Galaxies – The Space Reporter

Astronomers find remnant of 600-year-old nova

Based on the Korean astronomers’ description of the phenomenon, scientists today believe the outburst occurred in a binary system that contained a dead, highly dense white dwarf star and a companion.

A three-decade search for the remnant of a nova recorded by Korean astronomers almost 600 years ago has finally succeeded in finding the location of the stellar remnant.

Michael Shara, astrophysics coordinator at New York’s American Museum of Natural History, said the hunt for Nova Scorpii AD 1437 took so long because Korean records did not assign numbers or names to nearby stars, resulting in his team inadvertently looking in the wrong location.

Novae are nuclear explosions that occur at the end stages of massive stars’ lives. Unlike the more powerful supernovae, which completely destroy their precursor stars, standard novae leave the remains of their parent stars intact.

Fifteenth-century Korean astronomers recorded what they believed was a new star that appeared on March 11, 1437 near a known star in the tail of the constellation Scorpius. The bright “new” star was visible for two weeks before disappearing.

Over time, white dwarfs funnel material out of their companion stars, eventually causing them to explode.

Known as cataclysmic variables, binary systems composed of a white dwarf and a regular star experience many novae over time and possibly smaller explosions known as dwarf novae.

By analyzing data collected by the South African Large Telescope and Las Campanas Observatory’s Swope and du Pont telescopes, along with reviewing digital images of photographic plates of the sky taken by Harvard University for more than 100 years, the research team located debris from the nova in the constellation Scorpius.

Calculations of neighboring stars’ motions over the last six centuries confirmed a binary system once resided in the location where the nova was originally seen.

Evidence of dwarf novae in this location on photographic plates from the 1930s and 1940s suggests the binary system is producing both classical and dwarf novae.

The researchers, who published their findings in the journal Nature, hope to image the nova to find out what it looks like now as well as locate several additional novae recorded in history to confirm that classical and dwarf novae have common origins.

Alien civilizations may be trying to contact us

Some scientists are reporting “fast radio bursts” that might be alien civilizations trying to communicate.

“Fast radio bursts” are brief and intense pulses of radio waves that are picked up from outer space. Experts are almost certain that there is no way that these radio waves could have originated from Earth but are completely uncertain of what their cause is. A renaissance in radio astronomy has occurred since the discovery of the fast radio burst phenomenon. Some of the bursts have certain scientists speculating that the FRB’s are signals being transmitted by distant alien civilizations.

An international team of astronomers recently uncovered the brightest fast radio burst to date. Their detection was named FRB 150807 because of its discovery date. It was a radio wave that lasted less than half a millisecond, which is .1 percent of the amount of time it takes a human being to blink its eyes.

Their findings were published in a study in Science called “The magnetic field and turbulence of the cosmic web measured using a brilliant fast radio burst” and involved over a dozen scientists. The astronomers reported in the study that they had pinpointed the origin of the FRB to an area smaller than any other study before it. Their study was published only days after another study , “Discovery of a transient gamma ray counterpart to FRB 131104”, reported having seen gamma rays, or highly energetic electromagnetic radiation, closely associated with their fast radio burst.

Astronomers find galaxy cluster obscured by quasar

Search is on for more galaxy clusters hidden by very bright, active supermassive black holes.

Astronomers have discovered a large galaxy cluster with a mass of approximately 690 trillion suns that until now was obscured by an extremely bright quasar, an active supermassive black hole feeding on material surrounding it.

Composed of several hundred individual galaxies, the cluster is located about 2.4 billion light years from Earth and surrounds the quasar.

Designated PKS1353-341, the quasar, which is 46 billion times brighter than our Sun, was long thought to be alone in its region of space. It is surrounded by a huge disk of swirling material, of which large chunks are falling into it and in the process radiating high levels of energy as light.

“This might be a short-lived phase that clusters go through, where the central black hole has a quick meal, gets bright, and then fades away again. This could be a blip that we just happened to see. In a million years, this might look like a diffuse fuzzball,” explained Michael McDonald of MIT‘s Kavli Institute for Astrophysics and Space Research.

The discovery of the galaxy cluster suggests other, similar clusters could be hiding behind extremely bright objects. Such clusters provide important information about the amount of matter in the universe and the rate at which the universe is expanding, which is why astronomers are now searching for them.

One reason scientists missed this large cluster is their assumption that clusters appear “fluffy” and give off diffuse X-ray signals, very unlike quasars, which are bright, single-point sources.

“This idea that you could have a rapidly accreting black hole at the center of a cluster–we didn’t think that was something that happened in nature,” McDonald said.

