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UGC 2369

Hubble Space Telescope captures merging galaxies in a dazzling dance

The Hubble Space Telescope has managed to capture two galaxies making contact for the first time. The pair known as UGC 2369 will merge to become a single galaxy in the future. For now, the two galaxies are in close proximity thanks to gravitational forces.

The galaxies have been observed to be swirling around each other due to gravity. As per the European Space Agency, they are currently connected by a bridge of dust, gas and stars akin to a situation of holding hands. Right now UGC 2369 is 424 million light-years away from us.

Galaxies primarily belong to galactic groups or clusters making them “extroverts”. As a result of which it is quite common for two galaxies to have an interaction between them. Even though there is no collision between galaxies, the shape of the galaxy can be distorted by the strong gravitational pull. This makes galactic observations fascinating to view. In phenomena where no contact is made such as galaxy fly-bys, there can be a creation of permanent warps, tidal tails extending from the center of the galaxy resulting in strange shapes. It also induces bursts of star formation.

However, the galactic mergers are quite destructive in nature. It amplifies when the size of the two galaxies are almost the same. The frequency of these huge events is lower than the normal mergers. It is considered that the Milky Way might face a merger in the future. Currently, two dwarf galaxies in the vicinity of the Milky Way, Canis Major and Sagittarius are being destroyed and absorbed in the Milky Way.

Astronomers are pretty sure that Andromeda and the Milky Way will collide at some point in the future, even though it might be after several billion years and result in one galaxy. The details of how it is supposed to occur are still up for debates. This new galaxy is termed as “Milkomeda” by ESA.

Hubble Space Telescope has captured several galaxies in its 30 years of operations. It has also captured galaxies dating as far as the time just after the Big Bang occurred. It released the Ultra Deep Field in 2016. The merger of UGC 2369 is at an advanced stage. By training the Telescope on this merger, we can understand the fate of our own galaxy in the future.

Comet-67P

Astrophotographer finds Comet 67P has its own tiny Churymoon

The Rosetta mission of the European Space Agency spent two years at comet 67P/Churyumov-Gerasimenko. The mission ended in 2016 when the spacecraft collided with the comet. In the time spent at 67P, a huge number of images were captured. These images are now freely available at Rosetta website. An astrophotographer from Spain, Jacint Roger noticed something interesting in the images, an ice chunk traveling with 67P. He created a gif from the images which focused on the icy companion.

The images obtained were from two months after perihelion in the month of August 2015. 67P was basking in full sunlight at that time. The comet was inside dust as the heat of the Sun released comet gases in space which also carried dust with it. Along with dust, the ice chunk was also released from the comet in this time. The ice chunk is visible as the images focus on the nucleus of the comet. Less than 4 meters in diameter it is called Churymoon, a term coined by Julia Marín-Yaseli de la Parra, Ph.D. and ESA Researcher on Rosetta mission.

The images used by Jacint Roger are from OSIRIS instrument of Rosetta. It had a wide-angle camera for mapping the gas and dust near the comet and a Narrow-Angle Camera for mapping the nucleus of the comet in a high-resolution scale. Rosetta was at a distance of 400 kilometers from the center of the comet when the images were captured by the NAC. After leaving the comet, Churymoon spent the first 12 hours at a distance between 2.4km and 3.9km from the center of the comet in an orbital path. Then it went through the coma whose brightness made it hard to view it. It was again visible after emerging from the coma and its path was confirmed until 23rd October 2015.

Rosetta’s mission also included a study of the debris which was ejected from the planet. Churymoon is possibly the largest debris detected which will be further studied by researchers. It also had to watch the comet moving through perihelion. It took ten years for traveling to 67P/G-C. Earlier comets were only considered as dirty ice chunks moving through space. But Rosetta revealed the complexity of the comet in a detailed way. 67P is all possibility might be the result of a comet collision.

Eberhard Grün, a scientist working on Rosetta said that comets such as 67P/G-C are geographically complex worlds where several processes are involved in creating the comet’s surface and activity.

Fluorescent glow may reveal hidden life in the cosmos

Fluorescent glow may reveal hidden life in the cosmos

Astronomers seeking life on distant planets may want to go for the glow.

Harsh ultraviolet radiation flares from red suns, once thought to destroy surface life on planets, might help uncover hidden biospheres. Their radiation could trigger a protective glow from life on exoplanets called biofluorescence, according to new Cornell research.

Biofluorescent Worlds II: Biological Fluorescence Induced by Stellar UV Flares, a New Temporal Biosignature” was published Aug. 13 in Monthly Notices of the Royal Astronomical Society.

