Talk:z8_GND_5296
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[edit]What is the wikipedia protocol when a citation accurately represents the secondary source, but the secondary source (though reputable) is incorrect?
I ask this because the statement at the end of para 1 (//Because of the expansion of the universe, the galaxy is about 30 billion light-years away from Earth.//), backed up by footnote 2 is true to source but patently incorrect. I suspect a typo in the BBC article, which should read '13' in place of '30', but can't prove this.
While this galaxy's unprecedented redshift is down to the expansion of the universe, it can't be thirty billion light years away, unless the universe is much older than it looks... and i'm sure that would have been reported, were it to appear to be the case.
Please advise... 86.153.52.172 (talk) 21:41, 24 October 2013 (UTC)
- As I understand it, the BBC source is (or at least could be) correct. The situation in question is one where, in essence, the galaxy was ~13 Giga-light-years away - 13 billion years ago. Due to the expansion of the universe, it has now been carried much further away. According to my notes from an Astronomy course (which of course isn't a citable reference - if this explanation needs to go into the article, a reference will need to be found), our current light cone - the furthest distance we can currently see - is about 46 Gly. That corresponds to the distance something which was 13-or-so Gly away when the universe turned transparent can be at now.
- (Light-cones confuse the heck out of me, so apologies if I've gotten this muddled up, but I think I understand it correctly). --92.20.202.248 (talk) 21:57, 25 October 2013 (UTC)
The BBC article also says "(its distance from Earth of 30 billion light-years is because the Universe is expanding)." so its clearly not a typo. 216.138.195.20 (talk) 22:39, 25 October 2013 (UTC)
- “30 billion light-years” from the BBC article must be a mistake. The original source says “redshift z = 7.51”, which translates to approximately 13 billion light-years away [1]. Since the universe is ‘only’ 13.8 billion years old, there is no way we could see 30 billion year old light on Earth. --bender235 (talk) 23:14, 25 October 2013 (UTC)
- I am no expert on astrophysics, but the 30 billion light years sounds like a mistake. How can the light from this galaxy travel 30 billion years to reach Earth when light didn't exist until the Big Bang 13.8 billion years ago? Truthanado (talk) 23:33, 25 October 2013 (UTC)
- The observed redshift indicates that the light we are now seeing (or recording or whatever) has travelled for ~13 Gly. In the time taken for this light to reach earth (ie 13 billion years), expansion of the universe means that the source (galaxy Z8 GND 5269) should have receded to the estimated current distance of 30 Gly (assuming it hasn't fallen into an enormous black hole, turned into dark matter, moved into another dimension or been eaten by giant aliens).
- This is consistent with current theories on the age of the universe - the rate of expansion between widely separated points is greater than the speed of light, so the dimensions of the universe as measured in light years are greater than it's age as measured in years. 23funnel23 (talk) 23:38, 25 October 2013 (UTC)
- Since when do astronomers account for this “traveling” when announcing the distance of an object? If that was the case, then this whole list would be inaccurate (i.e., not "up-to-date"). --bender235 (talk) 23:53, 25 October 2013 (UTC)
- Ok, now it is correctly stated. Even tho I still don't see comoving distance to be generally used. --bender235 (talk) 00:58, 26 October 2013 (UTC)
- Even if actual current position is considered, instead of observed position, I still cannot understand how 2 objects could come to be 30 billion light-years apart in less than 14 billion years. Even if they were moving in exactly, precisely opposite directions, and each individually at 100% the speed of light, how is that possible? — Preceding unsigned comment added by 108.238.87.3 (talk) 04:31, 26 October 2013 (UTC)
There are a lot of good questions above! The subject is indeed complex. For a quick overview that can take you deeper, I recommend Ned Wright's Cosmology Tutorial, at [2], especially [3], and also the Cosmology Calculator at [4]. The calculator, in particular, allows one to calculate several of the various "distances" that are bandied about for the same object, and has links to explain the subtle differences among them. Be aware that these pages have been developed over a decade or more, and some of the "constants" are a bit out of date -- eg, 13.1 Gyr vs current best estimate of 13.8 Gyr for the age of the Universe. Wwheaton (talk) 06:47, 26 October 2013 (UTC)
It is a common error to assume that because of the limit of the constant speed of light...and the fact that we say the universe is 13 billion years old...that it must also have an upper size limit of approx. 13 billion light years. That is not correct. First, the speed of light restriction does not applie to the expansion of space-time. So in fact at the time of the Big Bang, the expansion of space-time occurred much more rapidly than the speed of light. The other posters have it right -- the usual "size of Universe" projetion is on the order of 40-60 billion light years...yet we can only "see" light back 13 billion years. Eventually, given additonal expansion, most neighboring galaxies will reach the edge of our observable light cone and then....disappear from view (i.e. they will so far away that their light cannot reach us in the elapsed age of the universe. Corrections are welcome -- 66.19.84.4 (talk) 08:54, 26 October 2013 (UTC)Chesspride
