S27E69: Webb's Record-Breaking Galaxy Discovery and the Hunt for New Worlds

[00:00:00] This is SpaceTime Series 27 Episode 69 for broadcast on the 7th of June 2024.

[00:00:07] Coming up on SpaceTime…

[00:00:09] The Webb Space Telescope discovers the most distant galaxy known.

[00:00:13] The unveiling of a massive new collection of exoplanet discoveries.

[00:00:17] And new X-ray observations highlight changes in two of our most famous supernova remnants.

[00:00:24] All that and more coming up on SpaceTime.

[00:00:28] Welcome to SpaceTime with Stuart Gary.

[00:00:48] Astronomers have detected the earliest known galaxy so far discovered,

[00:00:52] located a record-breaking 290 million years after the Big Bang some 13.8 billion years ago.

[00:01:00] Over the past two years, astronomers have been using NASA's Webb Space Telescope to explore what's

[00:01:06] often referred to as the Cosmic Dawn, that period in the first few hundred million years after the

[00:01:12] Big Bang when the very first stars and galaxies were born. These most ancient of all galaxies

[00:01:18] provide astronomers with vital insights into the ways in which the gas, stars and black holes were

[00:01:24] changing when the universe was still very young. Back in October last year and again in January

[00:01:30] this year, astronomers used Webb to observe galaxies as part of the James Webb Advanced

[00:01:35] Deep Extragalactic Survey, or JADES for short. Using Webb's near-infrared spectrograph, they

[00:01:41] obtained a spectrum of a galaxy at a redshift of 14. That's a measure of how much a galaxy's

[00:01:47] light has been stretched by the physical expansion of the universe over space time.

[00:01:52] The authors had already found hundreds of candidate galaxies from the first 650 million

[00:01:57] years after the Big Bang. But in early 2023, they discovered a galaxy which showed strong evidence

[00:02:03] of being above a redshift of 14. Now that's never happened before. There were some artifacts of this

[00:02:10] new source which made them wary. It was surprisingly bright, something astronomers wouldn't expect for

[00:02:15] such a distant galaxy. And it was also very close to another galaxy, such that the two appeared to

[00:02:21] be part of a single larger object. When observed again in October last year as part of the JADES

[00:02:27] Origin Field, new imaging data, this time obtained with Webb's narrow near-infrared camera filters,

[00:02:33] pointed even more towards the high redshift hypothesis. Now by this time, the study's authors

[00:02:38] knew they needed a spectrum to confirm their observations. So in January this year, Webb's

[00:02:44] near-infrared spectrograph observed this galaxy, which by now had been catalogued as JADES GSZ14.0,

[00:02:51] for almost 10 hours. And when the spectrum was first processed, it was unambiguous ever

[00:02:56] that the galaxy was indeed at a redshift of 14.32. Now that blows apart the previous most

[00:03:04] distinct galaxy record, which was at a redshift of 13.2. This discovery was not just a new distance

[00:03:11] record. The most important aspect of JADES GSZ14.0 was that at this distance, astronomers now know

[00:03:18] that this galaxy must be intrinsically very luminous. Now from the images, the source was

[00:03:24] found to be over 1600 light-years across, proving that the light was coming mostly from young stars,

[00:03:30] and not from a mission near a growing supermassive black hole. This much starlight implies the

[00:03:36] galaxy is already several hundreds of millions of times the mass of our sun. And of course it

[00:03:41] raises an important question, how can nature make such a bright massive and large galaxy

[00:03:46] in less than the 300 million years that the universe had at that stage been in existence?

[00:03:52] And the data has also revealed other important aspects of this astonishing galaxy.

[00:03:56] The colour of the galaxy is not as blue as it could be, that indicates that some of the light

[00:04:01] is being reddened by dust even at these very early epochs. JADES researcher Jack Hilton from

[00:04:07] the Stewart Observatory at the University of Arizona also identified that JADES GSZ14.0

[00:04:13] was detected at longer wavelengths with Webb's mid-infrared instrument, which was a remarkable

[00:04:18] achievement considering the distance. The mid-infrared observations cover wavelengths of

[00:04:23] light that were actually emitted in the visible light range, which are redshifted out of reach

[00:04:28] of Webb's near-infrared instruments. Jake's analysis indicates that the brightness of the source

[00:04:33] implied that the mid-infrared observation is above what would be extrapolated from the

