BREAKING NEWS: A Dramatic Galactic Explosion Arrived at Earth in 2012

A dramatic explosion occurred from a galaxy known as PKS B1424-418. Light from this blast began arriving at Earth in 2012. On Dec. 4, 2012, the IceCube Neutrino Observatory at the South Pole detected an event known as Big Bird – a neutrino gamma ray blazer with an energy exceeding 2 quadrillion electron volts (PeV). Now, an international team of astronomers, led by Matthias Kadler, professor for astrophysics at the University of Würzburg, has published their results in the scientific journal Nature Physics.

dec 2012 blazer hits milky way and earth

Starting in the summer of 2012, NASA’s Fermi satellite witnessed a dramatic brightening of PKS B1424-418, an active galaxy classified as a gamma-ray blazar. An active galaxy is an otherwise typical galaxy with a compact and unusually bright core. The excess luminosity of the central region is produced by matter falling toward a supermassive black hole weighing millions of times the mass of our Sun. As it approaches the black hole, some of the material becomes channeled into particle jets moving outward in opposite directions at nearly the speed of light. In blazars one of these jets happens to point almost directly toward Earth.

During the year-long outburst, PKS B1424-418 shone between 15 and 30 times brighter in gamma rays than its average before the eruption. The blazar is located within the Big Bird source region, but then so are many other active galaxies detected by Fermi.

milky-way-solar-system

The scientists searching for the neutrino source then turned to data from a long-term observing program named TANAMI. Since 2007, TANAMI has routinely monitored nearly 100 active galaxies in the southern sky, including many flaring sources detected by Fermi. Three radio observations between 2011 and 2013 cover the period of the Fermi outburst. They reveal that the core of the galaxy’s jet had been brightening by about four times. No other galaxy observed by TANAMI over the life of the program has exhibited such a dramatic change.

“Within their jets, blazars are capable of accelerating protons to relativistic energies. Interactions of these protons with light in the central regions of the blazar can create pions. When these pions decay, both gamma rays and neutrinos are produced,” explains Karl Mannheim, a coauthor of the study and astronomy professor in Würzburg, Germany. “We combed through the field where Big Bird must have originated looking for astrophysical objects capable of producing high-energy particles and light,” adds coauthor Felicia Kraub from the University of Erlangen-Nürnberg in Germany.

tanami_sky_world10

In published report, the team suggests the PKS B1424-418 outburst and Big Bird are linked, calculating only a 5-percent probability the two events occurred by chance alone. Using data from Fermi, NASA’s Swift and WISE satellites, the LBA and other facilities, the researchers determined how the energy of the eruption was distributed across the electromagnetic spectrum and showed that it was sufficiently powerful to produce a neutrino at PeV energies.

[

JUST IN: Scientists Beginning to Identify Signs That Galactic Cycles are Analogous with Sun-Earth’s Circumvolution

A Description of Extraterrestrial Galactic Obedience and Disobedience evolving within a tangled yet symmetrical display of what to some would appear to be as though disjointed and without direction. HOWEVER, when a person as myself, having watched closely for over 16 years and having intimately documented and published my research of the Sun-Earth connection, I found myself in a most optimized position to systematize newly disclosed research.

equation-1998

Equation:
Sunspots → Solar Flares (charged particles) → Magnetic Field Shift → Shifting Ocean and Jet Stream Currents → Extreme Weather and Human Disruption (mitch battros 1998).

Such findings include new discoveries of the inner-workings of our galaxy ‘Milky Way’ and its interaction with or solar system and of course our home planet Earth. Near mind-blowing insights into the mechanics of celestial events such as supernovas, gamma ray burst, pulsars, galactic cosmic rays, and closer to home – solar flares and coronal mass ejections.

milky-way-solar-system

New Equation:
Increase Charged Particles and Decreased Magnetic Field → Increase Outer Core Convection → Increase of Mantle Plumes → Increase in Earthquake and Volcanoes → Cools Mantle and Outer Core → Return of Outer Core Convection (Mitch Battros – July 2012).

New findings released yesterday described a large supernova event occurred in a galaxy near our own Milky Way named M74. The exploding star was 200 times larger than our Sun. The sudden blast hurled material outward from the star at a speed of 10,000 kilometers a second. That’s equivalent to 36 million kilometers an hour or 22.4 million miles an hour.

