S27E60: Unveiling Cosmic Ancestry: The Quest for Population III Stars

[00:00:00] This is SpaceTime Series 27 Episode 60 for broadcast on the 17th of May 2024.

[00:00:06] Coming up on SpaceTime, one of the most ancient stars ever seen in another galaxy,

[00:00:12] NASA's Hubble Space Telescope goes offline following a gyroscope issue,

[00:00:17] and Snoopy launched into space. All that and more coming up on SpaceTime.

[00:00:24] Welcome to SpaceTime with Stuart Gary.

[00:00:28] Astronomers have discovered one of the most ancient stars ever seen in another galaxy.

[00:00:49] It's an important find because it will help lead us to one of the holy grails of astronomy,

[00:00:54] that is the discovery of the very first generation of stars.

[00:00:58] These first generation stars, so-called Population III stars, transform the universe.

[00:01:05] They brought the cosmos out of the cosmic dark ages before the first stars were formed

[00:01:09] and into the epoch of reionization, when ultraviolet light from those first stars

[00:01:15] ionized the universe, making it appear clear as we see it today.

[00:01:20] But these first generation stars were very different from the stars we see around us today.

[00:01:25] For a start, they were created out of the pure hydrogen and helium formed in the Big Bang

[00:01:30] 13.8 billion years ago. After all, there were no other elements. Those elements were all

[00:01:36] formed from those first stars, either during their lifetimes or when they died.

[00:01:42] So everything from the iron in the blood running through your veins, to the calcium in your teeth

[00:01:46] and the sodium powering your thoughts were all first created by these most ancient of all stars.

[00:01:53] And being so pristine, these first stars are also thought to have been very different in

[00:01:57] appearance from the stars we see today. Astronomers think they're all very massive

[00:02:02] and extremely luminous, possibly hundreds of times bigger and brighter than today's big stars.

[00:02:08] And being so big, they would have burned through their nuclear fuel supplies very quickly.

[00:02:13] Like the James Deans of the stellar world, they would have lived fast and died young,

[00:02:18] living for maybe just a few million years or so, compared to the 12 billion year lifespan

[00:02:23] our sun is expected to have. Because of their short lifespans, no one has been able to see

[00:02:28] one of these first generation stars. But scientists do occasionally find unique stars

[00:02:34] formed directly out of their remains, so-called Population II stars. Now a report in the journal

[00:02:40] Nature Astronomy claims they've discovered one of these ancient Population II stars in another galaxy.

[00:02:47] The study's lead author Anirudh Chetty from the University of Chicago says the star provides

[00:02:51] a unique window on the very early element forming processes in galaxies other than our own.

[00:02:57] See, astronomers have built up an idea of how these stars were enriched chemically,

[00:03:01] how they were influenced by the first stars in the universe, by looking at these Population II stars

[00:03:06] in our own galaxy, the Milky Way. But what we don't know is whether or not these signatures

[00:03:12] are unique to the Milky Way, or whether it's pretty much the same in other galaxies as well.

[00:03:17] Chetty specializes in what's called stellar archaeology, reconstructing how the earliest

[00:03:22] generations of stars changed the universe in order to understand the properties of these

[00:03:27] first stars and the elements they produced. With no first generation stars left in the

[00:03:32] visible universe, Chetty and colleagues are looking for stars that formed out of the ashes

[00:03:36] of that first generation. But it's hard work because even second generation stars are incredibly

[00:03:42] ancient and rare. We've only ever found a handful in our own galaxy. And that's the problem. See,

[00:03:48] most stars in the universe, including our own sun, are the result of tens of thousands of

[00:03:53] generations, building up more and more heavy elements each time. Chetty says that maybe

[00:03:59] fewer than one in a hundred thousand stars in the Milky Way would be a second generation star.

[00:04:05] So finding them is incredibly laborious. But he says it's worth it to get snapshots of what

[00:04:11] the universe would have looked like way back in time. In their outer layers, these Population II

[00:04:16] stars are preserving the elements near where they were formed. So if you can find a very old star

[00:04:22] and get its chemical composition, you can understand what the chemical composition of

[00:04:26] the universe was like when that star was created billions of years ago. For this study, Chetty and

[00:04:31] colleagues aim their telescopes at an unusual target, the stars that make up the Large Magellanic

[00:04:37] Cloud. The Large Magellanic Cloud is a bright satellite dwarf galaxy orbiting the Milky Way.

