The metalens meets the stars

Metalenses have been used to image microscopic features of tissue and resolve details smaller than a wavelength of light. Now they are going bigger.

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a 10-centimeter-diameter glass metalens that can image the sun, the moon and distant nebulae with high resolution.

It is the first all-glass, large-scale metalens in the visible wavelength that can be mass produced using conventional CMOS fabrication technology.

The research is published in ACS Nano.

"The ability to accurately control the size of tens of billions of nanopillars over an unprecedentedly large flat lens using state-of-the-art semiconductor foundry processes is a nanofabrication feat that opens exciting new opportunities for space science and technology," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper.

Most flat metalenses, which use millions of pillar-like nanostructures to focus light, are about the size of a piece of glitter.

In 2019, Capasso and his team developed a centimeter-scale metalens using a technique called deep-ultraviolet (DUV) projection lithography,which projects and forms a nanostructure pattern that can be directly etched into the glass wafer, eliminating the time-consuming writing and deposition processes that were required for previous metalenses.

DUV projection lithography is commonly used to pattern fine lines and shapes in silicon chips for smartphones and computers.

Joon-Suh Park, a former graduate student at SEAS and current postdoctoral fellow in Capasso's team, demonstrated that the technique could not only be used to mass produce metalenses but also increase their size for applications in virtual and augmented reality.

But making the metalens even larger for applications in astronomy and free-space optical communications posed an engineering problem.

"There is a major limitation with the lithography tool because these tools are used to make computer chips, so chip size is restricted to no more than 20 to 30 millimeters," said Park, co-first author of the paper.

"In order to make a 100-millimeter diameter lens, we needed to find a way around this limitation."

Park and the team developed a technique to stitch together several patterns of nanopillars using the DUV projection lithography tool.

By dividing the lens into 25 sections but using only the 7 sections of a quadrant considering the rotational symmetry, the researchers showed that DUV projection lithography could pattern 18.7 billion designed nanostructures onto a 10-centimeter circular area in a matter of minutes.

The team also developed a vertical glass etching technique that allows the creation of high-aspect ratio, smooth-sidewall nanopillars etched into glass.

"Using the same DUV projection lithography, one could produce large-diameter, aberration-correcting meta-optics or even larger lenses on larger glass diameter wafers as the corresponding CMOS foundry tools become increasingly available in the industry," said Soon Wei Daniel Lim, a postdoctoral fellow at SEAS and co-first author of the paper.

Lim played a lead role in the full simulation and characterization of all the possible fabrication errors that could arise during mass-manufacturing processes and how they could impact the optical performance of metalenses.

After addressing possible manufacturing challenges, the researchers demonstrated the power of the metalens in imaging celestial objects.

Mounting the metalens on a tripod with a color filter and camera sensor, Park and the team took to the roof of Harvard's Science Center.

There, they imaged the Sun, the moon and the North America nebula, a dim nebula in the constellation Cygnus about 2,590 light years away.

"We were able to get very detailed images of the Sun, the moon and the nebula that are comparable to images taken by conventional lenses" said Arman Amirzhan, a graduate student in the Capasso Lab and co-author of the paper.

Using only the metalens, the researchers were able to image the same cluster of sunspots as a NASA image taken that same day.

The team also demonstrated that the lens could survive exposure to extreme heat, extreme cold and the intense vibrations that would occur during a space launch without any damage or loss in optical performance.

Because of its size and monolithic glass composition, the lens could also be used for long-range telecommunications and directed energy transport applications.

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Astronomers dissect the anatomy of planetary nebulae using Hubble Space Telescope images

 Images of two iconic planetary nebulae taken by the Hubble Space Telescope are revealing new information about how they develop their dramatic features. Researchers from Rochester Institute of Technology and Green Bank Observatory presented new findings about the Butterfly Nebula (NGC 6302) and the Jewel Bug Nebula (NGC 7027) at the 237th meeting of the American Astronomical Society on Friday, Jan. 15.

Hubble's Wide Field Camera 3 observed the nebulae in 2019 and early 2020 using its full, panchromatic capabilities, and the astronomers involved in the project have been using emission line images from near-ultraviolet to near-infrared light to learn more about their properties. The studies were first-of-their-kind panchromatic imaging surveys designed to understand the formation process and test models of binary-star-driven planetary nebula shaping.

"We're dissecting them," said Joel Kastner, a professor in RIT's Chester F. Carlson Center for Imaging Science and School of Physics and Astronomy. "We're able to see the effect of the dying central star in how it's shedding and shredding its ejected material. We're able to see that material that the central star has tossed away is being dominated by ionized gas, where it's dominated by cooler dust, and even how the hot gas is being ionized, whether by the star's UV or by collisions caused by its present, fast winds."

Kastner said analysis of the new HST images of the Butterfly Nebula is confirming that the nebula was ejected only about 2,000 years ago -- an eyeblink by the standards of astronomy -- and that the S-shaped iron emission that helps give it the "wings" of gas may be even younger. Surprisingly, they found that while astronomers previously believed they had located the nebula's central star, it was actually a star not associated with the nebula that is much closer to Earth than the nebula. Kastner said he hopes that future studies with the James Webb Space Telescope could help locate the actual central star.

The team's ongoing analysis of the Jewel Bug Nebula is built on a 25-year baseline of measurements dating back to early Hubble imaging. Paula Moraga Baez, an astrophysical sciences and technology Ph.D. student from DeKalb, Ill., called the nebula "remarkable for its unusual juxtaposition of circularly symmetric, axisymmetric, and point-symmetric (bipolar) structures." Moraga noted, "The nebula also retains large masses of molecular gas and dust despite harboring a hot central star and displaying high excitation states."

Jesse Bublitz '20 Ph.D. (astrophysical sciences and technology), now a postdoctoral researcher at Green Bank Observatory, has continued analysis of NGC 7027 with radio images from the Northern Extended Millimeter Array (NOEMA) Telescope, where he identified molecular tracers of ultraviolet and X-ray light that continue to shape the nebula. The combined observations from telescopes at other wavelengths, like Hubble, and bright molecules CO+ and HCO+ from NOEMA indicate how different regions of NGC 7027 are affected by the irradiation of its central star.

"We're very excited about these findings," said Bublitz. "We had hoped to find structure that clearly showed CO+ and HCO+ spatially coincident or entirely in distinctive regions, which we did. This is the first map of NGC 7027, or any planetary nebula, in the molecule CO+, and only the second CO+ map of any astronomical source."

