closely.

  3. #1203
    Join Date
    Mar 2004
    Posts
    13,441
    Quote Originally Posted by dgruss23
    [snip]
    Quote Originally Posted by Nereid
    And while we're collecting stamps, how about NGC 3314 - how many of the {list} criteria does it meet?
    Well, you'll have to file NGC 3314 into a different stamp book. The only thing it shares with the bridges examples we're talking about is close proximity in the sky. To my knowledge, there is no evidence of any features that could be interpreted as interaction. Nor any evidence of any bridges. Here is the most recent paper on this pairing.

    This is actually a good illustration of the point. Close proximity on the sky is not enough evidence. But then we're talking about other forms of evidence than proximity alone.
    Hold that thought!

    This may prove to provide an excellent example of a test or three that we'll undertake, at the appropriate time, on what there criteria give us, in terms of what's 'on the sky' (hint: at what X-ray/optical/radio angular resolution would NGC 3314 meet {list} criteria? How do we do the statistics on objects which, given 1972/1985/1998/2005 X-ray/optical/radio angular resolution/broadband spectral sensitivity/whatever, would meet {list} criteria? In particular, how do we go about estimating the number of "NGC 3314"s in any such lists?)

  4. #1204
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    7,601
    Quote Originally Posted by turbo-1
    You're trying to have your cake and eat it too.
    Well, actually I never ate the cake you're talking about, nor did I order it. I was just pointing out that NGC 7320 has been found to be a non-interacting member of Stephan's Quintet even though it is "apparently" very near the other members and there is an "apparent" x-ray bridge extending to it. Now, did you have a specific comment about this finding, or is changing the subject the only way you can handle this information?
    Everyone is entitled to his own opinion, but not his own facts.

  5. #1205
    Join Date
    Nov 2005
    Posts
    1,023
    Quote Originally Posted by Cougar
    Well, actually I never ate the cake you're talking about, nor did I order it. I was just pointing out that NGC 7320 has been found to be a non-interacting member of Stephan's Quintet even though it is "apparently" very near the other members and there is an "apparent" x-ray bridge extending to it. Now, did you have a specific comment about this finding, or is changing the subject the only way you can handle this information?
    From the earlier post:

    Quote Originally Posted by Cougar
    I'm not sure what you're talking about. Here the resolution is similar, so why would anyone apply that fact it they're arguing the companion is a background object? (In the previous case, the resolution was clearly different.) At any rate, this is another example of a redshift difference that's right on the borderline of possibly being due to local relative velocities. The redshift difference corresponds to a difference in relative velocity of about 4800 km/sec.
    As you can clearly see, I did not "change the subject" - I merely followed up your statment that the resolution argument should not be applied if you think that the companion is a background object. If comparing resolution is a valuable tool in determining whether or not two galaxies are likely to be at the same distance from us, it can be be used both to support or refute such an observation. We are looking for tests independent of redshift to determine whether galaxies are interacting or not. If you demand that we take image resolution off the table except when it supports your arguments, we are not going to get very far.

  6. #1206
    Join Date
    Sep 2003
    Posts
    2,608
    Quote Originally Posted by Cougar
    Well, actually I never ate the cake you're talking about, nor did I order it. I was just pointing out that NGC 7320 has been found to be a non-interacting member of Stephan's Quintet even though it is "apparently" very near the other members and there is an "apparent" x-ray bridge extending to it. Now, did you have a specific comment about this finding, or is changing the subject the only way you can handle this information?

    As dgruss23 said there is more to the image than just the stars/clumpiness of NGC7320, what about the stars/clumpiness in the "debris arc"? And you might have missed the recent details here.

    The case is at best undecided, and certainly intriguing and in need of more detailed measurements.

    Cheers.
    Last edited by VanderL; 2006-Apr-06 at 05:54 AM.

  7. #1207
    Join Date
    Sep 2005
    Posts
    144
    Quote Originally Posted by VanderL
    Quote Originally Posted by dgruss23
    Last week I was going through the Arp-Madore catalog images on NED. What actually shocked me - was how many of those objects do not have redshifts measured for either, both and/or all components. There is a tremendous amount of work to be done. For some of the objects 2dF or SDSS did get redshifts - and I know as I took some notes that there were instances where the new redshifts showed that there was a large redshift difference. But that is dwarfed by the number of objects in the catalog that still need redshift measurements.
    Really? If you give me some hints on how to do this easily, I can spend a few hours looking up known redshifts, maybe others would like to give it a shot too?