The massive explosion was one of the closest to Earth in recent years, visible as a point of light in the night sky starting July 24, 2013, said Robert Kehoe, SMU physics professor, who leads SMU’s astrophysics team.

supernovam74

“There are so many characteristics we can derive from the early data,” said astrophysicist Govinda Dhungana of Southern Methodist University. “This was a big massive star, burning tremendous fuel. When it finally reached a point its core couldn’t support the gravitational pull inward, suddenly it collapsed and then exploded.”

fatblackhole-m

The star’s original mass was about 15 times that of our Sun, Dhungana said. Its temperature was a hot 12,000 Kelvin (approximately 22,000 degrees Fahrenheit) on the tenth day after the explosion, steadily cooling until it reached 4,500 Kelvin after 50 days. The Sun’s surface is 5,800 Kelvin, while the Earth’s core is estimated to be about 6,000 Kelvin.

The new measurements are published online here in the May 2016 issue of The Astrophysical Journal, “Extensive spectroscopy and photometry of the Type IIP Supernova 2013j.”

 

Possible Extragalactic Source Of High-Energy Neutrinos

Nearly 10 billion years ago in a galaxy known as PKS B1424-418, a dramatic explosion occurred. Light from this blast began arriving at Earth in 2012. Now, an international team of astronomers, led by Prof. Matthias Kadler, professor for astrophysics at the university of Würzburg, and including other scientists from the new research cluster for astronomy and astroparticle physics at the universities of Würzburg and Erlangen-Nürnberg, have shown that a record-breaking neutrino seen around the same time likely was born in the same event. The results are published in Nature Physics.

Neutrinos are the fastest, lightest, most unsociable and least understood fundamental particles, and scientists are just now capable of detecting high-energy ones arriving from deep space. The present work provides the first plausible association between a single extragalactic object and one of these cosmic neutrinos.

blazar

Although neutrinos far outnumber all the atoms in the universe, they rarely interact with matter, which makes detecting them quite a challenge. But this same property lets neutrinos make a fast exit from places where light cannot easily escape such as the core of a collapsing star and zip across the universe almost completely unimpeded. Neutrinos can provide information about processes and environments that simply aren’t available through a study of light alone.

Recently, the IceCube Neutrino Observatory at the South Pole found first evidence for a flux of extraterrestrial neutrinos, which was named the Physics World breakthrough of the year 2013. To date, the science team of IceCube Neutrino has announced about a hundred very high-energy neutrinos and nicknamed the most extreme events after characters on the children’s TV series “Sesame Street.” On Dec. 4, 2012, IceCube detected an event known as Big Bird, a neutrino with an energy exceeding 2 quadrillion electron volts (PeV). To put that in perspective, it’s more than a million million times greater than the energy of a dental X-ray packed into a single particle thought to possess less than a millionth the mass of an electron. Big Bird was the highest-energy neutrino ever detected at the time and still ranks second.

Where did it come from? The best IceCube position only narrowed the source to a patch of the southern sky about 32 degrees across, equivalent to the apparent size of 64 full moons. “It’s like a crime scene investigation,” says lead author Matthias Kadler, a professor of astrophysics at the University of Würzburg in Germany, “The case involves an explosion, a suspect, and various pieces of circumstantial evidence.”

Starting in the summer of 2012, NASA’s Fermi satellite witnessed a dramatic brightening of PKS B1424-418, an active galaxy classified as a gamma-ray blazar. An active galaxy is an otherwise typical galaxy with a compact and unusually bright core. The excess luminosity of the central region is produced by matter falling toward a supermassive black hole weighing millions of times the mass of our sun. As it approaches the black hole, some of the material becomes channeled into particle jets moving outward in opposite directions at nearly the speed of light. In blazars one of these jets happens to point almost directly toward Earth.

During the year-long outburst, PKS B1424-418 shone between 15 and 30 times brighter in gamma rays than its average before the eruption. The blazar is located within the Big Bird source region, but then so are many other active galaxies detected by Fermi.

The scientists searching for the neutrino source then turned to data from a long-term observing program named TANAMI. Since 2007, TANAMI has routinely monitored nearly 100 active galaxies in the southern sky, including many flaring sources detected by Fermi. Three radio observations between 2011 and 2013 cover the period of the Fermi outburst. They reveal that the core of the galaxy’s jet had been brightening by about four times. No other galaxy observed by TANAMI over the life of the program has exhibited such a dramatic change.