[00:04:43] It's visible to the unaided eye in the southern hemisphere. Now, because it's a separate

[00:04:48] independent galaxy from the Milky Way, its older stars will form outside the Milky Way, thereby

[00:04:53] giving astronomers a chance to learn about whether conditions in another galaxy are the same as what

[00:04:58] they are in our galaxy, whether the early universe was uniform or whether it was different in different

[00:05:04] places. The authors search for evidence of especially ancient stars in the Large Magellanic

[00:05:09] Cloud and catalog 10 of them, first with the European Space Agency's Gaia satellite and then

[00:05:15] with the Magellan Telescope in Chile. And one of these stars immediately jumped out as an oddity.

[00:05:22] It had fewer heavier elements than any other star ever observed in the Large Magellanic Cloud.

[00:05:27] And that's the key. It means it was probably formed in the wake of the very first generation of stars.

[00:05:34] So it had not yet built up heavier elements over the course of repeated starbursts and deaths.

[00:05:40] As they mapped out the star's elements, they were surprised to see it had a lot less carbon than

[00:05:45] iron compared to what we see in ancient Milky Way stars. That's intriguing and it suggests that

[00:05:51] perhaps carbon enhancement in the earliest generation as we see it in the Milky Way

[00:05:55] isn't universal. It suggests that on a cosmic scale there are differences from place to place.

[00:06:02] The findings also corroborate other studies that have suggested the Large Magellanic Cloud

[00:06:06] is made up of far fewer stars early on compared to the Milky Way. Chitty says this discovery

[00:06:12] suggests there should be many of these very ancient stars in the Large Magellanic Cloud

[00:06:17] if you can look closely enough. This is Space Time.

[00:06:21] Still to come, NASA's Hubble Space Telescope plunges into safe mode following ongoing gyroscope

[00:06:27] problems and Snoopy launched into orbit. All that and more still to come on Space Time.

[00:06:49] NASA's Hubble Space Telescope is back in operation after suddenly entering safe mode last month due

[00:06:54] to an ongoing gyroscopic issue. Mission managers say the orbiting observatory's instruments are

[00:06:59] stable and the telescope is in good health. Hubble automatically entered safe mode when one

[00:07:04] of its three gyroscopes gave a faulty reading. The gyros measure the telescope's turn rates and

[00:07:10] are part of the system that determines which direction the telescope is pointing in. While

[00:07:15] in safe mode, science operations are suspended and the telescope waits for new directions from

[00:07:20] the ground. Now this particular gyro also caused Hubble to enter safe mode back in November after

[00:07:26] returning similar faulty readings. Mission managers are currently working to try and identify

[00:07:31] permanent solutions. If necessary, the spacecraft can be reconfigured to operate with only one gyro

[00:07:38] with the other remaining gyro placed in reserve. The spacecraft actually had six new gyros installed

[00:07:44] during the fifth and final Space Shuttle servicing mission back in 2009. And to date, three of those

[00:07:50] gyros remain operational including the one that's constantly experiencing fluctuations.

[00:07:55] NASA scientists like Hubble to use three gyros to maximize efficiency but they could continue

[00:08:01] to make science observations using only one gyro if required. Launched back in 1990, Hubble has been

[00:08:08] observing the universe for more than three decades and recently celebrated its 34th anniversary.

[00:08:15] However, while mission managers were resolving the latest Hubble issue, NASA's exoplanet hunter,

[00:08:20] the Transiting Exoplanet Survey Satellite TESS, remained shut down after it too went offline.

[00:08:27] TESS initially stopped functioning back on April the 8th but was returned to operations on the 17th.

[00:08:33] However, it shut down again just six days later. Scientists are now trying to determine if both

[00:08:38] shutdowns were caused by the same problem. TESS completed its primary science mission back in July

[00:08:44] 2020 and it finished its first extended mission in September 2022. And it's now underway in its

[00:08:51] second extended mission. This is Space Time. Still to come, a new CubeSat called Snoopy

[00:08:58] launched from the International Space Station. And later in the Science Report, a first known

[00:09:03] example of a wild animal using a plant with medicinal properties to treat a wound. All that

[00:09:10] and more still to come on Space Time. A new CubeSat's been launched from the International

[00:09:29] Space Station. Called Snoopy, the Signals of Opportunity P-band investigation, the six-unit

[00:09:35] CubeSat's designed to test new passive technologies to measure soil moisture and improve crop yields.