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Blue Ring Nebula: 16-year-old cosmic mystery solved, revealing stellar missing link

 In 2004, scientists with NASA's space-based Galaxy Evolution Explorer (GALEX) spotted an object unlike any they'd seen before in our Milky Way galaxy: a large, faint blob of gas with a star at its center. Though it doesn't actually emit light visible to the human eye, GALEX captured the blob in ultraviolet (UV) light and thus appeared blue in the images; subsequent observations also revealed a thick ring structure within it. So the team nicknamed it the Blue Ring Nebula. Over the next 16 years, they studied it with multiple Earth- and space-based telescopes, including W. M. Keck Observatory on Maunakea in Hawaii, but the more they learned, the more mysterious it seemed.

A new study published online on Nov. 18 in the journal Nature may have cracked the case. By applying cutting-edge theoretical models to the slew of data that has been collected on this object, the authors posit the nebula -- a cloud of gas in space -- is likely composed of debris from two stars that collided and merged into a single star.

While merged star systems are thought to be fairly common, they are nearly impossible to study immediately after they form because they're obscured by debris kicked up by the collision. Once the debris has cleared -- at least hundreds of thousands of years later -- they're challenging to identify because they resemble non-merged stars. The Blue Ring Nebula appears to be the missing link: astronomers are seeing the star system only a few thousand years after the merger, when evidence of the union is still plentiful. It appears to be the first known example of a merged star system at this stage.

Operated between 2003 and 2013 and managed by NASA's Jet Propulsion Laboratory in Southern California, GALEX was designed to help study the history of star formation by observing young star populations in UV light. Most objects seen by GALEX radiated both near-UV (represented as yellow in GALEX images) and far-UV (represented as blue), but the Blue Ring Nebula stood out because it emitted only far-UV light.

The object's size was similar to that of a supernova remnant, which forms when a massive star runs out of fuel and explodes, or a planetary nebula, the puffed-up remains of a star the size of our Sun. But the Blue Ring Nebula had a living star at its center. Furthermore, supernova remnants and planetary nebulas radiate in multiple light wavelengths outside the UV range, whereas the Blue Ring Nebula did not.

PHANTOM PLANET

In 2006, the GALEX team looked at the nebula with the 5.1-meter Hale telescope at the Palomar Observatory in San Diego County, California, and then with the even more powerful 10-meter Keck Observatory telescopes. They found evidence of a shockwave in the nebula using Keck Observatory's Low Resolution Imaging Spectrometer (LRIS), suggesting the gas composing the Blue Ring Nebula had indeed been expelled by some kind of violent event around the central star.

"Keck's LRIS spectra of the shock front was invaluable for nailing down how the Blue Ring Nebula came to be," said Keri Hoadley, an astrophysicist at Caltech and lead author of the study. "Its velocity was moving too fast for a typical planetary nebula yet too slow to be a supernova. This unusual, in-between speed gave us a strong clue that something else must have happened to create the nebula."

Data from Keck Observatory's High-Resolution Echelle Spectrometer (HIRES) also suggested the star was pulling a large amount of material onto its surface. But where was the material coming from?

"The HIRES observations at Keck gave us the first evidence that the system was accreting material," said co-author Mark Seibert, an astrophysicist with the Carnegie Institution for Science and a member of the GALEX team at Caltech, which manages JPL. "For quite a long time we thought that maybe there was a planet several times the mass of Jupiter being torn apart by the star, and that was throwing all that gas out of the system. Though the HIRES data appeared to support this theory, it also told us to be wary of that interpretation, suggesting the accretion may have something to do with motions in the atmosphere of the central star."

To gather more data, in 2012, the GALEX team used NASA's Wide-field Infrared Survey Explorer (WISE), a space telescope that studied the sky in infrared light, and identified a disk of dust orbiting closely around the star. Archival data from three other infrared observatories also spotted the disk. The finding didn't rule out the possibility that a planet was also orbiting the star, but eventually the team would show that the disk and the material expelled into space came from something larger than even a giant planet. Then in 2017, the Hobby-Eberly Telescope in Texas confirmed there was no compact object orbiting the star.

More than a decade after discovering the Blue Ring Nebula, the team had gathered data on the system from four space telescopes, four ground-based telescopes, historical observations of the star going back to 1895 (in order to look for changes in its brightness over time), and the help of citizen scientists through the American Association of Variable Star Observers (AAVSO). But an explanation for what had created the nebula still eluded them.

STELLAR SLEUTHING

When Hoadley began working with the GALEX science team in 2017, "the group had kind of hit a wall" with the Blue Ring Nebula, she said. But Hoadley was fascinated by the thus-far unexplainable object and its bizarre features, so she accepted the challenge of trying to solve the mystery. It seemed likely that the solution would not come from more observations of the system, but from cutting-edge theories that could make sense of the existing data. So Chris Martin, principal investigator for GALEX at Caltech, reached out to Brian Metzger of Columbia University for help.

As a theoretical astrophysicist, Metzger makes mathematical and computational models of cosmic phenomena, which can be used to predict how those phenomena will look and behave. He specializes in cosmic mergers -- collisions between a variety of objects, whether they be planets and stars or two black holes.

"It wasn't just that Brian could explain the data we were seeing; he was essentially predicting what we had observed before he saw it," said Hoadley. "He'd say, 'If this is a stellar merger, then you should see X,' and it was like, 'Yes! We see that!'"

The team concluded the nebula was the product of a relatively fresh stellar merger that likely occurred between a star similar to our Sun and another only about one tenth that size (or about 100 times the mass of Jupiter). Nearing the end of its life, the Sun-like star began to swell, creeping closer to its companion. Eventually, the smaller star fell into a downward spiral toward its larger companion. Along the way, the larger star tore the smaller star apart, wrapping itself in a ring of debris before swallowing the smaller star entirely.

This was the violent event that led to the formation of the Blue Ring Nebula. The merger launched a cloud of hot debris into space that was sliced in two by the gas disk. This created two cone-shaped debris clouds, their bases moving away from the star in opposite directions and getting wider as they travel outward. The base of one cone is coming almost directly toward Earth and the other almost directly away. They are too faint to see alone, but the area where the cones overlap (as seen from Earth) forms the central blue ring GALEX observed.

Millennia passed, and the expanding debris cloud cooled and formed molecules and dust, including hydrogen molecules that collided with the interstellar medium, the sparse collection of atoms and energetic particles that fill the space between stars. The collisions excited the hydrogen molecules, causing them to radiate in a specific wavelength of far-UV light. Over time, the glow became just bright enough for GALEX to see.

Stellar mergers may occur as often as once every 10 years in our Milky Way galaxy, meaning it's possible that a sizeable population of the stars we see in the sky were once two.

"We see plenty of two-star systems that might merge someday, and we think we've identified stars that merged maybe millions of years ago. But we have almost no data on what happens in between," said Metzger. "We think there are probably plenty of young remnants of stellar mergers in our galaxy, and the Blue Ring Nebula might show us what they look like so we can identify more of them."

Though this is likely the conclusion of a 16-year-old mystery, it may also be the beginning of a new chapter in the study of stellar mergers.

