Researchers using the Hubble Space Telescope have confirmed that electrically charged molecules are present in the space, which gives information on the contents of Interstellar Medium (ISM) – the gas and dust particles that fill the interstellar space. The study has been published in the Astrophysical Journal Letters.
Martin Cordiner,Catholic University of America who is currently at NASA’s Goddard Space Flight Centre said that the interstellar space can be considered as the initial point of the chemical reactions which ultimately leads to the formation of planets and life. As a result, identifying the contents of this diffused medium gives knowledge on the elements needed for the creation of planets.
Cordiner and his team of researchers identified the molecules that are a form of carbon known as “Buckminsterfullerene“, also called Buckyballs. It consists of an arrangement of 60 carbon atoms and is found rarely in rocks and minerals of Earth.
C60 has been identified in space in the past. But this is the first time that there has been confirmation about the presence of an electrically charged version in the diffuse ISM. Ionization of C60 occurs when UV light rays from the stars remove an electron, resulting in the formation of a positive charge (C60+). It was earlier considered that the harsh conditions of diffused ISM are not suitable for the presence of large molecules. Before C60 detection, the biggest molecule to be present in the space had only 12 atoms. The presence of a positively charged C60 shows that astrochemistry is quite complex even in the low density, high UV radiated areas.
Formation of life is based on carbon molecules and this discovery shows that complex carbon molecules can survive even in the harshest conditions in interstellar space. Due to the remote location of interstellar space, scientists study its contents with the help of its effects of light on distant stars. When researchers analyze the starlight with the help of its spectrum, the absorbed colors either appear dim or are not present. Some absorption patterns cover a greater range of colors, which is different from any atom on Earth. These are known as Diffuse Interstellar Bands(DIBs). They were first discovered by Mary Lea Heger in 1922.
There are more than 400 DIBs that are known at present, but they have not yet been identified. But the absorption pattern of C60+ was properly matched with the observations of ISM by Hubble Telescope. The Hubble Telescope had a clear view as it orbits above the atmosphere in space, which most of the ground-based telescopes did not have.
The team now aims to detect more C60+ to identify how widespread it is in the Universe.
June 8, 2019(updated June 8, 2019) Published by NASA
This striking image was taken by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3), a powerful instrument installed on the telescope in 2009. WFC3 is responsible for many of Hubble’s most breathtaking and iconic photographs.
Shown here, NGC 7773 is a beautiful example of a barred spiral galaxy. A luminous bar-shaped structure cuts prominently through the galaxy’s bright core, extending to the inner boundary of NGC 7773’s sweeping, pinwheel-like spiral arms. Astronomers think that these bar structures emerge later in the lifetime of a galaxy, as star-forming material makes its way towards the galactic center — younger spirals do not feature barred structures as often as older spirals do, suggesting that bars are a sign of galactic maturity. They are also thought to act as stellar nurseries, as they gleam brightly with copious numbers of youthful stars.
Our galaxy, the Milky Way, is thought to be a barred spiral like NGC 7773. By studying galactic specimens such as NGC 7773 throughout the universe, researchers hope to learn more about the processes that have shaped — and continue to shape — our cosmic home.
An earlier discovery that a galaxy without dark matter existed was indeed a mystery and was incompatible according to current theories however it has now been resolved. According to a new analysis the NGC1052-DF2 galaxy which was found last year is closer to us than expected and previously calculated, which means it is likely to contain dark matter. The study has been published in the Monthly Notices of the Royal Astronomical Society.
Dark matter is indeed a big mystery in itself as we cannot detect that it exists and even we do not know it exists but we know it is present which creates the effect of mass in the universe. Objects in the galaxies move faster than they should be moving because of this undetectable force due to the extra mass of dark matter which in turn generates more gravitational force than normal.
Dark matter is fundamental to our understanding of the universe. It has helped in the formation of stars and galaxies from the primaeval soup that existed after big bang and dark matter is what prevents bodies in the galaxy from just flying off into the unknown.
After reading and seeing the formation of the NGC1052-DF2 galaxy it changes the way as to how we think galaxies are formed. For decades we have thought that galaxies were formed due to dark matter and later forms stars due to the gases present in the dark matter. It is a critical ingredient in understanding the universe.
An international team of researchers led by the Instituto de Astrofísica de Canarias (IAC) decided to take a closer look at this galaxy and found out that anomalous measurements that were recorded in previous research have pointed out the absence of dark matter was dependant on the distance to the galaxy around 64 million light years away. Researchers used five separate telescopes including Hubble and the Gemini Observatory to recalculate the distance to NGC1052-DF2 galaxy.