    Cheers.
    I wouldn’t bother if I were you, I doubt if they’ve actually been calculated. In “Seeing Red” (sorry for referring to a book which, despite being full of numbers and references, most mainstreamers proudly claim not to have read, but I assume that’s OK in a thread on “More from Arp et al.”), Arp makes the point that detailed observation of many of his most striking examples of discordant redshift has inexplicably been avoided by major telescopes….

  8. #1208
    Join Date
    Sep 2005
    Posts
    144
    Quote Originally Posted by Cougar
    Quote Originally Posted by dgruss23
    Could you point to an instance where a bridge between two objects is not evidence of interaction?
    I recall someone in this discussion was making a big deal about recent x-ray images of Stephan's Quintet where the x-ray flux from NGC 7318A/B (or 7319?) was overlapping NGC 7320, thereby concluding they were interacting despite their significantly different redshifts. But then a more recent Hubble image of the system showed individual stars in NGC 7320, confirming it was a foreground galaxy significantly closer than the other "fuzzy" members of the quintet, just as its redshift indicated.
    I assume you are referring to one of my recent posts. I’m not sure I made such a “big deal” of this Chandra observation. I would admit to making a slightly bigger deal of the fact that the infrared “shock-wave” shown in the more recent Spitzer image of Stephan’s Quintet, which is strikingly similar in location, extent and even shape to the Chandra X-ray emission zone, also appears to be superimposed over exactly the same part of the so-called “foreground” galaxy NGC 7320. I certainly made the biggest deal about the fact that this already extremely intriguing system also happens to be host to what Arp et al. interpret as a foreground quasar sitting in front of the core of NGC 7319 (ApJ, or astro-ph/0409215 if like me, you do not have access to ApJ). And, to come full circle, that the two main hotspots in the Chandra observation seem, by some extraordinary coincidence (?), to correspond to the position of the alleged quasar and its associated jet. In the ApJ paper cited above, one of these hotspots is identified as being an ULX whose optical counterpart is the quasar in question. Big deal or not?

  9. #1209
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    7,601
    Quote Originally Posted by VanderL
    And you might have missed the recent details http://here.

    The case is at best undecided, and certainly intriguing and in need of more detailed measurements.
    If this case "is at best undecided," then why does your link state:
    Four of the five galaxies in this picture are involved in a violent collision... NGC7318b, is the left of two small bright regions in the middle right of the image. One galaxy, the large spiral at the bottom left of the image, is a foreground object and is not associated with the cluster.
    That large spiral at the bottom left of the image is, of course, NGC 7320, the non-interacting galaxy I'm talking about.
    Everyone is entitled to his own opinion, but not his own facts.

  10. #1210
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by Cougar
    If this case "is at best undecided," then why does your link state:That large spiral at the bottom left of the image is, of course, NGC 7320, the non-interacting galaxy I'm talking about.
    And the reason the article says its a foreground object is because of its redshift. There is nothing new in that which we have not already discussed. We are looking for criteria independent of redshifts to establish whether or not these galaxies are interacting.

  11. #1211
    Join Date
    Mar 2004
    Posts
    13,441
    Have we ceased discussing the Arpian view of 'bridges'?

    Whatever; perhaps we could add Stephan's Quintet to the 'if it weren't an NGC galaxy/object (i.e. relatively large in angular extent), how well would it meet {criteria}'?

  12. #1212
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by VanderL
    As dgruss23 said there is more to the image than just the stars/clumpiness of NGC7320, what about the stars/clumpiness in the "debris arc"? And you might have missed the recent details http://here.

    The case is at best undecided, and certainly intriguing and in need of more detailed measurements.

    Cheers.
    Here is a larger version of that image. Speaking of resolution -in the spitzer infrared image the resolution of NGC 7319 appears the same as that of NGC 7320.

  13. #1213
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by Nereid
    Have we ceased discussing the Arpian view of 'bridges'?

    Whatever; perhaps we could add Stephan's Quintet to the 'if it weren't an NGC galaxy/object (i.e. relatively large in angular extent), how well would it meet {criteria}'?
    Well, you know where I stand on discussing the bridges - but there is nothing new for me to add until someone provides arguments that require new explanation.