Read more at Science Daily

On the origin of massive stars

A scene of stellar creation, captured by the NASA/ESA Hubble Space Telescope, sits near the outskirts of the famous Tarantula Nebula. This cloud of gas and dust, as well as the many young and massive stars surrounding it, is the perfect laboratory to study the origin of massive stars.

The bright pink cloud and the young stars surrounding it in this image taken with the NASA/ESA Hubble Space Telescope have the uninspiring name LHA 120-N 150. This region of space is located on the outskirts of the Tarantula Nebula, which is the largest known stellar nursery in the local Universe. The nebula is situated over 160,000 light-years away in the Large Magellanic Cloud, a neighbouring irregular dwarf galaxy that orbits the Milky Way.

The Large Magellanic Cloud has had one or more close encounters in the past, possibly with the Small Magellanic Cloud. These interactions have caused an episode of energetic star formation in our tiny neighbour -- part of which is visible as the Tarantula Nebula.

Also known as 30 Doradus or NGC 2070, the Tarantula Nebula owes its name to the arrangement of bright patches that somewhat resemble the legs of a tarantula. It measures nearly 1000 light-years across. Its proximity, the favourable inclination of the Large Magellanic Cloud, and the absence of intervening dust make the Tarantula Nebula one of the best laboratories in which to study the formation of stars, in particular massive stars. This nebula has an exceptionally high concentration of massive stars, often referred to as super star clusters.

Astronomers have studied LHA 120-N 150 to learn more about the environment in which massive stars form. Theoretical models of the formation of massive stars suggest that they should form within clusters of stars; but observations indicate that up to ten percent of them also formed in isolation. The giant Tarantula Nebula with its numerous substructures is the perfect laboratory in which to resolve this puzzle as in it massive stars can be found both as members of clusters and in isolation.

With the help of Hubble, astronomers try to find out whether the isolated stars visible in the nebula truly formed alone or just moved away from their stellar siblings. However, such a study is not an easy task; young stars, before they are fully formed -- especially massive ones -- look very similar to dense clumps of dust.

LHA 120-N 150 contains several dozen of these objects. They are a mix of unclassified sources -- some probably young stellar objects and others probably dust clumps. Only detailed analysis and observations will reveal their true nature and that will help to finally solve the unanswered question of the origin of massive stars.

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Matter around a young star helps astronomers explore our stellar history

Orion Nebula.

Astronomers map the substance aluminum monoxide (AlO) in a cloud around a distant young star -- Origin Source I. The finding clarifies some important details about how our solar system, and ultimately we, came to be. The cloud's limited distribution suggests AlO gas rapidly condenses to solid grains, which hints at what an early stage of our solar evolution looked like.

Professor Shogo Tachibana of the UTokyo Organization for Planetary and Space Science has a passion for space. From small things like meteorites to enormous things like stars and nebulae -- huge clouds of gas and dust in space -- he is driven to explore our solar system's origins.

"I have always wondered about the evolution of our solar system, of what must have taken place all those billions of years ago," he said. "This question leads me to investigate the physics and chemistry of asteroids and meteorites."

Space rocks of all kinds greatly interest astronomers as these rocks can remain largely unchanged since the time our sun and planets formed from a swirling cloud of gas and dust. They contain records of the conditions at that time -- generally considered to be 4.56 billion years ago -- and their properties such as composition can tell us about these early conditions.

"On my desk is a small piece of the Allende meteorite, which fell to Earth in 1969. It's mostly dark but there are some scattered white inclusions (foreign bodies enclosed in the rock), and these are important," continued Tachibana. "These speckles are calcium and aluminum-rich inclusions (CAIs), which were the first solid objects formed in our solar system."

Minerals present in CAIs indicate that our young solar system must have been extremely hot. Physical techniques for dating these minerals reveal a fairly specific age for the solar system. However, Tachibana and colleagues wished to expand on the details of this stage of evolution.

"There are no time machines to explore our own past, so we wanted to see a young star that could share traits with our own," said Tachibana. "With the Atacama Large Millimeter/submillimeter Array (ALMA), we found the emission lines -- a chemical fingerprint -- for AlO in outflows from the circumstellar disk (gas and dust surrounding a star) of the massive young star candidate Orion Source I. It's not exactly like our sun, but it's a good start."

ALMA was the ideal tool as it offers extremely high resolution and sensitivity to reveal the distribution of AlO around the star. No other instrument can presently make such observations.

"Thanks to ALMA, we discovered the distribution of AlO around a young star for the first time. The distribution of AlO is limited to the hot region of the outflow from the disk. This implies that AlO rapidly condenses as solid grains -- similar to CAIs in our solar system," explained Tachibana. "This data allows us to place tighter constraints on hypotheses that describe our own stellar evolution. But there's still much work to do."

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Hubble celebrates its 29th birthday with unrivaled view of the Southern Crab Nebula

This is the Southern Crab Nebula -- Hubble's 29th anniversary image.

This incredible image of the hourglass-shaped Southern Crab Nebula was taken to mark the NASA/ESA Hubble Space Telescope's 29th anniversary in space. The nebula, created by a binary star system, is one of the many objects that Hubble has demystified throughout its productive life. This new image adds to our understanding of the nebula and demonstrates the telescope's continued capabilities.

On 24 April 1990, the NASA/ESA Hubble Space Telescope was launched on the space shuttle Discovery. It has since revolutionised how astronomers and the general public see the Universe. The images it provides are spectacular from both a scientific and a purely aesthetic point of view.

Each year the telescope dedicates a small portion of its precious observing time to take a special anniversary image, focused on capturing particularly beautiful and meaningful objects. This year's image is the Southern Crab Nebula, and it is no exception [1].

This peculiar nebula, which exhibits nested hourglass-shaped structures, has been created by the interaction between a pair of stars at its centre. The unequal pair consists of a red giant and a white dwarf. The red giant is shedding its outer layers in the last phase of its life before it too lives out its final years as a white dwarf. Some of the red giant's ejected material is attracted by the gravity of its companion.

When enough of this cast-off material is pulled onto the white dwarf, it too ejects the material outwards in an eruption, creating the structures we see in the nebula. Eventually, the red giant will finish throwing off its outer layers, and stop feeding its white dwarf companion. Prior to this, there may also be more eruptions, creating even more intricate structures.

Astronomers did not always know this, however. The object was first written about in 1967, but was assumed to be an ordinary star until 1989, when it was observed using telescopes at the European Southern Observatory's La Silla Observatory. The resulting image showed a roughly crab-shaped extended nebula, formed by symmetrical bubbles of gas and dust.

These observations only showed the outer hourglass emanating from a bright central region that could not be resolved. It was not until Hubble observed the Southern Crab in 1998 that the entire structure came into view. This image revealed the inner nested structures, suggesting that the phenomenon that created the outer bubbles had occurred twice in the (astronomically) recent past.

