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A 3-D model of the Milky Way Galaxy using data from Cepheids

Astronomers generate the largest 3D model of Milky Way using Cepheid data

We do not possess a GPS system for our twisted and warped galaxy. As a result, astronomers have to be crafty for pointing our location among stars and producing maps of the Milky Way galaxy. Astronomers from the US and Europe successfully managed to create a 3D model of Milky Way galaxy which is based on the interstellar distance. The study has been published in the Science journal

It draws on the population of stars that are called Cepheids. They are massive, young, pulsing stars having brightness more than that of the Sun. The University of Warsaw ran a sky survey with the help of data from the Optical Gravitational Lensing Experiment from Las Campanas Observatory in Chile. Researchers managed to pick out 2,431 Cepheids through the thick dust and gas of Milky Way and used them for generating the map of the galaxy. 

Dorota Skowron, a researcher with Wroclaw University of Science and Technology and the study’s lead author said that the OGLE project observed the Milky Way’s galactic disk for a period of six years while capturing 206,726 sky images that contained 1,055,030,021 stars. In this they found the Cepheids population to be very useful for the purpose of map plotting since their brightness varies over time. 

This allowed the researchers to observe how bright the star actually is versus how it appears from the Earth. This difference between the two can inform us how far the star is from our Sun. With the help of this fluctuation, scientists produced the galaxy’s 3D model which confirmed the previous work that the galaxy is flared at the edges. They were able to determine the Cepheid’s age where the younger stars were closer to the center and older stars farther away from the galactic disk. 

With the simulation of star formation in the early Milky Way, scientists showed the evolution of the galaxy in past 175 million years with star formation in spiral arms resulting in distribution of Cepheids from 20 million to 260 million years old. Skowron hopes that the paper will be a good initial point for sophisticated modeling of our Galaxy’s past, as the Cepheids are a great testbed for checking the accuracy of the models. 

A study was earlier published in Nature Astronomy which looked at 1339 Cepheids and generated a comprehensive 3D map of Milky Way which found that our galaxy is twisted at the edges. It observed stars from the Wide-field Infrared Survey Explorer (WISE) of NASA. These two studies produced similar results which found about the warped edges of Milky Way. Both the studies relied on the fact that the Cepheids are present on our side of the Milky Way. An important question is whether there is a similar warp in the opposite side too.

Skowron does not think observing the other side will increase the probability of finding Cepheids. The future projects will observe the pulsing star found in our Galaxy called  RR Lyrae. They are present from an earlier time in the Milky Way and can provide another way of mapping the Galaxy. 

Journal Reference: Science journal

impression of pulsar planet

Astronomers discover a new type of strange pulsating star

Astronomers have discovered a type of very small, hot star which brightens and dims very often as the outer layers try to maintain an equilibrium. These stars are named as hot subdwarf pulsators and they might be related to a recently discovered rare star known as blue large-amplitude pulsator. The paper has been published in The Astrophysical Journal Letters.

Physicist Thomas Kupfer, Kavli Institute for Theoretical Physics, UC Santa Barbara said that there are many stars that pulsate including the Sun on a small scale. The ones having the largest brightness changes are known as radial pulsators which breath in and out as the size of the star changes. Although our Sun pulsates, its cycle is 11 years and the variation in brightness is only by 0.1 percent in the entire timeframe, hence it is not a pulsator in the truest sense. 

The brightness of the pulsators often vary by as much as 10 percent due to size and temperature change. 

Researchers identified four new stars from Zwicky Transient Facility survey that pulsate on timescales between 200 and 475 seconds with variation in brightness upto 5 percent. This change in brightness occurs in eclipsing binaries thus it was ruled out before being classified as a new type. Researchers then realised it to be subdwarf B stars

Subdwarf B stars are pretty small, about 10 percent of the sun’s size although very dense. In their small diameter, they pack in almost 20 to 50 percent of the mass of Sun. They are very bright as they burn at 20000 to 40000 Kelvin. It is considered that they form along a star’s evolutionary path upto eight times the mass of Sun when it dies.

