206 results found for ""
- Seven Odd Stars
Dark matter Dark matter: It’s illusive in every respect, outweighing the more well-understood visible matter by around six to one, making up 27% of our entire Universe. And unlike normal matter, Dark matter cannot be seen: it doesn’t absorb, reflect or emit light, instead interacting only by its gravitational effect , theorised because of its effect on the mass of galaxies and galaxy clusters, like 'Abell 1656' or the 'Coma Galaxy Cluster'. Galaxy clusters revolve, like a carousel, with the speed of this movement dependent on both the mass and position of the galaxies (mass calculated using light coming from the cluster). However, Fritz Zwicky, a Swiss Astronomer, noticed it wasn’t revolving at the right speed for its mass. Instead, it was going at a speed suggestive of a greater mass, from another, invisible, source: dark matter. This has since been measured in many galaxy clusters, as well as galaxies, raising the question of “What are we missing?”. The Fermi Gamma-Ray Telescope (FGST for short) is one of many projects hoping to solve this. One part of its mission is to find possible gamma ray emissions due to the collision of dark matter particles . It looks at dwarf spheroidal galaxies (dSphs) -galaxies with little dust, old stars and low light emission-, the galactic centre -the centre of our Milky Way, where there may be an excess of dark matter-, galaxy clusters -the largest gravitationally bound structures, filled with dark matter-, and background emissions -with dark matter particle collisions thought to have happened throughout the Universe’s history-. Axions Axions are illusive particles, important because they could be one part of the answer to the question of a century: “What is dark matter?”. If they are real, they’re low mass elementary particles that could make up most, or all, of what we call “dark matter”. They’ve been found to possibly work like neutrinos : discovered because of a lack of conservation of energy, momentum and angular momentum (or spin) , with detectors like Super-Kamiokande (or Super K) in Japan. It uses a large stainless-steel tank filled with 50,000 tons of pure water, put 1,000 metres underground, using 13,000 bubble-like photon-multipliers (converts photons, particles that make up light, into electrical signals) to detect these particles, which are in abundance . So could we detect and study axions in this way? Quite possibly, since they’re likely produced in extreme environments, like star cores (like in our Sun). In fact, there is one such experiment, run at CERN (European Organisation for Nuclear Research), called the CERN Axion Solar Telescope, or CAST for short. It uses a strange type of telescope, using everything from a hollow beam pipe (like the tubes from normal telescope) to a dipole magnet (a prototype of that used in the Large Hadron Collider -LHC), along with an X-ray focusing mirror system and X-ray detectors at each end. But, why X-rays? Well, the magnetic field produced by the tube will convert axions into X-rays (read on to find out more about this process), making them easy to detect, since, as you will find out, X-rays from Space can’t be seen on Earth, even at the more high-tech observatories . The Magnificent Seven Yes, it’s a film, but it’s also a fun name for a group of seven neutron stars (also called the X-ray Dim Isolated Neutron Stars, or XDINS for short ): RX J0420.0-5022, RX J0720.4-3125, RX J0806.4-4123, RBS1223, RX J1605.3+3249, RX J1856.5-3754, and last but not least RBS 1774 (catchy!) . They’re important because, for their age, they emit too many ultra-high-energy X-rays . All stars have a lifecycle that can be plotted on a Hertzsprung-Russell Diagram: a diagram which relates luminosity (how bright) to temperature (what colour they are, using the letters OBAFGKM to denote this, O being the hottest and bluest, whilst M is the coolest and reddest). Stars, depending on their mass, follow various patterns across the graph . However, as recently found by using archive data from ESA’s XMM-Newton (or X-ray Multi-Mirror Mission) Space Telescope and NASA’s Chandra X-ray Space Telescope, these stars aren’t following