[00:09:42] The spacecraft's testing a low-noise radio receiver designed to measure root zone soil

[00:09:47] moisture by harnessing radio signals produced by commercial satellites. The probe was initially

[00:09:53] launched into space back on March 21st from the Cape Canaveral Space Force Station in Florida

[00:09:58] aboard a Dragon cargo ship as part of SpaceX's 30th commercial resupply mission for NASA.

[00:10:04] Once on the station, Snoopy was released into low-Earth orbit on April 21st.

[00:10:10] Snoopy principal investigator Professor James Garrison from Purdue University

[00:10:14] says Signals of Opportunity will try to reutilize what already exists. It'll try and collect the

[00:10:20] P-band radio signals produced by many commercial telecommunications satellites and repurpose them

[00:10:25] for scientific applications. In this way, the instrument would maximize the value of space-based

[00:10:31] assets already in orbit, transforming existing radio signals into research tools. Garrison says

[00:10:37] by looking at what happens when satellite signals reflect off the Earth's surface and then comparing

[00:10:42] that to signals that hadn't been reflected, scientists can extract important information

[00:10:47] about the surface where the signal is reflecting. P-band radio signals are powerful, penetrating

[00:10:53] the Earth's surface to a depth of around 30 centimeters. This makes them ideal for studying

[00:10:58] roots and soil moisture and snow water equivalent. By monitoring the amount of water in the soil,

[00:11:04] scientists will get a good understanding of crop growth. Garrison says you can also monitor

[00:11:09] irrigation levels. Snoopy is going to be the first technology demonstration of a new technique for

[00:11:15] measuring roots on soil moisture and snow water equivalent. So Signals of Opportunity tries to

[00:11:21] reutilize what already exists. There are all these communication satellites that are transmitting

[00:11:26] in these frequencies that would be of use to us. And by looking at what happens when they reflect

[00:11:31] off the surface of the Earth and comparing that to the signal that has not reflected, we can extract

[00:11:38] important properties of what's going on in the surface where the signal reflects.

[00:11:43] So by monitoring the amount of water in the soil, we get a good understanding of the forecast for

[00:11:49] crop growth. We can also more intelligently monitor irrigation so we're not wasting water,

[00:11:54] we're not over-irrigating. Similarly, snow is very important because that's also a place where water

[00:12:00] is stored. It also has not been accurately measured globally with remote sensing. So there are some

[00:12:07] unknowns in terms of forecasting the availability of fresh water that comes from snow. So we are

[00:12:12] offering the first capability of directly measuring this roots on soil moisture. The reason we use

[00:12:17] satellites is because we can make these measurements globally. It's one thing to go out to

[00:12:23] one field and put some sensors in the ground. Understanding all of these processes globally

[00:12:28] requires satellites. The antennas is another interesting part of this design. We're basically

[00:12:34] using communications antennas. And one of the problems in working with low frequency signals

[00:12:40] is the need for a large antenna. And we're using the CubeSat platform because it's a standard

[00:12:45] platform. It allows low cost rapid launch of new instruments to design an antenna that is about a

[00:12:52] meter across of a very thin material but then can fold up prior to launch and fit within the CubeSat

[00:12:59] architecture. Snoopy is going to be a technology demonstration mission launched off of the

[00:13:05] International Space Station and our plan is to collect data for about six months.

[00:13:11] ESCO has been a great partner. I mean they're very good at working with universities and did

[00:13:15] the support under the ACT, Advanced Components Technology Program. And so then the next stage

[00:13:21] would be to put together a design for a constellation of small satellites using Snoopy.

[00:13:29] That's James Garrison, Professor of Aeronautics and Astronautics at Purdue University and principal

[00:13:38] investigator for the Snoopy project. This is Space Time. And time now to take another brief

[00:14:00] look at some of the other stories making use in science this week with a science report.

[00:14:05] A new study claims that long-term daily use of aspirin could help slow and even prevent the

[00:14:11] progression of colorectal cancer. A report in the journal Cancer looked at tissue samples of 238

[00:14:18] patients who underwent surgery for colorectal cancer, 12% of whom were using aspirin.

[00:14:24] Compared with tissue samples from patients who did not use aspirin,

[00:14:27] samples from aspirin users showed less cancer spread to the lymph nodes and also showed immune

[00:14:32] cells were able to get into the tumors a lot easier. When they replicated the experiment in

[00:14:37] cells, the team found that cells treated with aspirin seemed to have more molecules that

[00:14:42] encouraged immune cell activity, supporting the notion that aspirin may be supporting

[00:14:46] immune cells patrolling the area. The results indicate aspirin use could complement

[00:14:51] cancer prevention or therapy. A new study has shown that chimpanzees learn to improve

[00:14:58] their tool use as they age, learning and honing their skills throughout their lives.