- The "size" of the Universe is unknown, as discussed in the flatness problem. The best estimates (cf. Table 8 on p. 39 of Jarosik, N. et al. (WMAP Collaboration). "Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Sky Maps, Systematic Errors, and Basic Results" (PDF). nasa.gov. Retrieved 2010-12-04. (from NASA's WMAP Documents page) ) of the curvature parameter have a perfectly flat universe (ie, Euclidean spatial geometry) near the center of the uncertainty range. If the curvature is exactly 0, then (subject to the assumptions of these parametrizations) the universe is apparently (and always has been) infinite. Values for the curvature slightly larger than zero imply very large finite universes, but if the uncertainty range closely includes 0, as it does, an infinite flat universe is indicated. Note that, since we can never prove that the curvature is exactly 0.0, we can never prove that it is actually infinite by such measurements. While many of us recoil from the idea that the universe could actually be infinite, the true answer seems to be "nobody knows." Wwheaton (talk) 23:48, 27 October 2013 (UTC)
Fixed. Really, was that so hard? Maury Markowitz (talk) 15:55, 26 October 2013 (UTC)
- Thanks, Maury Markowitz, that's a good start, but my own experience suggests it's not really an adequate fix just yet. I read the article looking for an explanation of how 13.8 Billion and 30 Billion are compatible with the speed of light barrier, and I failed to notice one. I then read the Talk, and didn't find an official explanation (though the above comments were somewhat helpful); perhaps your comment and fix weren't yet there. I wrote up a request for an urgent fix as the article is in our In The News section, and then, to avoid the risk of posting an unnecessary request, I checked the article to see was there a fix added in the meantime; I noticed none. I went back to Talk and spotted your comment. I went back to the article and still noticed no fix. I went to the article history to find your mod, I looked at it, and then deduced that the explanation would be found by clicking on 'expanding universe', which I did. This got me to the start of a long and seemingly difficult technical article, most (and perhaps all) of which presumably has little or nothing to do with the explanation I'm looking for. So, as I don't want to read that whole article if there is any other way, I still haven't got any explanation better than the unofficial and perhaps unreliable ones in this Talk section. Apart from anything else, they seem to conflict with possibly mistaken notions I've received from other sources. For instance they suggest that the explanation is that spacetime itself (also known as The Universe) can expand faster than the speed of light, but my recollection from some BBC Horizon programme is that under most theories of Cosmological Inflation this extraordinarily fast expansion only lasts for the fraction of a second it takes for 'the Universe' to reach the approximate size of a grapefruit, though perhaps Horizon was oversimplifying a bit as they often seem to do; I also vaguely remember an article in the Irish Times many years ago about seemingly 'faster than light' redshifts written by a professional astronomer in which there was no suggestion that these had any simple explanation, though I suppose he may perhaps have been talking about redshifts much larger than this one, or he may even have been ill-informed himself, or things may have got clearer since the time when he wrote. Perhaps what we now have is in practice the best that can be hoped for. Perhaps there is no simple and accurate explanation except "that's the current theory". Perhaps there is no clearer yet accurate way of saying in the article 'Here is where you need to be looking if you're confused about the apparent incompatibility of 13.8Billion and 30 Billion with the speed of light barrier'. And perhaps the start of the linked article (rather than some section within it, and/or even some other article) really is the best place to which to link. But if anybody knows how to do any better on any of these points, could they please do so. Tlhslobus (talk) 18:09, 26 October 2013 (UTC)
- After a bit more reading, I've now added my own attempted fix to the problems I mention above. If anybody can do better, please do so. Tlhslobus (talk) 18:33, 26 October 2013 (UTC)
- And thanks again, Maury Markowitz, for what eventually proved to be a very useful fix by you. Tlhslobus (talk) 19:06, 26 October 2013 (UTC)
It is simple:
13 billion years ago, the galaxy was closer than 13 billion lightyears. Because of expansion of the universe, it took 13 billion years for the light to reach us. If we could travel superluminarily, because of the expansion of the universe, it would be 30 billion lightyears away. — Preceding unsigned comment added by 76.103.108.158 (talk) 05:04, 27 October 2013 (UTC)
Um... No. I don't know why this is so hard for people to understand, but the light from this galaxy STARTED OUT 13 billion years ago. Space has expanded since then, which it can do because space isn't matter (which is bound by the speed-of-light speed limit). Therefore, if we tried to reach the galaxy now, it would take 30 billion years. The 30 billion year figure is correct and this article should be fixed. Geesh.