It is fitting that Hubble has returned to this object twenty years after its first observation. This new image adds to the story of an active and evolving object and contributes to the story of Hubble's role in our evolving understanding of the Universe.

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Hubble reveals cosmic Bat Shadow in the Serpent's Tail

This image, taken with the NASA/ESA Hubble Space Telescope shows the Serpens Nebula, a stellar nursery about 1300 light-years away. Within the nebula, in the upper right of the image, a shadow is created by the protoplanetary disc surrounding the star HBC 672. While the disc of debris is too tiny to be seen even by Hubble, its shadow is projected upon the cloud in which it was born. In this view, the feature -- nicknamed the Bat Shadow -- spans approximately 200 times the diameter of our own Solar System.

The NASA/ESA Hubble Space Telescope has captured part of the wondrous Serpens Nebula, lit up by the star HBC 672. This young star casts a striking shadow -- nicknamed the Bat Shadow -- on the nebula behind it, revealing telltale signs of its otherwise invisible protoplanetary disc.

The Serpens Nebula, located in the tail of the Serpent (Serpens Cauda) about 1300 light-years away, is a reflection nebula that owes most of its sheen to the light emitted by stars like HBC 672 -- ?a young star nestled in its dusty folds. In this image the NASA/ESA Hubble Space Telescope has exposed two vast cone-like shadows emanating from HBC 672.

These colossal shadows on the Serpens Nebula are cast by the protoplanetary disc surrounding HBC 672. By clinging tightly to the star the disc creates an imposing shadow, much larger than the disc -- approximately 200 times the diameter of our own Solar System. The disc's shadow is similar to that produced by a cylindrical lamp shade. Light escapes from the top and bottom of the shade, but along its circumference, dark cones of shadow form.

The disc itself is so small and far away from Earth that not even Hubble can detect it encircling its host star. However, the shadow feature -- nicknamed the Bat Shadow -- reveals details of the disc's shape and nature. The presence of a shadow implies that the disc is being viewed nearly edge-on.

Whilst most of the shadow is completely opaque, scientists can look for colour differences along its edges, where some light gets through. Using the shape and colour of the shadow, they can determine the size and composition of dust grains in the disc.

The whole Serpens Nebula, of which this image shows only a tiny part, could host more of these shadow projections. The nebula envelops hundreds of young stars, many of which could also be in the process of forming planets in a protoplanetary disc.

Although shadow-casting discs are common around young stars, the combination of an edge-on viewing angle and the surrounding nebula is rare. However, in an unlikely coincidence, a similar looking shadow phenomenon can be seen emanating from another young star, in the upper left of the image.

These precious insights into protoplanetary discs around young stars allow astronomers to study our own past. The planetary system we live in once emerged from a similar protoplanetary disc when the Sun was only a few million years old. By studying these distant discs we get to uncover the formation and evolution of our own cosmic home.

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The ghost of Cassiopeia

IC 63 -- nicknamed the Ghost Nebula -- is about 550 light-years from Earth. The nebula is classified as both a reflection nebula -- as it is reflecting the light of a nearby star -- and as an emission nebula -- as it releases hydrogen-alpha radiation. Both effects are caused by the gigantic star Gamma Cassiopeiae. The radiation of this star is also slowly causing the nebula to dissipate.

About 550 light-years away in the constellation of Cassiopeia lies IC 63, a stunning and slightly eerie nebula. Also known as the ghost of Cassiopeia, IC 63 is being shaped by radiation from a nearby unpredictably variable star, Gamma Cassiopeiae, which is slowly eroding away the ghostly cloud of dust and gas. This celestial ghost makes the perfect backdrop for the upcoming feast of All Hallow's Eve -- better known as Halloween.

The constellation of Cassiopeia (constellation)], named after a vain queen in Greek mythology, forms the easily recognisable "W" shape in the night sky. The central point of the W is marked by a dramatic star named Gamma Cassiopeiae.

The remarkable Gamma Cassiopeiae is a blue-white subgiant that is surrounded by a gaseous disc. This star is 19 times more massive and 65,000 times brighter than our Sun. It also rotates at the incredible speed of 1.6 million kilometres per hour -- more than 200 times faster than our parent star. This frenzied rotation gives it a squashed appearance. The fast rotation causes eruptions of mass from the star into a surrounding disk. This mass loss is related to the observed brightness variations.

The radiation of Gamma Cassiopeiae is so powerful that it even affects IC 63, sometimes nicknamed the Ghost Nebula, that lies several light years away from the star. IC 63 is visible in this image taken by the NASA/ESA Hubble Space Telescope.

The colours in the eerie nebula showcase how the nebula is affected by the powerful radiation from the distant star. The hydrogen within IC 63 is being bombarded with ultraviolet radiation from Gamma Cassiopeiae, causing its electrons to gain energy which they later release as hydrogen-alpha radiation -- visible in red in this image.

This hydrogen-alpha radiation makes IC 63 an emission nebula, but we also see blue light in this image. This is light from Gamma Cassiopeiae that has been reflected by dust particles in the nebula, meaning that IC 63 is also a reflection nebula.

This colourful and ghostly nebula is slowly dissipating under the influence of ultraviolet radiation from Gamma Cassiopeiae. However, IC 63 is not the only object under the influence of the mighty star. It is part of a much larger nebulous region surrounding Gamma Cassiopeiae that measures approximately two degrees on the sky -- roughly four times as wide as the full Moon.

This region is best seen from the Northern Hemisphere during autumn and winter. Though it is high in the sky and visible all year round from Europe, it is very dim, so observing it requires a fairly large telescope and dark skies.

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Structurally 'inside-out' planetary nebula discovered

Planetary nebula HuBi 1 (left) and another planetary nebula Abell39 (right, 6800 light years away from our solar system). Abell39 is an archetypal, textbook case of a spherical nebula surrounding a bright central star (a white dwarf), its nebula composes of hydrogen-rich ionized gas. HuBi 1, its central star has undergone a "born-again" event ejecting metal-rich material into the old, hydrogen-rich nebula, has a double-shell structure - a hydrogen-rich outer shell and a nitrogen-rich inner shell.

The Instituto de Astrofísica de Andalucía (IAA-CSIC) in Spain, the Laboratory for Space Research (LSR) of the University of Hong Kong (HKU), and an International team comprising scientists from Argentina, Mexico and Germany have discovered the unusual evolution of the central star of a planetary nebula in our Milky Way. This extraordinary discovery sheds light on the future evolution, and more importantly, the ultimate fate of the Sun.

The discovery of a structurally 'inside-out' planetary nebula -- the ionized material that surrounds a white dwarf -- was just reported online in Nature Astronomy. This is also the eighth research paper produced by HKU LSR with its international collaborators in the Nature journals since 2017.