  14. #1214
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    7,601
    Quote Originally Posted by dgruss23
    And the reason the article says its a foreground object is because of its redshift. There is nothing new in that which we have not already discussed.
    Take it up with Mariano:

    Quote Originally Posted by SpaceRef.com
    The Spanish scientist Mariano Moles from Instituto de Matematicas y Fisica Fundamental (C.S.I.C.) in Madrid has studied Stephan's Quintet for many years: "It is a personal pleasure for me to see this magnificent image from Hubble. Stephan's Quintet has been a very puzzling object for many years because of the discordant redshift of NGC 7320 and because of the high 1000 km/s relative velocities of NGC 7318A and NGC7318B. Just by looking at this splendid image, it is clear that the redshift discordance of NGC 7320 is now finally resolved. Hubble's resolution is so high that individual stars can be discerned in NGC 7320, showing that it is definitely closer than the more remote, compact group of galaxies.
    Everyone is entitled to his own opinion, but not his own facts.

  15. #1215
    Join Date
    Nov 2005
    Posts
    1,023
    Quote Originally Posted by Nereid
    Have we ceased discussing the Arpian view of 'bridges'?

    Whatever; perhaps we could add Stephan's Quintet to the 'if it weren't an NGC galaxy/object (i.e. relatively large in angular extent), how well would it meet {criteria}'?
    It would be wonderful to continue discussing companions apparently attached to spiral arms, tidal streams, and other types of bridges. In the process, we have to make sure that our criteria for evaluating interaction other than redshift are applied fairly. Unfortunately, some people drag red herrings across the trail and insist on selective application of the evaluating tools (the tools are only appropriate when they yield results supportive of their interpretation of the data). The mods will (and rightly so) hold us "intrinsic redshift types" to a high standard of behavior, and we should expect the supporters of the concordance view to adhere to the same standards. This thread may be more productive if we rein in ad-hom attacks, simple nay-saying without references, and hit-and-run dismissive statements intended to create more heat than light. It is tough not to respond in kind, but doing so would degenerate the discussion and deny us "intrinsic redshift types" a valuable venue for explain our views. Who knows, Nereid? We may turn you to the dark side yet.

  16. #1216
    Join Date
    Mar 2004
    Posts
    13,441
    Quote Originally Posted by dgruss23
    Well, you know where I stand on discussing the bridges - but there is nothing new for me to add until someone provides arguments that require new explanation.
    There are two:
    Quote Originally Posted by Nereid
    Quote Originally Posted by dgruss23
    And how has the mainstream demonstrated that these bridges are a false positive? They must have done something - because nearly everyone is convinced that these are chance alignments. Certainly they must have very strong counter evidence to almost universally argue that these examples are chance alignments.
    {source} IIRC, this was explicitly addressed in one of the 15 papers you cited (I don't recall which one though).

    There's also the work of Bill Keel (selected papers):
    To what extent do these references answer/address your concern?
    {source} Unless I miscounted, there are a total of 15 papers in the two long posts by dgruss23. I'd like to hear from anyone - Arp supporter or challenger or merely onlooker - who's read all 15 (other than dgruss23, of course!).
    Your explicit request, dgruss23, to all reading this thread that Nereid's question here is worthy of being answered, would be quite helpful (an indication of an estimated date by which all 15 would be expected to be read would exceed expectations).

  17. #1217
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by Cougar
    Take it up with Mariano:
    I'm taking it up with anybody here at BAUT that is interested in discussing it. Are you done discussing it?

  18. #1218
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by Nereid
    There are two:To what extent do these references answer/address your concern?
    I'll take a look at them. Give me some time.

    Your explicit request, dgruss23, to all reading this thread that Nereid's question here is worthy of being answered, would be quite helpful (an indication of an estimated date by which all 15 would be expected to be read would exceed expectations).
    I think its worthy for both of us. Anybody else want to answer Nereid's question regarding the papers I've linked to? And Nereid's list too?

  19. #1219
    Join Date
    Nov 2005
    Posts
    1,023
    Quote Originally Posted by dgruss23
    I think its worthy for both of us. Anybody else want to answer Nereid's question regarding the papers I've linked to? And Nereid's list too?
    I have not read all the papers you linked (life intervenes) although I have delved into them and have reviewed the abstracts (and some of the results) of all of them. It can be tough to approach these papers objectively one-by-one without trying to discern the intent of the authors. i.e. "Can I tentatively present a result that may refute the strict interpretation of redshift+distance?" "Can I get further funding if my observations support the interpretations of Arp, the Burbidges, et al?". and on and on.