To find more hidden clusters, he and fellow researchers set up a survey titled Clusters Hiding in Plain Sight (CHiPS), which involved looking at archival X-ray images of very bright objects. They then followed up by studying these objects using the Magellan Telescope, an optical observatory in Chile.

If the Magellan observations revealed more galaxies than expected surrounding the bright object, they then observed the point source using the space-based Chandra X-ray Observatory.

“Some 90 percent of these sources turned out not to be clusters,” McDonald said.

The CHiPS survey did find one new galaxy cluster obscured by a very bright supermassive black hole.

Findings of the study have been published in the Astrophysical Journal.

Milky Way disk spans 200,000 light years

Metal-rich stars have been discovered far beyond what was thought to be the galactic disk’s boundary.

The Milky Way’s disk, the flat, central region of the galaxy that contains mostly young stars, gas, and dust within the structure of its spiral arms, measures 200,000 light years across, making it significantly larger than initially thought, according to a new study.

Previous studies calculated the galaxy’s diameter at 100,000 to 160,000 light years.

In the most recent study, scientists analyzed data collected by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) on the spectra of stars in the galactic disk.

A star’s spectrum breaks down its light into different colors whose patterns reveal the specific elements present within that star.

For this study, researchers analyzed the metallicities or amounts of heavy elements, within disk stars and were surprised to find stars with high metallicities beyond the region they believed to be the boundary of the galaxy’s disk.

“We have shown that there is an appreciable fraction of stars with higher metallicity, characteristic of disk stars, further out than the previously assumed limit on the radius of the galaxy disk,” said Carlos Allende of the Astrophysics Institute of the Canary Islands (IAC).

Although spiral disks are usually thin, that is not the case for the Milky Way. “The disk of our galaxy is huge, around 200,000 light years in diameter,” stated Martin Lopez-Corredoira, also of the Astrophysics Institute.

The newly-discovered metal-rich disk stars are located about three times further and possibly as far as four times further from the galactic center than our Sun.

One light year is equal to approximately six trillion miles (10 trillion km). A spacecraft traveling at the speed of light would take 200,000 years to cross from one end of the galaxy to the other.

A paper detailing the study’s findings has been published in the journal Astronomy and Astrophysics.

Astronomers report latest detection of radio bursts coming from space

The recent detection reflects lower frequencies than what astronomers have reported in the past.

Fast Radio Bursts (FRBs) are some of the most explosive events in the Universe. They can generate as much energy as 500 million Suns in milliseconds, and there could be as many as one happening every second, writes Fiona Macdonald for Science Alert. Now, astronomers report detection of another FRB hitting Earth from an unknown source. This particular radio burst falls within the lower end of the spectrum, within the 50 megahertz frequency range, nearly 200 MHz lower than any other signal scientists have detected before. FRBs are incredibly mysterious, astronomers don’t yet know what’s causing them.

Although one of the signals detected has sent out multiple FRBs from the same location—allowing scientists to pinpoint where in the Universes it’s coming from—they still aren’t certain what caused it. Most signals are only detected once, making it difficult for astronomers to determine the source. The recent FRB was detected on July 25, 2018 and reported in The Astronomer’s Telegram. It has been named FRB 180725A, and was caught by an array of radio telescopes in British Columbia, Canada. The Astronomer’s Telegram is a bulletin board of observations posted by accredited researchers, however these observations haven’t been peer reviewed and verified by independent teams. Still, the results make it the first detection of a FRB under 700 MHz. “These events have occurred during both the day and night, and their arrival times are not correlated with known on-site activities or other known sources,” stipulates Patrick Boyle, project manager for the Canadian Hydrogen Intensity Mapping Experiment (CHIME).

Hypotheses abound for the source of FRBs, including black holes, imploding pulsars, and magnetars emitting giant flares to name a few. According to a Harvard physicist, it’s not impossible that FRBs could be engines firing on alien spaceships. While scientists are working to discover the source, they have learned that FRBs cover a spread of frequencies, they seem to be coming from billions of light-years away, and the source of the bursts has to be very energetic. Solving this mystery could help further understanding of the origin of the Universe.

Distant galaxy forms stars at incredible pace, study reports

A newly discovered galaxy makes stars much, much faster than the Milky Way does.

Scientists working with Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) have observed a galaxy that forms stars at an unprecedented rate, a new study published in Nature reports.

The distant “Monster Galaxy” — known as COSMOS-AzTEC-1 — came about roughly 2 billion years after the Big Bang. While it appears normal at first glance, it is unique because it generates over a thousand Suns worth of gas of stars each year.

That trait is important because, while scientists do not understand early galaxies, the new discovery could shed light on why certain systems form stars so fast.

When studying the new system, astronomers found that the clumpy gas inside of it has a stronger gravitational pull on itself than the force of the galaxy’s rotation from stars and supernovae. In addition, they also discovered it had two extra areas of gas-generating stars, rather than just one dense cloud of material.

“We found that there are two distinct large clouds several thousand light-years away from the center,” said lead author Ken-ichi Tadaki, a researcher at the Japan Society for the Promotion of Science and Japan’s National Astronomical Observatory, according to Space.com. “In most distant starburst galaxies, stars are actively formed in the center. So it is surprising to find off-center clouds.”

A team of international researchers found the galaxy while using ALMA’s 66 radio telescope dishes in the Chilean desert to look for signatures of carbon monoxide gas. Once they discovered it, they created a map based on what they found.

That showed the large, dense gas clumps inside AzTEC-1 are quite unstable and likely burn out within 100 million years of their formation. However, they form stars extremely quickly in that time.

Scientists are still not sure how galaxies like AzTEC-1 manage to build up so much gas before beginning their star formation, but they believe it could be the result of a galactic merger. Even so, as there is no evidence to support that process, more observations need to be done on such systems in the coming years to get a better idea of how they work.

“At this moment, we have no evidence of merger in this galaxy,” added Tadaki, according to Phys.org. “But by observing other similar galaxies with ALMA, we want to unveil the relation between galaxy mergers and monster galaxies.“

Scientists conduct experiments to explain the origins of our Universe

Experiments searching for a solution to one of physics’ biggest mysteries have delivered their first rounds of results.

Right now there are four major experiments being conducted around the world, hunting for signs of barely-detectable particles undergoing rare changes. In an article for Science Alert, Mike Mcrae explains why matter shouldn’t exist based on our current understanding of physics.

As subatomic particles cooled out of the radiation following the first moments of Universe, they took one of two forms—matter and antimatter. Therein lies the paradox, however, because these mirror-opposite objects also cancel out in a flash of energy when they meet again. So, if both types of particles are created next to one another in equal amounts, the math says we should have nothing left over. However, most visible objects are made from just one kind of particle—matter.

Neutrinos (a type of neutrally charged particle) may provide answers to this paradox. Neutrinos are a million times lighter than an electron, meaning they barely interact with other particles. Properties of these ‘ghost particles’ may mean that neutrinos are matter and anti-matter in one. Exploring neutrinos may be the pathway to explaining why our universe didn’t immediately cancel itself out.

Experiments are taking place to explore this mystery. The Cryogenic Underground Observatory for Rare Events (CUORE) at Gran Sasso Laboratory in Italy is based on just a flash in one of 1,000 crystals of tellurium dioxide to advertise the moment of neutrinoless double beta decay. They expect to see only five decays in the next five years. CUORE member, Lindley Winslow told Jennifer Chu at MIT News that it’s a very rare process. “If observed, it would be the slowest thing that has ever been measured,” she said. A second experiment at Gran Sasso is using isotope germanium-76 instead. They have less material to catch the decay, but the whole set-up is proving to be extremely sensitive, reducing the risk of missing the event if it happens.

In the U.S. at the Sanford Underground Research Facility, collaborators are working on an experiment called the MAJORANA Demonstrator. All of these experiments are looking for the conservation of a particular quantum number as pairs of neutrons decay within certain isotopes. To-date, the results from these experiments have narrowed the field of places to search for neutrinos.

Hubble images spiral galaxy two times the size of Milky Way

Milky Way’s “big sister” continues to grow and experience new star formation.

NASA’s Hubble Space Telescope (HST) has captured an image of a massive spiral galaxy, which is shaped like the Milky Way but twice its size.

Using its Wide Field Camera 3 (WFC3), the space telescope photographed NGC 6744, obtaining detailed images of the galaxy, which has a diameter of 200,000 light years, in comparison with the 100,000-light-year-wide Milky Way.

Located approximately 30 million light years from Earth in the constellation Pavo, NGC 6744 appears as a faint, extended object when viewed by most small telescopes. It is not visible to the naked eye.

“NGC 6744 is similar to our home galaxy in more ways than one,” a NASA statement notes.

It resembles the Milky Way in that it has a central core region made up largely of old yellow stars and dusty spiral arms further out that appear pink and blue. The pink areas are stellar nurseries, where star formation is underway, while the blue areas are regions filled with young stars.

Within the long, curved spiral arms are numerous stars, planets, gas, and dust.

The fact that star formation is still going on indicates the galaxy remains active. Scientists believe NGC 6744 is still growing.

Near the massive galaxy is a smaller, companion galaxy with a distorted shape, similar to the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way.

Although the feature is not visible in the Hubble images, scientists spotted a Type Ic supernova, caused by the death of a massive star, within NGC 6744 in 2005.

Installed in 2009, the WFC3 has given Hubble unprecedented depth and range. It has studied a wide range of phenomena, from star formation to remote galaxies, and has taken the majority of the telescope’s most iconic images over the last nine years.

Spiral galaxies’ outskirts host massive stellar black holes

Discovery will help scientists pinpoint more potential sources of gravitational waves.

The outer regions of spiral galaxies can host massive black holes formed when giant stars ended their lives in supernova explosions, according to a new study led by Sukanya Chakrabarti of the Rochester Institute of Technology (RIT) School of Physics and Astronomy.

Chakrabarti’s team analyzed data from the Lick Observatory Supernova Search, which compared the rates of supernova explosions in the outskirts of spiral galaxies with the rates of those that occur in smaller dwarf or satellite galaxies.

According to the Lick data, the supernova rates are comparable for the outskirts of both types of galaxies, with each having an average of two every millennium.

Knowing that these locations host black holes created by the core collapse of massive stars is a boon to scientists who study gravitational waves, which are produced by black hole collisions.

Dwarf and satellite galaxies are known to have low levels of elements heavier than hydrogen and helium, a condition ideal for both the formation and merger of stellar mass black holes. The new study, about which a paper will be published in Astrophysical Journal Letters, reveals similar favorable conditions for black holes can also be found in the outer regions of spiral galaxies.

“If these core collapse supernovae are the predecessors to the binary black holes detected by LIGO (Laser Interferometer Gravitational-wave Observatory), then what we’ve found is a reliable method of identifying the host galaxies of LIGO sources,” Chakrabarti noted.

“Because these black holes have an electromagnetic counterpart at an earlier stage in their life, we can pinpoint their location in the sky and watch for massive black holes.”

The electromagnetic counterparts to which Chakrabarti referred are the dying massive stars whose cores collapse before they explode as supernovae. As these stars die, they produce bright signatures in the electromagnetic spectrum.

Additional surveys of the outskirts of both dwarf and spiral galaxies will likely help scientists detect more LIGO events, Chakrabarti said.

Andromeda Galaxy consumed Milky Way’s galactic neighbor

Further study of ancient merger will help scientists better understand galactic evolution.

About two billion years ago, the Milky Way’s neighboring spiral galaxy, Andromeda, devoured a third large spiral galaxy that was once a sibling of the two.

Now the two largest galaxies within the Local Group, a region of over 50 galaxies spanning a diameter of more than 10 million light years, Andromeda, also known as M31, and the Milky Way, have both absorbed numerous smaller galaxies during their long lifetimes.

Because Andromeda devoured hundreds of smaller galaxies, it is difficult for scientists to trace evidence of any single one.

However, two astronomers at the University of Michigan (UM), Eric Bell and Richard D’Souza, successfully used computer simulations to study the stars in Andromeda’s outer halo and found that all originated in a single, large collision.

“It was a “Eureka’ moment. We realized we could use this information of Andromeda’s outer stellar halo to infer the properties of the largest of these shredded galaxies,” D’Souza said in a public statement.

Through the computer simulations, the researchers determined the large collision occurred about two billion years ago and even teased out properties of the cannibalized galaxy, which they determined to be 20 times larger than any galaxy consumed by the Milky Way.

These findings match those of another recent study that indicated Andromeda underwent a large merger that triggered major star formation sometime between 1.8 and three billion years ago.

A remnant of the large galaxy Andromeda consumed, designated M32p, still exists within an Andromeda satellite galaxy known as M32. Although M32 has the shape of an elliptical galaxy, it is filled with young stars. Elliptical galaxies are typically composed of older stars.

“It’s one of the most compact galaxies in the universe,” Bell said of M32. “There isn’t another galaxy like it.”

While scientists have long theorized that merging spiral galaxies both lose their spiral shapes during mergers, becoming a single larger elliptical galaxy, this did not happen to Andromeda, which kept its spiral shape after merging with and devouring M32p.

Noting that astronomers have long studied the Local Group, Bell commented, “It was shocking to realize that the Milky Way had a large sibling, and we never knew about it.”

An even larger galactic collision will occur in approximately four billion years, when the Milky Way and Andromeda Galaxy merge.

Findings of the study have been published in the journal Nature Astronomy.