[00:15:03] The findings reported in the journal PLOS Biology are based on observations of 70 wild

[00:15:09] chimps of various ages using sticks to retrieve food in a national park in West Africa.

[00:15:14] They found that as the chimpanzees aged, they became more skilled at employing subtle finger

[00:15:19] grips to handle the sticks and these motor skills became fully functional by age 6.

[00:15:25] Beyond this age, chimps continued to hone their skills and displayed more advanced manoeuvres,

[00:15:30] such as using sticks to extract insects from hard-to-reach places or adjusting their grip

[00:15:35] to suit different tasks. These skills seem to have become fully developed by age 15.

[00:15:42] The findings suggest that these skills aren't just a matter of physical development, but also

[00:15:46] of learning capabilities for new technological skills continuing on into adulthood.

[00:15:53] The new findings followed the release last week of a study by a team of German and Indonesian

[00:15:57] scientists who witnessed the first known example of a wild animal using a plant with medicinal

[00:16:03] properties to treat a wound. The observations, published in the journal Scientific Reports,

[00:16:08] involved a male Sumatran orangutan named Rackus, who was seen chewing up the leaves of a plant

[00:16:14] called Eka Cunning and then applying the resulting mush to a wound on his cheek repeatedly for

[00:16:19] several minutes. Interestingly, this same plant is used by local people to treat wounds and

[00:16:24] conditions including dysentery, diabetes and malaria. After applying this improvised ointment

[00:16:30] to the wound for seven minutes, covering it entirely, Rackus continued to munch on the

[00:16:34] plant's leaves for around half an hour. He then repeated the same procedure for several days in a

[00:16:40] row. And it worked! There were no signs of infection over the following days and the wound had closed

[00:16:46] up within five days and fully healed within a month. The authors say that because Rackus repeatedly

[00:16:52] coated his wound with the plant material and then kept eating the leaves for half an hour afterwards,

[00:16:57] it's likely that he was intentionally treating the wound with a plant that he knew would help him heal.

[00:17:02] Among the most haunting of movie images are the final scenes of the 1970s horror movie

[00:17:08] The Wicker Man. And while this story itself is fiction, there are stories of ancient pagan

[00:17:14] traditions which could well be the basis for such festivals. But as Tim Mendham from Australian

[00:17:19] Skeptics points out, some of these traditions are far more recent than you'd think.

[00:17:23] There's a story that came out recently, just a historical article, looking at a town called,

[00:17:28] now I'm not quite sure of the pronunciation, Painswick, P-A-I-N-S-WICK, an English town

[00:17:33] that foreshadowed the Wicker Man concept. Now let's talk about the town first and its ceremony.

[00:17:39] A little ceremony started up in the 18th century by the son of a wealthy merchant who lived in the

[00:17:43] area who wanted to introduce a bit of a pagan festival. They all danced around and they'd have

[00:17:47] a statue of Pan, who was pretty much common in pagan festivals etc. And the people were crying,

[00:17:53] making lots of noises and things and possibly doing naughty things.

[00:17:56] What do you mean by naughty things? You mean two scoops of ice cream instead of one?

[00:18:00] Absolutely. Yeah, with lots of nuts on top or they had romantic encounters or they drank too much

[00:18:05] or they cheated at Scrabble. I don't know. But anyway, so there's this festival going on,

[00:18:10] a bit of a pagan festival. They weren't really pagans but they're having a bit of a good time.

[00:18:14] They had a thing called Feast Sunday which was supposed to be part of it and naturally some of

[00:18:19] the local clergy weren't too keen on it. They were saying it's bad etc. They'd eat puppy dog pie.

[00:18:23] Puppy dog pie is not made with puppy dogs. Just a bowl is in the shape of a dog so that becomes

[00:18:27] a puppy dog pie and the bow wow sauce which also has nothing to do with puppies etc. It's just a

[00:18:32] mixture of various concoctions. Apparently very interesting, nothing particularly nasty in there.

[00:18:37] And they did this for a while from the 1700s, 1800s until one clergyman who was there said

[00:18:43] this is appalling, this is demonic, we have to stop this. And he stopped them doing it and took

[00:18:47] the statue of Pan and buried it. And another clergyman later on who heard about this festival,

[00:18:53] thought it was an ancient like pre-Roman festival or something like that, dug up the statue and

[00:18:58] started it again but then it died out. Yeah I thought it was Celtic too. I thought it was

[00:19:02] really old stuff. This is before the Druids. Well the whole concept of Druids is a bit dodgy as well.

