Astronomers Discover an Ultra-Massive Grand-Design Spiral Galaxy (phys.org) 23
Astronomers using the James Webb Space Telescope have discovered Zhulong, the most distant grand-design spiral galaxy identified so far, located at a redshift of approximately 5.2. Phys.Org reports: The galaxy was named Zhulong, after a giant red solar dragon and god in Chinese mythology. [...] Its mass was found to be comparable to that of the Milky Way, which is relatively high for a galaxy that formed within one billion years after the Big Bang, as the redshift indicates. The study found that Zhulong has a classical bulge and a large face-on stellar disk with spiral arms extending across 62,000 light years. The spectral energy distribution (SED) analysis points to a quiescent-like core and a star-forming stellar disk. Furthermore, it turned out that compared to the stellar disk, the center core of Zhulong is red and has the highest stellar mass surface densities measured among quiescent galaxies. The core is quiescent, which is consistent with the expectations of inside-out galaxy growth and quenching.
The study also found that although the disk is still forming stars, Zhulong has a relatively low overall star-formation rate -- at a level of 66 solar masses per year. The baryons-to-stars conversion efficiency was calculated to be approximately 0.3, which is about 1.5 times higher than even the most efficient galaxies at later epochs. These results suggest that Zhulong must have been forming stars very efficiently and is in the transformation phase from star-forming to quiescence. In concluding remarks, the authors of the paper note that Zhulong appears to be the most distant spiral galaxy discovered to date. The properties of this galaxy seem to suggest that mature galaxies emerged much earlier than expected in the first billion years after the Big Bang. The findings have been published on the pre-print server arXiv.
The study also found that although the disk is still forming stars, Zhulong has a relatively low overall star-formation rate -- at a level of 66 solar masses per year. The baryons-to-stars conversion efficiency was calculated to be approximately 0.3, which is about 1.5 times higher than even the most efficient galaxies at later epochs. These results suggest that Zhulong must have been forming stars very efficiently and is in the transformation phase from star-forming to quiescence. In concluding remarks, the authors of the paper note that Zhulong appears to be the most distant spiral galaxy discovered to date. The properties of this galaxy seem to suggest that mature galaxies emerged much earlier than expected in the first billion years after the Big Bang. The findings have been published on the pre-print server arXiv.
Well... (Score:2, Insightful)
The demise of the "standard model" crap is finally near. Its "cosmological" projections don't hold up too well.
Ultra massive? (Score:3)
"Its mass was found to be comparable to that of the Milky Way,"
I wouldn't call our milky way an ultra massive galaxy.
Re:Ultra massive? (Score:4, Funny)
Re: (Score:3)
Re:Ultra massive? (Score:4, Insightful)
There is a single galaxies in the Virgo SuperCluster which, IIRC, outmasses tLG, IIRC. So the Milky Way is also not particularly massive.
Humans and their languages don't really handle logarithms and exponentials very well. Galaxy masses (and star masses) are distributed approximately on a log-normal distribution - double the mass at which you're drawing any particular line, and you'll capture a factor of 1/(2^f(n N>1)) galaxies. Until someone improves our languages, you've little choice but to use, uh, the language of mathematics?
Grand Design? (Score:2)
That's a term I haven't heard on astronomy podcasts.
Too bad TFS didn't define it.
I am left to guess that they consider Milky Way to be one? Seems a bit geocentric but OK.
I could read the paper but I'm really just suggesting that future summaries define uncommon terms.
Re:Grand Design? (Score:4, Informative)
It's sufficiently common to have it's own wikipedia page [wikipedia.org].
It's maybe clearer in contrast to other spiral galaxies, such as barred spirals, or the ones with many, really thin arms confined to the outer part of the disc. Then there is the "strand" of galazy classification extending from "flocculent" spirals to "irregular" galaxies.
I don't listen to podcasts much, but my occasional listening to them sees "grand design spirals" turn up from time to time. It's a pretty common term, widely understood within the general field of "astronomy".
Off the top of my head, I'd expect it to date back to the "tuning fork" classification of spirals [wikipedia.org] from ... late 1930s? After Hubble had shown that "galactic nebulae" were outside the Milky Way, and not structures within it ; before CCD astronomy rendered (wet) darkrooms in observatories superfluous and hugely increased the rate of astronomical discovery. Late 1930s would be about right.
Re: (Score:2)
Or even, you know, read as far as the second paragraph of TFA.
But, of course, sometimes I forget where I am. Comes with age, I guess.
Re: (Score:2)
I'd have to look back to the discussion page to find out who wrote "TFA". It was one of the journal-publishing organisations, wasn't it ? In which case, they'd almost certainly provide links to TFP too, and for the same reason. The paper's authors said what they intended to say in the paper, and
Nice AI-generated summary (Score:1)
"These results suggest that Zhulong must have been forming stars very efficiently and is in the transformation phase from star-forming to quiescence. In concluding remarks, the authors of the paper note that Zhulong appears to be the most distant spiral galaxy discovered to date"
Either this was written by AI or the human author was a key contributor to the training data for ChatGPT.
Re: (Score:3)
OK - there being a "transformation phase" in the evolution of galaxies is a novelty to me. But the word "transformation" isn't very ambiguous, and the "from" and "to" are given. So it's not rocket science.
The people you're picking on are probably the writers at "p
The spelling is "ZhÃlÃng" (Score:2)
Slash's inability to handle the languages it's users use is just plain insulting. It's not that difficult.
Re: The spelling is "ZhÃlÃng" (Score:2)
its*
Re: (Score:2)
But the non-septic members here (and a modest proportion of Americans - not all of them are inbred, navel-gazing idiots, just the ones who vote for Tangerine Shitgibbon criminals) do give a shit. and we know well enough the not complaining will not lead to change in the direction we desire.
The claim is
Age (or date ; pick a direction) ; appearence (Score:3)
TFP says "Unlike the other ultra-massive candidates described above, it [ZhÃlÃng damn you Slash!] has a striking evolved morphology: [morphology details trimmed] already at 1 billion years after the Big Bang." Their formal limits (+/- 1 sigma confidence interval, I think) from z = 5.5 to 5.0 translate (by my calculator, using standard Planck cosmology) to age-of-the-universe of 1.048 to 1.168 Gyr at time of release of this light (look-back times to 12.744 to 12.624 Gyr). To put that into context, in the time it takes the Sun to go 4~5 times around our galaxy, this object went from being a cloud of fairly uniform gas (the cosmic microwave background) to a galaxy with a structure quite similar to our own, today. That is rapid evolution.
I also note, not that the authors make much of it (figure 1, footnote), that there is a brightening ("star-forming region") at the margins of this body which gives a redshift with tighter bounds ( z = 5.19 to 5.12 ; age of universe 1.139 Gyr ; look-back time 12.653 Gyr), which would give the system an appearance more like the "Whirlpool galaxy" M51 [wikipedia.org] than ours. Actually, the masses are not dissimilar either. The Whirlpool is in our cosmic back yard - only 200 to 300 Milky Way diameters away from us. Which may make the evolved appearance of ZhÃlÃng even more remarkable.