The research team believes this inverted ionization structure of the nebula is resulted from the central star undergoing a 'born-again' event, ejecting material from its surface and creating a shock that excites the nebular material.

Planetary nebulae are ionized clouds of gas formed by the hydrogen-rich envelopes of low- and intermediate-mass stars ejected at late evolutionary stages. As these stars age, they typically strip their outer layers, forming a 'wind'. As the star transitions from its red giant phase to become a white dwarf, it becomes hotter, and starts ionizing the material in the surrounding wind. This causes the gaseous material closer to the star to become highly ionized, while the gas material further out is less so.

Studying the planetary nebula HuBi 1 (17,000 light years away and nearly 5 billion years ahead of our solar system in evolution), however, Dr Martín Guerrero et al. found the reverse: HuBi 1's inner regions are less ionized, while the outer regions more so. Analysing the central star, with the participation of top theoretical astrophysicists, the authors found that it is surprisingly cool and metal-rich, and is evolved from a low-mass progenitor star which has a mass 1.1 times of the Sun.

The authors suggest that the inner nebula was excited by the passage of a shockwave caused by the star ejecting matter unusually late in its evolution. The stellar material cooled to form circumstellar dust, obscuring the star; this well explains why the central star's optical brightness has diminished rapidly over the past 50 years. In the absence of ionizing photons from the central star, the outer nebula has begun recombining -- becoming neutral. The authors conclude that, as HuBi 1 was roughly the same mass as the Sun, this finding provides a glimpse of a potential future for our solar system.

Dr Xuan Fang, co-author of the paper and a postdoctoral fellow at the HKU LSR and Department of Physics, said the extraordinary discovery resolves a long-lasting question regarding the evolutionary path of metal-rich central stars of planetary nebulae. Dr Fang has been observing the evolution of HuBi 1 early since 2014 using the Spanish flagship telescope Nordic Optical Telescope and was among the first astrophysicists to discover its inverted ionization structure.

He said: "After noting HuBi 1's inverted ionization structure and the unusual nature of its central star, we looked closer to find the reasons in collaboration with top theoretical astrophysicists in the world. We then came to realize that we had caught HuBi 1 at the exact moment when its central star underwent a brief 'born-again' process to become a hydrogen-poor [WC] and metal-rich star, which is very rare in white dwarf stars evolution."

Dr Fang, however, said the discovery would not alter the fate of the Earth. He remarked: "Our findings suggest that the Sun may also experience a 'born-again' process while it is dying out in about 5 billion years from now; but way before that event, our earth will be engulfed by the Sun when it turns into a superhot red giant and nothing living will survive."

Read more at Science Daily

Unusual laser emission from the Ant Nebula

The Ant Nebula, as imaged by the NASA/ESA Hubble Space Telescope, resembles the head and body of a garden ant. In reality, it's the result of a dying sun-like star and complex interactions of material at its heart.

An international team of astronomers have discovered an unusual laser emission that suggests the presence of a double star system hidden at the heart of the "spectacular" Ant Nebula.

The extremely rare phenomenon is connected to the death of a star and was discovered in observations made by European Space Agency's (ESA) Herschel space observatory.

When low- to middleweight stars like our Sun approach the end of their lives they eventually become dense, white dwarf stars. In the process, they cast off their outer layers of gas and dust into space, creating a kaleidoscope of intricate patterns known as a planetary nebula. Our Sun is expected to one day form such a planetary nebula.

A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases. The Ant Nebula earns its nickname from the twin lobes that resemble the head and body of an ant.

The recent Herschel observations have shown that the dramatic demise of the central star in the core of the Ant Nebula is even more theatrical than implied by its colourful appearance in visible images -- such as those taken by the NASA/ESA Hubble Space Telescope.

The new data shows that the Ant Nebula also beams intense laser emission from its core. Lasers are well-known down on earth in everyday life, from special visual effects in music concerts to health care and communications. In space, laser emission is detected at very different wavelengths and only under certain conditions. Only a few of these infrared space lasers are known.

By coincidence, astronomer Donald Menzel who first observed and classified this particular planetary nebula in the 1920s (it is officially known as Menzel 3 after him) was also one of the first to suggest that in certain conditions natural 'light amplification by stimulated emission of radiation' -- from which the acronym 'laser' derives -- could occur in nebulae in space. This was well before the discovery of lasers in laboratories.

Dr Isabel Aleman, lead author of a paper describing the new results, said "We detected a very rare type of emission called hydrogen recombination laser emission, which is only produced in a narrow range of physical conditions.

"Such emission has only been identified in a handful of objects before and it is a happy coincidence that we detected the kind of emission that Menzel suggested, in one of the planetary nebulae that he discovered."

This kind of laser emission needs very dense gas close to the star. Comparison of the observations with models found that the density of the gas emitting the lasers is around ten thousand times denser than the gas seen in typical planetary nebulae and in the lobes of the Ant Nebula itself.

Normally, the region close to the dead star -- close in this case being about the distance of Saturn from the Sun -- is quite empty, because its material is ejected outwards. Any lingering gas would soon fall back onto it.

Co-author Prof Albert Zijlstra, from the Jodrell Bank Centre for Astrophysics at University of Manchester, added: "The only way to keep such dense gas close to the star is if it is orbiting around it in a disc. In this nebula, we have actually observed a dense disc in the very centre that is seen approximately edge-on. This orientation helps to amplify the laser signal.

"The disc suggests there is a binary companion, because it is hard to get the ejected gas to go into orbit unless a companion star deflects it in the right direction. The laser gives us a unique way to probe the disc around the dying star, deep inside the planetary nebula."

Astronomers have not yet seen the expected second star, hidden in the heart of the Ant nebula.

Göran Pilbratt, ESA's Herschel project scientist, added: "It is a nice conclusion that it took the Herschel mission to connect together Menzel's two discoveries from almost a century ago."

Read more at Science Daily

New models give insight into the heart of the Rosette Nebula

Rosette Nebula image is based on data obtained as part of the INT Photometric H-Alpha Survey of the Northern Galactic Plane.

A hole at the heart of a stunning rose-like interstellar cloud has puzzled astronomers for decades. But new research, led by the University of Leeds, offers an explanation for the discrepancy between the size and age of the Rosetta Nebula's central cavity and that of its central stars.

The Rosette Nebula is located in the Milky Way Galaxy roughly 5,000 light-years from Earth and is known for its rose-like shape and distinctive hole at its centre. The nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases with several massive stars found in a cluster at its heart.

Stellar winds and ionising radiation from these massive stars affect the shape of the giant molecular cloud. But the size and age of the cavity observed in the centre of Rosette Nebula is too small when compared to the age of its central stars.