    Some papers that seem to be quite supportive of the concept of intrinsic redshift are written in a way as to distance the authors from Arp et al. Frankly, I might be the same way myself, since I embrace the concept of intrinsic redshift, but cannot reconcile myself with the variable-mass model of Arp/Narlikar/Hoyle. These are (were, in the case of Fred) really sharp guys thinking outside of the box, and perhaps there is a kernel of truth in their work that can enlighten us.
    Last edited by turbo-1; 2006-Apr-06 at 02:05 AM.

  20. #1220
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    7,601
    Quote Originally Posted by dgruss23
    I'm taking it up with anybody here at BAUT that is interested in discussing it. Are you done discussing it?
    Excuse me. Let me rephrase. I am in agreement with the Spanish scientist Mariano Moles from Instituto de Matematicas y Fisica Fundamental (C.S.I.C.) in Madrid who has studied Stephan's Quintet for many years and who has concluded, "7320... is definitely closer than the more remote, compact group of galaxies." And please note that this conclusion is not based on redshift, but rather the simple fact that Hubble's visible light image of galaxy NGC 7320 resolves into individual stars, and if one looks at the other galaxies in the group, they most definitely do not resolve into individual stars. In the face of this evidence, who can claim that the lower redshift 7320 is not a foreground galaxy not associated with the rest of the quintet? Your only response has been....
    Quote Originally Posted by dgruss
    As for the argument that NGC 7320 is more resolved and that proves it is foreground, its always seemed to me very odd that the star forming debris arc shows the same level of resolution as NGC 7320.
    You should also notice that the debris arc appears much more resolved than the colliding galaxies that generated it. But colliding galaxies should be expected to create regions of extremely active star formation regions. Unlike the point-like stars resolved in 7320, the debris arc looks like it's made up of huge starburst regions, luminous globs, and embedded condensations. To say the debris arc is just as resolved as the point sources in 7320 is like comparing apples and peas. The fact remains that the stars making up NGC 7318A and B are not at all resolved like those in 7320, allowing for 7320 to be conclusively positioned as a foreground galaxy that is not involved in the highly interacting group behind it.
    Everyone is entitled to his own opinion, but not his own facts.

  21. #1221
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    7,601
    Quote Originally Posted by turbo-1
    ...Arp/Narlikar/Hoyle. These are (were, in the case of Fred) really sharp guys thinking outside of the box...
    Do you think there are not a lot of really sharp guys in the astrophysical community who have considered the evidence and have concluded that Arp/Narlikar/Hoyle are off on the wrong track? In case you weren't there, in Seattle at the American Astronomical society's April 1972 meeting, Arp took the opportunity to read a short paper arguing an extreme proposition: The excess redshifts were related to the age of the objects, and the atomic constants were changing with time... [Hoyle] concluded, "This concept appears necessary if we are to understand the result reported by Arp... Martin Schwarzchild told them: "You are both crazy!" 1

    Quote Originally Posted by turbo-1
    ...and perhaps there is a kernel of truth in their work that can enlighten us.
    A kernal. Perhaps. A bit, a grain, a morsel, a nubbin, a crumb... Perhaps.

    1 Conflict in the Cosmos, Fred Hoyle's Life in Science - Simon Mitton (2005)
    Everyone is entitled to his own opinion, but not his own facts.

  22. #1222
    Join Date
    Dec 2004
    Posts
    1,017
    Schwarzchild was correct, IMO.

  23. #1223
    Join Date
    Nov 2005
    Posts
    1,023
    Quote Originally Posted by Cougar
    Do you think there are not a lot of really sharp guys in the astrophysical community who have considered the evidence and have concluded that Arp/Narlikar/Hoyle are off on the wrong track? In case you weren't there, in Seattle at the American Astronomical society's April 1972 meeting, Arp took the opportunity to read a short paper arguing an extreme proposition: The excess redshifts were related to the age of the objects, and the atomic constants were changing with time... [Hoyle] concluded, "This concept appears necessary if we are to understand the result reported by Arp... Martin Schwarzchild told them: "You are both crazy!" 1
    I do not subscribe to the notion that the intrinsic redshift of objects is dependant on their age. A time-dependent mechanism for the emergence of any fundamental property seems a bit silly and I will not be party to it, nor will I agree to defend such an idea. Re Schwarzchild: If you think that the cosmologists working 30-40 years ago had an accurate and profound understanding of the Universe that we cannot improve upon today, perhaps you can take the time to explain the misapprehensions under which we are laboring. (Apologies to Winston Churchill for the "correct" language re prepositions.) I for one think that there still might be room for improvement.