I don't know why this is so hard for people to understand, but the light from this galaxy STARTED OUT 13 billion years ago. Space has greatly expanded since then, which it can do because space isn't matter, thus it isn't bound by Einstein's speed limit. Therefore, if we tried to reach the galaxy now, it would take 30 billion years. — Preceding unsigned comment added by 206.209.101.186 (talk) 22:36, 5 May 2015 (UTC)
I must say I think the 30 billion light year figure is very misleading. I have looked at the arXiv preprint, and do not see it referred to there, though I have not checked the (voluminous) supplementary materials. As Ned Wright (a very reputable senior scientist and professor at UCLA) explains in his Cosmology Tutorial (referenced by the NASA IPAC NED extragalactic website maintained at Caltech), there are many "distances" mentioned in cosmology, with subtly different meanings and assumptions going into them. The distance traversed by the light from the emitting object to us is 13.1 billion light years. The distance from us to that object at some future time, after its emission, is a theoretical construct, forever unobservable and unknown. It depends on assumptions about the geometry of spacetime, the very definition of the particular relativistic "now" involved, and unobservable events in that galaxy's future. Astronomers seldom use that "distance". The galaxy may not even exist at that "now", and will certainly be very different (many times larger, probably) than when observed. It appears that the number 30 billion probably first appeared in a press release, to be later picked up by the BBC. I think it is a journalistic distortion that we are under no obligation to take seriously here, or perpetuate the confusion it creates. Wwheaton (talk) 17:59, 27 October 2013 (UTC)
- Here (The Horn, Oct. 26) is a reference from a University of Texas newspaper, with information provided by Finkelstein, quoting 13.1 billion light years as the distance. Based on this, I am going to change the 30 billion light year distances in the article back to 13.1 billion light years, unless there is objection here in the next day or so. Wwheaton (talk) 22:25, 27 October 2013 (UTC)
- 13 billion lightyears is a correct answer. The trouble is that 3 correct answers exist:
- Originally, the galaxy was closer (about 1/3rd its current lighttraveldistance or about ~4 lightyears) . As the light traveled, the universe grew. The total distance the light travelled was 13 billion lightyears. If one could travel superluminarily, it is about 30 billion lightyears away now because the intervening space expanded. — Preceding unsigned comment added by 76.103.108.158 (talk) 05:58, 28 October 2013 (UTC)
- Can we add that using an Angular diameter distance(ADD) measurement, we see z8_GND_5296 as it was when the Milky Way was 1032.2 Mpc or 3.3665 Gly away from it. This calculation uses calculations from 'A Cosmology Calculator for the World Wide Web' E. L.Wright on the webpage http://www.astro.ucla.edu/~wright/CosmoCalc.html.[1] If the calculator on the award-winning iCosmos is used, then the ADD is 1009.5949 Mpc or 3.2929 Gly (http://www.icosmos.co.uk/index.html). Perhaps we should leave out the measurement of the Luminosity distance, which gives a figure of 78183.0301 Mpc or 254.9989 Gly (iCosmos). Richard Nowell, 12:45 GMT 26th May 2014.