[00:04:38] measurements by other Webb instruments, indicating the presence of strong ionized gas emission in the

[00:04:43] galaxy in the form of bright emission lines for hydrogen and oxygen. And that's interesting in

[00:04:48] itself because the presence of oxygen so early in the life of this galaxy came as a real surprise

[00:04:53] because it is suggested there must have already been multiple generations of very massive stars

[00:04:58] that had lived out their lives and died before the galaxy was even observed by Webb. Now all

[00:05:04] these observations together are telling us that JADES GSC14.0 isn't like the types of galaxies

[00:05:10] that had been predicted by theoretical models or for that matter by computer simulations to exist

[00:05:15] in this very early part of the universe. Given the observed brightness of the source, astronomers can

[00:05:21] now forecast just how it might grow over cosmic time and so far they've not found any suitable

[00:05:27] analogs from hundreds of other galaxies they've observed at very high redshift. Of course given

[00:05:32] the relatively small region of the sky searched to find JADES GSC14.0, its discovery has profound

[00:05:39] implications for the predicted number of bright galaxies that are likely to exist in the early

[00:05:44] universe. This is space time. Still to come, discovery of a massive new collection of exoplanets

[00:05:52] and new x-ray observations highlight the changes that have taken place in two of the most famous

[00:05:58] known supernova remnants. All that and more still to come on Space Time. Astronomers have announced

[00:06:20] the discovery of no less than 120 confirmed and six new candidate exoplanets, that is planets

[00:06:26] orbiting stars other than our sun. The findings reported in the Astrophysical Journal was made

[00:06:32] using NASA's Transiting Exoplanet Survey Satellite test as part of the Keck Test Survey Program.

[00:06:39] It brings to more than 6,000 the number of confirmed exoplanets now known to exist.

[00:06:46] The new catalogue provides astronomers with a new database to explore, paving the way to study

[00:06:51] their properties and environments in finer detail, especially those planets thought capable of

[00:06:55] harbouring life as we know it. This latest installment of the survey provides thousands

[00:07:01] of radial velocity observations, that is measurements of the reflex motion of a star

[00:07:07] due to an orbiting planet's gravity, what astronomers call the wobble method.

[00:07:11] The observations are revealing a fascinating mix of planet types beyond our solar system.

[00:07:17] They include rare worlds with extreme environments to ones that could possibly support life as we

[00:07:22] know it. The study's authors analysed 9,204 measurements, more than half of which were

[00:07:28] taken over the course of 301 observing nights using the Keck Observatory's Planet Hunting

[00:07:32] Spectrometer instrument. The results represent the single largest contribution to the understanding

[00:07:39] of the physical nature and system architectures of new planets, TESS has discovered. With all

[00:07:44] of the radial velocities combined, they were able to calculate the masses of 120 confirmed planets,

[00:07:50] as well as 6 candidate planets. The survey has revealed a vast diversity of exotic worlds.

[00:07:57] This time, astronomers honed in on planets orbiting so-called sub-giant stars, their future

[00:08:02] versions of the Sun, undertaking the largest homogeneous study of such planets to date.

[00:08:07] You see, eventually, after it runs out of hydrogen in its core, our Sun will expand to become one of

[00:08:14] these giant stars. Now, astronomers already have some pretty good ideas about what might happen to

[00:08:19] the planets in our solar system when the Sun expands into a red giant. But by directly observing

[00:08:25] these more evolved systems, they can begin to put together the puzzle pieces and tie the observations

[00:08:31] to the theory. The results could help predict the future fate of the Earth when the Sun swirls up

[00:08:36] and most likely engulfs our planet. In particular, the study bridges the gap to other systems that

[00:08:42] have already shown to somehow survive this fate or those that are currently in the process of being

[00:08:47] engulfed. In another example of extreme worlds, the authors discovered the largest rocky planet

[00:08:53] ever found, cataloguing it as TOI 1347b. Their work suggests that terrestrial planets, that is those

[00:09:00] with rocky surfaces like the Earth, likely cannot have masses much more than 10 times that of the

[00:09:06] Earth. See, a larger planet would almost certainly accrete a thick envelope of lighter gases, such as

[00:09:12] hydrogen and helium from its nascent gas disk, and therefore it would produce planets far more similar

[00:09:18] to the ice giants Uranus and Neptune or the gas giants Jupiter and Saturn. This is space time!