[00:19:09] They were Druids but not necessarily the way they're portrayed in the middle of Stonehenge.

[00:19:12] Okay. There's a lot of stuff that's been made up since Romanticize at about the same time as this

[00:19:17] 17th, 18th century where the fascination with what's called megalithomania with stone,

[00:19:23] Stonehenge type things and all these stone circles etc became a real thing. And suddenly rather than

[00:19:28] these stones which farmers hated because they were in the way and they'd break them up and try to move

[00:19:32] them on because they couldn't plough their fields, suddenly they become special. And some people

[00:19:36] suggested the giant stones, put there by giants because they're so big. Others saying it's pagan

[00:19:41] festivals blah blah blah. Others saying it's Druids involved and the Druids would not have

[00:19:44] been involved in any of these stone circles. Those stone circles predated very much any Druid

[00:19:49] period and the Druids themselves became Romanticized. So this festival in Painswick, I'm sure it's

[00:19:54] pronounced Penic probably, is a recent, if you recall a couple of hundred years recent development

[00:19:58] for this clergyman who thought it'd be good idea to re-institute this ancient Celtic festival.

[00:20:03] They suddenly found out it wasn't and then it stopped and the statue was then put away in the

[00:20:07] local manor house gardens or something like that. Now some people have been comparing this festival,

[00:20:12] this pagan festival, wouldn't be the only one in Britain either. But comparing this one to the

[00:20:15] Wicker Man which is interesting. The Wicker Man is a film from the 70s starring Christopher Lee,

[00:20:21] Vampire, Dracula and Edward Woodward. I remember it well, yeah. Edward Woodward's serious actor

[00:20:26] figures. It's a good film, British film, scary. I won't give away the ending but it's about this

[00:20:31] pagan festival where they build this huge Wicker Man, looks like a man, out of sticks, out of hay

[00:20:37] or whatever they use and it's so many tens of meters tall. And this policeman who's a strong

[00:20:42] Christian goes and investigates this pagan festival and he meets up with all sorts of people

[00:20:46] dancing around, singing and doing naughty things again. The trouble is the Wicker Man film is based

[00:20:51] on a book called The Ritual which is written by an actor, writer, who had an unsuccessful play that

[00:20:57] was never produced and then wrote it as a book and the book became the film Wicker Man except

[00:21:01] they didn't use much of the book in the film Wicker Man. But yeah, it's regarded as pretty good,

[00:21:05] pretty scary, pretty decently made film. There's a remake done fairly recently with Nicholas Cage

[00:21:10] which everyone would prefer to forget but therefore the link between this Painswick festival

[00:21:15] that doesn't happen anymore and the Wicker Man is a bit tenuous. They just both are pagan festivals

[00:21:19] and you'll find across Britain there's all sorts of pagan festivals, some of them more exciting

[00:21:23] than others. It's normally just fun, people dancing around and they stick little masks on and dance

[00:21:27] around at Maypole etc. I think it's all very exciting. Half of these things have no ancient

[00:21:32] heritage at all, others do. But it's an interesting thing especially in England,

[00:21:35] things happen a lot actually. I'd rather go and see the Hellfire Club which was a real

[00:21:39] sort of group of people about the same time as this was first invented who used to do supposedly

[00:21:45] satanic rituals in High Wycombe which is in the middle of England run by a nobleman and they

[00:21:51] used to drink a lot and probably do naughty things as well. Seems to be a common practice.

[00:21:55] The whole idea of the Wicker Man, that's the bit that interests me in this story,

[00:21:58] that's based on early pagan rituals, isn't it? Sort of. Again, it's a book, a fictional book

[00:22:06] that came out in the early 70s. The practice itself of doing this? I don't know if the

[00:22:11] practice ever really happened, I don't know. Is the Wicker Man a real thing? Is there a burning

[00:22:18] like a Guy Fawkes type burning of an effigy? That stuff's probably been going on for a long time,

[00:22:22] creating an animal or a person or something and then there's a huge bonfire, who knows?

[00:22:28] Wouldn't be surprised if that has been going on a long time, but whether the Wicker Man is based

[00:22:32] on an actual event like that, there's no indication that I've seen that the guy who wrote the book

[00:22:36] really based it on real things. That's Tim Mendham from Australian Skeptics.

[00:22:41] And that's the show for now. Space Time is available every Monday, Wednesday and Friday

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