The distance obtained was close to 42 million light years away instead of 62 million light years which was recorded earlier and based on this, the mass of galaxy was half as less than it was previously assumed to be and the stars were about a quarter their weight. This galaxy has lesser mass but the existing mass contains more dark matter than traditional matter. The previous theory of absence of dark matter was due to the slow movement of star clusters however now the movement seems normal. It now appears as an ordinary low brightness galaxy with plenty of room for dark matter. More such galaxies exist where absence of dark matter is speculated, the NGC1052-DF4 being a similar case.
Using NASA’s Hubble Space Telescope, astronomers have created the largest mosaic of the universe containing about 265,000 galaxies. This image is known as the Hubble Legacy Field, and it contains 265,000 galaxies which have been formed up to 500 million years after the Big Bang.
This is the widest view which has been taken of the universe using Hubble Space Telescope’s observations spanning 16 years. The faintest galaxies on the photograph are about one ten-billionth of the brightness which can be viewed by the human eye. This is a remarkable image as it enables us to view the entire history of the evolution of the universe and it also shows how changes occur in the galaxies over a period of time to come up as a giant galaxy.
The image has been possible due to the many deep field surveys which have been taken by Hubble which includes the eXtreme Deep Field(XDF) which is the deepest observation of the universe. The range of wavelength is from the ultraviolet light to the near-infrared light which enables to capture the main features of the changes in the galaxies as time passes.
Garth Illingworth, from the University of California, Santa Cruz, commented that as it has been possible to get a wider view in the universe than the previous surveys, many distant galaxies have been captured in the biggest ever dataset which has been produced by Hubble. A single image captures the entire history of the growth of galaxies.
Scientists feel that no image ever can compete with the image produced now, till space telescopes are launched in the future. Illingworth added that this image is meant to be a tool for studying by the astronomers and it will be an aid in the deeper understanding of the evolution of the universe.
Edwin Hubble once remarked that galaxies act as the markers of the space. They allow scientists to keep track of the expansion of the universe. This image is almost equal to the width of Full Moon. It is the culmination of the work of 31 Hubble programs which comprises several teams of astronomers.
Dan Magee, from the University of California, Santa Cruz, who is the data processing lead of the team explained that this legacy image has been made by judging the exposures spanning 16 years. It was not put in this manner previously and thus was not suitable for use by scientists. The Hubble Space Telescope is a project among several institutes such as NASA, ESA and Space Telescope Science Institute.
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In the latest researches, the results have been shown that the universe is enlarging much quicker than it should be based on the conditions after Big Bang. The constantly increasing rate of the universe is known as Hubble Constant and it has been very hard to pin down the rate. The results of the research have been published in The Astrophysical Journal.
Adam Riess, professor of astronomy and physics at The Johns Hopkins University in Baltimore said that there has been a huge mismatch between what they calculated and the rate by which the size of the universe is increasing and also added that this was totally unexpected. Riess also won a Nobel Prize in physics in the year 2011 for research in the late ’90s about the increase in the speed of expansion of the universe. Astronomers are totally astonished about what’s the reason behind this expansion and many of them use it as an unknown repulsive force known as dark energy.
Riess and his colleagues used a new method with the help of Hubble Space Telescope to study about the 70 Cepheid variable stars present in the Large Magellanic Cloud which is one of the Milky Way’s satellite galaxies. Standard candles are used by the astronomers to calculate the distances since the Cepheid variables faint and enrichen up at an expected rate. The researchers derived a new Hubble Constant of 74.03 kilometers per second per megaparsec using the data which is 9% faster than the data estimated in the Planck data and that the chance of an error is about one in 100,000 now. Adam Riess also said that the Hubble tension connecting the late and early universe might be the most thrilling development in cosmology in decades.
The mysterious form of energy known as dark energy which is thought to be comprised of about 70 percent of the matter-energy as well as the density of the universe and it is currently the most believed statement behind the speed of the growth of the universe. Astronomers aren’t sure about the reason but they say that maybe the dark matter is interchanging with the normal matter strongly that they have thought it to be the reason behind the expansion but it can also mean that the result is cannot be elaborated according to the physics present currently so some brand new and strange kind of physics might be needed.
Riess also added that these aren’t only the two failed experiments but many more are there We can conclude that researchers are calculating something basically different and the first one is how quickly the universe is expanding and the second is the reason behind its expansion and its calculation.
March 10, 2019(updated March 10, 2019) Published by Kshitij Kumar
The new calculation of the measurement of the size and mass of the Milky Way is more accurate and the galaxy turned out to be more massive than thought earlier.