[00:09:26] Still to come, new X-ray observations highlighting changes to two famous supernova remnants,

[00:09:31] and later in the Science Report, a new study shows that changes in global ocean circulation

[00:09:37] caused by climate change are increasing the frequency and intensity of extreme cold events.

[00:09:42] All that and more still to come on Space Time. NASA's Chandra X-ray telescope has released two

[00:10:03] new movies spanning two decades which are showing astronomers the dramatic changes that have taken

[00:10:09] place in two of the most famous objects in the sky, the Crab Nebula and Cassiopeia A supernova

[00:10:16] remnants. The new observations show that the Crab Nebula shows a stunning view of the activity in

[00:10:22] the inner region around the nebulous pulsar, a rapidly rotating neutron star. A wisp is moving

[00:10:28] outwards at half the speed of light from the inner ring around the pulsar. It then appears to merge

[00:10:34] with a larger outer ring, visible in both X-rays and optical images. The inner X-ray ring consists

[00:10:39] of about two dozen knots that form, brighten and fade. The new movie also shows a high-speed wind

[00:10:46] of matter and antimatter particles from the pulsar which are ploughing through the surrounding nebula,

[00:10:51] in the process creating a shock wave which forms the inner ring. Meanwhile energetic shock particles

[00:10:57] are also seen moving outwards to brighten the outer ring and produce an extended X-ray glow.

[00:11:02] The observations are also showing enormous electrical voltages which are being generated by

[00:11:07] the rotating highly magnetized neutron star. The star is accelerating particles outwards along its

[00:11:14] equator in order to produce the pulsar wind. Now these pulsar voltages are also producing polar jets

[00:11:20] which are spewing X-ray emitting matter and antimatter particles perpendicular to the rings.

[00:11:26] Meanwhile new observations of Cassiopeia A have revealed the distribution of elements

[00:11:31] essential for life as we know it being ejected by the supernova explosion. This report from NASA TV.

[00:11:38] The Crab Nebula, the result of a bright supernova explosion seen by Chinese and other astronomers

[00:11:44] in the year 1054, is 6,500 light-years from Earth. At its center is a neutron star,

[00:11:51] a super dense star produced by the supernova. As it rotates at about 30 times per second,

[00:11:57] its beam of radiation passes over the Earth every orbit like a cosmic lighthouse.

[00:12:03] As the young pulsar slows down, large amounts of energy are injected into its surroundings.

[00:12:09] In particular, a high-speed wind of matter and antimatter particles ploughs into the surrounding

[00:12:14] nebula creating a shock wave that forms the expanding rings. Jets from the poles of the

[00:12:19] pulsar spew X-ray emitting matter and antimatter particles in a direction perpendicular to the ring.

[00:12:26] Over 22 years, Chandra has taken many observations of the Crab Nebula.

[00:12:31] With this long runtime, astronomers see clear changes in both the ring and the jets.

[00:12:37] Previous Chandra movies showed images taken for much shorter time periods,

[00:12:41] a five-month period between 2000 and 2001, and over seven months between 2010 and 2011 for another.

[00:12:50] The longer time frame highlights mesmerizing fluctuations,

[00:12:54] including whip-like variations in the X-ray jet that are only seen in this much longer movie.

[00:13:01] A new set of Chandra observations will be conducted later this year

[00:13:05] to follow changes in the jet since the last Chandra data was obtained in early 2022.

[00:13:11] The second billing in this doubleheader is just as spectacular. Cassiopeia A, or Cas A for short,

[00:13:19] is the remains of a supernova that is estimated to have exploded about 340 years ago in Earth's sky.

[00:13:27] While other Chandra movies of Cas A have previously been released,

[00:13:31] including one with data extending from 2000 to 2013,

[00:13:35] this new movie is substantially longer, featuring data from 2000 through 2019.

[00:13:42] The outer region of Cas A shows the expanding blast wave of the explosion.

[00:13:47] The blast wave is composed of shock waves, similar to the sonic booms generated by a supersonic

[00:13:53] aircraft. These expanding shock waves are sites where particles are being accelerated to energies

[00:13:59] that are higher than the most powerful accelerator on Earth, the Large Hadron Collider.