Through computer simulations, astronomers at Leeds and at Keele University have found the formation of the Nebula is likely to be in a thin sheet-like molecular cloud rather than in a spherical or thick disc-like shape, as some photographs may suggest. A thin disc-like structure of the cloud focusing the stellar winds away from the cloud's centre would account for the comparatively small size of the central cavity.

Study lead author, Dr Christopher Wareing, from the School of Physics and Astronomy said: "The massive stars that make up the Rosette Nebula's central cluster are a few millions of years old and halfway through their lifecycle. For the length of time their stellar winds would have been flowing, you would expect a central cavity up to ten times bigger.

"We simulated the stellar wind feedback and formation of the nebula in various molecular cloud models including a clumpy sphere, a thick filamentary disc and a thin disc, all created from the same low density initial atomic cloud.

"It was the thin disc that reproduced the physical appearance -- cavity size, shape and magnetic field alignment -- of the Nebula, at an age compatible with the central stars and their wind strengths.

"To have a model that so accurately reproduces the physical appearance in line with the observational data, without setting out to do this, is rather extraordinary.

"We were also fortunate to be able to apply data to our models from the ongoing Gaia survey, as a number of the bright stars in the Rosette Nebula are part of the survey.

Applying this data to our models gave us new understanding of the roles individual stars play in the Rosette Nebula. Next we'll look at the many other similar objects in our Galaxy and see if we can figure out their shape as well."

The simulations, published today in the Monthly Notices of the Royal Astronomical Society, were run using the Advanced Research Computing centre at Leeds. The nine simulations required roughly half a million CPU hours -- the equivalent to 57 years on a standard desktop computer.

Read more at Science Daily

Crab nebula in the limelight: Unified model for the entire radiation spectrum

This composite image of the Crab Nebula was assembled with arbitrary colour scaling by combining data from five telescopes spanning nearly the entire electromagnetic spectrum: the radio emission representing the wind of charged particles from the central neutron star in red (from the Karl G. Jansky Very Large Array), the infrared including the glow of dust particles absorbing ultraviolet and visible light in yellow (from the Spitzer Space Telescope), the visible-light image featuring the hot filamentary structures in green (from the Hubble Space Telescope), the ultraviolet image in blue and the X-ray image in purple showing the effect of an energetic cloud of electrons (from the XMM-Newton Observatory and the Chandra X-ray Observatory).

The origin of cosmic rays, high-energy particles from outer space constantly impacting on Earth, is among the most challenging open questions in astrophysics. Now new research published in the journal Monthly Notices of the Royal Astronomical Society sheds new light on the origin of those energetic particles.

Discovered more than a hundred years ago and considered a potential health risk to airplane crews and astronauts, cosmic rays are believed to be produced by shock waves, for example those resulting from supernova explosions. The most energetic cosmic rays streaking across the universe carry 10 to 100 million times the energy generated by particle colliders such as the Large Hadron Collider at CERN.

The Crab nebula, the remnant of a supernova explosion that was observed almost a thousand years ago in AD1054, is one of the best studied objects in the history of astronomy and a known source of cosmic rays. It emits radiation across the entire electromagnetic spectrum, from gamma rays, ultraviolet and visible light, to infrared and radio waves. Most of what we see comes from very energetic particles (electrons), and astrophysicists can construct detailed models to try to reproduce the radiation that these particles emit.

The new study, by Federico Fraschetti at the University of Arizona, USA, and Martin Pohl at the University of Potsdam, Germany, reveals that the electromagnetic radiation streaming from the Crab nebula may originate in a different way than scientists have traditionally thought: the entire zoo of radiation can potentially be unified and arise from a single population of electrons, a hypothesis which was previously deemed impossible.

According to the generally accepted model, once the particles reach a shock boundary, they bounce back and forth many times due to the magnetic turbulence. During this process they gain energy -- in a similar way to a tennis ball being bounced between two rackets that are steadily moving nearer to one other -- and are pushed closer and closer to the speed of light. Such a model follows an idea introduced by the Italian physicist Enrico Fermi in 1949.

"The current models do not include what happens when the particles reach their highest energy," said Federico, a staff scientist at the University of Arizona's Departments of Planetary Sciences, Astronomy and Physics. "Only if we include a different process of acceleration, in which the number of higher energy particles decreases faster than at lower energy, can we explain the entire electromagnetic spectrum we see. This tells us that while the shock wave is the source of the acceleration of the particles, the mechanisms must be different."

Co-author Martin Pohl added: "The new result represents an important advance for our understanding of particle acceleration in cosmic objects, and helps to decipher the origin of the energetic particles that are found almost everywhere in the universe."

Read more at Science Daily

A Star's Explosive Death May Have Spawned Our Solar System

The explosive death of a star — that may have been up to a dozen times the sun's mass — might have triggered the formation of the solar system, a new study finds.

The sun as well as the rest of the solar system was born from a cloud of gas and dust about 4.6 billion years ago. According to previous research, some event disturbed this cloud, prompting a gravitational collapse that formed the sun and a surrounding disk of matter, where the planets were born.

By searching for telltale patterns that have been left in matter from the dawn of the solar system, Yong-Zhong Qian, co-author of the new study and an astrophysicist at the University of Minnesota in Minneapolis, and his colleagues now suggest that the explosive death of a small star could have kicked off that collapse.

Prior work has suggested that a supernova's shock wave might have packed enough energy to compress the preexisting cloud of dust. And researchers have searched for evidence of that blast: Supernovas generate telltale patterns of unstable, short-lived radioactive isotopes. The discovery of the signatures of such anomalies in ancient rocks would help confirm the idea that a supernova triggered the solar system's formation. (The isotopes of an element have different numbers of neutrons. A different number at the end of the isotope's name identifies each variety: for example, beryllium-9 or beryllium-10.)

Until now, researchers have failed to find the fingerprints of these isotopic anomalies in ancient meteorites that were left over from the birth of the solar system. However, researchers had been examining supernovas from relatively high-mass stars — those that are 15 or more times the sun's mass, Qian told Space.com. Qian's group chose to model lower-mass supernovas instead, from stars that are 12 times the sun's mass or less, and they investigated what isotopes would be formed from those explosions. They focused on the production of beryllium-10, an isotope that is commonly found in meteorites. Its prevalence in meteorites was already a mystery for researchers, Qian said. One theory held that high-energy cosmic rays could have stripped away protons or neutrons from atomic nuclei to create the beryllium-10 — a process called spallation.

Using new supernova models, Qian and his colleagues found that a low-mass supernova could generate vast amounts of ghostly particles known as neutrinos, whose influence on atomic nuclei could have created beryllium-10 — which would explain the high levels of that isotope in the meteorite record.

Moreover, the researchers said that the influence of a low-mass supernova might also explain the presence of other short-lived isotopes that are also found in meteorites, such as calcium-41 and palladium-107. "A low-mass supernova can explain the wide range of data that we have," Qian told Space.com.