As they run out of hydrogen to fuse in cores, they fuse helium turning to a red giant.  subdwarf B star is what happens when the outer hydrogen layers of a red giant are stripped away before helium fusion begins – possibly by a binary companion, but the exact mechanisms are unknown.

The V361 Hya class have a mode of pressure oscillation meaning that their pulsations are produced by the star’s internal pressure fluctuations. The V1093 Her class are gravity-mode pulsators that are produced by gravity waves. (not to be confused with gravitational waves).

Researchers are trying to find the exact mechanism of the oscillations of hot subdwarf pulsators although some believe it might be due to the unstable radial modes that are produced by iron kappa mechanism where iron buildup in star creates an energy layer resulting in pulsation. Subdwarf B stars are normally considered to be fusing helium, in their core or shell around the core. However, scientists believe that hot subdwarf pulsators lost the outer material before the helium was hot and dense.

Physicist Evan Bauer explained that rapid pulsations are understood by matching them to theoretical models where the low mass cores are composed of cold helium. The next step is to understand the actual mechanism behind pulsation and where the stars fit in the stellar evolution. 

Journal Reference:The Astrophysical Journal Letters

Mini Sun

Researchers recreate mini sun for studying solar winds and plasma burps

The stars in our universe have a magnetic field that interacts with the winds which they produce including our sun. As a result of the collaboration between the Sun’s magnetic field and the solar wind leads to the formation of a heliospheric magnetic field like a spiralling structure known as the Parker spiral. This spiral is important for administering the plasma processes that source the solar wind.

According to a new study at the University of Wisconsin-Madison, the physicists have reported the creation of a mini sun like a laboratory model of the Parker spiral system based on the idea of rotating plasma magnetosphere and measurement of the global structure and dynamic behaviour. The study has been published in Nature Physics.

Physicists have access to this Big Red Ball, which is a three-meter wide hollow sphere which contains different probes and a strong magnet at the centre. The helium gas is siphoned and ionized to create plasma and then an applied electric field alongside the magnetic field which copies the ideal case of spinning plasma and the electromagnetic fields of the sun. Estimations can be taken at numerous points inside the bass which enables physicists to study the solar phenomena in three dimensions.

They have an option to replicate the Parker Spiral, a magnetic field which covers the entire solar system, the magnetic field transmits straight out of the sun. From there onwards, the solar wind dynamics take over and haul the magnetic field into a spiral.

A graduate student in the Physics department at UW-Madison, Ethan Peterson said that the satellite measurements are pretty consistent with the Parker Spiral model, only at one point at a time and so can never make simultaneous and map it on a large scale map. The plasma from the sun’s plasma burps fuel up the slow solar winds.

The speed of light and magnetic field are probed and the data has mapped a region where plasma is moving fast enough and where the plasma could break off and eject radially. The ejections have been spotted by satellites and no one knows the reason as to what drives them. They found similar burps in the experiment and found out how they developed.

The work has shown that understanding fundamental physics of these processes is possible through laboratory experiments and the Big Red Ball being funded as a National User Facility allows scientists to study the physics of solar winds. The Earthbound experiments can not replace satellite missions like the Parker Solar Probe which was launched in August 2018 can reach the Alfven surface and can even dip below it. It is expected to provide direct measurements of the solar wind.

Journal Reference: Nature Physics

LightSail 2

Crowdfunded spacecraft LightSail 2 deployed its solar sails in space

LightSail 2 has successfully deployed their solar sails as confirmed by The Planetary Society in a tweet which showed the deployment of their sails and that the spacecraft was sailing with sunlight as the propulsion source. We can now explore and wonder how solar sails will fit into humanity’s plan for space exploration.