- I cannot reproduce your measurements with that calculator. Not only can I not be sure of your inputs, but the calculator doesn't even output "angular diameter distance". The only similar output is "angular size distance", but this is not the same thing. Therefore I'm removing this new material...while strict calculations are fine for articles, we need more (and more reliable) information in this circumstance. — Huntster (t @ c) 01:20, 27 May 2014 (UTC)
- Agreed. This violates WP:SYNTH as it's not a routine calculation. I'm not sure if you got sidetracked, Huntster, but I reverted the addition. Woodroar (talk) 01:47, 27 May 2014 (UTC)
- Thanks Woodroar, I started cleaning up other aspects of the article, heh. — Huntster (t @ c) 02:12, 27 May 2014 (UTC)
- Agreed. This violates WP:SYNTH as it's not a routine calculation. I'm not sure if you got sidetracked, Huntster, but I reverted the addition. Woodroar (talk) 01:47, 27 May 2014 (UTC)
- I cannot reproduce your measurements with that calculator. Not only can I not be sure of your inputs, but the calculator doesn't even output "angular diameter distance". The only similar output is "angular size distance", but this is not the same thing. Therefore I'm removing this new material...while strict calculations are fine for articles, we need more (and more reliable) information in this circumstance. — Huntster (t @ c) 01:20, 27 May 2014 (UTC)
Hi. I think the Angular Diameter Distance (ADD) is a value that is worthy of inclusion because, (quoting from Wiki article), it "is a good approximation to the "real distance", i.e. the proper distance when the light left the object." Still using that article, the ADD measures the "the angular size of the object". ADD and 'angular size distance (ASD)' both use the mathematical abbreviation as they are terms for the same measurement. Quoting from Hogg 1999 (http://arxiv.org/abs/astro-ph/9905116), "The angular diameter distance DA [] is defined as the ratio of an object's physical transverse size to its angular size". Hogg 1999, revised 2000, is a recognised scientific paper that deals with cosmic distances. Edward L. Wright's 'Cosmology Calculator' (http://arxiv.org/abs/astro-ph/0609593) uses formulae from Hogg 1999, as can be seen from the paper's refs. He refers to 'angular size distance DA'. ADD and ASD are the same.
Reproducing the calculations using the 'Cosmology Calculator for the World Wide Web' (CC), a recognised calculator used in over 222 refereed scientific papers (http://adsabs.harvard.edu/cgi-bin/nph-ref_query?bibcode=2006PASP..118.1711W&refs=REFCIT&db_key=AST), can be troublesome as it hinges on the value of the Hubble constant. Hubble's constant has the mathematical term H0. As can be seen from that Wiki article, the constant's value has changed over time (values are (km/s)/Mpc). The CC has as its default a value of '71'. I used a 'consensus' value of '72.5'. According to the latest results (2013) from the Planck mission, a value of '67.8' is given. In some papers I have seen a value of '75'. In some there is a value of '70'. My consensus value is half way between these values and is one that I have also seen used. Unfortunately, the Finkelstein et al. paper does not give the value they used.
In order to satisfy the most recent thinking, if we use a value of '67.8' and a redshift z=7.51 using the CC, we come up with these results: (the formulae remain the same whatever values are input). Light travel time (LTT) was 13.568 Gyr, co-moving distance is 30.707 Gly and ASD (ADD) is 3.6083 Gly. If we use a consensus value of '72.5' then we get: LTT 12.689 Gyr, co-moving distance is 28.718 Gly and ASD (ADD) is 3.3746 Gly, the value I used. Using the default CC value of '71', we get: LTT 12.957 Gyr, co-moving distance is 29.324 Gly and ASD (ADD) is 3.4458 Gly. If we use the value of LTT from the paper of 13.1 Gyr and a Hubble constant of '70.2' we get values of: redshift z=7.477, comoving distance 29.622 Gly, ASD (ADD) 3.4946 Gly.
We can thus see that the calculation depends a great deal on the value of the Hubble constant. If we use the values given using the LTT of 13.1 Gyr, might this be a way forward? A calculation that gives us how close z8_GND_5296 was to the Milky Way when the light from z8_GND_5296 was first released is a value for the proper distance, and so should not be ignored with an object that existed only a few hundred million years after the Big Bang. Thanks for the interest! Richard Nowell 07:25 GMT 27/05/2014.