“This is a completely novel way to search for life in the universe. Just imagine an alien world glowing softly in a powerful telescope,” said lead author Jack O’Malley-James, a researcher at Cornell’s Carl Sagan Institute.

“On Earth, there are some undersea coral that use biofluorescence to render the sun’s harmful ultraviolet radiation into harmless visible wavelengths, creating a beautiful radiance. Maybe such life forms can exist on other worlds too, leaving us a telltale sign to spot them,” said co-author Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute

Astronomers generally agree that a large fraction of exoplanets – planets beyond our solar system – reside in the habitable zone of M-type stars, the most plentiful kinds of stars in the universe. M-type stars frequently flare, and when those ultraviolet flares strike their planets, biofluorescence could paint these worlds in beautiful colors. The next generation of Earth- or space-based telescopes can detect the glowing exoplanets, if they exist in the cosmos.

Ultraviolet rays can get absorbed into longer, safer wavelengths through a process called “photoprotective biofluorescence,” and that mechanism leaves a specific sign for which astronomers can search.

“Such biofluorescence could expose hidden biospheres on new worlds through their temporary glow, when a flare from a star hits the planet,” said Kaltenegger.

The astronomers used emission characteristics of common coral fluorescent pigments from Earth to create model spectra and colors for planets orbiting active M stars to mimic the strength of the signal and whether it could be detected for life.

In 2016, astronomers found a rocky exoplanet named Proxima b – a potentially habitable world orbiting the active M star Proxima Centauri, Earth’s closes star beyond the sun – that might qualify as a target. Proxima b is also one of the most optimal far-future travel destinations.

Said O’Malley-James: “These biotic kinds of exoplanets are very good targets in our search for exoplanets, and these luminescent wonders are among our best bets for finding life on exoplanets.”

Large, land-based telescopes that are being developed now for 10 to 20 years into the future may be able to spot this glow.

“It is a great target for the next generation of big telescopes, which can catch enough light from small planets to analyze it for signs of life, like the Extremely Large Telescope in Chile,” Kaltenegger said.

Canadian Hydrogen Intensity Mapping Experiment

Eight new repeating signals detected from deep space

A total of eight new radio signals termed as fast radio bursts (FRBs) have been detected from deep space. One of these signals, FRB 121102 was known to be flashing repeatedly at the beginning of the year while a second signal, FRB 180814 was reported by researchers in January.  Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope detected eight repeating signals. The research work has been submitted to The Astrophysical Journal Letters and can be found here.

Currently, a total of 10 repeating FRBs are known that can help the astronomers to figure out more about these signals. These FRBs are spikes in radio data that last only a few milliseconds however possessing the energy of more than 500 million Suns. Tracing the source of FRBs is indeed difficult hence repeaters are important.

As they are not as rare as initially considered, it might be possible to determine the environment from where they originate. Ziggy Pleunis, McGill University said that there are differences between the sources as the bursts are quite irregular. It may not burst for several hours but then multiple bursts can be seen in a short span of time. For FRB 180916.J0158+65, 10 bursts were reported. 6 FRBs only repeated once with the longest pause being more than 20 hours. FRB 181119 repeated three times. These could actually indicate that all FRBs are repeaters with some being more active than others similar to volcanoes. Bursts from repeaters last longer than individual FRBs.

FRB 121102 and FRB 180814 demonstrated a downward frequency drift with each burst getting lower. Pleunis mentioned that there might be some important revelation in the structure to be encoded. CHIME can detect a wide range of lower frequencies unlike ASKAP or the Parkes Observatory in Australia. It can detect one-off bursts however is not optimized to trace sources.

Scientists announced that they were able to localize the eight new repeaters to known galaxies based on the signal direction. It is also possible to determine the distance of the origin of the bursts based on the signal dispersion. FRB 180916 has the lowest dispersion currently which indicates it is located nearby. It can be viewed directly if we know its exact location in the sky.

Signal polarisation also indicates that it came from a very magnetic environment such as black hole as detected in case of  FRB 121102. FRB 180916 had a low polarisation indicating that all FRBs do not come from magnetic environments.

It is not yet known whether there are many types of objects producing these signals or if they all repeat or not. But this work is giving some of the answers which will also influence the strategy of other research teams.

Research Paper: https://arxiv.org/abs/1908.03507

kilopower nasa

Nuclear reactor for crewed outposts on Mars and Moon could be ready by 2022

A new type of nuclear reactor has been designed to power outposts on Moon and Mars and it could be ready for its first in-space trial within a few years. The next step is a flight test for Kilopower experimental fission reactor which completed a series of ground tests from 2007 to 2018. Patrick McClure, Kilopower project lead at the Los Alamos National Laboratory said that Kilopower should be ready by 2022 although no off-earth demonstration has been scheduled yet.