“Within their jets, blazars are capable of accelerating protons to relativistic energies. Interactions of these protons with light in the central regions of the blazar can create pions. When these pions decay, both gamma rays and neutrinos are produced,” explains Karl Mannheim, a coauthor of the study and astronomy professor in Würzburg, Germany. “We combed through the field where Big Bird must have originated looking for astrophysical objects capable of producing high-energy particles and light,” adds coauthor Felicia Krauß, a doctoral student at the University of Erlangen-Nürnberg in Germany. “There was a moment of wonder and awe when we realized that the most dramatic outburst we had ever seen in a blazar happened in just the right place at just the right time.”

In a paper published Monday, April 18, in Nature Physics, the team suggests the PKS B1424-418 outburst and Big Bird are linked, calculating only a 5-percent probability the two events occurred by chance alone. Using data from Fermi, NASA’s Swift and WISE satellites, the LBA and other facilities, the researchers determined how the energy of the eruption was distributed across the electromagnetic spectrum and showed that it was sufficiently powerful to produce a neutrino at PeV energies.

“Taking into account all of the observations, the blazar seems to have had means, motive and opportunity to fire off the Big Bird neutrino, which makes it our prime suspect,” explains Matthias Kadler.

Francis Halzen, the principal investigator of IceCube at the University of Wisconsin-Madison, and not involved in this study, thinks the result is an exciting hint of things to come. “IceCube is about to send out real-time alerts when it records a neutrino that can be localized to an area a little more than half a degree across, or slightly larger than the apparent size of a full moon,” he concludes. “We’re slowly opening a neutrino window onto the cosmos.”

But this study also demonstrates the vital importance of classical astronomical observations in an era when new detection methods like neutrino observatories and gravitational-wave detectors open new but unknown skies.

Light Echoes Give Clues To Planet Nursery Around Star

Imagine you want to measure the size of a room, but it’s completely dark. If you shout, you can tell if the space you’re in is relatively big or small, depending on how long it takes to hear the echo after it bounces off the wall.

echoes

Astronomers use this principle to study objects so distant that they can’t be seen as more than points. In particular, researchers are interested in calculating how far young stars are from the inner edge of their surrounding protoplanetary disks. These disks of gas and dust are sites where planets form over the course of millions of years.

“Understanding protoplanetary disks can help us understand some of the mysteries about exoplanets, the planets in solar systems outside our own,” said Huan Meng, postdoctoral research associate at the University of Arizona’s Department of Astronomy and Steward Observatory. “We want to know how planets form and why we find large planets called ‘hot Jupiters’ close to their stars.”

Meng is the first author on a new study published in the Astrophysical Journal using data from NASA’s Spitzer Space Telescope and four ground-based telescopes to determine the distance from a star to the inner rim of its surrounding protoplanetary disk.

Making the measurement wasn’t as simple as laying a ruler on top of a photograph. Doing so would be as impossible as using a satellite photo of your computer screen to measure the width of the period at the end of this sentence.

Instead, researchers used a method called “photo-reverberation,” also known as “light echoes.” When the central star brightens, some of the light hits the surrounding disk, causing a delayed “echo.” Scientists measured the time it took for light coming directly from the star to reach Earth, then waited for its echo to arrive.

Thanks to Albert Einstein’s theory of special relativity, we know that light travels at a constant speed. To determine a given distance, astronomers can multiply the speed of light by the time light takes to get from one point to another.

To take advantage of this formula, scientists needed to find a star with variable emission — that is, a star that emits radiation in an unpredictable, uneven manner. Our own sun has a fairly stable emission, but a variable star would have unique, detectable changes in radiation that could be used for picking up corresponding light echoes. Young stars, which have variable emission, are the best candidates.

The star used in this study is called YLW 16B, which lies about 400 light-years from Earth. YLW 16B has about the same mass as our sun, but at one million years old, it’s just a baby compared to our 4.6-billion-year-old home star.