[00:14:05] As the blast wave travels outwards, it encounters surrounding material and slows down,

[00:14:10] generating a second shock wave that travels backwards relative to the blast wave,

[00:14:15] analogous to a traffic jam traveling backwards from the scene of an accident on a highway.

[00:14:22] These two movies show Chandra's capabilities of documenting changes in astronomical objects over

[00:14:27] human timeframes. Such movies would not be possible without Chandra's archives that

[00:14:33] serve as public repositories for the data collected over Chandra's nearly 25 years of operations.

[00:14:40] This is Space Time. Time now to take another brief look at some of the other stories making

[00:15:01] news in science this week with a science report. A new study warns that changes in global ocean

[00:15:07] circulation caused by climate change may be increasing the frequency and intensity of

[00:15:12] extreme cold events in our oceans. Scientists already know that climate change shifts ocean

[00:15:18] currents and pressure systems. And the researchers have now found that changes in the East Australian

[00:15:24] current and the Augustus current of the coast of South America have led to an intensification

[00:15:29] of ocean upwelling, a process in which deep, cold water is pushed to the surface. A report in the

[00:15:35] journal Nature Climate Change found that these upwellings can create colder killer events,

[00:15:40] leading to mass deaths of animals living close to their temperature limits. The authors were

[00:15:45] in fact able to link mass animal deaths in 2021 to such an intense cold upwelling, and they've

[00:15:51] given the example of bull sharks as one of the species that may be vulnerable to these cold events.

[00:15:58] A bit of good news now, and a new study has shown that kids conceived by IVF have no overall

[00:16:03] increased risk of childhood cancers than the general population. The new findings reported

[00:16:09] in the Journal of the American Medical Association looked at a cohort of about eight and a half

[00:16:13] million children, 260,000 of whom had been born using medically assisted reproduction.

[00:16:20] However, while the researchers say there was no overall increase in childhood cancer rates in the

[00:16:25] assisted reproduction cohort, there was a slightly higher risk of leukemia among those born by fresh

[00:16:31] or frozen embryo transfer. However, it's important to note this increased risk is not certain,

[00:16:36] and it's likely to have a very marginal impact on overall leukemia cases at the population level.

[00:16:43] The use of recycled concrete and glass aggregates in concrete production has now emerged as a highly

[00:16:48] promising means of increasing the recycling rates of waste materials. However, durability issues

[00:16:54] have plagued some combinations of recycled ingredients. Now, a report in the Journal of

[00:16:59] Structural Concrete claims researchers from Flinders University have developed a high

[00:17:04] performance and sustainable concrete formula which can resist alkalized silica reactions,

[00:17:09] which until now have had a negative impact on the mechanical properties and durability of concrete.

[00:17:14] That was due to the significant silica content of some recycled aggregates.

[00:17:20] We usually think of the idea of UFOs, flying saucers and alien life as a fairly recent

[00:17:26] invention of humankind, most likely sparked by the Cold War fears of the evils of communism,

[00:17:31] as well as secret military tests in the 1940s and 50s which government officials didn't want

[00:17:37] to explain. But actually, when you think about it, there are references to alien life going back

[00:17:42] thousands of years, all the way back to the Old Testament. There are tales like those of Ezekiel

[00:17:47] speaking of an immense dust storm coming from the north with an immense cloud full of lightning

[00:17:52] flashes and a huge ball of fire glowing like bronze. The passage goes on to describe four

[00:17:58] human-like creatures within the fire, each with four faces, four wings and legs like columns with

[00:18:04] feet that sparkled from the fire like burnished bronze. In front, each had a human face. On the

[00:18:11] right side, the face of a lion, on the left the face of an ox and in the back the face of an eagle.

[00:18:18] Ezekiel then speaks of things that look like wheels within wheels on the ground beside each

[00:18:23] of the four-faced creatures, and the wheels were sparkling like diamonds in the sun and with rims

[00:18:29] circled with eyes. Tim Mendham from Australian Skeptics says the idea of alien life is a

[00:18:35] reoccurring theme throughout history. It goes back a long way and certainly before the UFO flap that

[00:18:40] as you say started in the 40s and continues to this day, not so much UFOs and things as much as

[00:18:45] there's a new one on X right now in fact it's like a manta ray flying through the skies above

[00:18:49] Florida that's brand new one yeah. I'll have to look at that one okay. Beliefs before this the

[00:18:53] UFO flap were largely about life elsewhere. If you know your HD world and look at the first men