Qian noted that the study group's findings do not explain the presence of all short-lived isotopes that are found in meteorites. "We think that some of these other short-lived nuclei might have been contributed by other mechanisms," Qian said. "I don't think that should be taken as a weakness of our model — it's just that our model cannot explain everything. Our work is a major piece of the puzzle about the solar system's formation, but there are other pieces of the puzzle that should be looked at as well."

Read more at Discovery News

Pillars of cosmic destruction: Colorful Carina Nebula blasted by brilliant nearby stars

These composite image shows several pillars within the Carina Nebula which were observed and studied with the MUSE instrument, mounted on ESO's Very Large Telescope. The massive stars within the star formation region slowly destroy the pillars of dust and gas from which they are born.

Spectacular new observations of vast pillar-like structures within the Carina Nebula have been made using the MUSE instrument on ESO's Very Large Telescope. The different pillars analysed by an international team seem to be pillars of destruction -- in contrast to the name of the iconic Pillars of Creation in the Eagle Nebula, which are of similar nature.The spires and pillars in the new images of the Carina Nebula are vast clouds of dust and gas within a hub of star formation about 7500 light-years away. The pillars in the nebula were observed by a team led by Anna McLeod, a PhD student at ESO, using the MUSE instrument on ESO's Very Large Telescope.

The great power of MUSE is that it creates thousands of images of the nebula at the same time, each at a different wavelength of light. This allows astronomers to map out the chemical and physical properties of the material at different points in the nebula.

Images of similar structures, the famous Pillars of Creation* in the Eagle Nebula and formations in NGC 3603, were combined with the ones displayed here. In total ten pillars have been observed, and in so doing a clear link was observed between the radiation emitted by nearby massive stars and the features of the pillars themselves.

In an ironic twist, one of the first consequences of the formation of a massive star is that it starts to destroy the cloud from which it was born. The idea that massive stars will have a considerable effect on their surroundings is not new: such stars are known to blast out vast quantities of powerful, ionising radiation -- emission with enough energy to strip atoms of their orbiting electrons. However, it is very difficult to obtain observational evidence of the interplay between such stars and their surroundings.

The team analysed the effect of this energetic radiation on the pillars: a process known as photoevaporation, when gas is ionised and then disperses away. By observing the results of photoevaporation -- which included the loss of mass from the pillars -- they were able to deduce the culprits. There was a clear correlation between the amount of ionising radiation being emitted by nearby stars, and the dissipation of the pillars.

Read more at Science Daily

Stellar 'Time Bomb' Proves Cosmic Crime Doesn't Pay

This beautiful Hubble image shows the ghostly remains of a star, which detonated 160,000 light-years away, blasting hot gases through interstellar space. But this explosion wasn't caused by a massive star running out of hydrogen, it was a different type of supernova that started with a thieving white dwarf and ended with a boom.

The stellar remains, called DEM L71, were spied by Hubble's Wide Field Camera 3 in the Large Magellanic Cloud (a satellite galaxy that orbits the Milky Way) and was formed by a type of supernova seeded by a binary star system that consists of a white dwarf and another star.

White dwarfs are the leftover husks of stars that once resembled our sun. Rather than exploding when they reach the ends of their lives, they run out of hydrogen and puff up into spectacular red giants. Once expanded, violent stellar winds strip away their outer layers, creating a planetary nebula. In the center, a dense, tiny star remains that can persist for many billions of years long after its parent star becomes a distant memory. In around 4 billion years time, our own sun will experience this fate.

But things get interesting should a white dwarf be paired up with another star; it will steal the other star's gas, causing the white dwarf to form a new outer layer. As this stellar thievery unfolds, the white dwarf seals its own fate by inadvertently starting the timer on a bomb.

When the gas reaches a certain threshold around the white dwarf, swelling to around one and a half times the size of our sun, it becomes critically unstable and explodes as a special kind of supernova -- a Type 1a. (Aside: Type 1a supernovae are used as cosmic "standard candles" by astronomers to precisely measure cosmic distances as they explode with the same amount of gas, and therefore with the same luminosity, every time.) In the case of DEM L71, we're seeing the aftermath of what happens when the hot debris from the supernova ripped into the cool interstellar gases, creating this beautiful nebulous remnant.

In other words, if you're a greedy white dwarf, crime doesn't pay and, if you steal your neighbor's gas, you'll explode. Also, the binary partners of exploding stars have been found to survive, amazingly. Although the cosmos is often cruel and unforgiving, in this case, justice can be served.

From Discovery News

Beating heart of the Crab Nebula

Crab Nebula.

Peering deep into the core of the Crab Nebula, this close-up image reveals the beating heart of one of the most historic and intensively studied remnants of a supernova, an exploding star. The inner region sends out clock-like pulses of radiation and tsunamis of charged particles embedded in magnetic fields.

The neutron star at the very center of the Crab Nebula has about the same mass as the sun but compressed into an incredibly dense sphere that is only a few miles across. Spinning 30 times a second, the neutron star shoots out detectable beams of energy that make it look like it's pulsating.

The NASA Hubble Space Telescope snapshot is centered on the region around the neutron star (the rightmost of the two bright stars near the center of this image) and the expanding, tattered, filamentary debris surrounding it. Hubble's sharp view captures the intricate details of glowing gas, shown in red, that forms a swirling medley of cavities and filaments. Inside this shell is a ghostly blue glow that is radiation given off by electrons spiraling at nearly the speed of light in the powerful magnetic field around the crushed stellar core.

The neutron star is a showcase for extreme physical processes and unimaginable cosmic violence. Bright wisps are moving outward from the neutron star at half the speed of light to form an expanding ring. It is thought that these wisps originate from a shock wave that turns the high-speed wind from the neutron star into extremely energetic particles.

When this "heartbeat" radiation signature was first discovered in 1968, astronomers realized they had discovered a new type of astronomical object. Now astronomers know it's the archetype of a class of supernova remnants called pulsars -- or rapidly spinning neutron stars. These interstellar "lighthouse beacons" are invaluable for doing observational experiments on a variety of astronomical phenomena, including measuring gravity waves.

Observations of the Crab supernova were recorded by Chinese astronomers in 1054 A.D. The nebula, bright enough to be visible in amateur telescopes, is located 6,500 light-years away in the constellation Taurus.

From Science Daily

Hubble Spies 26th Birthday Bubble Beauty

To celebrate its 26th year in space — yes, twenty-six years! — Hubble has gotten into the birthday spirit and captured a stunning portrait of the aptly-named “Bubble Nebula.”

