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  • Mapping the Invisible

    Let’s Start at the Very Beginning… 13.7 billion years ago the Big Bang happened: the birth of the Universe. The building blocks of nuclei (protons and neutrons) formed, before combining to form the nuclei of the first elements of the Universe. However, the temperature and pressure of the Universe was so high atoms couldn’t form, since electrons weren’t able to combine with the nuclei. Instead, a hot ionised plasma fog was formed, scattering radiation with each forced separation of electrons from a nucleus. This then created an impenetrable wall of radiation which lasted for 380,000 years, before it was then cool enough for electrons to finally meet with nuclei to form neutral atoms (the epoch of recombination - the biggest reunion in the history of the Universe, it could be said). This radiation left a mark on the Universe, still visible to this day in the form of the Cosmic Microwave Background Radiation (CMBR) [1][2]. The CMBR is the key to understanding everything that comes later. Hidden within it are seemingly random fluctuations in the amount of radiation emitted: the weaker the radiation, the more the photons had to fight their way through the impenetrable fog and loose energy because of it, meaning weaker radiation shows denser areas of matter. And these minute fluctuations in density, quantum fluctuations, were formed in random incidences in the first event of rapid inflation in the 0.00000000000000000000000000000001 seconds (that’s 32 zeros: a one hundred-nonillionth), with an increase in size by a factor of 1,000,000,000,000,000,000,000,000,000,000 (1 with 30 zeros: a nonillion). This increase dramatically amplified the small quantum fluctuations to an enormous scale, leading to denser areas of matter and sparser areas of matter. The denser areas then became denser and denser due to gravitational attraction, leading to what we see today: the cosmic web [3]. The Cosmic Microwave Background Radiation (CMBR) Credit: NASA/WMAP Science Team Universe Wide Web Over the next 13.7 billion years or so, these quantum fluctuations kept on amplifying, ordering objects, such as galaxies, into thick long strings (filaments), creating voids of near-empty space (where the laws of physics may not be the same as here on Earth). These filaments then condensed into large galaxy clusters, which are where galaxy groups (such as the Local Group, made of galaxies such as the Milky Way, Andromeda, and Triangulum) congregate, making up thousands of galaxies with a collective mass of between 100 trillion and 1 quadrillion times the mass of our Sun, and around 30 million light years across [4]. As time goes on, the filaments will feed into the galaxy clusters, forming galaxy superclusters, at more than 100 million light years across. Eventually, these superclusters will become islands of galaxies, separated by voids of very low density, containing isolated stars and galaxies[4][5] There’s one problem though: there’s not enough stuff to produce that much of a pull to create such structures. Computer simulation of the 3 Universe, at 3 billion years old, where filaments and voids are forming, along with areas of slightly higher densities: galaxy clusters. Credit: ESO, CC BY 4.0 The Invisible Web The answer lies in dark matter. Making up 27% of the Universe and 80% of matter in the Universe, dark matter creates a skeleton for the cosmic web to form around. And around galaxies dark matter clusters further, creating dark halos (the Milky Way has a halo which is 300,000 light years across, and possibly even further -the Milky Way itself is only 100,000 light years across), linking galaxies together gravitationally [6][7][8][9][10]. But, if it’s invisible, how come we’ve got pictures of it? There are a number of methods. Chandra X-Ray Image of Abell 2029: a cloud of hot gas where multiple galaxies lie. Credit: NASA/CXC/UCI/A.Lewis et al What’s not there? The first method is to observe how the stars and gas within galaxies move about. If the amount of matter which can be seen doesn’t account for how the stars and gas move, then there’s something at play, and that something could be dark matter. The higher the speed of motion, the greater the mass there is to pull those objects around the galaxy [8]. This can then be applied to much much larger scales, such as galaxy groups or clusters. If the speed of the galaxies that make up the groups and clusters are so high that, theoretically, they should fly out of the group or cluster, it could be dark matter that’s keeping everything together. In fact, this particular theory explains how the gravitational pull between the nearby Andromeda Galaxy and the Milky Way is so strong as to pull them together to then collide in 3 billion years [8][10]. Then there’s the observations of high energy X-rays, which are emitted from gases found throughout galaxy clusters. The gas physically shouldn’t