[00:18:59] in the moon which came out I think before war of the worlds, maybe it was after yeah when people

[00:19:03] travel to the moon and they met up with the Thalamites who were the moon people. There's a

[00:19:08] movie made over in the 60s and they looked a bit more anti than people but never mind. So certainly

[00:19:13] there was this idea of life elsewhere and people back in the several hundred years ago philosophers

[00:19:18] like the bible as you say have always spoken about life elsewhere and the way they saw it then in

[00:19:23] their day in the you're looking at the sort of 1600s and when you're looking at some specific

[00:19:28] philosophers, they called it divine plenitude which was basically the idea that God in all her wisdom

[00:19:34] wouldn't have missed the opportunity of populating the whole universe with living beings. If God could

[00:19:38] create life whether humans or animal or whatever why stop at earth right? Why not put it everywhere?

[00:19:43] That's pretty cool that people back then were thinking that there were places other than earth.

[00:19:48] Oh they knew there were places other than earth, they'd seen planets after all right?

[00:19:51] They'd known about Saturn and Jupiter who were sort of you know they were well known to the

[00:19:54] ancients. They didn't know what they were, they thought they were stars. No, no they thought

[00:19:58] they were hard rock planets. Did they? Yeah that's why you could put an animal on it or a creature

[00:20:02] an alien. They didn't know they were gassy things and it goes straight through. This is actually seen

[00:20:06] as being something of the move towards Copernicus. This is often because of the change of the view

[00:20:13] about astronomy in this time from a geocentric, Ptolemaic view of the solar system that the earth

[00:20:20] is in the middle and everything else revolves around the earth to the Copernican view which

[00:20:24] he wasn't the first etc but others had suggested it but he was perhaps the most famous suggesting

[00:20:28] that no the earth is not in the middle, the sun is and all the planets, all these bodies, planets

[00:20:33] meaning wanderers because they go back and forth in the sky, the night sky, we evolve around the

[00:20:38] sun and they obviously knew about Mercury, Venus, Mars, Jupiter and Saturn. They were known, they

[00:20:44] were known from ancient times and Uranus and Neptune were added not long after and then Pluto

[00:20:50] after that. You know the earth will fit 62 times in Uranus? 63 if you squeeze hard. Right okay

[00:20:57] yeah because earth was a planet and the other bodies that they knew about were also planets

[00:21:02] therefore they had to see them as similar and if ours was populated why aren't they populated

[00:21:06] like you can set up a society which they thought would be like our society. People would have

[00:21:10] social lives, they'd live in houses, they'd make music, contemplate the works of God etc and they probably

[00:21:16] sort of you know did their own everything else as well so the God was the center of their explanation

[00:21:21] of why these other planets, these other bodies would be populated so given the intramarital

[00:21:27] Copernicus you like to say that these are all planets, these are all bodies, these are things

[00:21:30] rotating in space, these are solid and that therefore you use the God bit so God could put life on all

[00:21:36] of them. So they were pretty convinced 400 years ago whatever 500 years ago that there was life

[00:21:40] out there not that they were contacting us but they were out there. The question then came to

[00:21:45] what are these things on other planets? Are they men or are they different sort of works? Had they

[00:21:51] been redeemed by divine intervention by Jesus etc as the people on earth had been? Did they look like

[00:21:57] us? Did they not look like us? It was because you're not quite sure that they had been redeemed through

[00:22:02] the death of Jesus that therefore you think have all of these been fine therefore they say well

[00:22:06] they're not humans. They would say it's easy to reject the alien as being humans because that

[00:22:11] made life easier about how Jesus died for us here on earth but did he do the same thing on every other

[00:22:16] planet? So this is basically where our belief that aliens are not human, humanoid from this idea that

[00:22:22] it's from a religious idea if there is life why not because God would have done it but they couldn't

[00:22:26] be like us because Jesus didn't die for them. It's an interesting situation but yeah there's

[00:22:30] people talking about life elsewhere for ages and ages and ages so that these people in the

[00:22:35] 1600s were torn between their religious beliefs and their scientific beliefs and they tried to

[00:22:39] accommodate both and I think that's where it becomes quite interesting from a historical

[00:22:42] and sociological point of view even if they're not very good on the scientific point of view.

[00:22:46] That's Tim Mindem from Australian Skeptics. That's the show for now. Space Time is available

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