He added that three years is a doable time frame which is not NASA’s stand who has been developing the project in collaboration with DOE. NASA’s Voyager 1 and Voyager 2 probes along with Curiosity Mars rover and New Horizons spacecraft employ radioisotope thermoelectric generators which convert the heat produced by the radioactive decay of plutonium-238 into electricity. RTGs produce relatively low power. It produces nearly 110 watts of electricity in Curiosity and the upcoming Mars 2020 rover.

A crewed outpost on Mars has higher energy demands around 40 kilowatts even for a small research envisioned by NASA for the late 2030s. Electricity will be required for water purification, oxygen generation for carbon-dioxide dominated atmosphere, charging up rovers, etc. Kilopower is a fission reactor and generates heat by splitting atoms into electricity through Sterling engines. The reactor was able to successfully convert 30% of the fission heat into electricity compared to 7% of regular RTG’s in a ground test series known as KRUSTY (Kilopower Reactor Using Sterling Technology). The project started in 2015 but the basic concepts were proved back in 2012 via an experiment called Demonstration Using Flattop Fissions (DUFF). KRUSTY and DUFF are characters in the Simpsons animated universe.

The reactor is designed to produce an output of 1 kilowatt of electrical power and can be scaled up to 10 kilowatts. NASA would need 4 of such reactors including one spare reactor. The 10-kilowatt machines would be just 11 feet in height and weigh close to 2000 kilograms. Without the astronaut shielding, it would weigh close to 1500 kilograms which would mean burying it in the ground.

The reactors are quite safe and there is no threat of radiation exposure if the rocket crashes back on Earth. The reactor is a self-regulating one if it gets too hot, the Stirling engines draw more heat away from uranium core and if temperature drops, the core naturally contracts which trap more neutrons and more splitting collisions. The device will need to dump a lot of heat on Mars due to the conversion efficiency of 30% will mean 70% of the heat will remain. It will come equipped with radiators.

A potential moon lander was the first task given to them as a demonstration mission for Kilopower but the concept will not end up flying as it targeted the lunar North pole and NASA was interested in the South Pole. Kilopower is the first fission reactor concept developed in the US in the last 40 years and is surely a milestone. US had previously launched reactors in experimental satellite, SNAP-10A in April 1965 but had to shut down after just 43 days. Although the Soviet Union was able to launch more than 30 fission reactors aboard satellites from 1967 to late 1980s.

Dusty cloud G2 passes the supermassive black hole

Mysterious flare emitted by the supermassive black hole of our galaxy

The supermassive black hole present at the centre of the Milky Way, Sagittarius A* has a low activity level most of the time as it is quiet, does not possess an active nucleus and has minimum brightness fluctuations. However recently, astronomers observed that its brightness increased 75 times before it went back to normal levels. 

Tuan Do, an astronomer at University of California Los Angeles said he was both surprised and excited to observe this. He even mistook it to be the star S0-2 for its brightness. Scientists have been trying to find out what is the reason behind this event. Their observations are accepted in The Astrophysical Journal Letters and can be found here

 

The galactic centre was observed by Do and his team with the help of WM Keck Observatory located in Hawaii. This unusual brightening was observed on May 13 for a period of two hours that was converted into a time-lapse of a few seconds. Although black holes themselves do not emit any radiation which can be detected by the instruments, the surrounding gases emit radiation due to the friction generated by the gravitational forces of the black hole. The radiation is observed as brightness when viewed in the infrared range of the telescope. When the surroundings of the black hole glow brightly it indicates that the black hole’s gravity has captured something.

The first frame of the observation is brightest indicating that the black hole might have been brighter however it was not known that any object was approaching closer to be swallowed. There are two possible situations. An object initially considered as a gas cloud, G2 was within 36 light hours of Sagittarius A* in 2014. Being a gas cloud, it would have been shredded by the black hole however this did not occur. It was later classified as a “cosmic fizzle”. 

Another possibility is that when the star S0-2 passed close to the black hole, it might have changed the pattern of gas flow into the black hole generating more variations. Having more data is the only way of confirmation, more observations are being made by the Keck Observatory as long as the centre of the galaxy is visible from Earth. Several other telescopes have also been observing the galactic centre which includes Chandra and Spitzer space telescopes. The data could help in understanding more aspects behind the change of brightness. Scientists are eagerly awaiting the results to have a better understanding.

Journal Reference: arxiv 

Kohnen-Station

Researchers detect radioactive interstellar dust in the Antarctic Ice

In new research, scientists have found evidence of dust from a nearby supernova under several thousand pounds of Antarctic snow. Our solar system not only comprises of celestial objects such as planets, moon, sun but also a lot of dust that might have originated from the interstellar sources. A group of researchers in Germany, Austria and Australia is in the search of the presence of dust on Earth to understand the circumstances in which the solar system is moving forward. The study has been published in the Physical Review Letters. 

Dominik Koll, first author of the study and a PhD candidate from Australian National University mentioned he is very excited to learn about the stellar explosions and structures present around our planet which have faraway origins. Scientists transported fresh snow which is not more than 20 years old, weighing almost 1100 pounds from the Kohnen Station located in Antarctica to Munich, Germany.

Then the snow was melted in the laboratory, filtered and evaporated for collecting dust and other micrometeorites. Dust was incinerated and put into Accelerator Mass Spectrometer. It is used to create charged ions from the sample, pass through the magnet and then into a particle accelerator before finally sending to a detector. This technique is useful for collecting only specific atomic isotopes. 

The team wanted to find iron-60, a radioactive isotope released by the supernova. It can also have other sources such as the matter irradiated by the cosmic rays. For guaranteeing it to be interstellar dust, researchers also searched for manganese-53 and compared the ratio of iron-60 to manganese-53 to the ratio expected if there was no presence of interstellar dust. A lot more iron-60 was found than expected from the cosmic rays. 

Thomas Faestermann, TU Munich explained that it was previously established that iron-60 was deposited in the solar system by a nearby supernova in the past 1.5 to 3 million years. Its prolonged presence on Earth indicates it is coming from a remaining dust cloud from a supernova.

These studies show better conditions of the interstellar environment through which Sun is travelling. It has been detected that the Sun is in a “Local Bubble” where the density of the interstellar medium is quite less than average possibly due to a recent supernova. It contains the Local Interstellar Cloud which has a higher density than the Bubble. We can know more about these regions from the dust found in Antarctica. 

There are lots of findings remaining as the Antarctic ice could lead an exposition of the history of an ancient supernova. 

Journal Reference: Physical Review Letters. 

Massive Galaxy Formation

Researchers create Universe Machine to understand the formation and evolution of galaxies

The science behind the formation of galaxies and their evolution has remained a puzzle for decades, but the answer might be found soon with the help of simulations carried using supercomputers by a group of scientists from the University of Arizona.

Observation of galaxies can only provide their snapshots over time however understanding their evolution requires computer simulations. Astronomers have used this technique for testing different theories of the formation of galaxies. Peter Behroozi, an assistant professor at the UA Steward Observatory generated millions of universes on a supercomputer, each having different physical theories on the formation of galaxies. The paper has been published in Monthly Notices of the Royal Astronomical Society. It challenges the conventional ideas on the role of dark matter in galaxy formation and the evolution of galaxies.

Universes are created on the supercomputer and then compared to real ones which help in identifying the rules. This research managed to create self-consistent universes for the first time which are replicas of the real one and simulations which contain 12 million galaxies spanning over 400 million years.

The universes were put through several tests to understand how galaxies appeared in the simulated universe compared to the real one. The universe resembling ours had similar physical rules.

The results from “UniverseMachine” have helped to resolve as to why galaxies stop making new stars even when plenty of hydrogen gas and other raw materials are present.

The classical theories suggest the presence of supermassive black holes in the galactic centres prevent gases to cool down to form stars. Similarly, dark matter heats up the surrounding gas and prevents forming stars. However, it was found that many galaxies in the universe were more likely to form stars at higher rates which is a contradiction. The team then created virtual galaxies in which the opposite happened. The universe based on current theories which stopped star formation early on appear much redder they actually are. The galaxy appears red due to its age and moving away faster, which shifts the light into the red spectrum called “redshift”. Also if a galaxy stops forming stars, there will be lesser blue stars and old red stars will be left.

If galaxies stopped creating stars, the colour of the universe would have been entirely different, hence it can be concluded that galaxies formed stars more efficiently in the earlier than we expected and the energy from the black holes and exploding stars is less efficient in decreasing the formation of stars.

A mock universe requires huge complexity which requires an entirely new approach not limited by computing power or memory and provided enough resolution to observe both supernovae as well as a major portion of the universe. Simulating a galaxy needs 10 to the 48th computing operations. The team used the “Ocelote” supercomputer at the UA High-Performance Computing cluster. 2000 processors churned the data for three weeks and over the course of the project, the team generated 8 million universes. The team took past 20 years of observations and compared them to the millions of mock universes generated and checked for matches. They plan to expand the UniverseMachine to include the morphology of galaxies and how their shapes evolve over time.

Journal Reference: Monthly Notices of the Royal Astronomical Society

big bang expansion

New research claims dark matter might be older than the Big Bang

Dark matter may be considered as the universe’s biggest mystery. It is known that something makes objects faster than they should but we do not actually know what it is and where it came from.

The origins of dark matter might be even more peculiar than it is known. They might be particles that appeared for a very brief amount of time before the Big Bang occurred. This not only suggests a new connection between astronomy and particle physics, but it could also indicate a new technique for searching mysterious stuff.

Tommi Tenkanen, a physicist at Johns Hopkins University said that if the dark matter comprises of new particles which were born before Big Bang then it affects the distribution of the galaxies in a unique manner. The connection may bring new conclusions about the time before Big Bang too. The paper by Tommi Tenkanen has been published in the journal Physical Review Letters.

The beginning of the Universe is a murky time period and the order of events is tangled up. It is still being debated about the events Big Bang comprised of. There is also cosmic inflation, a very small time period in which the Universe expanded like a balloon. It is accepted that it occurred in the range of 10-36 to 10-32 seconds after Big Bang took place. Some scientists feel that it occurred just before Big Bang took place. Avi Loeb, Hardvard-Smithsonian physicist said that cosmic inflation right now is a flexible idea which cannot be falsified experimentally.

Dark matter which comprises 80 percent of matter present in the Universe is considered Big Bang’s product sometimes. However, scientists feel if it were truly a product of Big Bang, there would have been evidences in experiments of particle physics. Instead, Tenkanen’s mathematical modelling suggests that it could have been a result of cosmic inflation. If cosmic inflation occurred before Big Bang then it implies that dark matter was present before everything in the Universe.

It also brings the idea that scalar particles could lead to dark matter. These particles have a spin of zero and according to inflaton theory, they were produced during cosmic inflation in a blink of the eye. The detection of Higgs boson, a scalar particle did not tell us much about dark matter.

Dark matter might be revealed in astronomical observations. We might know more about the origin of dark matter after the launch of the Euclid satellite in 2022. It might present some interesting revelations about Dark Matter and the time period before the Big Bang. Although the discussion right now is mainly theoretical, the search for dark matter will be fascinating in the coming times.

Journal: Physical Review Letters

abell 85

Researchers detect a gigantic black hole weighing 40 billion times more than Sun

Black holes can be very big, but there is a separate class which is huge and monstrous. Astronomers have identified such a giant black hole whose mass is 40 billion times that of the Sun. It is present at a galaxy’s centre that is known as Holmberg 15A. It is a supergiant elliptical galaxy present at a distance of 700 million light-years away from us that sits at the centre of the galaxy cluster, Abell 85.

 This new black hole is one of the largest black holes that have been identified and is the largest among the ones detected by tracking the motion of the stars around it. Past calculations based on the galaxy’s dynamics and its cluster found the mass of Holm 15A*(the black hole) which estimates it to be 310 billion times that of the Sun’s mass. These were indirect measurements of the black hole. The first direct measurement is obtained in this research and the paper has been submitted for peer review to The Astrophysical Journal.

Researchers mentioned in the paper that they used orbit-based, axisymmetric Schwarzschild models for analysing the stellar kinematics of Holm 15A from better resolution, spectral observations obtained with the help of MUSE at VLT. They found a supermassive black hole of mass (4.0 ± 0.80) × 1010 solar masses at Holm 15A’s center. This is the most massive black which has been detected directly in the local Universe.

The black hole with the greatest mass which has been detected so far is quasar TON 618, which weighs nearly 66 billion times the Sun’s mass according to indirect measurements. Event horizon of Holm 15A* which is also called as Schwarzschild radius would be enough to engulf the orbits of all the planets in Solar System and still have space left for some more. Pluto is 39.5 astronomical units from Sun. Heliopause is estimated to be nearly 123 AU. According to the mass of Holm 15A*, the Schwarzschild radius would be 790 AU.

The supermassive black hole of Holm 15A is almost four to nine times bigger than estimated according to stellar velocity and bulge stellar mass of the galaxy. It fits the collision model between two early-type galaxies that have depleted cores. It occurs when there are not many stars present in the core according to the number of stars which are there in the galaxy’s outer regions.

Researchers mentioned that the masses of black holes in cored galaxies such as Holm 15A vary inversely to the mass density and the central stellar surface brightness. They intend to keep studying about the black hole and conduct complex, detailed modelling thereby compare the results with the observations. This can help to understand how often such a merger occurs and how many such black holes remain yet to be discovered.

Journal Reference: arXiv