be emitting that much energy, sometimes exceeding a million Kelvin (around a million ºC), but instead drifting away from the galaxy clusters and evaporating. However, a dark source of extra gravitational pull seems to be holding this gas together: dark matter [8][11]. And then there’s gravitational lensing: an effect whereby the light from something behind a place with a strong gravitational field distorts and magnifies that light behind, sometimes even creating multiple images of the same thing. The are various effects involving this, including rings, crosses and arcs. If there’s no obvious source of mass distorting the light, one source could be dark matter [12][13][14]. The Einstein Cross: four images of a distant quasar, being an effect of the gravitational lensing of a nearby galaxy. Credit: NASA/ESA/STScI The Map Using the gravitational lensing technique, along with some handy artificial intelligence to look at the 100 million galaxies in the data set, the Dark Energy Survey (an international collaboration to survey the night sky and uncover the secrets of dark energy and dark matter) were able to produce a map of the dark matter in a quarter of the southern hemisphere’s sky. There are two key findings that were produced from the paper behind this magnificent map (the largest dark matter map made using gravitational lensing). First is that the dark matter in our Universe is smoother than computer simulations expect (using equations from the standard model: the model from Einstein’s theory of general relativity), suggesting there may be something missing in the maths. The next is that we now know exactly where the voids are in that part of the sky (since they’re more obvious when looking specifically at the layout of dark matter), meaning we can point our telescopes there to see if physics seems to work any differently, and if so, how [9][15][16][17][18]. Map of the optical Gaia sky overlaid with the map of dark matter, showing: filaments, voids, and halos (where galaxy clusters lie) Credit: N. Jeffrey/Dark Energy Survey Collaboration Hopefully this discovery, along with many more to come, will open the horizons for more meaningful observations of the Universe, so we can get a broader view of how our Universe functions and find out what dark matter actually is. by George Abraham, ADAS member. #DarkMatter #CMBR #CosmicWeb #Halo #DES #GravitationalLensing #GeneralRelativity #StandardModel #Filament #GalaxyGroup #GalaxyCluster Click here for the previous news article Click here for the next news article Click here to look at the paper behind the map Click here to watch the video to learn more about the papers released by DES, and the enormity of the project, and here for a more in-depth view Click here to look at the other papers produced in the DES Year 3 cosmology analysis Click here to look at galaxy cluster IDCS 1426, here to look at the Einstein Cross and here to look at the sheer number of galaxies in Abel 2029, all on ESA Sky Click here for an activity by JPL to simulate how we detect dark matter in the Universe. References "How did the first element form after the Big Bang". Astronomy Magazine. Archived from the original on 29th May 2021. "Cosmic Microwave Background". Swinburne Astronomy Online. Archived from the original on 29th May 2021. "The cosmic microwave background and inflation". ESA. Archived from the original on 29th May 2021. "Galaxy Cluster". Universe Today. Archived from the original on 29th May 2021. "'We Don't Planet' Episode 7: The Vast Cosmic Web". Space.com. Archived from the original on 29th May 2021. "Dark matter". CERN. Archived from the original on 29th May 2021. "New Map of Local Dark Matter Reveals 'Bridges' between Galaxies". Sci News. Archived from the original on 29th May 2021. "Dark Halo". Swinburne Astronomy Online. Archived from the original on 29th May 2021. "New dark matter map reveals cosmic mystery". BBC News. Archived from the original on 29th May 2021. "Hyperfast Star Was Booted From Milky Way". NASA. Archived from the original on 29th May 2021. "Study Suggests Andromeda Crashed into the Milky Way 10 Billion Years Ago". SciTechDaily. Archived from the original on 29th May 2021. "7 Incredible Discoveries from two Decades of X-Rays". Sky & Telescope. Archived from the original on 29th May 2021. "Gravitational Lensing". Hubblesite. Archived from the original on 29th May 2021. "Ask Astro: If dark matter is invisible, then how do we detect it?". Astronomy Magazine. Archived from the original on 29th May 2021. "Astronomers have created the largest ever map of dark matter". NewScientist. Archived from the original on 29th May 2021. "Astronomers create largest map of the universe's dark matter". The Guardian. Archived from the original on 29th May 2021. "Overview". The Dark Energy Survey. Archived from the original on 29th May 2021. "DES Year 3 Cosmology Results: Papers". The Dark Energy Survey. Archived from the original on 29th May 2021.

  • Icy Elements from the Early Solar System

    Element Nucleosynthesis Elements; the building blocks of what makes up: us, the Earth we live on, and the entire Universe. They shape everything that happens throughout each day of our lives, from the copper supplying our energy; to the lithium storing it; and the oxygen we breathe. However, they haven’t been here forever. Through processes of nucleosynthesis (creating new nuclei of atoms from the protons and neutrons that make them up) which have happened and are happening throughout the Universe, we are able to live the way we do. These processes include: big bang fusion, cosmic ray fission, neutron star mergers, explosions, and dying low mass stars (as well as many other methods, including in particle accelerators here on Earth) [1]. Colour coded periodic table showing the origins of elements in the Solar System. Credit: Jennifer Johnson, CC BY-SA 4.0 The Big Bang We start our elementary journey at the beginning of time; the beginning of everything: the Big Bang. An event so powerful the effects are still seen today in the form of the Cosmic Microwave Background Radiation (the remains of the Big Bang, emanating from the voids of space at the freezing 2.7 kelvin: 2.7ºC above the coldest possible temperature [2]), the Big Bang emitted so much energy that it’s no wonder some crazy things went on back then. Over the first 3 minutes after the beginning of the Universe (starting at the Universe’s spritely age of 1 second), the first elements came into being: hydrogen (specifically deuterium -a neutron and a proton- and tritium -two neutrons and a proton-), helium (helium-3 and helium-4 to be precise), lithium (lithium-7) and beryllium (beryllium-7). And they all came into being through fusion: the smashing together of particles and atoms to make atoms of elements with higher masses. In fact some of the deuterium, helium and lithium from the Big Bang (known as primordial elements) is still around in the Universe today, as a 13.7 billion year old relic of the Universe’s past. However, the same cannot be said for the beryllium and tritium, with half lives (the time it takes for an atom to decay by half into another element) of just 53 days and 12 years respectively. The Cosmic Microwave Background Radiation (CMBR) Credit: NASA/WMAP Science Team Cosmic Rays The Universe is therefore full of hydrogen and helium… but not lithium. The third element in the periodic table and one of the three to have braved 13.7 billion years of time to be here today is not a very abundant element, yet, generally speaking, the lower (the less protons) in the periodic table an element is, the more of it there is. So why is lithium an exception? The real amount of lithium made in the Big Bang was a feeble 0.0000001% (a ten millionth of a percent) of the Universe’s elements at the time (as opposed to the ~75% hydrogen and ~25% helium). In other methods all involving stars (which we’ll talk about later), lithium (along with beryllium and boron) also can’t be created in the same quantities we see it in today. Instead, enter cosmic ray spallation [4]. When cosmic rays (usually high energy neutrons) collide with an atom’s nucleus, multiple particles from that nucleus are released, which then begin a chain reaction of more and more collisions and emissions of particles, known as a cosmic ray cascade. And this isn’t even the best part! The particles, or spalls, that fly out from the atoms which have had a collision are then absorbed into an atom, creating a new isotope (a new number of neutrons in the atom) or even a new element (a new number of protons in the atom), leading to lithium, beryllium and boron being formed. [5][6][1]. There’s only one problem though. Lithium-6 is the isotope made by cosmic ray spallation; not lithium-7: the most common type, and also the type made in the Big Bang [7]. Artist conception of showers of cosmic rays passing through Earth's atmosphere. Credit: Simon Swordy (U. Chicago), NASA Explosions and Mergers Jumping to the much larger scale, r-process nucleosynthesis is the source of many useful elements we see in the Universe, and on Earth, today, including the likes of: gold, silver and iodine (all useful to us in many ways) [7]. And there are two ways r-process nucleosynthesis could occur: neutron star mergers and supernovae [8]. Supernovae are by far the most famous method of the two. As massive stars (greater than 9 times our Sun’s mass) come to the end of their lives as burning giants, they begin to collapse at around a quarter of the speed of light at their fastest collapse, before bouncing outwards, splurging neutrinos and gases into the surrounding environment in a shockwave (moving at up to a tenth of the speed of light), beginning nuclear fusion, whereby atoms fuse to make heavier and heavier elements. This then breaks out into a full blown supernova, where the star shines at around 10 billion times the Sun’s brightness (brighter than whole galaxies) to leave a core behind. However, it’s the hot bright phase that is the most important: a flurry of rapid neutron captures (the ‘r’ in ‘r-process’ is for ‘rapid’) occur, where neutrons enter atoms to turn them into larger and larger isotopes of their element. However, this only happens to a point, since the nucleus of the atoms (what is receiving the neutrons) reach neutron drip. This is where the forces holding the neutrons together in the atom’s nucleus stars to decrease and become negative, stopping any more neutrons from entering. Beta-minus decay then occurs, where the neutrons change into protons, both increasing the number of neutrons that can enter the atom (since there’s now less negative charge because of the proton’s positive charge) and increasing the atom’s atomic number, creating heavier and heavier elements [9][10]. This isn’t it for the massive stars though! Instead, those that are on the less massive range turn into neutron stars: stars made of protons and electrons which are crushed together so much they turn into neutrons. In fact, they’re so compressed just one sugar cube sized piece would weigh as much as 1 trillion kilograms (or one seventh the mass of Mount Everest [11][12]) [11]. And this abundance of neutrons can only mean one thing: rapid neutron capture. When two neutron stars merge (having pulled each other closer by their immense gravitational attraction -I know, so romantic!) the r-process kicks in, creating many more useful elements and throwing them out into the Universe to become, along with what's produced in Supernovae, what’s in our smartphones and what’s in our sushi [13]. Type 1a Supernova SN 1994D (bottom left) near galaxy NGC 4526 Credit: NASA/ESA/ The Hubble Key Project Team/ the High-Z Supernova Search Team, CC BY 3.0 A Bit Closer to Home Low mass stars (such as our Sun), unlike the massive stars that have their destiny making high mass elements, have more humble, yet arguably more important, destinies. All these low mass stars burn through hydrogen but, unlike the modern fuel source hydrogen has come to be here on Earth, they fuse it to get energy; a lot of energy! Apart from energy though, this fusion of hydrogen atoms forms helium, leading to hydrogen and helium being the most abundant elements in the Universe (though not on Earth, since they are very good at escaping due to their low masses). Once all the hydrogen has been eaten up though, a star’s next meal will be the heavier elements, all the way up to iron [14]. Why stop at iron though? This is because it takes more energy to fuse than what the fusion process produces, resulting in there being not enough energy to sustain a star, leading to its collapse. However, our Sun, along with many other low mass stars (less than 9 times the mass of the Sun) will stop much earlier (somewhere around carbon), forming a red giant [15][16]. That said, they may have a few more elements in them, forming by the s-process (’s’ for ‘slow’). This process involves neutrons which are emitted (or liberated) from neutron rich atoms like carbon-13 and neon-22, before being captured by other atoms and turning into protons (through beta-minus decay) to create new elements (up to lead) This is the slow process though, taking place over thousands of years instead of the seconds that the r-process takes [17][18]. Eventually, this excess mass accumulating around the red giant is blown away in a planetary nebula, leading to a white dwarf. This white dwarf is then the source of the majority of the lithium in the Universe (25%) due to novae: the emission of a bit of the white dwarf due to the absorption of some hydrogen from a nearby star, leading to the white dwarf emitting a lithium producing isotope in the process [19]. GK Persei Nova Remnant. Credit: X-ray: NASA/CXC/RIKEN/D.Takei et al; Optical: NASA/STScI; Radio: NRAO/VLA Cold Metal Why have I been going on about the formation of elements though? It all comes down to the recent news which has come from ESO (the European Southern Observatory), who have provided the data for a study by a Belgian team of scientists who discovered iron and nickel vapours on the surface of comet C/2016 R2 (PANSTARRS), 480 million kilometres from the Sun, where they’ve never been observed before due to the expectation that only hot environments would provide the correct temperatures for the vaporisation of these heavy metals. Iron, with atomic number 26, and nickel, with atomic number 28, are inherently formed in different ways and therefore, most importantly, in different quantities. So, you’d expect lots of iron and a bit less nickel (10 times the amount of iron to be precise). However, through spectroscopy, the chemical signatures of iron and nickel were found in equal amounts! What’s more, the interstellar comet 2I/Borisov is also showing similar amount of these two elements, therefore hinting that both comets were formed in similar environments, suggesting that what we see in our Solar System is a good template for what’s seen in other parts of the galaxy, and maybe even the Universe; whilst also bringing up the question of why there is this equal amount of nickel and iron seen on comets [20]. Heavy metal detection in the atmosphere of comet C/2016 R2 Credit: ESO/L. Calçada, SPECULOOS Team/E. Jehin, Manfroid et al., CC BY 4.0 by George Abraham, ADAS member. #Element #Nucleosynthesis #Comet #Spectroscopy #Neutrino #Neutron #Proton #Supernova #NeutronStar #CosmicRay #BigBang Click here for the previous news article Click here for the next news article Click here to watch an animation of the heavy metal composition of comet C/2016 R2 (PANSTARRS) Click here to find out where comet 2I/Borisov is on its journey out of the Solar System, and here to look where comet C/2016 R2 (PANSTARRS) is on its orbit References "The Origin of Elements". The Ohio State University. Archived from the original on 22nd May 2021. "Lecture 31: The Cosmic Microwave Background Radiation". University of Alberta. Archived from the original on 22nd May 2021. "How the Big Bang forged the first elements". Astronomy.com. Archived from the original on 22nd May 2021. "This is Why Three of the Lightest Elements are so Cosmically Rare". Forbes. Archived from the original on 22nd May 2021. "Cosmic Rays". AntarcticGalciers.org. Archived from the original on 22nd May 2021. "Spallation and the creation of the elements lithium, beryllium and boron". YouTube. Archived from the original on 22nd May 2021. "Origin of the Elements in the Solar System". Science Blog from the SDSS. Archived from the original on 22nd May 2021. "Colliding Neutron Stars as the Source of Heavy Elements". AAS Nova. Archived from the original on 22nd May 2021. "Lecture 18: Supernovae". The Ohio State University. Archived from the original on 22nd April 2021. "The R-Process". Caltech. Archived from the original on 22nd May 2021. "Neutron Stars". NASA. Archived from the original on 22nd May 2021. "Estimating the Mass of Mount Everest". Viktor Plamenov. Archived from the original on 22nd May 2021. "DOE Explains... Nucleosynthesis". US Department of Energy. Archived from the original on 22nd May 2021. "Stars". NASA. Archived from the original on 22nd May 2021. "Stars & Their Energy Sources". CSIRO. Archived from the original on 22nd May 2021. "What Happens when Stars Produce Iron". Futurism. Archived from the original on 22nd May 2021. "s-process". David Darling. Archived from the original on 22nd May 2021. "A New Site for the s-Process". AAS Nova. Archived from the original on 22nd May 2021. "Most Lithium in the Universe is Forged in Exploding Stars". Smithsonian Magazine. Archived from the original on 22nd May 2021. "Heavy metal vapours unexpectedly found in comets throughout our Solar System – and beyond". ESO. Archived from the original on 22nd May 2021.

  • The Hum of the Universe

    The Interstellar Medium At 153 AU (153 times the average distance from Earth to the Sun) and counting [1], Voyager 1 is a long, long, long way away. And at these astronomical distances there are things that can be observed which can’t be observed with precision within the reach of the Sun (the heliosphere), namely the interstellar medium. This is made up of all the low density gas and dust that fills the area between stars: 99% interstellar gas and 1% interstellar dust, making up 10-15% of the Milky Way visible from Earth [2][3]. And this concoction of material has recently been directly observed by the Voyager 1 probe, but before we delve into the findings, let’s have a look at the science behind the interstellar medium. Survey of the ionised gas in the Milky Way, surveyed by WHAM (Wisconsin H-Alpha Mapper) Credit: Haffner, L, et al. (2003), funded by the NSF Interstellar Gas The lion’s share of the interstellar medium is taken up by interstellar gas: a mixture of some helium (10-25%) and a lot of hydrogen (75-90%). However, it’s not the even and perfect spread of the odd atom or two in a partial vacuum that you might expect. Instead, both temperature and pressure can vary vastly, with temperatures ranging from just a few ºC above absolute zero (the coldest temperature, where no energy is released), to millions of ºC above absolute zero (i.e. millions of Kelvin, shortened to K); and pressures ranging from just one atom in a cubic centimetre of space, to enough atoms to block the light behind it. There are generally four forms of interstellar gas, the first being cold (around 100K), neutral hydrogen clouds (called HI regions, pronounced “H-one”). This is what most interstellar gas is, but due to its cold temperature, it’s not the most visible, since there needs to be some energy to emit light. However, there’s help in the form of absorption, where particular wavelengths of light passing through the cloud are absorbed, leaving characteristic absorption lines (gaps) in the spectra of light emitted from stars (creating absorption nebulae when in high concentrations). The Lockman Hole, where redder light is taken out by the HI region to give astronomers a clearer view of the bluer light. Credit: Chandra X-Ray Observatory, NASA Then theres the hotter (10,000K) ionised hydrogen gas clouds (called HII regions, pronounced “H-two”). Like HI regions, HII regions absorb light, but because HII regions can absorb so much energy from near by hot stars, they emit light (through a process of electrons loosing the energy they absorbed from nearby stars and emitting photons -light), creating characteristic emissions lines (most notably the red H-alpha, Hα, line) in the spectra of these objects (making emission nebulae when in high enough concentrations). The Orion Nebula (an HII region and emission nebula). Credit: NASA/ESA/M. Robberto (Space Telescope Science Institute/ESA)/Hubble Space Telescope Treasury Project Team Then there’s the even hotter interstellar gas (millions of Kelvin) made of not just hydrogen but some oxygen, and not even the normal oxygen we breathe: oxygen with 5 electrons missing. What’s more, the gas emits not low energy red Hα light, but very high energy X-rays. But how? The answer lies in the high energy supernovae explosions (a stage towards the end of a star’s life) which eject gas at fast speeds of tens of thousands to millions of kilometres per hour, heating the interstellar gas it comes into contact with and creating these high energy gas clouds. Vela Supernova Remnant (one of the largest x-ray features in the sky) Credit: Harel Boren, CC BY-SA 4.0 Extremely cool (10K) molecular gas clouds are the last type, made up of not individual atoms, but molecules such as CN (cyanide, made of carbon and nitrogen) and CH (hydridocarbon, made of carbon and hydrogen), as well as CO (carbon monoxide, made of carbon and oxygen) and many other molecules. Like the HI regions, they absorb light at specific wavelengths which correspond with the atoms present, and, if the gravitational pull is strong enough, these regions can grow into complex and colourful clouds of interstellar gas [3][4][5][6]. Taurus molecular cloud, glowing due to star formation within the cloud Credit: ESA/Herschel/NASA/JPL-Caltech/R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO However, how can these interstellar gas clouds contain molecules when they’re bombarded by high energy rays such as ultra-violet (UV) light which splits apart such molecules? The answer lies in the important and complex world of interstellar dust; the next stop on our journey. Interstellar Dust Unlike the dust you tried to get rid of when you were doing a bit of spring cleaning, this dust is a bit more ‘space-age’. Interstellar dust (not to be confused with interplanetary dust or galactic dust) is made of carbon, iron compounds, silicates, and/or ice, measuring just 0.1 microns (a 750th of the width of a human hair) across and taking irregular shapes. Due to the solid form of dust, if it collects into high enough densities, it can scatter the light through extinction. This is where the size and density of the dust comes into play, with most interstellar dust being the size which can scatter bluer light (such as the UV light which can split apart molecules), removing this light to create an appearance that the dust is red: interstellar reddening (not to be confused with redshift). This then protects those all important gas molecules in molecular gas clouds. Barnard 68, also known as the Bok globule, shows interstellar reddening through the red infrared section in the centre Credit: ESO, CC BY 4.0 However, if it is in high enough concentrations (100-1000 grains per cubic centimetre), then all the light from behind the dust is absorbed, creating dark nebulae (seen as patches of perfectly dark sky with no stars). Barnard 56, also known as the Pipe Nebula, is a dark nebula Credit: ESO, CC BY 4.0 The dust doesn’t just affect the light passing through it, but also the light being directed onto it. It reflects this light, creating reflection nebulae [3][7]. Reflection nebula Messier 78 in Orion Credit: ESO/Igor Chekalin CC BY 4.0 However, we don’t just observe these wonderful and complex nebulae from afar; there’s a cloud going through our own Solar System right now. Aptly known as the Local Galactic Cloud, it creates a constant flow of particles, known as interstellar wind, coming from the middle of the constellations of Sagittarius, Scorpius, Libra and Ophiuchus. This then shows the direction of the movement of the Solar System relative to the cloud, which we’re moving through at 80,000kph (with the location of the source of wind having changed by 4 to 9 degrees within 40 years, possibly due to the fact we’re near the edge of the cloud and may be experiencing ‘turbulence’) [8]. Direction of the interstellar wind. Credit: NASA/Goddard Space Flight Centre But wait… nebulae? How come interstellar dust and gas can get into these intricate formations instead of becoming an even spread throughout the Universe? Stellar Wind The final piece to this interstellar puzzle lies in stellar wind (not to be confused with interstellar wind): a force which interacts with and shapes in the interstellar medium. It is made up of the high-energy protons and electrons ejected by stars across the Universe, including our own Sun. This fast-moving and energetic stream of particles then ‘blows’ the interstellar dust and gas about to then create the structures we observe today. However, along with interstellar wind, supernovae also play a key role, moving high energy particles at high speeds through the interstellar medium, shaping it and creating HII regions. However, as well as shaping these nebulae, stellar wind adds dust and metals to the interstellar medium, and, along with the numerous stars that ‘die’ and shed their material, help the formation of new stars through creating an environment where gas and dust can compress to trigger star formation [9][10]. The Pillars of Creation (the purple points throughout are new stars forming) Credit: ESO, CC BY 4.0 Observations from the Edge This is where we pick up the story of Voyager 1 and the recent news stemming from its observations. It used its onboard plasma wave instrument to detect the minute densities of plasma (ionised gas, in this case being charged interstellar gas) it’s passing through (unlike previous observations which only looked at specific high energy events). The frequency of the audible signals produced by the plasma suggest an increase in plasma density. This is an observation of specific waves of ‘turbulence’ in the interstellar medium, produced by our galaxy’s rotation, as well as supernovae and solar eruptions (such as Coronal Mass Ejections or CMEs). These measurements will then help scientists map out the interstellar medium around our own Solar System [11]. The continuous weak signals (in red) detected by Voyager 1's Plasma Wave Subsystem and filtered through by Stella Ocker Credit: NASA's Voyager 1 Plasma Wave Subsystem/Stella Ocker Hopefully, with much more data from Voyager 1 and 2 to be sent back and processed by scientists on Earth, we will begin to build an accurate picture of how the interstellar medium behaves and what processes drive it. by George Abraham, ADAS member. #Interstellar #Cloud #Gas #Dust #Wind Click here for the previous news article Click here for the next news article Click here to find where Voyager 1 and 2 are currently Click here to see ESO's 3D visualisation of the Pillars of Creation Click here to view the paper published in Nature Astronomy about the detections of waves in the interstellar medium Click here to look at the sky in Hα Click here to look at the Vela Supernova remnant in X-rays, here to look at the Lockman Hole in X-rays, here to look at the Orion Nebula in Hα, here to look at Barnard 68 in near-infrared, here to look at the dark Pipe Nebula, here to look at the reflection of M78 and here to look at the star formation in the Pillars of Creation, all on ESA Sky Click here to listen to the hum of the Universe taken back in 2013 References "Mission Status". NASA JPL. Archived from the original on 15th May 2021. "Interstellar Medium (ISM)". Astronomy Notes. Archived from the original on 15th May 2021. "What is the Interstellar Medium?". The University of New Hampshire. Archived from the original on 15th May 2021. "Interstellar Gas". Lumen Learning. Archived from the original on 15th May 2021. "Interstellar Gas Cloud". Swinburne Astronomy Online. Archived from the original on 15th May 2021. "The Vela Supernova Remnant and Surrounds - a Photographic Tour". Pretoria Centre. Archived from the original on 15th May 2021. "Interstellar Dust". Astronoo. Archived from the original on 15th May 2021. "Eleven Spacecraft Show Interstellar Wind Changed Directions Over 40 Years". NASA. Archived from the original on 15th May 2021. "Stellar Winds". Swinburne Astronomy Online. Archived from the original on 15th May 2021. "Stellar Formation: Interstellar Gas and Dust". Michigan States University. Archived from the original on 15th May 2021. "As NASA's Voyager 1 Surveys Interstellar Space, its Density Measurements are Making Waves". NASA. Archived from the original on 15th May 2021.

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  • Upcoming Events | Altrincham and District Astronomical Society | Timperley

    UPCOM ING EVENTS Date Subject Presenter 02/07/2021 Children of Another Sun Paul Fellows NEXT PRESENTER Timperley Village Club, 268, Stockport Road, Timperley, Greater Manchester, WA15 7UT 15 parking spaces available behind the Timperley Village Club Local tram stop 22min walk (1.1 miles) 6 bus stops from 177ft to 0.1 miles First Friday of every month, except in July and August. Arrive at 8pm £3 for non-members to attend a meeting (email secretary.adas@gmail.com while we're meeting online) £1 for children to become members for a year - Click for more information £20 for adults to become members for a year - Click for more information How exoplanets are discovered, how many there are, what they're like and how we know this are all discussed first, before a section on the current science behind alien life Children of Another Sun 2 Jul 2021 Chairman of Cambridge Astronomical Association Paul Fellows 576th Meeting Subscribe Google Calendar Subscribe Apple Calendar Click here to learn more about Paul Fellows

  • Home | Altrincham and District Astronomical Society | Timperley

    Latest News WELCOME Next Event Website Updates We are a friendly society of around 30 people who meet regularly to talk about and enjoy the night sky. We have several telescopes and other pieces of equipment which can be borrowed by society members for their own use. Throughout the year we meet on the first Friday of each month (except July and August) at 8pm until 10pm at Timperley Village Club. At these monthly meetings we discuss the society's business and have an event such as a lecture, video, slide show etc. NEXT EVENT How exoplanets are discovered, how many there are, what they're like and how we know this are all discussed first, before a section on the current science behind alien life Children of Another Sun 2 Jul 2021 Chairman of Cambridge Astronomical Association Paul Fellows 576th Meeting Subscribe Google Calendar Subscribe Apple Calendar Click here to learn more about Paul Fellows For more information on future events like this, look at our 'Upcoming Events ' page. ​ To attend, become a member or pay a £3 fee at the door (email secretary.adas@gmail.com while we're meeting online) Download Previous Slide Show Click here to see more previous events with any slide shows of them linked, and click here for a list of presentations. Watch Video of Previous Meeting Click here to see more previous events with any videos of them linked, and click here for a list of videos. LATEST NEWS Mapping the Invisible Icy Elements from the Early Solar System The Hum of the Universe Click here for the latest news article Click here for the latest post about an event The This is the line up of the three people that keep this fantastic society ship shape, bringing the cosmos to you, even if the clouds cover it. LEARN MORE COMMITTEE

  • Videos |Altrincham and District Astronomical Society|Timperley

    PAST VIDEOS Date Speaker Position Subject Video 4 Jun 2021 Rodger Livermore Former ADAS member A Very Amateur Approach to Astro-Imaging: 13.6 Billion Years Ago to the Present 2 May 2014 Dr. Phil Masding, Dr. Andrew Fearnside ADAS member, Manchester AS member The Polarisation of Moonlight and the Composition of Moonrocks 7 Mar 2014 Eddie Bruce, Ewan Hill-Norris ADAS members "Moon Landing: Fact of Fiction" 3 Jan 2014 Richard Bullock ADAS member "The Night Sky this Month" 1 Nov 2013 Chris Suddick ADAS member "How to Measure the Universe"

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