- I'm sorry, but we can't include calculations like this as they are against policies like WP:SYNTH. We simply can't, say, take an equation from one source and plug in values from a different source. We need a single source that calculates it for us and gives an answer. WP:CALC gives a few uncontroversial exceptions, like arriving at a person's age from their birth date. Arriving at our own consensus value to plug into an equation is not one of those exceptions. Woodroar (talk) 08:25, 27 May 2014 (UTC)
- Woodroar is correct, Richard. Wikipedia must only report what is stated by reliable sources. We as editors cannot arbitrarily come up with figures, plug them into a calculator, and present the results. Also, I'm not sure what you mean by ADD and ASD being the same...from what I understand, they are similar but distinct. Regardless, I agree that this data point would be useful in the article, but it appears that we will have to wait for a third party to publish it. — Huntster (t @ c) 10:05, 27 May 2014 (UTC)
- Ok, fair enough. I only hoped that seeing the distances in a different, but recognised, way might be of use to the article. At least they are presented here in Talk. Distance in an expanding Universe can depend on your point-of-view. Richard Nowell (talk) 11:02, 27 May 2014 (UTC) Richard Nowell
In the discussion further up the Talk page there is 'confusion' about how the Universe and spacetime can expand faster than the speed of light. I hope I can add useful info by referring to a webpage and published literature. First up is an article from Scienceline. Scienceline is a student-run online magazine published by the Science, Health and Environmental Reporting Program (SHERP) in the Arthur L. Carter Journalism Institute at New York University. The article is called "How could the universe expand faster than the speed of light? That seems impossible!" and the last paragraph states: "So, while the speed of light remains an unbreakable barrier for those of us within the universe, it can’t limit the expansion of space-time itself." This is from the webpage: http://scienceline.org/2007/07/ask-romero-speedoflight/
In the published literature, this paper "Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the universe" by Tamara M. Davis, Charles H. Lineweaver of the University of New South Wales, Sydney, Australia might help. From that paper, available from http://arxiv.org/abs/astro-ph/0310808v2 , section 3.1 is titled "3.1 Misconception #1: Recession velocities cannot exceed the speed of light". It continues: "A common misconception is that the expansion of the Universe cannot be faster than the speed of light." It then outlines their reasoning.
I hope these refs help. Richard Nowell (talk) 22:55, 27 May 2014 (UTC)
References
UDFy-38135539
[edit]But UDFy-38135539, apparently also a galaxy, has a redshift of 8.55, so is more distant? Hobbema (talk) 00:38, 25 October 2013 (UTC)
- Indeed. And last Wed Oct 16, at a Watson Lecture at Caltech in Pasadena, Richard Ellis showed us a slide of the Hubble 2012 UDF ("UDF12") with seven "Lyman dropout" galaxies. Six had redshift z between 7.5 and 9.5. The seventh appeared to have z ~ 9.8, but was not yet fully confirmed spectroscopically by the Keck 10 m. See http://arxiv.org/abs/1211.6804, http://arxiv.org/abs/1301.1228 and http://arxiv.org/abs/1212.5222 for more info from seven months ago. It seems clear that things are changing rapidly (as in exoplanet discoveries), so "the greatest..." on one date, may not hold up very long. Wwheaton (talk) 05:57, 26 October 2013 (UTC)
- UDFy-38135539 was spectroscopically confirmed, but by SED fitting. The abstract of the Nature article says that z8_GND_5296 is the galaxy with the greatest redshift that has been confirmed by looking for the Lyman-alpha line. I made an edit to clarify this. —rybec 18:39, 29 October 2013 (UTC)
- Six of the seven galaxies Ellis showed had been spectroscopically confirmed; the seventh, at z apparently ~9.8, was by SED fitting, using 3.6 and 4.5υ images from IRAC (as also used by Finkelstein et al.) It must be that Ellis's work has not yet appeared in refereed form, though arXiv preprints of submitted papers are available, see above.