The Planetary Society is the world’s largest non-profit space organization. LightSail 2 was their third spacecraft which launched on June 25 and has been orbiting since then, sending the pictures of Earth. The sail of LightSail 2 is a system of 4 smaller triangular sails which combine to form one large square around 32 sq. meters. After the deployment, it can be used for raising the spacecraft’s orbit and demonstrating the power and usefulness of solar sails. After receiving some telemetry from the tiny satellite, it showed the motor count to be rising and the cameras were active.

The idea of the Solar Sail is relatively simple in theory. A solar sail utilizes the momentum of the photons which reaches from the sun just like how a sailboat gains energy from the wind. The photons bounce off from the reflective surface and propel the sail as it is lightweight. Although it uses simple technology, it has great potential.

There is no resistance to the momentum due to vacuum in the space and as more and more photons bounce off, it leads to greater speeds and this can be achieved without any fuel or propulsion system. It is similar to that of a boat, the sail can be aimed at angles to direct the travel of spacecraft. If the sails are aimed at the sun, the spacecraft will directly propel away from the sun. By changing the angles it can steer and propel itself through the solar system. They keep gaining speed and momentum as they travel and can accelerate as long as photons hit the sail. It can achieve speeds which a chemical rocket could never reach, although they cannot escape the Earth’s gravitational pull on their own.

As it moves further away from the sun, fewer photons will hit the sail but the spacecraft will not slow down but the only rate of acceleration will decrease. It is aimed at long journeys where their simple yet effective system can shine. It is thought that even lasers could be pointed at the sails to increase their acceleration.

The Breakthrough Starshot aims to send a fleet of solar sails to the nearest neighbor star, Alpha Centauri. Rather than being fully dependent on the sun rays, it can be propelled by using an array of lasers. Lasers can accelerate the spacecraft to a velocity close to 60,000 km/s. At this rate, the Alpha Centauri which is 4.37 light-years away will be reached only in 20 years time. Breakthrough Starshot is a project by a Russian billionaire and LightSail is built with money raised from enthusiasts. LightSail 2 is a demonstration mission that shows how a small solar sail can raise the orbit of the spacecraft. There are many obstacles to overcome for commercial applications so that the technology is suitable to explore the Solar System.

Magnificent CME Solar eruption of plasma

Researchers discover mystery of exotic material in Sun’s atmosphere

A group of researchers from Ireland and France have declared an important finding on the behaviour of matter in the highly extreme conditions of the atmosphere of Sun. They used radio telescopes and UV cameras on a spacecraft of NASA for knowing about the exotic “fourth state of matter” about which very less is known. This state of matter called plasma may be significant in the development of safe, green and environment-friendly nuclear generator. The results of the study have been published in the Nature Communications journal.

Although the matter we encounter in our daily lives can be differentiated to either solid, liquid or gas, the Universe is majorly made of plasma. It is an extremely unstable fluid which is also highly electrical in nature. Even the Sun is composed of plasma. However, the irony lies in the fact that although the plasma is the most common state of matter in the Universe, human beings have a vague idea of it. Reason being its scarcity on Earth, which makes it difficult to understand.

Laboratories on Earth try to simulate the conditions of space however the Sun is the natural laboratory in which the behaviour of plasma can be understood, which is not possible for the ones attempted on Earth.

Dr Eoin Carley, a Postdoc researcher at the Trinity College Dublin who led the joint collaboration said that the sun’s atmosphere has very extreme conditions with the temperatures of plasma soaring to excess of one million degrees Celsius and particles travelling very close to the speed of light. These particles shine very brightly at the radio wavelengths, hence the behaviour of the plasma can be monitored with the aid of large radio telescopes.

Scientists worked with the researchers at the Paris Observatory and the observations of the Sun were performed by a radio telescope situated in Nançay, central France. These observations were combined with the UV cameras mounted on the Solar Dynamics Observatory spacecraft. It was then seen that plasma on the Sun can eject pulses resembling those from the light house. Scientists were aware of this for many years but could observe it directly for the first time with the help of these highly advanced equipments.