Astronomers combined Spitzer data with observations from ground-based telescopes: the Mayall telescope at Kitt Peak National Observatory in Arizona, the SOAR and SMARTS telescopes in Chile, and the Harold L. Johnson telescope in Mexico. During two nights of observation, researchers saw consistent time lags between the stellar emissions and their echoes in the surrounding disk. The ground-based observatories detected the shorter-wavelength infrared light emitted directly from the star, and Spitzer observed the longer-wavelength infrared light from the disk’s echo. Because of thick interstellar clouds that block the view from Earth, astronomers could not use visible light to monitor the star.

Researchers then calculated how far this light must have traveled during that time lag: about 0.08 astronomical units, which is approximately 8 percent of the distance between Earth and its sun, or one-quarter the diameter of Mercury’s orbit. This was slightly smaller than previous estimates with indirect techniques, but consistent with theoretical expectations.

Although this method did not directly measure the height of the disk, researchers were able to determine that the inner edge is relatively thick.

Previously, astronomers have used the light echo technique to measure the size of accretion disks of material around supermassive black holes. Since no light escapes from a black hole, researchers compare light from the inner edge of the accretion disk to light from the outer edge to determine the disk size. This technique is also used to measure the distance to other features near the accretion disk, such as dust and the surrounding fast-moving gas.

While light echoes from supermassive black holes represent delays of days to weeks, scientists measured the light echo from the protoplanetary disk in this study to be a mere 74 seconds.

The Spitzer study marks the first time the light echo method was used in the context of protoplanetary disks. The approach can be applied to other systems of stars with planet-forming disks around them, the scientists pointed out.

“Knowing the exact position of the inner boundary of a protoplanetary disk is important to anyone who wants to understand planet evolution,” Meng says.

Most stars are born with a protoplanetary disk around them, and astronomers have known for a long time that there is a gap between the star and its disk because of two competing processes: Close to the star, its strong radiation ionizes gas particles in the disk, diverting them along the star’s magnetic field lines above and below the plane of the disk. The other mechanism that prevents the disk from reaching all the way to the star’s surface is heat. Once a dust particle gets too close to the star, it simply vaporizes and either falls onto the star or gets blown out of the system.

“The predominant one of those two mechanisms plays an important role in the evolution of the disk, and right now, we don’t know which it is,” Meng says.

Until now, astronomers used a technique called interferometry to determine the position of the inner edge of protoplanetary disks, but that method requires assumptions about the shape of the disk, resulting in controversial findings.

“Our method provides a completely independent measurement of which mechanism plays the predominant role now and in the future,” Meng says.

Nearby Massive Star Explosion 30 Million Years Ago Equaled Detonation Of 100 Million Suns

A giant star that exploded 30 million years ago in a galaxy near Earth had a radius prior to going supernova that was 200 times larger than our Sun, according to astrophysicists at Southern Methodist University, Dallas.

star

The sudden blast hurled material outward from the star at a speed of 10,000 kilometers a second. That’s equivalent to 36 million kilometers an hour or 22.4 million miles an hour, said SMU physicist Govinda Dhungana, lead author on the new analysis.

The comprehensive analysis of the exploding star’s light curve and color spectrum have revealed new information about the existence and sudden death of supernovae in general, many aspects of which have long baffled scientists.

“There are so many characteristics we can derive from the early data,” Dhungana said. “This was a big massive star, burning tremendous fuel. When it finally reached a point its core couldn’t support the gravitational pull inward, suddenly it collapsed and then exploded.”

The massive explosion was one of the closest to Earth in recent years, visible as a point of light in the night sky starting July 24, 2013, said Robert Kehoe, SMU physics professor, who leads SMU’s astrophysics team.

The explosion, termed by astronomers Supernova 2013ej, in a galaxy near our Milky Way was equal in energy output to the simultaneous detonation of 100 million of the Earth’s suns.

The star was one of billions in the spiral galaxy M74 in the constellation Pisces.

Considered close by supernova standards, SN 2013ej was in fact so far away that light from the explosion took 30 million years to reach Earth. At that distance, even such a large explosion was only visible by telescopes.

Dhungana and colleagues were able to explore SN 2013ej via a rare collection of extensive data from seven ground-based telescopes and NASA’s Swift satellite. The data span a time period prior to appearance of the supernova in July 2013 until more than 450 days after.

The team measured the supernova’s evolving temperature, its mass, its radius, the abundance of a variety of chemical elements in its explosion and debris and its distance from Earth. They also estimated the time of the shock breakout, the bright flash from the shockwave of the explosion.

The star’s original mass was about 15 times that of our sun, Dhungana said. Its temperature was a hot 12,000 Kelvin (approximately 22,000 degrees Fahrenheit) on the tenth day after the explosion, steadily cooling until it reached 4,500 Kelvin after 50 days. The sun’s surface is 5,800 Kelvin, while the Earth’s core is estimated to be about 6,000 Kelvin.

Shedding new light on supernovae, mysterious objects of our universe

Supernovae occur throughout the universe, but they are not fully understood. Scientists don’t directly observe the explosions but instead detect changes in emerging light as material is hurled from the exploding star in the seconds and days after the blast.

Telescopes such as SMU’s robotic ROTSE-IIIb telescope at McDonald Observatory in Texas, watch our sky and pick up the light as a point of brightening light. Others, such as the Hobby Eberly telescope, also at McDonald, observe a spectrum.

SN 2013ej is M74’s third supernova in just 10 years. That is quite frequent compared to our Milky Way, which has had a scant one supernova observed over the past 400 years. NASA estimates that the M74 galaxy consists of 100 billion stars.

M74 is one of only a few dozen galaxies first cataloged by the astronomer Charles Messier in the late 1700s. It has a spiral structure — also the Milky Way’s apparent shape — indicating it is still undergoing star formation, as opposed to being an elliptical galaxy in which new stars no longer form.

It’s possible that planets were orbiting SN 2013ej’s progenitor star prior to it going supernova, in which case those objects would have been obliterated by the blast, Kehoe said.

“If you were nearby, you wouldn’t know there was a problem beforehand, because at the surface you can’t see the core heating up and collapsing,” Kehoe said. “Then suddenly it explodes — and you’re toast.”

Distances to nearby galaxies help determine cosmic distance ladder

Scientists remain unsure whether supernovae leave behind a black hole or a neutron star like a giant atomic nucleus the size of a city.

“The core collapse and how it produces the explosion is particularly tricky,” Kehoe said. “Part of what makes SN 2013ej so interesting is that astronomers are able to compare a variety of models to better understand what is happening. Using some of this information, we are also able to calculate the distance to this object. This allows us a new type of object with which to study the larger universe, and maybe someday dark energy.”

Being 30 million light years away, SN 2013ej was a relatively nearby extragalactic event, according to Jozsef Vinko, astrophysicist at Konkoly Observatory and University of Szeged in Hungary.

“Distances to nearby galaxies play a significant role in establishing the so-called cosmic distance ladder, where each rung is a galaxy at a known distance.”

Vinko provided important data from telescopes at Konkoly Observatory and Hungary’s Baja Observatory and carried out distance measurement analysis on SN 2013ej.

“Nearby supernovae are especially important,” Vinko said. “Paradoxically, we know the distances to the nearest galaxies less certainly than to the more distant ones. In this particular case we were able to combine the extensive datasets of SN 2013ej with those of another supernova, SN 2002ap, both of which occurred in M74, to suppress the uncertainty of their common distance derived from those data.”

Supernova spectrum analysis is like taking a core sample

While stars appear to be static objects that exist indefinitely, in reality they are primarily a burning ball, fueled by the fusion of elements, including hydrogen and helium into heavier elements. As they exhaust lighter elements, they must contract in the core and heat up to burn heavier elements. Over time, they fuse the various chemical elements of the periodic table, proceeding from lightest to heaviest. Initially they fuse helium into carbon, nitrogen and oxygen. Those elements then fuel the fusion of progressively heavier elements such as sulfur, argon, chlorine and potassium.

“Studying the spectrum of a supernova over time is like taking a core sample,” Kehoe said. “The calcium in our bones, for example, was cooked in a star. A star’s nuclear fusion is always forging heavier and heavier elements. At the beginning of the universe there was only hydrogen and helium. The other elements were made in stars and in supernovae. The last product to get created is iron, which is an element that is so heavy it can’t be burned as fuel.”

Dhungana’s spectrum analysis of SN 2013ej revealed many elements, including hydrogen, helium, calcium, titanium, barium, sodium and iron.

“When we have as many spectra as we have for this supernova at different times,” Kehoe added, “we are able to look deeper and deeper into the original star, sort of like an X-ray or a CAT scan.”

SN 2013ej’s short-lived existence was just tens of millions of years

Analysis of SN 2013ej’s spectrum from ultraviolet through infrared indicates light from the explosion reached Earth July 23, 2013. It was discovered July 25, 2013 by the Katzman Automatic Imaging Telescope at California’s Lick Observatory. A look back at images captured by SMU’s ROTSE-IIIb showed that SMU’s robotic telescope detected the supernova several hours earlier, Dhungana said.

“These observations were able to show a rapidly brightening supernova that started just 20 hours beforehand,” he said. “The start of the supernova, termed ‘shock breakout,’ corresponds to the moment when the internal explosion crashes through the star’s outer layers.”

Like many others, SN 2013ej was a Type II supernova. That is a massive star still undergoing nuclear fusion. Once iron is fused, the fuel runs out, causing the core to collapse. Within a quarter second the star explodes.

Supernovae have death and birth written all over them

Massive stars typically have a shorter life span than smaller ones.

“SN 2013ej probably lived tens of millions of years,” Kehoe said. “In universe time, that’s the blink of an eye. It’s not very long-lived at all compared to our sun, which will live billions of years. Even though these stars are bigger and have a lot more fuel, they burn it really fast, so they just get hotter and hotter until they just gobble up the matter and burn it.”

For most of its brief life, SN 2013ej would probably have burned hydrogen, which then fused to helium, burning for a few hundred thousand years, then perhaps carbon and oxygen for a few hundred days, calcium for a few months and silicon for several days.

“Supernovae have death and birth written all over them,” Kehoe said. “Not only do they create the elements we are made of, but the shockwave that goes out from the explosion — that’s where our solar system comes from.”

Outflowing material slams into clouds of material in interstellar space, causing it to collapse and form a solar system.

“The heavy elements made in the supernova and its parent star are those which comprise the bulk of terrestrial planets, like Earth, and are necessary for life,” Kehoe said.

New Herschel Maps Reveal Stellar Nurseries

ESA’s Herschel mission releases today a series of unprecedented maps of star-forming hubs in the plane of our Milky Way galaxy. This is accompanied by a set of catalogs of hundreds of thousands of compact sources that span all phases leading to the birth of stars in our Galaxy.

????????????????????????????????????????????????????????????

These maps and catalogs will be very valuable resources for astronomers, to exploit scientifically and for planning follow-up studies of particularly interesting regions in the Galactic Plane.

During its four years of operations (2009-2013), the Herschel space observatory scanned the sky at far-infrared and sub-millimeter wavelengths. Observations in this portion of the electromagnetic spectrum are sensitive to some of the coldest objects in the Universe, including cosmic dust, a minor but crucial component of the interstellar material from which stars are born.

4-newherschelm-a

The Herschel infrared Galactic Plane Survey (Hi-GAL) is the largest of all observing programs carried out with Herschel, in terms of both observing time – over 900 hours of total observations, equivalent to almost 40 days – and sky coverage – about 800 square degrees, or two percent of the entire sky. Its aim was to map the entire disc of the Milky Way, where most of its stars form and reside, in five of Herschel’s wavelength channels: 70, 160, 250, 350 and 500 μm.

Over the past two years, the Hi-GAL team has processed the data to obtain a series of calibrated maps of extraordinary quality and resolution. With a dynamical range of at least two orders of magnitude, these maps reveal the emission by diffuse material as well as huge filament structures and individual, point-like sources scattered across the images.

3-newherschelm

The images provide an unprecedented view of the Galactic Plane, ranging from diffuse interstellar material to denser filament structures of gas and dust that fragment into clumps where star formation sets in. They include pre-stellar clumps, proto-stars in various evolutionary stages and compact cores on the verge of turning into stars, as well as fully-fledged stars and the bubbles carved by their highly energetic radiation.

Today, the team releases the first part of this data set, consisting of 70 maps, each measuring two times two degrees, and provided in the five surveyed wavelengths.

2-newherschelm

“These maps are not only stunning from an aesthetic point of view, but they represent a rich data set for astronomers to investigate the different phases of star formation in our Galaxy,” explains Sergio Molinari from IAPS/INAF, Italy, Principal Investigator for the Hi-GAL Project.

Astronomers have been able to avail of data from Hi-GAL from the very beginning of the observing program since the team agreed to waive their right to a proprietary period. The observations have been made available through the ESA Herschel Science Archive, including raw data as well as data products generated by systematic pipeline processing. The data has regularly been reprocessed to gradually higher quality and fidelity products.

1-newherschelm

The present release represents an extra step in the data processing. The newly released maps are accompanied by source catalogs in each of the five bands, which can be directly used by the community to study a variety of subjects, including the distribution of diffuse dust and of star-forming regions across the Galactic Plane.

The maps cover the inner part of the Milky Way, towards the Galactic Center as seen from the Sun, with Galactic longitudes between +68° and -70°. A second release, with the remaining part of the survey, is foreseen for the end of 2016.

“It is not straightforward to extract compact sources from far-infrared images, where pre-stellar clumps and other proto-stellar objects are embedded in the diffuse interstellar medium that also shines brightly at the same wavelengths,” explains Molinari.

“For this reason, we developed a special technique to extract individual sources from the maps, maximising the contrast in order to amplify the compact objects with respect to the background.”

The result is a set of five catalogs, one for each of the surveyed wavelengths, listing the source position, flux, size, signal-to-noise ratio and other parameters related to their emission. The largest catalogue is the one compiled from the 160-μm maps, with over 300 000 sources.

“The Hi-GAL maps and catalogs provide a complete census of stellar nurseries in the inner Galaxy,” says Göran Pilbratt, Herschel Project Scientist at ESA.

“These will be an extremely useful resource for studies of star formation across the Milky Way, helping astronomers to delve into the Galactic Plane and also to identify targets for follow-up observations with other facilities.”

Cosmic Beacons Reveal The Milky Way’s Ancient Core

An international team of astronomers led by Dr. Andrea Kunder of the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany has discovered that the central 2000 light years within the Milky Way Galaxy hosts an ancient population of stars. These stars are more than 10 billion years old and their orbits in space preserve the early history of the formation of the Milky Way.

beacons

For the first time the team kinematically disentangled this ancient component from the stellar population that currently dominates the mass of the central Galaxy. The astronomers used the AAOmega spectrograph on the Anglo Australian Telescope near Siding Spring, Australia, and focussed on a well-known and ancient class of stars, called RR Lyrae variables. These stars pulsate in brightness roughly once a day, which make them more challenging to study than their static counterparts, but they have the advantage of being “standard candles.” RR Lyrae stars allow exact distance estimations and are found only in stellar populations more than 10 billion years old, for example, in ancient halo globular clusters. The velocities of hundreds of stars were simultaneously recorded toward the constellation of Sagittarius over an area of the sky larger than the full moon. The team therefore was able to use the age stamp on the stars to explore the conditions in the central part of our Milky Way when it was formed.

Just as London and Paris are built on more ancient Roman or even older remains, our Milky Way galaxy also has multiple generations of stars that span the time from its formation to the present. Since heavy elements, referred to by astronomers as “metals,” are brewed in stars, subsequent stellar generations become more and more metal-rich. Therefore, the most ancient components of our Milky Way are expected to be metal-poor stars. Most of our Galaxy’s central regions are dominated by metal-rich stars, meaning that they have approximately the same metal content as our Sun, and are arrayed in a football-shaped structure called the “bar.” These stars in the bar were found to orbit in roughly the same direction around the Galactic Centre. Hydrogen gas in the Milky Way also follows this rotation. Hence it was widely believed that all stars in the centre would rotate in this way.

But to the astronomers’ astonishment, the RR Lyrae stars do not follow football-shaped orbits, but have large random motions more consistent with their having formed at a great distance from the centre of the Milky Way. “We expected to find that these stars rotate just like the rest of the bar” states lead investigator Kunder. Coauthor Juntai Shen of the Shanghai Astronomical Observatory adds, “They account for only one percent of the total mass of the bar, but this even more ancient population of stars appears to have a completely different origin than other stars there, consistent with having been one of the first parts of the Milky Way to form.”

The RR Lyrae stars are moving targets — their pulsations result in changes in their apparent velocity over the course of a day. The team accounted for this, and was able to show that the velocity dispersion or random motion of the RR Lyrae star population was very high relative to the other stars in the Milky Way’s center. The next steps will be to measure the exact metal content of the RR Lyrae population, which gives additional clues to the history of the stars, and enhance by three or four times the number of stars studied, that presently stands at almost 1000.