The galaxy has been calculated to have a mass of about 1.5 trillion Sun’s worth of mass (solar masses) within a radius of around 129,000 light years. This calculation exceeds over twice as much as previous estimates of 2016’s study in which it was estimated to have around 700 billion solar masses.
To accurately map the Milky Way in three dimensions, ESA’s Gaia Mission has been launched. This mission has given the most detailed map of our home galaxy ever made and has been refining our knowledge all over the shop.
A search team has been able to infer the galaxy’s size and mass based on the orbital motion of groups of stars called globular clusters, out in the galactic halo by combining Gaia data with those from Hubble Space Telescope observations.
The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis, flying STS-125, HST Servicing Mission 4. Image Credit: Wikimedia/ Ruffnax (Crew of STS-125)
With the dark matter in play, the mass of the Milky Way can’t just be guessed based on what we can see. And the dark matter cannot be detected directly. But there is an assumption that something is out there, because of the orbital velocity of the outer region of the galaxy.
The matter orbits much faster than it should, based on the matter that can be detected – as though something, some undetectable mass, is creating extra gravity in the Universe.
It is important to infer its mass based on other methods because the dark matter can’t be observed directly. By starting with that outer-galaxy orbital velocity, astrophysicists can work backward to calculate the mass responsible, based on Kepler’s laws of orbital motion.
On the same subject, Gaia and Hubble are dedicated to working. It has been 10 years since they have been combined. And they have provided more accurate measurements of the orbital motion of globular clusters in the outer reaches of the Milky Way.
“The more massive a galaxy, the faster its clusters move under the pull of its gravity,” said astrophysicist Wyn Evans of the University of Cambridge in the UK.
“Most previous measurements have found the speed at which a cluster is approaching or receding from Earth that is the velocity along our line of sight. However, we were able to also measure the sideways motion of the clusters, from which the total velocity, and consequently the galactic mass, can be calculated.”
On this basis, the team reached the 1.5 trillion solar masses figure. But the thing is that there are only about 200 billion stars in the galaxy. Sagittarius A*, the supermassive black hole at the galactic center, accounts for another 4 million solar masses. And there’s a bunch of dust and gas. But all that concludes around 90% of the mass meaning, there is the dark matter that is yet to be found out.
“We want to know the mass of the Milky Way more accurately so that we can put it into a cosmological context and compare it to simulations of galaxies in the evolving universe,” explained physicist Roeland van der Marel of the Space Telescope Science Institute in the US.
The Milky Way galaxy has been noted to be in an intermediate range according to the new measurements put it at a pretty healthy size and mass for its class, but the extra heft doesn’t even put us near the biggest galaxies – those are in the range of 30 trillion solar masses.
For many years, the Milky Way has been thought to the biggest galaxy in nearby intergalactic space was Andromeda, with the Milky Way coming in second.
But according to Andromeda’s new calculations last year, the Milky Way was put to be at around 800 billion solar masses which could mean that it is actually number one – and has been all along. And so, rather than the other way around as we previously thought, it could mean that Andromeda gets subsumed into the Milky Way when the pair collide in 4.5 billion years.
February 4, 2019(updated August 24, 2019) Published by Kshitij Kumar
Astronomers calculated that the Big Bang occurred between twelve and fourteen billion years ago. To place this in perspective, the solar system is assumed to be 4.5 billion years old and humans have existed for a few million years.
Astronomers estimate the age of the universe in 2 ways:
By trying to find the oldest stars
By finding out the speed of expansion of the universe and extrapolating back to the Big Bang
Is it older than the stars?
Astronomers could place a lower limit to the age of the universe by studying about Globular clusters. These circular clusters are a dense assortment of roughly 1,000,000 stars. Stellar densities close to the middle of these clusters are huge. If we lived close to the middle of one, there would be several hundred thousand stars closer to us than the Proxima Centauri, the nearest star after the Sun.
The life cycle of a star is solely depended upon its mass. High Mass stars are a lot brighter than Low Mass stars; therefore they quickly burn through their supply of hydrogen fuel. A star just like the Sun has enough fuel in its core to burn at its current brightness for roughly nine billion years. A star that is twice as massive as the Sun will burn through its fuel supply in only 800 million years. A 10 solar mass star, a star that is 10 times more massive than the Sun, burns nearly a thousand times brighter and has only a 20 million year fuel supply. Conversely, a star that is half as massive as the Sun burns slowly enough for its fuel to last more than 20 billion years.