This nebula is located around 8,000 light-years away in the constellation of Cassiopia. Although the Hubble Space Telescope has observed this iridescent object before, as it is so big, we’ve usually only seen close-up sections of its shape. This time, however, 4 separate images taken by Hubble’s Wide Field Camera 3 (WFC3) have been stitched together as a mosaic, capturing it’s full, bubbly personality for the first time.

At first sight, you may assume the Bubble Nebula to be the aftermath of some kind of stellar eruption; a supernova remnant perhaps. But the engine behind the bubble is actually a star generating powerful stellar winds, producing a near-perfect bubble that looks like it came straight from a bubble bath.

The star, called SAO 20575, can be seen to the left of center of the bubble. It is a massive star, around 10 to 20 times the mass of our sun. The star is embedded inside a molecular cloud of gas and dust, the type of cloud where young stars are born. But in the case of SAO 20575, its powerful stellar winds are blasting through the molecular cloud, pushing against the surrounding cloud, producing the bright bubbly appearance.

The bubble is approximately 10 light-years across — more than double the distance from the sun to neighboring star system Alpha Centauri — and the stellar winds have been clocked traveling some 100,000 kilometers per hour. This is a bubble of epic proportions and it continues to expand, driven by the ferocious stellar hurricane that relentlessly rips through the molecular cloud.

Interestingly, previous close-up Hubble observations have shown small knots of gas and dust sitting in the middle of this relentless wind, around the mass of the Earth but with elegant tails blown back.

26 years after launch aboard NASA’s space shuttle Discovery on April 24, 1990, Hubble continues to wow us with stunning science and beautiful imagery we never thought possible and, though aging, is showing few signs of slowing down.

From Discovery News

Baby Star's 'Placenta' Precisely Measured for the First Time

It is well known that as a massive cloud of gas collapses under its own gravity, baby stars may form. The intense gravitational collapse kicks off fusion processes that begin the coalescence of more matter that feeds into a newborn star. Though the general process is fairly well understood, the details are not.

For example, a stellar embryo growing inside a gas cloud isn’t “fed” directly from that cloud; matter from the cloud spirals toward the baby star, creating a rapidly-swirling, hot disk. The star is therefore fed by the disk, which is itself fed by gas from the surrounding cloud. This disk acts almost like a mother’s placenta; it’s the placenta that provides nutrients for the developing embryo, not the mother herself.

But astronomers have not been able to precisely observe where the disk around a newborn star ends (the “placenta”) and where the inner boundary of the gas cloud (the “mother”) begins. Now, astronomers using the stunningly powerful Atacama Large Millimeter/submillimeter Array (ALMA) have seen this boundary, a direct observation that will undoubtedly improve star (and planetary) formation models.

“The disks around young stars are the places where planets will be formed,” said Yusuke Aso, of the University of Tokyo and lead author of a paper published in the Astrophysical Journal. “To understand the formation mechanism of a disk, we need to differentiate the disk from the outer envelope precisely and pinpoint the location of its boundary.”

Zooming in on a protostar named TMC-1A, which is located around 450 light-years away in the constellation Taurus, Aso’s team were able to see its spinning inner disk (the protoplanetary disk) and differentiate it from the cloud feeding it. ALMA’s extreme precision at measuring velocity distributions was key to this endeavor.

In the case of TMC-1A, the transition boundary from spinning disk to surrounding gas cloud envelope was measured to extend 90 AU (astronomical units; where 1 AU is the average distance the Earth orbits the sun) from the central baby star, a distance 3-times bigger than the orbit of Neptune. What’s more, the ALMA observations revealed the protostar’s disk obeys Keplarian motion; the material closest to the star orbits faster, whereas the material further out orbits slower.

This is important: using the rotation speed of the disk’s gas, the researchers could calculate the mass of the baby star. This stellar infant “weighs in” at a healthy 0.68 times (68 percent, or roughly two-thirds) the mass of our sun. They were also able to deduce the rate matter was falling from the disk onto the star — one-millionth of the mass of our sun is falling into TMC-1A every year at a speed of 1 kilometer per second.

Read more at Discovery News

Stunning Survey Reveals Our Mesmerizing Milky Way

They say a picture is worth a thousand words, but this picture is worth tens of billions of stars.

And that’s what we are seeing here; this is the plane of our galaxy, seen through the eyes of a powerful telescope called the Atacama Pathfinder EXperiment telescope (APEX), located high on the Chajnantor Plateau in Chile’s Atacama region and managed by the European Southern Observatory (ESO).

The mosaic of images represents the completion of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) project that imaged the entirety of the Milky Way’s plane seen edge-on from APEX’s Southern Hemisphere location. It is the first galactic survey in sub-millimeter wavelengths — a region of the electromagnetic spectrum between infrared and radio waves — and because of the telescope’s awesome 12-meter wide aperture, astronomers can reveal far more detail in these observations than even space-based telescopes.

Sub-millimeter wavelengths are important to astronomers as they are generated by gas and dust only a few tens of degrees above absolute zero. Seeing our galaxy in these wavelengths can help us better understand the distribution of interstellar gas clouds that ultimately provide fuel for baby stars.

“ATLASGAL provides exciting insights into where the next generation of high-mass stars and clusters form,” said Timea Csengeri from the Max Planck Institute for Radio Astronomy (MPIfR), Bonn, Germany, in an ESO news release. “By combining these with observations from Planck, we can now obtain a link to the large-scale structures of giant molecular clouds.”

In a selection of release images, ATLASGAL is compared with data from the European Planck space observatory, surveys in visible light and views from NASA’s Spitzer Space Telescope, which sees the universe in infrared.

From Discovery News

Hubble Zooms-in on Veil Nebula's Shocked Tendrils

These beautiful, shimmering tendrils of plasma are all that remain of an ancient massive star that, approximately 8,000 years ago, died and exploded as a supernova. This zoomed-in section of the Veil Nebula has just been released by the Hubble Space Telescope, revealing the intricate beauty that’s left in the wake of one of the most violent events in the universe.

The Veil Nebula is one of the best known supernova remnants in the sky, featuring vast wispy structures of hot plasma some 110 light-years across. The nebula is located around 2,100 light-years away in the constellation Cygnus, the Swan.

Vast as it may be, this new observation features 6 images stitched together as a mosaic, only spanning 2 light-years, providing a very detailed look at the innermost detail of this fascinating object.

The Veil’s brightest components are caused by the ancient supernova’s shock wave that is traveling through interstellar space, blasting into the edge of a cavity, or bubble, etched out into a region of cool interstellar gas. Viewed edge-on, the crumpled structure of the expanding bubble’s leading edge glows in a range of vivid colors, heated by the interaction between the shock waves and cavity gas.

These colors represent the superheated glow of various different gases in the cavity wall — red is the glow of hydrogen; green is sulfur; blue is oxygen. The less defined, more diffuse glow is caused by cooler gases that was heated by the traveling shock wave in the past.

Read more at Discovery News