The problem with nuclear fusion plasmas is that they are highly unstable. When the plasma starts producing energy, the reaction is switched off by natural processes. This indicates that it is difficult to produce energy while keeping the plasma stable. By learning about the instability of plasma on the Sun, scientists can learn how to control plasma.

solar panels array

How Solar Cells Work and are They Important for Our Future?

Solar cell technology: How it works and the future of sunshine

Why do we waste time drilling for oil and shoveling coal once there is a mammoth powerhouse within the sky up on top of us, causing out clean, non-stop energy for free? The Sun, an agitated ball of atomic energy, has enough fuel aboard to drive our scheme for an additional 5 billion years—and solar panels will flip this energy into an endless, convenient provider of electricity.

energy-generation-worldwide-by-wikipedia

Image Source: Wikipedia

Solar power might sound strange or futurist, however, it’s already quite commonplace. You may have a solar-powered quartz watch on your wrist joint or a solar-powered calculating machine. Many folks have solar-powered lights in their garden. Spaceships and satellites typically have solar panels on them too. The yank house agency NASA has even developed a solar-powered plane! As warming continues to threaten our surroundings, there looks very little doubt that solar energy can become a fair additional vital style of renewable energy within the future. However specifically will it work?

How much energy are we talking about?

Solar power is wonderful. On average, each square measure of layer receives 164 watts of alternative energy (a figure we’ll make a case for in additional detail during a moment). In alternative words, you may stand a very powerful (150 watt) lamp on each square measure of layer and lightweight up the entire planet with the Sun’s energy! Or, to place it otherwise, if we have a tendency to line only one p.c of the Sahara with solar panels, we have a tendency to may generate enough electricity to power the entire world. That is the smart factor concerning solar power: there is associate degree awful ton of it—much quite we have a tendency to may ever use.

But there is a drawback too. The energy the Sun sends out arrives on Earth as a combination of sunshine and warmth. each of those area units implausibly important—the light-weight makes plants grow, providing us with food, whereas the {warmth} keeps us warm enough to survive—but we will not use either the Sun’s light-weight or heat on to run a TV or an automobile. We have to search out how of changing alternative energy into alternative styles of energy we will use a lot of simple, like electricity and that is specifically what solar cells do.

What are solar cells?

Solar power is rattling. On average, every area unit of layer receives 164 watts of other energy (a figure we’ll build a case for an extra detail throughout a moment). In different words, you will stand an awfully powerful (150 watt) lamp on every area unit of layer and light-weight up the complete planet with the Sun’s energy! Or, to put it otherwise, if we have an inclination to line only 1 p.c of the Sahara Desert with solar panels, we have an inclination to could generate enough electricity to power the complete world. That’s the good issue regarding solar power: there’s academic degree awful ton of it—much quite we have an inclination to could ever use.

solar cell principle

Image Source : Wikipedia

But there’s a downside too. The energy the Sun sends out arrives on Earth as a mixture of sunshine and heat. every of these space units incredibly important—the light-weight makes plants grow, providing us with food, whereas the keeps us heat enough to survive—but we’ll not use either the Sun’s light-weight or heat on to run a TV or associate degree automobile. We’ve to look out however of fixing energy into different types of energy we’ll use a great deal of easy, like electricity. Which is specifically what solar cells do.

Just like the cells in a very battery, the cells in a very electrical device area unit designed to come up with electricity; however wherever a battery’s cells build electricity from chemicals, a solar panel’s cells generate power by capturing daylight instead. they’re generally known as electrical phenomenon (PV) cells as a result of they use daylight (“photo” comes from the Greek word for light) to form electricity (the word “voltaic” could be a relation to Italian electricity pioneer Alessandro Conte Alessandro Giuseppe Antonio Anastasio Volta, 1745–1827).