All the stars in a globular cluster are formed roughly at the same time; therefore they function like cosmic clocks. If a cluster is over twenty million years old, then all of its hydrogen-burning stars will be less massive than 10 solar masses. This suggests that no hydrogen-burning star is going to be over a thousand times brighter than the Sun. If a cluster is over two billion years old, then there’ll be no hydrogen-burning star more massive than 2 solar masses.
The oldest cluster contains only those stars which are less massive than 0.7 solar masses. Low Mass stars are a lot less dim than the Sun. This observation suggests that the oldest clusters are between 11 and 14 billion years old. The uncertainty in this estimate is because of the problem in finding the precise distance to cluster (hence, uncertainty within the brightness (and mass) of the stars in the cluster). Another source of uncertainty during this estimate lies in our ignorance of finer details of stellar evolution.
Astronomers also study some old stars and try to detect remaining dust from ancient supernova to have some more limits to the age of the universe.
However, there are some stars found which contradicts the currently believed age of 13.8 billion years. Read about one such star called HD 140283 here
An alternative approach to estimate the age of the universe is to calculate the “Hubble constant”. The Hubble constant is a measure of the expansion rate of the universe. Cosmologists use this activity to extrapolate back to the Big Bang. This extrapolation depends on the history of the expansion rate that depends on the present density of the universe and on the composition of the universe.
If the universe is flat and composed largely of matter, then the age of the universe is
where Ho denotes the Hubble’s constant.
If the universe has a very low density of matter, then its extrapolated age is larger:
If the universe contains a form of matter similar to the cosmological constant, then the inferred age can be even larger.
Many astronomers are operating exhaustingly to calculate the Hubble’s constant employing a type of completely different techniques. Till recently, the simplest estimates ranged from 65 km/sec/Megaparsec to 80 km/sec/Megaparsec. In additional acquainted units, astronomers believe that 1/Ho is between 12 and 14 billion years.
In the latest researches, the results have been shown that the universe is enlarging much quicker than it should be based on the conditions after Big Bang. The constantly increasing rate of the universe is known as Hubble Constant and it has been very hard to pin down the rate.
AN AGE CRISIS?
On comparing the two age determinations, there is a potential crisis. If the universe is flat and dominated by ordinary or dark matter, the age of the universe as estimated from the Hubble constant would be around 9 billion years. This would lead to a contradiction as the age of the universe would be shorter than the age of oldest stars. This contradiction implies that either
Our measurement of the Hubble constant itself is incorrect
The Big Bang theory has to be replaced
That we need a form of matter like a cosmological constant that implies an older age for a given observed expansion rate.
Some astronomers believe that this crisis will pass as soon as measurements improve. If the astronomers who have measured the smaller values of the Hubble constant are correct, and if the smaller estimates of globular cluster ages are also correct, then all is well for the Big Bang theory, even without a cosmological constant.
Measurements by the WMAP (Wilkinson Microwave Anisotropy Probe) satellite facilitated and confirmed the age of the universe. By measuring the thermal radiation left over from the Big Bang(known as Cosmic Microwave Background), missions such as WMAP are able to determine the density, composition and expansion rate of the universe. As of 2013, WMAP determined these parameters with an accuracy of higher than 1.5%. In turn, knowing the composition with this precision, we could estimate the age of the universe to about 0.4%: 13.77 ± 0.059 billion years!
WMAP satellite artist depiction. Image Source: NASA
How does WMAP data enable us to determine the age of the universe is 13.77 billion years, with an uncertainty of only 0.4%? The key to this is that by knowing the composition of matter and energy density in the universe, we will use Einstein’s theory of relativity to calculate how fast the universe has been expanding in the past. With this information, we will flip the clock back and estimate when the universe had “zero” size, in line with Einstein.
The time between then and now could be the age of the universe. There’s one caveat to keep in mind that affects the understanding of the age determination: we have a tendency to assume that the universe is flat, that is well supported by WMAP and alternative knowledge. If we relax this assumption, the uncertainty will increase. Inflation naturally predicts a really nearly flat universe.
The expansion age measured by WMAP is larger than the oldest globular clusters, so, Big Bang theory has passed a crucial test using data independent of the type collected by WMAP. If the expansion age measured by WMAP had been smaller than the oldest globular clusters, then there would be something wrong in either the Big Bang theory or the theory of stellar evolution. Either way, astronomers would have required rethinking several of their cherished concepts. However, our current estimate of age fits well with what we all know from other forms of measurements.
So, in conclusion, we’ve 2 methods — one from our cosmic history and one by measuring native stars — that show us our Universe’s age is between thirteen and fourteen billion years. Today it is widely accepted that our universe in 13.772 billion years old with a possible error of 59 million years. However, there are a lot of observations and experiments going on to get more precise age of our universe
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