  24. #1224
    Join Date
    Nov 2005
    Posts
    1,023
    Quote Originally Posted by Thanatos
    Schwarzchild was correct, IMO.
    Yet another hit-and-run post with no substance, intended to inflame but not enlighten. Will the mods continue to allow this behavior? It would be wonderful if you could contribute something constructive to this thread, but you seem intent on insult and denigration instead of conversation. Sad.

  25. #1225
    Join Date
    Oct 2003
    Posts
    1,530
    Couple of interesting issues I encountered in the first reference (Toomre & Toomre 1972, very interesting paper) of dgruss23's bridge posts:

    Bridge between M51 and NGC 5195 seems not to be real bridge, but a tidal tail that just happens to be located so that it looks like a connecting bridge. However, the situation still needs a tidal interaction between the two galaxies. Images in NED archive seems to support this conclusion in my opinion.

    They also mention in passing the situation in ARP 175 system:

    Quote Originally Posted by Toomre & Toomre (1972)
    ...the Zwicky triplet ( = ARP 175) has often been cited (e.g., Hoyle and Narlikar 1971; Arp 1971b) as a possible example of a bridge connecting galaxies with very disparate redshifts. Yet now even the shape of that "bridge" warns of an impostor: Such a long, broad, curving crescent seems much more characteristic of a tail emanating from the anonymous galaxy solely as the result of an encounter with IC 3481. This makes IC 3483 presumably just a foreground galaxy.
    (I assume that by "anonymous galaxy" they mean IC 3481A.) If the above is true, then there should be vastly more cases where the tails are not ending to a galaxy with disparate redshift than there are cases where the tail ends in such galaxy.

  26. #1226
    Join Date
    Aug 2004
    Posts
    3,116
    Quote Originally Posted by Ari Jokimaki
    If the above is true, then there should be vastly more cases where the tails are not ending to a galaxy with disparate redshift than there are cases where the tail ends in such galaxy.
    I don't have the time (and knowledge) to read the 15 papers, so I won't comment on them. I can try to shed some light on interesting statements like the above one. I have no easy method or access to data to decide if there are or are not "vastly more cases", but I can give some (probably obvious) examples of tails and the redshift of the galaxies involved. I have not selected these because they are identical, but it may well be that those with different redshifts are harder to find by Googling as they are perhaps not mainstream accepted as interacting.

    The Antennae: identical redshift:
    - NGC 4038 has a redshift of 0.00548 +/- 0.00004
    - NGC 4039 has a redshift of 0.00547 +/- 0.00003
    The Mice: identical redshift
    - NGC 4676A has a redshift of 0.022059
    - NGC 4676B has a redshift of 0.022039
    The Leo Triplet Galaxy: identical
    - NGC 3627 (Messier 066) redshift 0.002425
    - NGC 3628 redshift 0.002812
    - NGC 3623 redshift 0.002692
    Arp 299: identical
    - NGC 3690: redshift 0.010220
    - IC 0694: redshift 0.010377
    NGC5291: identical:
    - NGC 5291: redshift 0.014510
    - NGC 5291N: redshift 0.015544
    - NGC 5291S: redshift 0.014630
    QSO HE 1013-2136: identical?
    - HE 1013-2136: redshift 0.785000
    Text gives redshift for companion as probably 0.785 as well (best fit), but uncertain
    ARP188 (Chainsaw galaxy / Tadpole): identical
    - VV029c: redshift 0.032456
    - ARP188 (UGC 10124): redshift 0.031358
    COSMOS J100003+020146: identical? I can't find their redshifts...
    Whirlpool Galaxy (M51): identical
    NGC 5194: redshift 0.001544 (M51a)
    NGC 5195: redshift 0.001551 (M51b)

    I can look for more examples (no idea if I'll easily find them), but are these in any way relevant or am I wasting my time? It certainly looks to me as if there are a lot of galaxies with tails ending in or accompanied by other galaxies with identical redshifts. But if there are vastly more of those or not is beyond me.

