Dark Stars and Cosmic Origins: Unraveling the Early Universe

This is Spacetime Series twenty eight, episode one hundred and twenty two, for broadcast on the tenth of October twenty twenty five. Coming up on space Time, a potential smoking gun signature for super massive darkstars, Australia's new lunar Rova, and piecing together the early Solar System. All that and more coming up on space Time. Welcome to space Time with Stuart Gary. Astronomers have identified a new type of star in the very early universe which fits the profile of the long hypothesized super massive darkstar. If they exist. Darkstars are very different from the kinds of stars we see in today's universe. The first stars in the universe, so called Population three stars, were formed out of the pristine hydrogen and helium created in the Big Bang thirteen point eight billion years ago. They were extremely massive, hot blue stars formed in the first few hundred million years after the Big Bang. They ended the cosmic dark ages and brought about the epoch of realization, resulting in the universe we see today. During their lives, fusing hydrogen and helium on the main sequence, and when they died, they produced all the other elements in the cosmos today, but now new observations by the WEB space telescope have revealed that some of the very first stars in the cosmos could have been very different from these regular fusion powered stars. WEB has identified four extremely distant objects which are consistent both from the point of view of their observed spectra and morphology, with being super massive dark stars. The studies authors described super massive dark stars as extremely bright, giant yet puffy clouds primary made out of hydrogen and helium, which is supported against gravitational collapse by the minute amounts of self annihilating dark matter inside them, hence the term dark stars. These super massive dark stars and their black hole remnants could be keys to solving two recent astronomical puzzles, the larger than expected extremely bright yet compact distant galaxies observed by WEB and the origin of the super massive black holes powering the most distant quasars in the universe, black holes which theoretically didn't have enough time to get that big. One of the sturdies authors Katherine Freese from the University of Texas at Austin, developed the original theory behind dark stars with Doug Spolier and Parlo Gondolo back in two thousand and eight, which was reported at the time in the journal Physical Review Letters. In that paper, they envisioned how dark stars might have led to super massive black holes in the early universe. Then, in a twenty ten Astrophysical Journal publication, Freezing colleagues identified two mechanism through which dark stars could grow to become super massive. They also predicted that these could seed super massive black holes powering many The most distinct wasars in the universe. Although dark matter makes up twenty five percent of the universe, its nature has continued to elude scientists. They know it exists because they can see its impact on normal baryonic matter, preventing galaxies from spinning apart as they rotate and magnifying more distant objects behind them through gravitational lensing. The current thinking is that. Dark matter probably consists of a new type of elementary particle yet to be observed or detected. While the hunter to text such particles has been on for a few decades now, no conclusive evidence has ever been found. Among the leading candidates for. Dark matter are weakly interacting massive particles or whimps. When they collide, these particles would theoretically annihilate themselves depositing heat into collapsing clouds of hydrogen and converting them into brightly shining dark stars. And the conditions for the formation of dark stars would have been just right a few hundred million years after the Big Bang at the center of dark matter Halo's and this is when and where the first stars in the universe are expected to have formed. Free says the new WEB observations have now identified spectroscopic super massive dark star candidates, including the very earliest objects at redshift fourteen. Now that's just three hundred million years after the Big Bang, she says, the dark stars would have had a million times the mass of our sun. Such early dark stars are important not only in teaching astronomers about dark matter, but also as precursors for the early super massive black holes seen by WEB, which would otherwise be difficult to explain. In the twenty twenty three PNAS study by Freezing colleagues, the first super massive dark star candidates jades JZ thirteen zero, Jade's GSZ twelve zero, and JADE'SJZ eleven zero. We're all identified using furtomture death from WEBSNEE infrared camera. Since then, spectrum from WEBSNEE Infrared Spectrographic instrument has provided additional data allowing astronomers to identify the spectrum morphology of four of the most distant objects ever seen, including two candidates from that twenty twenty three study. These include JDASJSZ fourteen zero, JDAS GC fourteen one, JDAS GC thirteen zero, and jds GZ eleven zero. Each is consistent with the super massive darkstar interpretation. JDSGC fourteen one is not resolved, meaning it's consistent with a point source such as a very distant supermassive. Star would be. The other three are all extremely compact and can be modeled by super massive dark stars powering a nebula of ionized hydrogen and helium surrounding the star. Importantly, dark stars would have a smirking gun's signature, an absorption feature at one thousand, six hundred and forty angstrom, due to the large amounts of singly ironiz helium in their atmospheres, and in fact, one of the four objects analyzed, JJZ fourteen zero, does show signs of this feature. Astronomers using ALMA the ATTICAM, a large millimeter submillimeter array telescope Inicele measured the spectrum of the same object, revealing the presence of oxygen through a nebular emission line. The authors say that if both specual features are confirmed, this object cannot be an isolated dark star, but rather a dark star embedded in a metal rich environment, and that could be the outcome of a merger where a dark matter halo hosting a dark star merges with a galaxy. Alternatively, dark stars and regular stars could have formed in the same halo. The identification of supermassive dark stars would open up the possibility of learning about dark matter particles based on the observed properties of those objects, and would establish a new field of astronomy, the study of dark matter powered stars. This is space time. Still to come, Australia's new lunar and piecing together the early Solar System. All that and more still to come on space time. Works now under way on the Australian Space Agency ace's first lunar rover mission, which is slated to launch before the end of the decade. The twenty kilogram four world robotic vehicle, called the Ruver, would be used by NASARE as part of its Artemis program. The study lunar geology, detecting rocks, craters, and other phenomena of interest. It'll be launched as part of NASA's CT for Commercial Lunar Payload Services initiative. Once on the Moon's surface, the roovers expected to be operational for a full lunar day that's equivalent to fourteen Earth days. Scientists at the Queensland University of Technology are building the navigation systems for the rover. They're developing positioning systems that assist the semi autonomous vehicle to safely explore the lunar surface with limited onboard computing power. The rover will be designed, built, tested and operated in Australia through a consultium of industry partners, research organizations, and ten OSI universities working in partnership with ASA, the Australian Space Agency. Once launched, it will be remotely operated from an Australian mission control center and work alongside NASA in establishing a sustainable human presence on the Moon. As part of the project, QTS developed a new lunar test center, which includes an enclosed test bed filled with a lunar regular simulant designed to replicate the kinds of environment surface conditions and lighting the vehicle will likely encounter during its time on the Moon. This is space time still to come. Piecing together the early Solar System and the constellation of the Southern Cross. The Magellanic clouds. And three Medial showers are among the highlight of the October night skies ont SkyWatch. A new study suggest that from its earliest period, even before the last of its protoplanetary nebula gas had been consumed, the Sun's Solar System and its planets, including the Earth, looked a lot more like a bin of well used lego blocks than slowly evolving spheres of untouched elements and minerals. The findings, reported in the journal Science Advances, suggest that far from being made of pristine material, the planets were constructed out of recycled fragments of shattered and rebuilt bodies. The studies lead author, Damen V. Singh Grew from the l University, says the research paints a clear picture of the violent origins of our Solar System. Scientists have long known that in the earliest days of the Solar System, planets and protoce planets known as planetesimals formed through a combination of collisions known as accretion and core formation, which triggered chemical changes in the cause composition, but the level of influence of each of these forces has been unknown. Adding to the mystery, some planetesimals have unusual chemical signatures that would evolve the presence of highly unlikely metals at the start of a naturally evolving core formation process. Gruel and colleagues say. The explanation lies with the smash and rebuild nature of the early Solar System. For their study, the authors created simulations of how planetary cause developed in the early years of the Solar System's formation, based on a reinterpretation of data taken from iron meteorites thought to be the remnants of the metallic cause of the first planetesimals. They hypothesized that high energy collisions began between about one and two million years after the formation of our Solar System four point six billion years ago. At that stage, some planet tesimals had formed metal rich cores, but the wasn't complete. Collisions shattered these early cause and their fragments later reassembled themselves into new planetary bodies through acretion. Grul says these events determine which elements and minerals young worlds carried to the next stage of planetary formation. The findings showed that the pathway to planetary formation was far more dynamic and complex than previously thought. This is space time. And time now eternalized to the skies and check out the celestious sphere for October on SkyWatch. October is the tenth month of the year, and that may seem confusing, since Octo in Latin means eight rather than ten. The answer lies in the old Roman calendar, which had just ten months before the addition of j February, and that ten month year is still reflected today with the name September or Septum being Latin for seven October or Octo meaning eight November and November nine, and December of Desi meaning ten. Of course, the harlot of October for kids and those who are young at heart has to be the last day of the month, celebrated as All Hallows Evening or Halloween. Halloween is based on ancient Celtic pagan festivals such as sou Wynn, the Gaelic festival of the Dead. Soaowyn was eventually christionized by the early Church to become all saints or Hallow's Eve, or simply Halloween. It's a time when darkness overtakes the light of day, a reference to the increasing hours of darkness as the planet's northern hemisphere moves towards longer winter nights, and so it's a time when the harvest comes to an end. The increased hours of darkness mean the boundary between the ward of the living and the ward of the dead becomes especially thin, allowing the dead and supernatural to rise in search of the living, and so the living were disguises so as not to be recognized by the dead, and it's this which has led to today's tradition of the Halloween fancy dress party. In some parts of the world, cross dressing is popular on Halloween, a reflection of the secret desires and fantasies of their pagan ancestors. Sometimes not so Many generations removed to ensure that crops and livestock survive the cold winter months ahead, Offerings of food and drink would be left outside for the spirits and fairies of the other side, and it was this which automately led to today's practice of trek or treat. Also, candles would be lit and prayers offered to the souls of the dead, as Halloween was a time when the spirits of the dead would return to their former homes. Special bonfires were also lit on Halloween to light the darkness, thereby preventing souls of the dead from returning and keeping the evil way. The flames, smirk and ashes were deemed to have protective and cleansing powers and we use for diviniation. As for the tradition of carving pumpkins and the jack o' lanterns, well, that was originally meant either to represent spirits or supernatural beings, or alternatively to ward off evil spirits. In many parts of the world, the Christian religious observances of All Hallows Eve include attending church services and lighting candles on the graves of the dead, and Christians historically abstained from eating meat on All Hallows Eve, a tradition reflected in the eating of certain vegetable foods on the day, including apples, poteta, pancakes, and sal cakes. Apple bobbing originated because the apple was a Celtic symbol of love, and so grabbing the apple with your teeth had certain erotic overtones. Halloween is a time of fortune telling, and divination games, playing pranks to scare people, visiting haunted attractions, telling scary stories, and of course, watching horror movies. Looking to the southwest, you'll see the two bright point of stars which show the weight of the Southern Cross. The brightest and what also looks like the more distant of the two stars from the Southern Cross is Alpha Centauri, which is actually the nearest star system to our own solar system. Alpha Centauri is a triple star system comprising two stars Alpha Centaury a and B, which orbit each other in a binary and a third star, Proximate Centaury, which orbit the pair like the Sun. Alpha Centauri A is a spectrotype G yellow dwarf star. It's about ten percent more massive than our Sun and about one and a half times as luminous. Astronomers describe stars in terms of spectral types. It's a classification system based on temperature and characteristics. The hottest, most massive, and most luminous stars are known as spectrotype O blue stars. They're followed by specturotype B blue white stars, then spectro type A white starsal type F whitish yellow stars, spectual type G yellow stars. That's where our Sun fits in spectual type K orange stars, and the coolest and least massive stars of all are the spectual type M red stars. Each spetual classification is also subdivided using a numeric digit to represent temperature, with zero being the hardest, deny in the coolest, and a Roman numeral to represent luminosity. Now you pull of that together and our Sun becomes a G two V or G two five yellow dwarf star. Also included in the stellar classification system are special types LT and Y, which are assigned to failed stars known as brown dwarves, some of which were actually born as spectual type M red stars but became brown dwarves after losing some of their mass. Brown dwarves fit into a unique category between the largest planets, which can be up to thirteen times the mass of Jupiter, and the smaller stars, those spetual type M red dwarf stars we mentioned earlier. These can be seventy five to eighty times the mass of Jupiter or about zero point zero eight solar masses. Alphicentury a's binary partner, Alphaicentury B, is a speciotype K orange dwarf star, a little smaller and cooler than its companion with about ninety percent of the Sun's mass and about half its luminosity. This binary pair, alphaicentaury A and B orbit each other at between eleven point two and thirty five point six astronomical units. An astronomical unit is the average distance between the Earth and the Sun, which equates to about one hundred and fifty million kilometers or around eight point three line minutes. So the pairs orbit around each other varies by between the average distance between the Sun and Satin and between the Sun and Pluto. It takes the two stars seventy nine point nine to one earth years to complete each orbit. On average, alphicentaury A and B are located four point three seven light years from this Sun. Now. Although a light year sounds like a measure of time, it's actually a measure of distance. A light year is the distance of about ten trillion kilometers. That's the distance of photon can travel in a year at the speed of light, which is around three hundred thousand kilometers per second in a vacuum, and the ultimate speed limit of the universe. The third star in the Alpha Centaury system is a spectrotype m red dwarf start named Proxima Centaury. Right now, Proxima Centaury is just four point twenty five light years away, making it the nearest start of the Earth other than the Sun. It is only loosely gravitationally bound to Alpha centaury A and B, orbiting the pair at an average distance of thirteen thousand astronomical units or around zero point two one light years. That's about four hundred and thirty times the size of Neptune's thirty astronomical unit orbit around the Sun. In twenty sixteen, astronomers confirm the existence of an Earth sized terrestrial planet orbiting within the habitable zone of Proxmasentori, making it the nearest known extra sol or exo planet to Earth. The habitable zone, which is sometimes also referred to as the Gaudylock zone, is that area out from a star where it's not too hot, not too cold, but just right for liquid water, central for life as we know it to exist on the planet's surface. The planet, known its Proxima B, takes just eleven Earth days to complete one orbit around its host star. That's far close to the mercury's eighty eight earth day orbit around the Sun. A few years ago, A second, more distant planet, Proximus C, was also discovered orbiting around the star, but well outside its habitable zone. The second and slightly fainter of the two pointer stars is Bitter Centaury, and while Alpha Centauri is the third brightest star in the night sky, outshone only by Sirius in Canopus, Bitter Centauri is only about the tenth brightest. Looking to the southeast and you'll see the bright blue white star Alpha Ridney or Akinar, which represents the southern tip of Eridanus, one of the largest and longest constellations in the sky. Akinar is located about one hundred and thirty nine light years away. It's actually a binary star system comprising two stars, Alpha Ridney A and Alpha Ridney B. Alpha Ridney A is a high, young spirtual type B blue star. It has about six point seven times the mass of the Sun and is stunning three than one hundred and fifty times the Sun's luminosity. By comparison, the companion star Alpha Ridney B appears to be a spectrotype A white star with about twice the Sun's mass. The two stars orbit each other every fourteen to fifteen earth years at an average distance of about twelve point three astronomical units. Because of its high rotation rate of over sixteen kilometres per second, Alpha Aridney as actually one of the least spherical stars in the Milky Way, spinning so rapidly, it's assumed the shape of an obleque sphere with an equatorial diameter fifty six percent greater than its polar diameter. This distorted shape means the star displays a significant latitudinal temperature, with its polar temperature being about twenty thousand kelvin, while it's equatorial temperature is only around ten thousand kelvin. That's because it's much further away from its stellar core. The high polar temperatures are generating a fast polar wind that's ejecting matter from the star and creating spectacular polar envelope of hot gas and plasma. Now, if you look up between the south celestial poland Akina from a really dark place, you'll see two faint, fuzzy looking clouds. Now, these aren't actually clouds. They are two satellite dwarf galaxies which are but the Milky Way, known as the Large and Small Magillani Clouds. They're named after Ferdinand Magellan, who became the first European to officially record them during his expedition to circumnavigate the Earth between fifteen nineteen and fifteen twenty two. The bigger and nearer of the pair is the large Magellanic Cloud, which is located around one hundred and sixty light years away. It's easier to spot about halfway between Akinar and the horizon. It's about fourteen thousand light years across, twice that of the small Magellanic Cloud, which is located a more distant two hundred thousand light years from the Milky Way. Now, by comparison to these two satellite galaxies, the Milky Way is huge one hundred thousand light years across. These two dwarf galaxies are separated from each other by roughly seventy five thousand light years. The Magellanic clouds were considered the closest galaxies to the Milky Way until the nineteen ninety four discovery of the Sagittarius dwarf elliptical galaxy and the two thousand and three confirmation that the Canis major dwarf galaxy is actually Ourneares s galactic neighbor. The total mass of the Magellanic clouds is uncertain. Only a fraction of their gas seems to have coalesced into stars. They also probably both have very large dark matter halos. Still, one recent estimate places the total mass of the large Magellanic cloud at about one tenth out of the Milky Way. The Magellanic clouds of both being greatly distorted by gravitational tidal interactions as they're gradually torn apart and absorbed by the Milky Way. These huge tidal forces have turned both Magellanic clouds into irregular, disrupted buds spiral galaxies. The large Magilani cloud still retains a very clear spiral structure, at least in radio telescope images of neutral hydrogen. But gravity isn't a one way street, and the combined gravitational force of both Magileni clouds is also affecting the Milky Way, distorting the outer parts of our galactic disk. And there are streams of neutral hydrogen gas clouds and isolated stars connecting both dwarf galaxies to each other and to the Milky Way, a brilliant example of galactic cannibalism at work. Now, if you look just above the small magellanic cloud. Using a backyard telescope or a good pair of binoculars, you'll see a small blurry dot that is the forty seven to Canna globular cluster, a tightly packed ball of stars some sixteen thousand light is away. They were all originally formed at the same time through the gravitational collapse of the same molecular gas and dust cloud. If you look to the west, you'll see the bright reddish iron supergiant star and Taris the heart of the constellation Scorpius, the Scorpion, and above it you'll see a bunch of stars stretching out shaped like a reverse question mark. That's the tail of the Scorpion. Now just above and to the north is the constellation Sagittarius, the archer. Sagittarius shows the weight to the super massive black hole at the center of the Milky Way galaxy some twenty seven thousand light is away. This monster black hole, known as Sagittarius a star, has about four point three million times the mass of our Sun. Now, looking to the north northwest this time of the year, see the constellation Lyra the harp and its brighter star Vega, the fifth brighter star in the night sky, and one of the closest are just twenty five light years away. Vega is a special type, a white star, more than twice the size and some forty times the mass of our Sun. Now just to the right of Lyra and almost directly north, just above the horizon is the constellation of Signus the Swan and its sprider star Deneb, one of the most luminous stars in the sky. Deneb is a massive spectrotype, a white super giant, some nineteen times the mass and over one hundred times that I am of the Sun. The star is somewhere between fifty five thousand and one hundred and ninety six thousand times as luminous as the Sun. The huge range in luminosity estimate is caused by the difficult in determining Deneb's exact distance from US. Science's best estimates place it somewhere around twenty six hundred light years away, give or take two hundred and twelve light years high. In the northern sky right now is the constellation Aquilla the Eagle and its spider star all Tair. Altair is another spectrotype, a white star, but located a lot closer just seventeen light years away. It's about ten times brighter than the Sun, with about one point eight nine times the Sun's mass. Despite its size, Altear spins on its axis in just ten hours, compared to our Sun's twenty eight earth day rotation. Now, these three stars Alte Denebinvega forms stillar grouping known as the Summer Triangle. Now. Also in October, there are three meteor showers, the Draconids, the Taurreds, and the Orionids. The Dracernids take place on October the eighth. They're so named because the meteors appear to radiate out from the constellation Draco the Dragon, and so are best viewed from the northern Hemisphere. They're actually produced as the Earth's orbit takes it through the debris trail left behind by the comet twenty one p chrkobini Zina, which takes about six point six earth years to make a single. Revolution of the Sun. The Torred's media shower takes place on October tenth, and, as their name suggests, they appear to radiate out from the constellation Taurus the Ball. Their mediors are composed of larger than average pebbles, and dust grains, and are thought to be generated by a debris left behind by the comet two p Anki, although it's thought that both the Torreds and Anchi could be the remains of an earlier comet which disintegrated over the past twenty thousand to thirty thousand years, breaking into several pieces and releasing material both by normal cometary activity and possibly also by gravitational title interactions with the Earth and other planets. The Torred's debris stream is the largest in the Inner Solar System, taking the Earth several weeks to pass through and resulting in an extended period of media activity compared to other meteor showers, which are usually over in just a matter of days. Now, due to the gravitational perturbations planets, especially Jupiter, the Tourreds have been spread out over time, allowing separate segments labeled the Northern Toureds and Southern Torereads to be observable at different times in different hemispheres. The Southern Tourreds are active from around September tenth to November twentieth, while the Northern Tourreds are active from October the twentieth to December tenth. The third medior shower this month is the Orionids, which peak on October the twentieth. They're caused by debris from the Comet Halley, which also causes the Etta Accuridz media shower in May. Commet Halley takes seventy six years to complete each orbit around the Sun. It'll next become visible near Earth in twenty sixty one. The Orionids are equally spectacular in both northern and southern Hemisphere skies, with up to twenty meteors an hour radiating out from the constellation Orion. The best time to see the Orionids is just after midnight and ripe before dusk. This is Spacetime and that's the show for now. Spacetime is available every Monday, Wednesday and Friday through Apple Podcasts, iTunes, Stitcher, Google podcast, pocker Casts, Spotify, Acast, Amazon Music, Bites, dot Com, SoundCloud, YouTube, your favorite podcast download provider, and from space Time with Stuart Gary dot com. Space Time's also broadcast through the National Science Foundation, on Science Own Radio and on both iHeartRadio and tune In Radio. And you can help to support our show by visiting the Spacetime store for a range of promotional merchandising goodies, or by becoming a Spacetime Patron, which gives you access to triple episode commercial free versions of the show, as well as lots of burness audio content which doesn't go to wear, access to our exclusive Facebook group, and other rewards. Just go to space Time with Stewart Gary dot com for full details. You've been listening to space Time with Stuart Garry. This has been another quality podcast production from bytes dot com.