We can think about light-weight as being made from little particles known as photons, therefore a beam of daylight is sort of a bright yellow hose shooting trillions upon trillions of photons our means. Stick a photovoltaic cell in its path and it catches these energetic photons and converts them into a flow of electrons—a current. Every cell generates a number of volts of electricity, therefore a solar panel’s job is to mix the energy made by several cells to form a helpful quantity of electrical current and voltage. Nearly all of today’s solar cells area unit made up of slices of Si (one of the foremost common chemical parts on Earth, found in sand), though as we’ll see shortly, a range of different materials is often used similarly (or instead). Once daylight shines on a photovoltaic cell, the energy it carries blasts electrons out of the Si. These are often forced to flow around an electrical circuit and power something that runs on electricity.

How do solar cells work?

Solar cells convert the sun’s energy or solar energy into electricity. Whether or not they’re adorning your calculator or orbiting our planet on satellites, they admit the photoelectrical effect: the flexibility of concern emit electrons once a light-weight is shone thereon.

Silicon is what’s called a semiconductor, which means that it shares a number of the properties of metals and a few of these of an electrical non-conductor, creating it a key ingredient in solar cells. Let’s take a better inspect what happens once the sun shines onto a cell.

solar-cell-working

Sunlight consists of minuscule particles known as photons, which radiate from the sun. As these hit the element atoms of the cell, they transfer their energy to lose electrons, sound them clean off the atoms. The photons might be compared to the white ball in an exceedingly game of pool that passes on its energy to the colored balls it strikes.

Freeing up electrons is but solely the work of a star cell: it then has to herd these stray electrons into an electrical current. This involves making an electrical imbalance at intervals the cell, that acts a small amount sort of a slope down that the electrons can flow within the same direction.

Creating this imbalance is formed attainable by the interior organization of element. Element atoms area unit organized along in an exceedingly tightly certain structure. By compression little quantities of different parts into this structure, 2 differing kinds of element area unit created: n-type, that has spare electrons, and p-type, that is missing electrons, going away ‘holes’ in their place.

When these 2 materials area unit placed facet by facet within a cell, the n-type element’s spare electrons skip filling the gaps within the p-type silicon. This suggests that the n-type element becomes charged, and therefore the p-type element is charged, making an electrical field across the cell. As a result of the element may be a semiconductor, it will act as a non-conductor, maintaining this imbalance.

As the photons smash the electrons of the element atoms, this field drives them on in an orderly manner, providing the electrical current to power calculators, satellites and everything in between.

Are solar cells important for our future?

Solar energy has unbroken our species alive for thousands of years: heat, light, and crops. However, harnessing this energy to come up with electricity is, relatively, a really recent development. Because the Royal Society of London for Improving Natural Knowledge of Chemistry says, “The quantity of energy reaching the Earth’s surface each hour would meet the world’s current energy demands for a complete year… we have a tendency to not ought to gamble the lifestyles of future generations”. Additionally, technology is continually being improved and refined. But how, specifically, alternative energy be of profit in our lives and people of future generations worldwide?

The most obvious professionals of alternative energy, as we have a tendency to at solar Action Alliance indicate, a square measure that’s that it’s rife, property, free, secure, and reliable. Even in less sunny countries like the UK, there’s enough energy within the rays that reach the surface to come up with electricity. However, sunny locations like Calif., square measure ideal for a solar.

Just as individual households or businesses are able to do independence in reference to an influence provide, communities and cities will do a similar with whole communities living off-grid and being self-sustaining. In a world of restricted and strained resources, this can be a large advantage… and one that may be progressively necessary within the future.

Small, rural, and/or less affluent communities, regardless of however remote, won’t get to trust massive energy suppliers and their infrastructures or wait a protracted time for services to achieve them. Solar kits will reach any community and be fitted to homes, schools, clinics, and so on.

The fact that solar panels and systems square measure currently obtainable in varied sizes, shapes, and thicknesses conjointly make them much more versatile in terms of applications and wherever they will be used. New applications are perpetually being found and installations being created. There’s no reason to believe the longer term ones won’t be even a lot of exciting and liberating.