suit, pretending to look older than they really are, as though they’re further along the path stars take along the diagram (although neutrons stars aren’t usually found on it, since they’re extremely hot and extremely blue). This seems pretty odd, but there may be a good explanation for this, and it lies in the illusive axion. They’re special, not only because the may hold the key to discovering what dark matter is, but because they’re expected to be created in the core of stars, creating high-energy X-ray photons when inside a strong magnetic field: a feature of the Magnificent Seven (with magnetic fields billions of times stronger than that found on Earth). In order to cement this theory, the next step is seen to be observing white dwarfs (remnant of a low-mass star, like the Sun) with X-ray telescopes, since they have very strong magnetic fields, but aren’t expected to produce x-rays . For Your Eyes Only It isn’t easy though, since observing in the high-energy X-ray part of the electromagnetic spectrum (a spectrum from red low energy to blue high energy light) is impossible from Earth based telescopes, with our atmosphere being opaque to high energy X-ray emissions (which is good for our health, but less so for science -you can’t have everything!). Instead, the only method is by taking up valuable time on the few X-ray telescope orbiting Earth, like XMM-Newton . The telescope, launched on 10th December 1999, uses 58 mirrors to detect millions of stars in one observation, even if they’re very dim and far away, using “five X-ray imaging cameras and spectrographs” . And then there’s Chandra, launched a few months before, on 23rd July 1999, with just 4 mirrors, nested inside each other, focusing light onto detectors 9.2m from the front of the telescope . What ever research into why these stars are so bring brings up, it will still revolutionise our understanding of the Universe, even if the extra emissions aren’t made by quite the process we anticipated. by George Abraham, ADAS member. #DarkMatter #Axion #HRDiagram #Star #NeutronStar #Neutrino #XRay #XMMNewton #Chandra #CERN #SuperK #FGST #XDINS #CAST Click here for the previous news article Click here for the next news article Click here to see the CAST experiment in action Click here to see a video of stars, imaged by ESA's Gaia mission, get collated into the Hertzsprung-Russell diagram Click on the names to have a look at what the Magnificent Seven look like with XMM-Newton data on ESA Sky: RX J0420.0-5022, RX J0720.4-3125, RX J0806.4-4123, RBS1223, RX J1605.3+3249, RX J1856.5-3754, RBS 1774 References "Dark matter". CERN. Archived from original on 23rd January 2021. "What is Dark Matter". NASA. Archived from the original on 23rd January 2021. "Fermi Searches for Dark Matter". Fermi Gamma-ray Space Telescope, NASA. Archived from the original on 23rd January 2021. "Mystery particle may explain extreme X-rays shooting from the 'Magnificent 7' stars". Space.com. Archived from the original on 23rd January 2021. "How Massive Neutrinos Broke the Standard Model". Forbes. Archived from the original on 23rd January 2021. "Overview". Super-Kamiokande. Archived from the original on 23rd January 2021. "Search for axions from nearby star Betelgeuse comes up empty". Phys.org. Archived from the original on 23rd January 2021. "X-ray dim isolated neutron stars: What do we know?". Max-Planck Institute for Extraterrestrial Physics. Archived from the original on 23rd January 2021. "The Magnificent Seven: Magnetic fields and surface temperature distributions". arXiv. Archived from the original on 23rd January 2021. "The Hertzsprung-Russell Diagram". CSIRO. Archived from the original on 23rd January 2021. "Physicists May Have Found Dark Matter: X-rays Surrounding "Magnificent 7" May Be Traces of Theorised Particle". SciTech Daily. Archived from the original on 23rd January 2021. "Transparency of the atmosphere". ESO. Archived from the original on 23rd January 2021. "XMM-Newton Summary". ESA. Archived from the original on 23rd January 2021. "About Chandra". Chandra X-ray Observatory, Harvard. Archived from the original on 23rd January 2021. "CAST". CERN. Archived from the original on 23rd January 2021.
- A Distant Flash
What is a Quasar? A quasar is not an object as such, but the evidence of one: a supermassive black hole, in the centre of a galaxy. They are a subset of Active Galactic Nuclei (AGNs) and are the most luminous (brighter than 100 billion Suns) and most massive (heavier than 100 million Suns) of them all. They are also quite uncommon, since they take a while to “warm up” and have a short life, finishing once the sufficient fuel, dust and gas for a quasar to occur has been used up on creating such bright events. Any AGN smaller than 100 million Suns (1 million to 100 million) is then dimmer than 100 billion Suns (1 billion to 100 billion), and is known as a Seyfert galaxy: much more common than their quasar counterparts, comparable to how stars get less common and last for less time the brighter they are (known as “cosmic downsizing”). This brighter trait of quasars means that they can be seen from a larger distance away, and being less common, appear to exist in the older (further away) universe, with the number of AGNs increasing from 13 billion years ago, before decreasing in density at around 10.5 billion years ago . Then, after quasars come blazars: AGNs that are pointed directly at Earth. These are much brighter than quasars, since sometimes the light, emitted in jets from AGNs, remains concentrated for hundreds of thousands of light years, whilst usually moving at 99% the speed of light . How to Find a Quasar Even in amateur telescopes, the brightest quasars are visible, looking like a star, whilst the host galaxy of the AGN is invisible (click here for a guide on how to observe them). However, some are out of the optical range, since they are too near or far from Earth. The distance changes the colour (or wavelength) of the light due to how wavelength increases with distance, creating a redshift (i.e. the light is redder and so less energetic than bluer light) . When trying to locate them with large telescopes, professional astronomers use a survey technique, looking across the sky, specifically at the universe when it was less than 3 billion years old, at the place when most quasars are: redshift z=3, being the amount of redshift something has (the greater the number, the greater the redshift), corresponding to how far away from Earth it is (greater redshift means its further away), known as “Hubble’s Law”. Examples of surveys to do this include the Sloan Digital Sky Survey (SDSS), with its survey to find quasars among other things, called the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). It mapped the sky zone where quasars exist (outlined earlier), finding 500,000 of them when it observed 6,000 square degrees of sky (just over 14.5% of the sky ), showing how common they are at that age of the universe . The Oldest Quasar Ever Discovered Discovered at a distance where the light observed was made around 670 million years (5% of its current age ) after the Big Bang , the catchy named quasar "J0313-1806" was discovered, at a brightness 1,000 times that of our own galaxy and a mass 1.6 billion times that of our Sun, using the equivalent of 25 Suns per year (compared the the Milky Way’s rate of the equivalent of 1 Sun per year ) , making the gas flowing out at 20% the speed of light. In fact, this quasar is so old that the black hole it originates from didn’t form from the collapse of a large star, as the common stellar mass black hole do (found nearer to Earth), but by cold hydrogen gas from the early universe collapsing in on itself to form a black hole . This discovery was only 20 million light years further than the last record for the oldest quasar, but the supermassive black hole it originate from is double the mass . What Quasars Tell Us They help us understand the early universe, being some of the only objects that can be detected by telescopes on Earth that far back in the past. They show us how black holes were made in the early universe. As well as this, it can tell us about what is between us and the quasar being observed, showing what the temperatures and compositions of gasses in the early universe were, by studying the spectrograms of light coming from quasars, having passed through all this material . This means that, as we find more and more quasars going further and further back in time (since they're further and further away in space, and light takes time to travel), we can build a picture of the early universe, and what and how things formed in that unique era in our universe’s history. by George Abraham, ADAS member #Quasar #Blazar #SeyfertGalaxy #BlackHole #ALMA #Record #ESO #EarlyUniverse Click here for the previous news article Click here for the next news article Click here to see an animation by ESO (European Southern Observatory) of one of the most distant quasars in our universe: ULAS J1120+0641 Click here to see the paper on the discovery of J0313-1806 Click here to look at a quasar, 3C 273, in a giant elliptical galaxy in the constellation Virgo (the first quasar to be discovered, discovered in 1960 by Allan Sandage) on ESA's ESASky References “Why are all quasars far away?” Astronomy. Archived from the original on 17th January 2021. “Blazars and Active Galaxies”. NASA Fermi. Archived from the original on 17th January 2021. “Visually Observing Quasars”. Royal Astronomical Society Canada. Archived from the original on 17th January 2021. “How Big is the Sky?” Bad Astronomy. Archived from the original on 17th January 2021. “eBOSS”. SDSS. Archived from the original on 17th January 2021. “A Luminous Quasar at Redshift 7.642”. arXiv. Archived from the original on 17th January 2021. “Quasar Discovery Sets New Distance Record”. ALMA. Archived from the original on 17th January 2021. “Most distant quasar discovered sheds light on how black holes grow”. Phys.org. Archived from the original on 17th January 2021. “Ultrabright Quasar Lit Up the Early Universe”. Live Science. Archived from the original on 17th January 2021.
- Redesigning the Satellite
A lot to take into Consideration Satellites and the rockets that encapsulate them are made of many combinations of materials to keep us safe and keep it and its contents safe, whilst getting the best science possible from a mission. However, for the most part, space agencies like to focus on the safety of the machine and what’s in it, being complex, with satellites exposed to the noise, vibration and gravitational forces of takeoff. Then, there’s the dramatic changes in temperature from going into and out of the Sun’s reach, creating fast and large temperature changes, leading to “thermal stress, vibration and cracking”  (with the ISS orbiting once every 92 minutes, creating 15 to 16 sunrises daily , and Mercury, a planet with little atmosphere, having temperatures as hot as 472ºC in the Sun, and as cold as -180ºC when facing away ). And then, there’s the constant bombardment of UV (Ultra-Violet) radiation (along with other ionising forms of radiation), leading to plastics and coatings cracking, and materials outgassing (which also leads to the new car smell), contaminating the surface of instruments . This has then led to the creating of new combinations of materials that combat these problems, then making them space-ready. These include kevlar: the material featured in bullet proof vests back on Earth, but used on satellites in Space, for its resistance to temperature change and the constant threat of space debris impacting the satellite. Then, there’s aluminium: a light weight material that, when combined with others in an alloy, is strong, so much so that it’s used on the ISS’s shutters to protect windows from space debris impacts (which, incidentally, are made of twice the number of panes, all at greater thickness, than those used on Earth) . Progress in Temperature Control Satellites use a range of coatings and technologies to regulate their temperature, keeping both the equipment, and possibly people within, safe. One such technology is an Optical Solar Reflector (OSR), glued to the outside of the satellite’s radiator panels (panels threaded with pipes containing ammonia, which changes from gas to liquid to release waste heat from the craft, before cycling around again ), rejecting solar radiation whilst dissipating excess heat from the satellite. However, the OSRs, made of quartz, are heavy, fragile, and therefore expensive, whilst not having the ability to be applied to curved surfaces, with polymer foils having taking its place in such circumstances, while suffering from issues of longevity, lasting only 3-5 years. Another technology came out in 2018 that greatly improved this technology, known as meta-OSR, designed around metal oxides, with the added benefits of being lighter in weight, durable, and taking the place of not just the OSR, but louvers (which are rather like Venetian window blinds, regulating how much heat is lost ) as well, through different combinations of these metal oxides . Advances in Harvesting Solar Energy Energy is another very important resource in Space, with most satellites getting it from the Sun (except the few that use technologies like nuclear power, such as Voyager 1 and 2 ), shown by spacecraft such as ESA’s Philae lander, which lost power to transmit data back to Earth, because it was in a place with only 1.5 hours of sunlight in 67P’s (the comet) 12 hour day . However, what if you could use more efficient solar panels, getting more energy from the Sun so more data can be transferred, possibly helping the next big discovery to happen? One such technology is called perovskite: a crystal discovered 200 years ago, which is more efficient because of its wider use of the electromagnetic spectrum (made of light at different frequencies), with 27.3% efficiency instead of the 22% of typical silicon solar technology around now . It is also flexible , allowing for easier and cheaper designs of solar arrays on satellites in the future. Environmental Impact However, the technology for satellites is designed with the survival of the satellite and what’s inside it in mind; not who and what is left on Earth. The rockets that send those satellites up do have an affect on important parts of our atmosphere, like the Ozone Layer, located in the Stratosphere. Particles emitted by the rocket’s engines act as a nucleus, or starting point, for ice to form, leading to ozone being depleted. Moreover, some rockets emit chlorine gas, which acts like the CFCs (Chlorofluorocarbons) banned worldwide for their affect of creating a hole in the Ozone Layer . And then, there’s the space debris problem, where, upon reentry of a satellite, small particles of alumina (synthetic aluminium oxide), which, as Takao Doi (professor at Kyoto University and a Japanese astronaut) put it, “will float in the upper atmosphere for many years” , also contributing to the problem of loss of ozone when released in the Stratosphere. Wood: the Newish Super-Material The answer could lie in the new proposal (published on 24th December 2020) by Sumitomo Forestry (a Japanese forestry company) and Kyoto University (based north east of Osaka in Japan, south west of Tokyo), in which wood is the material of choice for a satellite, to be finished in 2023 . Wood, unlike traditional aluminium alloys, would burn up in the atmosphere upon reentry, releasing no harmful substances and releasing no debris to interact with the Ozone Layer or become space debris . Moreover, wood doesn’t stop electromagnetic radiation (light) or magnetic fields, meaning that devices like antennas (for transmission of information) and attitude control mechanisms (controlling the orientation of the satellite), leading to simpler, more cost effective satellite designs. However, the materials used will also be resistance to temperature change and harmful solar radiation described earlier . These new discoveries and inventions are just scratching the surface of what developments await in the future, making space technology more sustainable and good for our planet, whilst revealing more secrets of our universe. By George Abraham, ADAS member #Satellite #Ozone #ISS #SpaceDebris #Perovskite #MetaOSR #Wood Click here for the previous news article Click here for the next news article Click here to learn how to make your own satellite with JPL’s guide Click here to see the current state of the Ozone Layer Click here to see NASA’s “Beginner’s Guide to Rockets”, including information on everything on how they get rockets off the ground and into space to then survive References "Materials and Processes". ESA. Archived from the original on 4th January 2021. "International Space Station: 15 Facts for 15 Years in Orbit". Space.com. Archived from the original on 4th January 2021. "The Materials Used in Artificial Satellites and Space Structures". AZO Materials. Archived from the original on 4th January 2021. "Shaker test of radiator panel". ESA. Archived from the original on 4th January 2021. "Rosetta thermal louvres". ESA. Archived from the original on 4th January 2021. "New thermal coatings for spacecraft and satellites developed sing metamaterials". University of Southampton. Archived from the original on 4th January 2021. "Voyager's Heartbeat is Nuclear 'Battery'". The New York Times. Archived from the original on 4th January 2021. "Philae comet lander sends more data before losing power". BBC News. Archived from the original on 4th January 2021. "UK firm's solar power breakthrough could make world's most efficient panels by 2021". The Guardian. Archived from the original on 4th January 2021. "Perovskites: The future of solar?". BBC Sounds. Archived from the original on 4th January 2021. "Satellites and the Ozone Layer". BBC Sounds. Archived from the original on 4th January 2021. "Japan developing wooden satellites to cut space junk". BBC News. Archived from the original on 4th January 2021. "World's first wooden satellite to be launched by Japan in 2023". Nikkei Asia. Archived from the original on 4th January 2021. "How Hot is Mercury?" Space.com. Archived from the original on 4th January 2021.
- Useful Resources | Altrincham and District Astronomical Society | Timperley
- Beginners | Altrincham and District Astronomical Society | Timperley
BEGINNERS If you’re interested in astronomy the best thing to do is to contact ADAS and arrange to come to one of our meetings. We’re a friendly group who will help you by suggesting resources, equipment and you are welcome to listen to some of our talks and presentations. Like us on Facebook where you can ask questions and join in the discussion or follow us on Twitter. One of the first things people want to do when they start looking at the stars is to buy a telescope. However, before you do that, there are many amazing things to see without any equipment, with the naked eye. Here is a short video to tell you what there is to see. One of the best ways to find you way round the night sky is to learn the constellations. Here is a short video showing those you may see from the perspective of Northern Europe. Remember that if you visit anywhere in the southern hemisphere (like Australia) the night sky will look different. is a free piece of software that you can load onto laptops, tablets and even phones. and versions are available. It has a great function where you can see all the constellations (find this and many more in the " " section). Here’s a video showing you the constellations. Stellarium Android iOS other useful resources Next, once you've learnt your way round the sky, it's time to start looking with a smaller field of view, on a telescope. Here’s a short video by the BBC Sky at Night Magazine explaining a little more about what is on offer (left), followed by the ADAS Guide to Choosing the Right Telescope (right). Along with owning a telescope, it is useful to know how the various types of telescope work and how to use them. Here is the ADAS Guide to Telescope Instrumentation and Operation, produced by ADAS members in 2014. As well as the telescope itself, eye pieces are also needed to view the night sky with a small and detailed field of view. Here is the ADAS Guide to Using Eyepieces There are some great video resources on YouTube and other sites. Here’s one that explains the basics of astronomy. Remember that any books will probably be available from the or as we may have a copy available for you to borrow. local library contact us Of course stars aren’t the only thing you might like to look at. You can get a good view of some of the solar systems planets. This first video (left) gives you some great images of the planets in the solar system. The second video (right) is a much longer and in-depth video about the solar system. Please do get in touch with us and arrange to visit one of our meetings and presentations or stargazing nights.
- Previous Events | Altrincham and District Astronomical Society | Timperley