Webb’s Infrared Eye Reveals the Heart of the Milky Way

The full view of the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) instrument reveals a 50 light-years-wide portion of the Milky Way’s dense centre. An estimated 500,000 stars shine in this image of the Sagittarius C (Sgr C) region, along with some as-yet unidentified features. Image Credit: NASA, ESA, CSA, STScI, S. Crowe (UVA)

The JWST is taking a break from studying the distant Universe and has trained its infrared eye on the heart of the Milky Way. The world’s most powerful space telescope has uncovered some surprises and generated some stunning images of the Milky Way’s galactic center (GC.) It’s focused on an enormous star-forming region called Sagittarius C (Sgr C).

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Star Factories Haven’t Changed Much Over the Entire Age of the Universe

“Sh 2-209” is a rare and large-scale star-forming region in the outer region of the Milky Way Galaxy. It's notable for its low metallicity, a characteristic it shares with the early Universe. Image Credit: NAOJ/Subaru Telescope

The ancient Universe is weird and secretive. Scientists have made laudable progress in uncovering more and more information on how the Universe began and what conditions were like all those billions of years ago. Powerful infrared telescopes, especially the ground-breaking James Webb Space Telescope, have let astronomers study the ancient light from the early Universe and remove some of the secrecy.

One of the mysteries astronomers want to untangle concerns star formation. Has it changed much since the Universe’s early days?

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Recent Supernovae Produced Giant Cavities in the Orion Nebula

This image of the Orion Nebula shows the puzzilng Barnard's Loop feature, a structure made of gas first identified in 1898, Image Credit: Michael Foley

The Orion Nebula is a well-known feature in the night sky and is visible in small backyard telescopes. Orion is a busy place. The region is known for active star formation and other phenomena. It’s one of the most scrutinized features in the sky, and astronomers have observed all kinds of activity there: planets forming in protoplanetary disks, stars beginning their lives of fusion inside collapsing molecular clouds, and the photoevaporative power of massive hot stars as they carve out openings in clouds of interstellar gas.

But supernova explosions are leaving their mark on the Orion Nebula too. New research says supernovae explosions in recent astronomical history are responsible for a mysterious feature first formally identified in the night sky at the end of the 19th century. It’s called Barnard’s Loop, and it’s a gigantic loop of hot gas as large as 300 light-years across.

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Star Formation Begins When Clouds of Gas Crash Into Each Other

another seyfert galaxy
The NASA/ESA Hubble Space Telescope has captured this vivid image of spiral galaxy Messier 77 — a galaxy in the constellation of Cetus, some 45 million light-years away from us. The streaks of red and blue in the image highlight pockets of star formation along the pinwheeling arms, with dark dust lanes stretching across the galaxy’s starry centre. The galaxy belongs to a class of galaxies known as Seyfert galaxies, which have highly ionised gas surrounding an intensely active centre.

To trigger star formation, you need to compress a lot of gas into not a lot of volume. To make a lot of stars at once, you need to really pack it in. Until now, astronomers haven’t been sure how to pull this off. But a collection of 20 papers outlines how to do it: make giant clouds of gas crash into each other.

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Hubble Captures Giant Lensed Galaxy Arc

Thanks to the presence of a natural "zoom lens" in space, this is a close-up look at the brightest distant "magnified" galaxy in the universe known to date. Credit: NASA, ESA, J. Rigby (NASA Goddard Space Flight Center), K. Sharon (Kavli Institute for Cosmological Physics, University of Chicago), and M. Gladders and E. Wuyts (University of Chicago)


Less than a year ago, the Hubble Space Telescope’s Wide Field Camera 3 captured an amazing image – a giant lensed galaxy arc. Gravitational lensing produces a natural “zoom” to observations and this is a look at one of the brightest distant galaxies so far known. Located some 10 billion light years away, the galaxy has been magnified as a nearly 90-degree arc of light against the galaxy cluster RCS2 032727-132623 – which is only half the distance. In this unusual case, the background galaxy is over three times brighter than typically lensed galaxies… and a unique look back in time as to what a powerful star-forming galaxy looked like when the Universe was only about one third its present age.

A team of astronomers led by Jane Rigby of NASA’s Goddard Space Flight Center in Greenbelt, Maryland are the parties responsible for this incredible look back into time. It is one of the most detailed looks at an incredibly distant object to date and their results have been accepted for publication in The Astrophysical Journal, in a paper led by Keren Sharon of the Kavli Institute for Cosmological Physics at the University of Chicago. Professor Michael Gladders and graduate student Eva Wuyts of the University of Chicago were also key team members.

“The presence of the lens helps show how galaxies evolved from 10 billion years ago to today. While nearby galaxies are fully mature and are at the tail end of their star-formation histories, distant galaxies tell us about the universe’s formative years. The light from those early events is just now arriving at Earth.” says the team. “Very distant galaxies are not only faint but also appear small on the sky. Astronomers would like to see how star formation progressed deep within these galaxies. Such details would be beyond the reach of Hubble’s vision were it not for the magnification made possible by gravity in the intervening lens region.”