  27. #1227
    Join Date
    Sep 2005
    Posts
    144
    Quote Originally Posted by dgruss23
    Here is a larger version of that image. Speaking of resolution -in the spitzer infrared image the resolution of NGC 7319 appears the same as that of NGC 7320.
    Seen this big, the Spitzer infrared emission zone seems even more clearly to correspond to the Chandra X-ray emission zone as regards that critical area where they both overlay precisely the same part of NGC 7320.

  28. #1228
    Join Date
    Oct 2003
    Posts
    1,530
    Quote Originally Posted by Fram
    I can look for more examples (no idea if I'll easily find them), but are these in any way relevant or am I wasting my time?
    Thanks for the effort Fram.

    Actually, I meant a situation where the tail ends up in empty space. My description was little vague, sorry. Of course these examples of tails ending in similar redshift galaxy do as well, but there we would have to know that the tail is not connecting the two galaxies, because we want cases where the other end of the tail is not interacting with anything.

    See, the situation in the ARP 175 system is that there is two higher redshift galaxies and one lower redshift galaxy, and there is a "bridge" between the higher redshift galaxies and the lower redshift galaxy. Toomre & Toomre suggest that this "bridge" is tidal tail due to two higher redshift galaxies interacting with each other. That would make the lower redshift galaxy completely unrelated, positioned by chance at the end of the tail.

    What I was thinking there is that if we have two galaxies interacting with each other and producing a long tidal tail, then we should have lot more examples of such pairs of galaxies having tails ending up in empty space. Why? Assume that we have lot of similar cases where the lower redshift galaxy is always of same distance from the two higher redshift galaxies. Assume further that the angle of the lower redshift galaxy from the tails' point of view is in all cases, say, 10 degrees (if the tail is pointed within these 10 degrees, it ends up in the lower redshift galaxy). In all these similar, imaginary cases, the tail can point to any direction, so we should have 35 cases with tails ending up in empty space for one case where the tail ends up in the lower redshift galaxy.

    I'm not sure how we should proceed in testing this argument. Some kind of list of double galaxies with tails along a list of cases with bridges between a double galaxy and a disparate redshift galaxy might help. Also, I'm not quite sure if it proves anything, even if we could show that there are a lot more tails ending up in empty space, we probably couldn't still be sure about these few cases of disparate redshifts. But the result could be at least suggestive.

  29. #1229
    Join Date
    Oct 2003
    Posts
    1,530
    I'll just add that the 35 out of 36 estimate is just for the cases where the lower redshift galaxy is of same distance from the two higher redshift galaxies. Number gets bigger if we include cases where the tail falls short of the lower redshift galaxy, and the cases where the tail reaches beyond the lower redshift galaxy. Also the 10 degree angle might be an overestimate.

  30. #1230
    Join Date
    Dec 2002
    Posts
    4,273
    Quote Originally Posted by Cougar
    In the face of this evidence, who can claim that the lower redshift 7320 is not a foreground galaxy not associated with the rest of the quintet? Your only response has been....
    Anybody who notes that the X-ray and infrared emissions from the high z objects are in front of NGC 7320 and suspects that in order for something to be observed in front of something else - it must actually be between the observer and that which is being observed.

    But at any rate I noted the resolution looks quite different when you look at the infrared image .

    You should also notice that the debris arc appears much more resolved than the colliding galaxies that generated it. But colliding galaxies should be expected to create regions of extremely active star formation regions. Unlike the point-like stars resolved in 7320, the debris arc looks like it's made up of huge starburst regions, luminous globs, and embedded condensations. To say the debris arc is just as resolved as the point sources in 7320 is like comparing apples and peas. The fact remains that the stars making up NGC 7318A and B are not at all resolved like those in 7320, allowing for 7320 to be conclusively positioned as a foreground galaxy that is not involved in the highly interacting group behind it.
    Its quite a conundrum. Either NGC 7320 is foreground and X-ray and infrared emission is leaking through the disk of the galaxy or the the X-ray emission is not leaking through and NGC 7320 is at the same distance as the high z galaxies in which case it has to be explained why the resolution appears greater in optical wavelengths (although not in infrared).

    Of course as Turbo-1 has pointed out. This resolution evidence seems not to carry the same weight for you in the case of NGC 1232A.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
here
The forum is sponsored in-part by: