Category: Astronomy

Astronomers discover extremely luminous nova

First nova ever found in Small Magellanic Cloud is studied in multiple wavelengths.

What might be one of the most luminous stars ever detected is actually a nova or explosion that occurred in a binary system consisting of a white dwarf and Sun-like star in the Small Magellanic Cloud.

White dwarfs are stellar remnants of stars not massive enough to have died in supernova explosions.

The Small Magellanic Cloud is a satellite galaxy of the Milky Way located about 200,000 light years away.

Using NASA’s Swift satellite, scientists at the University of Leicester discovered the extremely bright nova, caused by the white dwarf’s sucking of material from the regular star until critical pressure was reached, causing the sudden brightness increase.

Led by researchers at the South African Astronomical Observatory, the scientists also observed the nova with ground-based telescopes in several countries, including South Africa, Australia, and South America.

Designated SMCN 2016-10a, the nova, one of the brightest observed in any galaxy, was discovered on October 14, 2016.

The term “nova” means new. Centuries ago, astronomers thought these suddenly bright objects to be new stars as opposed to what they really are–dying old ones.

White dwarfs emit both visible light and high-energy X-rays. By studying their emissions in various wavelengths, scientists can determine their temperatures and compositions.

This is the first time astronomers have spotted a nova in the Small Magellanic Cloud. Approximately 35 are seen in the Milky Way each year.

“Swift’s ability to respond rapidly, together with its daily-planned schedule, makes it ideal for the followup of transients, including novae,” said Swift team X-ray analysis leader Kim Page of the University of Leicester.

“It was able to observe the nova throughout its eruption, starting to collect very useful X-ray and UV data within a day of the outburst first being reported. The X-ray data were essential in showing that the mass of the white dwarf is close to the theoretical maximum; continued accretion might cause it eventually to be totally destroyed in a supernova explosion.”

Paul Kuin of the Mullard Space Science Laboratory at University College London, who organized the UV data, described the ability to observe the nova in multiple wavelengths as key to this being the most comprehensive nova study ever conducted.

Findings of the study have been published in Monthly Notices of the Royal Astronomical Society.

Auroras at Jupiter’s poles act independently

Researchers take advantage of rare opportunity to observe polar regions through Juno mission and space telescopes.

Auroras in Jupiter’s north and south polar regions act independently of one another, according to observations conducted by a study team using the European Space Agency’s (ESA) X-MM-Newton telescope and NASA’s Chandra X-ray Observatory.

Researchers at University College in London and at the Harvard-Smithsonian Center for Astrophysics led a study of high-energy X-ray auroras at both of Jupiter’s poles and were surprised to learn that unlike auroras on the poles of other planets, those at Jupiter’s poles do not mirror one another but pulse independently.

Activities of Earth’s north and south pole auroras mirror one another. Saturn does not appear to experience any X-ray auroras.

X-ray pulses at Jupiter’s south pole occur regularly every 11 minutes while those at its north pole are chaotic, with unpredictable increases and decreases in brightness.

“We didn’t expect to see Jupiter’s X-ray hot spots pulsing independently, as we thought their activity would be coordinated through the planet’s magnetic field,” explained study lead author William Dunn of both UCL Mullard Space Science Laboratory in the UK and the Harvard-Smithsonian Center for Astrophysics.

“We need to study this further to develop ideas for how Jupiter produces its X-ray aurora, and NASA’s Juno mission is really important for this.”

The researchers observed Jupiter using both space observatories in May and June of 2016 and in March 2007 to map the planet’s X-ray emissions and identify X-ray hot spots at its poles.

NASA’s Juno spacecraft, which arrived at Jupiter in 2016, does not have a science instrument capable of detecting X-rays; however, it is collecting other data at the polar regions that scientists hope to combine with the X-MM and Chandra data to better understand the planet’s auroras.

Scientists are fortunate that Juno is studying both of Jupiter’s poles at the same time, making it possible for them to compare activity at the poles with the giant planet’s complex magnetic interactions, emphasized study co-author Graziella Banduardi-Raymont of UCL Space and Climate Physics.

“If we can start to connect the X-ray signatures with the physical processes that produce them, then we can use those signatures to understand other bodies across the universe, such as brown dwarfs, exoplanets, or maybe even neutron stars,” Dunn stated.

One theory the researchers hope to test as they observe Jupiter’s polar activity over the next two years is that the northern and southern auroras form separately as a result of interactions between the planet’s magnetic field and the solar wind.

A paper discussing the findings has been published in the journal Nature Astronomy.

 

Most asteroids come from a few ancient planetesimals

Eighty-five percent of inner main belt asteroids come from five or six ancient objects.

Most asteroids in the belt between Mars and Jupiter as well as meteorites on Earth are the remnants of five or six planetesimals that broke apart in the ancient solar system, according to a new study published in the journal Nature Astronomy.

The asteroid belt is home to about 400,000 asteroids, with those posing the greatest possible threat to Earth located mostly in the inner main belt.

Understanding the origin and evolution of asteroids is important to protecting the Earth from potential impactors, noted study lead author Stanley Dermott of the University of Florida.

“These large bodies whiz by the Earth, so of course we’re very concerned about how many of these there are and what types of materials are in them. If ever one of these comes toward the Earth, and we want to deflect it, we need to know what its nature is.”

In earlier studies, scientists found that many asteroids have very similar compositions and orbits, which they labeled “asteroid families.” Each family likely originated from one larger body broken apart in a long ago impact.

Prior to this study, scientists believed just 44 percent of inner main belt asteroids to belong to five asteroid families.

Dermott and his research team studied asteroids never assigned to any families, specifically focusing on whether their orbits are circular or eccentric along with their tilt or inclination to the Sun’s equator. Their findings indicated 85 percent of inner main belt asteroids come from just five asteroid families. The remaining 15 percent either come from these same families or come from “ghost families,” most of whose asteroids have since been destroyed.

Meteorites on Earth, all of which are somewhat different from one another, also came from the same initial, ancient objects. “We’re saying these meteorites generally come from a small number of objects that were fairly large, hundreds of kilometers in diameter or more,” Dermott added.

Asteroids in the middle and outer main belt likely come from a different, but equally small number of larger parent bodies.

As a next step, Dermott plans to research the process by which asteroids leave the main belt and travel inward to become Near-Earth Objects.

A better understanding of ancient solar system bodies will also help scientists better understand the processes that shaped Earth and provide insight as to where to look for Earth-like exoplanets, he said.

 

Lunar meteorite suggests there could be water on the moon

A meteorite from the moon suggests that there is water on Earth’s natural satellite.

A lunar meteorite uncovered in Africa 13 years ago may hold a mineral that only forms in the presence of water, according to a new study published in the journal Science Advances.

The space rock — known as meteorite NWA2727 — is important because it is seemingly hard evidence that there is in fact water on or below the surface of the moon.

To make this discovery, scientists from Tohoku University analyzed the meteorite and found that it contained the substance moganite. As the mineral only forms in the presence of water, and as the meteorite landed in a desert, there must be some frozen liquid on the moon.

Moganite is commonly found within the cracks of rocks and appears through brecciation, where older rocks form a large mass. However, that process can only happen in the presence of water.

“For the first time, we can prove that there is water ice in the lunar material,” lead author Masahiro Kayama, a researcher at Tohoku University told Space.com. “In a moganite, there is less water, because moganite forms from the evaporation of water. That’s the case on the surface of the moon. But in the subsurface, much water remains as ice, because it’s protected from the sunlight.”

Though the team is not sure, they believe the water on the moon likely got there from asteroids and comets some three billion years ago. From there, they postulate the liquid became trapped in the surface and cooled. Then, another rock hit the moon and sent the water-filled rocks down to Earth.

The presence of moganite from a meteor that landed in a desert does suggest water on the moon, but it is not definitive evidence. Further missions need to collect samples from the lunar surface. It may also help to look back at older missions as well.

“It also highlights the need to study Apollo samples with modern analytical techniques,” said Noah Petro, a lunar geologist with NASA who was not involved in the research, according to Gizmodo.

In addition, scientists are not sure where water would sit on the moon or how much exists. Even if they do find water, nobody is sure how they would manage to extract or use it.

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.

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.

STEVEs are not auroras after all, study reports

New research into Strong Thermal Emission Velocity Enhancements show that they are not auroras

New research on unique atmospheric effects known as Strong Thermal Emission Velocity Enhancements (STEVEs) show that they are not auroras, but rather a never-before-recorded atmospheric phenomenon.

Researchers first began to analyze the cosmic lights a few years ago when citizens posted images of them to a Facebook group known as Alberta Aurora Chasers.

Though the bands look like typical auroras, they do not blanket the night sky. Rather, they are narrow and shoot up in colorful ribbons. That unique property is what drew scientists to them.

Auroras occur when electrons and protons from Earth’s magnetosphere rain down onto the ionosphere. That then shoots off a range of colors, including green, red, and blue.

While STEVEs look like auroras, they have key differences that set them apart. Not only do they appear as ribbons with purple and white hues, but they also run from east to west, and sit closer to the equator than auroras. In addition, though auroras are visible every night in their regions, STEVEs can only be viewed a few times each year.

Even so, despite the differences researchers still believed that STEVEs came about through the same processes that create auroras. The new research refutes that.

“Our main conclusion is that STEVE is not an aurora,” said lead author Bea Gallardo-Lacourt, a researcher from the University of Calgary, according to Gizmodo. “So right now, we know very little about it. And that’s the cool thing, because this has been known by photographers for decades. But for the scientists, it’s completely unknown.”

To learn more about the phenomena, the team in the study used a network of ground-based All-Sky Images to analyze the light from a STEVE event to see if the light came about from a known or new process.

That revealed no traces of particle precipitation, a finding that suggests that STEVEs are not auroras. Their light likely comes about from a brand new mechanism that is not on record.

Researchers plan to further study the events in the near future.

“This is a light display that we can observe over thousands of kilometers from the ground,” said Liz MacDonald, a space scientist at NASA’s Goddard Space Flight Center who was not involved in the research, according to USA Today. “It corresponds to something happening way out in space. Gathering more data points on STEVE will help us understand more about its behavior and its influence on space weather.”

This new research is published in the Geophysical Research Letters.

Spitzer telescope has been in space 15 years

Observatory is now in an extended mission through November 2019.

NASA’s Spitzer Space Telescope, which observes in infrared wavelengths, has now been operating for 15 years and remains in good condition.

The observatory was launched on August 25, 2003, for a 2.5-year primary mission. Its high sensitivity and ability to observe in the infrared have enabled it to study some of the universe’s most distant galaxies, observe exoplanets, and make numerous discoveries, including Saturn’s largest known ring, stellar nurseries, massive galaxy clusters, and more.

While the telescope was not initially designed to study exoplanets, it has spent more than half its time doing so, noted Spitzer project manager Lisa Storrie-Lombardi of NASA’s Jet Propulsion Laboratory (JPL).

One of NASA’s four Great Observatories in space, Spitzer has successfully peered through dust to study star-forming regions, black holes, and massive galaxy clusters.

By observing light that traveled 13.4 billion years from ancient galaxies, scientists can view these galaxies as they appeared just 400 million years after the Big Bang.

“In its 15 years of operations, Spitzer has opened our eyes to new ways of viewing the universe. Spitzer’s discoveries extend from our own planetary backyard, to planets around other stars, to the far reaches of the universe. And by working in collaboration with NASA’s other Great Observatories, Spitzer has helped scientists gain a more complete picture of many cosmic phenomena,” said Paul Hertz, director of the Astrophysics Division at NASA’s Washington, DC, headquarters.

One particular Spitzer discovery that surprised scientists was its observation of young galaxies much larger than expected, indicating they formed very early in the history of the universe.

The telescope has also observed some of the most distant known exoplanets. It was instrumental in the discovery of the TRAPPIST-1 system, in which seven planets orbit close to one another, three of which are located in the star’s habitable zone, where temperatures allow liquid water to exist on their surfaces.

A key to the success of NASA’s four Great Observatories is each one’s ability to observe in different wavelengths. By combining all their observations, scientists have been able to gain a more comprehensive understanding of the universe.

“The Great Observatories program was really a brilliant concept. The idea of getting multi-spectral images or data on astrophysical phenomenon is very compelling, because most heavenly bodies produce radiation across the spectrum. An average galaxy like our own Milky Way, for example, radiates as much infrared light as visible wavelength light. Each part of the spectrum provides new information,” stated Spitzer project scientist Michael Werner, also of JPL.

Opaque universe gives insight into galaxy formation

A new study sheds light on both the cosmic web, as well as what the universe was like when the first galaxies formed.

Researchers from numerous California universities found that 12.5 billion years ago the most opaque place in the universe had almost no matter, a new study in the Astrophysical Journal reports.

Almost all of the universe contains a vast, web-like network of dark matter and gas. Known as the “cosmic web,” that lattice accounts for most of the matter in the universe.

Though the gas within the network is almost completely transparent because it is kept ionized by ultraviolet radiation, it was not always that way.

Researchers first found that information roughly 10 years ago, when they realized 1 billion years after the Big Bang the gas hanging throughout the cosmos was not only opaque as a result of ultraviolet light, but also that its transparency changed greatly from region to region.

Then, a few years past that finding, the team behind the recent research found that the differences in opacity were so large that either the amount of gas — or the radiation in which it sits — also shifted in each area.

“Today, we live in a fairly homogeneous universe,” said lead author George Becker, a researcher from the University of California, Irvine, according to Science Daily. “If you look in any direction you find, on average, roughly the same number of galaxies and similar properties for the gas between galaxies, the so-called intergalactic gas. At that early time, however, the gas in deep space looked very different from one region of the universe to another.”

To take a closer look at the notable differences, scientists used the Subaru telescope in Hawaii to search for galaxies in a vast, 300-light-year stretch of the universe where intergalactic gas was extremely opaque.

In terms of the cosmic web, more opacity typically equals more gas, which means more galaxies. However, in the study the team found the exact opposite. The region they analyzed, despite being opaque, had much less galaxies on average.

Though they are not sure why that is, the researchers postulate it is because UV light could not travel very far in the early universe. As a result, any section with only a few galaxies would look much darker than one with more activity.  

This discovery is important because it could help scientists gain insight into the first billion years after the Big Bang, when ultraviolet light from the first galaxies filled the universe and permanently transformed the gas in deep space. In addition, analyzing deep space galaxies may also shed light on how the cosmic web first came to be. 

“There is still a lot we don’t know about when the first galaxies formed and how they altered their surroundings,” said Becker, according to SciTechDaily.

Spitzer telescope images supernova remnant

Precursor star exploded between 80,000 and one million years ago.

NASA’s Spitzer Space Telescope, which observes in infrared wavelengths, photographed one of the Milky Way’s largest supernova remnants in exquisite color and detail.

Supernova remnants are clouds left behind after a massive star explodes in a supernova after running out of fuel. Designated HBH 3, this particular remnant, which has a diameter of approximately 150 light years, was first detected by radio telescopes in 1966.

In addition to being one of the largest known supernova remnants, HBH 3 is also one of the oldest. Scientists estimate its precursor star exploded sometime between 80,000 and one million years ago.

Extremely high-energy light in the form of gamma rays was detected coming from near HBH 3 in 2016 by NASA’s Fermi Gamma-Ray Telescope.  Some scientists theorize that particles being emitted by the supernova remnant are exciting gas in nearby star-forming regions.

Supernova remnants emit both infrared and optical light. A white, cloud-like feature toward the left side of the Spitzer image is actually three separate star-forming regions, designated as W3, W4, and W5. Located 6,400 light years away, these regions extend far beyond what is seen in the image.

Red filaments seen in the center and top of the photo are made up of molecular gases, which were both produced and energized in the supernova explosion, causing them to radiate infrared light.

Infrared light is slightly less energetic than optical light. In this photo of HBH 3, infrared wavelengths of 3.6 microns are mapped to blue while those of 4.5 microns are mapped to red. The filaments radiate light solely at the 4.5-micron wavelength.

The white, star -forming region is a combination of both wavelengths.

To end their lives as supernovae, stars must have a minimum of eight to 15 solar masses.

As of August 25, Spitzer will mark 15 years of being in space.