- UDFy-38135539 was spectroscopically confirmed, but by SED fitting. The abstract of the Nature article says that z8_GND_5296 is the galaxy with the greatest redshift that has been confirmed by looking for the Lyman-alpha line. I made an edit to clarify this. —rybec 18:39, 29 October 2013 (UTC)
Definition of 'farthest galaxy'
[edit]I removed the comment "Sometimes the title "most distant galaxy" is reused for items at lower redshift than previously announced items." as it was uncited (...and a bit inflammatory) However, the press release is clearly 'spun' -- the author's make no such claim ("...farthest ever") in the actual manuscript. Instead, they focus on how the object has the largest distance to have been confirmed by measurement of the redshifted wavelength of the Lyman-alpha transition. I re-wrote the first sentence of the article in an effort to reflect this (while not getting too technical). The galaxy identified by User:Fotaun (UDFy-38135539) seems to be farther, but I assume that this has not been confirmed by the Lyman-alpha emission. This should be resolved by an expert. Supasheep (talk) 23:26, 25 October 2013 (UTC)
- There are two different "titles", determination of distance by spectroscopic measurement, and that by photometric measurement. The "gold standard" is measurement by spectroscopy. So, in that case, this galaxy is the most distant galaxy with a concrete confirmed distance. However, more distant galaxies are known by photometric estimation, which estimates the redshift by where the spectrum ends, instead of by measuring the emission or absorbtion line locations. -- 70.49.124.77 (talk) 05:52, 27 October 2013 (UTC)
300 Suns a Year
[edit]I wonder if that is per year in the local frame, or as observed from Earth? Also, it would be worth a reference to how this has been estimated. Damoore031 (talk) 00:14, 26 October 2013 (UTC)
underscores?
[edit]Why are the underscores in the article name, but not the talkpage?--Kintetsubuffalo (talk) 01:04, 26 October 2013 (UTC)
- I just tried adding DISPLAYTITLE to this talk page, but it didn't work. —rybec 01:13, 26 October 2013 (UTC)
- Are the underscores to be pronounced? Is the lower case z verbalized differently than the other letters?--Kintetsubuffalo (talk) 01:18, 26 October 2013 (UTC)
- There are established standard ways for naming astronomical objects, but for various reasons astronomers do not always follow them, or use shorthand notations for convenience. These have few standards, so best rule of thumb if you encounter something that looks non-standard (try putting it into Simbad, as a test), you should generally transcribe it verbatim. Underscores in particular are often treated as being an extra odd alphabetic character (as in computer science), and so need to be preserved. Also, in astronomy z is used both as a name and as a mathematical symbol, pronounced "zee" ("zed" if you are European), and written in lower case, with italics if you want to keep its mathematical (algebraic) usage in mind. Wwheaton (talk) 07:01, 26 October 2013 (UTC)
photo of the galaxy itself
[edit]In their press release, the astronomers provided a Hubble Space Telescope photo in which they zoomed in on z8_GND_5296. Thinking that their changes might be copyrightable, I losslessly cropped the TIFF they provided to get this:
It was promptly removed by Materialscientist, who explained taht "it is not helpful to add some blurry blob, a better explanation, and perhaps a wider image would be better." I suspect that the astronomers provided the best image obtainable; taking a larger section from it would be desirable, but I don't know how to find it, not even knowing the ascension and declination of the object. I don't think we can just use the image from the press release, because the freely licensed version is theoretically available. —rybec 02:06, 26 October 2013 (UTC)
- Notice that an image of a source at or near the resolution limit, particularly with no absolute coordinates, is essentially meaningless. Journalists often fail to understand this, and blithely pass on images from press releases (ultimately from scientists, who should really know better) that are ludicrously uninformative. Anyhow, we should not (IMHO) mindlessly pass on such images here, lest we mislead the reader into thinking they have some significance. (Of course sometimes an image that looks like this is actually an image of a physically fuzzy blob, and the author really wants us to notice that it is "slightly resolved", not a point. In such a case the author should really provide a comment or a "point response function" for comparison.) Anyhow, in this case, I would tend to agree with Materialscientist and not use it; it really adds nothing. Wwheaton (talk) 07:13, 26 October 2013 (UTC)
- I wonder what Carl Sagan would have made of that reasoning. (Pictures of "blobs" near the limits of resolution are not always meaningless.) - dcljr (talk) 00:35, 31 October 2013 (UTC)
- Yes, I don't understand the argument either. Are we waiting for some crystal clear image to come down the line? We'll be waiting a long time in that case. This is the clearest that modern technology can provide. Perhaps a slightly wider crop would be appropriate, but having some kind of illustration is better than none at all. — Huntster (t @ c) 22:34, 19 December 2013 (UTC)
missing information
[edit]Can't help but notice one thing missing that is almost always found in a page on a celestial object - the right ascension and declination for this galaxy (in other words, where is it?) — Preceding unsigned comment added by 192.252.203.252 (talk) 15:40, 26 October 2013 (UTC)
Discovery
[edit]The current article reads as though the team members from UC Riverside were responsible for the discovery and led the team. This is because the Discovery section was based on the referenced Science Daily article, which was based on the UC Riverside press release. The discovery team is led from University of Texas Austin by Steven Finkelstein, the first author on the Nature paper (see journal reference at the bottom of the Science Daily article). A better reference might be the McDonald Observatory press release as cited by e.g. the HubbleSite release — Preceding unsigned comment added by 129.219.35.25 (talk) 06:50, 27 October 2013 (UTC)
Etymology
[edit]The reasoning for the strange name should be explained. prat (talk) 01:41, 31 October 2013 (UTC)
- My WAG is that it is the 5296th galaxy examined in GOODS-North-deep, with a limiting redshift of z<=8. -- 70.49.124.77 (talk) 04:20, 31 October 2013 (UTC)
Estimate number of stars in the Z8 GND 5296 galaxy
[edit]What's the estimate number of stars in the Z8 GND 5296 galaxy since it's 12.957 billion light-years from us? Is it 1 billion or what? -- Dantescifi (talk • contribs) 21:10, 15 March 2014 (UTC)
- The Finkelstein paper has the value of 1.0 (+0.2 or −0.1) x 10^9, which is ~1,000,000,000 M☉(a billion solar masses). Perhaps we should include this in the article, as it puts the enormous star formation rate more in context? Richard Nowell (talk) 09:05, 29 May 2014 (UTC)
Uploading_Picture_Of_z8_GND_5296_With_Permission
[edit]I have contacted Steve Jefferson, the Communications Officer at the W. M. Keck Observatory with an enquiry about using the picture from this webpage: http://www.keckobservatory.org/recent/entry/astronomers_discover_most_distant_known_galaxy .
He emailed me back, knowing that I would use his reply email for clarification. He writes: "Richard, Thanks for your interest in Keck Observatory. We do have the right to let you use that image, but I believe Dr. Finkelstein, cc'd here, does. Good luck! -steve".
He kindly passed the message on to Steven Finkelstein, Assistant Professor of Astronomy, The University of Texas at Austin. S. Finkelstein replied: "Hi Richard, Sure, you have our permission. - Steve Finkelstein".
I hope to upload the picture tomorrow, as it will add to this article. A picture is always useful. Richard Nowell (talk) 23:24, 27 May 2014 (UTC)
- Richard Nowell, because of copyright issues, we have to know what license they are releasing this image under. Simply saying "you have permission" does not satisfy this. If you would, go to my user page and, on the left side, click "email this user" and send me an email address so I can figure this out with Finkelstein, confirm that he does actually hold copyright over this image, and that any release would be something like CC-by and not Wikipedia only. — Huntster (t @ c) 03:04, 28 May 2014 (UTC)
- Am sending you his email. He is credited underneath that picture, so presumably he holds the copyright. Best to be safe about such things though. It will make a significant addition to the article, which is why I think it is worth the trouble. Great image! Richard Nowell (talk) 07:31, 28 May 2014 (UTC)
- Got the email. Now I understand more, and it is an even bigger problem. He is only one of several persons credited...to release the image under a free license, they would all have to agree to the license if they all co-hold the copyright. Hopefully we can figure something out. — Huntster (t @ c) 08:12, 28 May 2014 (UTC)
- Well we live in hope... As Dr. Finkelstein is the author of the paper, perhaps he has a picture that he can give us? The one we are chasing seemed to be the most appropriate, but I guess there are others that might hold the same credibility but be easier to use. It would be good for this article to have a picture of the object this article is about. Thanks for your help, Richard Nowell (talk) 13:11, 28 May 2014 (UTC)
- Has anything happened with this yet? Can I do anything? Rgds Richard Nowell (talk) 13:35, 5 June 2014 (UTC)