This graphic shows a reconstruction (at lower left) of the brightest galaxy whose image has been distorted by the gravity of a distant galaxy cluster. The small rectangle in the center shows the location of the background galaxy on the sky if the intervening galaxy cluster were not there. The rounded outlines show distinct, distorted images of the background galaxy resulting from lensing by the mass in the cluster. The image at lower left is a reconstruction of what the lensed galaxy would look like in the absence of the cluster, based on a model of the cluster's mass distribution derived from studying the distorted galaxy images. Illustration Credit: NASA, ESA, and Z. Levay (STScI) Science Credit: NASA, ESA, J. Rigby (NASA Goddard Space Flight Center), K. Sharon (Kavli Institute for Cosmological Physics, University of Chicago), and M. Gladders and E. Wuyts (University of Chicago)

But the Hubble isn’t the only eye on the sky examining this phenomenon. A little over 10 years ago a team of astronomers using the Very Large Telescope in Chile also measured and examined the arc and reported the distant galaxy seems to be more than three times brighter than those previously discovered. However, there’s more to the picture than meets the eye. Original images show the magnified galaxy as hugely distorted and it shows itself more than once in the foreground lensing cluster. The challenge was to create a image that was “true to life” and thanks to Hubble’s resolution capabilities, the team was able to remove the distortions from the equation. In this image they found several incredibly bright star-forming regions and through the use of spectroscopy, they hope to better understand them.

Original Story Source: Hubble News Release.

Cooking Up Stars In Cygnus X

A bubbling cauldron of star birth is highlighted in this new image from NASA's Spitzer Space Telescope. Image credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA


Thanks to the incredible infra-red imagery of NASA’s Spitzer Space Telescope, we’re able to take a look into a tortured region of star formation. Infrared light in this image has been color-coded according to wavelength. Light of 3.6 microns is blue, 4.5-micron light is blue-green, 8.0-micron light is green, and 24-micron light is red. The data was taken before the Spitzer mission ran out of its coolant in 2009, and began its “warm” mission. This image reveals one of the most active and tumultuous areas of the Milky Way – Cygnus X. Located some 4,500 light years away, the violent-appearing dust cloud holds thousands of massive stars and even more of moderate size. It is literally “star soup”…

“Spitzer captured the range of activities happening in this violent cloud of stellar birth,” said Joseph Hora of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who presented the results today at the 219th meeting of the American Astronomical Society in Austin, Texas. “We see bubbles carved out by massive stars, pillars of new stars, dark filaments lined with stellar embryos and more.”

According to popular theory, stars are created in regions similar to Cygnus X. As their lives progress, they drift away from each other and it is surmised the Sun once belonged to a stellar association formed in a slightly less extreme environment. In regions like Cygnus X, the dust clouds are characterized with deformations caused by stellar winds and high radiation. The massive stars literally shred the clouds that birth them. This action can stop other stars from forming… and also cause the rise of others.

“One of the questions we want to answer is how such a violent process can lead to both the death and birth of new stars,” said Sean Carey, a team member from NASA’s Spitzer Science Center at the California Institute of Technology, Pasadena, Calif. “We still don’t know exactly how stars form in such disruptive environments.”

Thanks to Spitzer’s infra-red data, scientists are now able to paint a clearer picture of what happens in dusty complexes. It allows astronomers to peer behind the veil where embryonic stars were once hidden – and highlights areas like pillars where forming stars pop out inside their cavities. Another revelation is dark filaments of dust, where embedded stars make their home. It is visions like this that has scientists asking questions… Questions such as how filaments and pillars could be related.

“We have evidence that the massive stars are triggering the birth of new ones in the dark filaments, in addition to the pillars, but we still have more work to do,” said Hora.

Original Story Source: NASA Spitzer News Release.

PacMan Nebula Takes A “Bite” Out Of Space

n visible light, the star-forming cloud catalogued as NGC 281 in the constellation of Cassiopeia appears to be chomping through the cosmos, earning it the nickname the "Pacman" nebula after the famous Pac-Man video game of the 1980s. Image Credit: NASA/JPL-Caltech/UCLA


If you have a large telescope and an appetite for nebulae, then you’ve probably seen the Pac Man Nebula. Located 9,200 light years away in the constellation Cassiopeia, NGC 281 (RA 00 52 59.3 – Dec +56 37 19) is a seasonal favorite… and in this new image it’s showing a real “Halloween” face!

Discovered in August 1883 by E. E. Barnard, this diffuse HII region is home to open cluster IC 1590, the multiple star HD 5005, and several Bok globules. To the eye of the amateur telescope, it’s a soft, round region with a distinctive notch that makes it resemble the PacMan of video game fame. However, when seen in infrared light by NASA’s Wide-field Infrared Survey Explorer, or WISE, the PacMan appears to have “teeth”!

Of course, astronomers know these fanciful fangs are actually pillars where new stars are forming. They are created when stellar winds and radiation from the accompanying cluster blow away the gas and dust, revealing the dense star dough. If you see small red sprinkles in this cosmic cookie, then you’re looking at what could be very young stars in the process of springing to life.

According to JPL News, this image was made from observations by all four infrared detectors aboard WISE. Blue and cyan (blue-green) represent infrared light at wavelengths of 3.4 and 4.6 microns, respectively, which is primarily from stars, the hottest objects pictured. Green and red represent light at 12 and 22 microns, respectively, which is primarily from warm dust (with the green dust being warmer than the red dust).

It’s a great trick… or “treat”!

Original Story Source: JPL News.

Solo Star Synthesis

Young binary stars. Image credit: NASA


“Swing your partner round and round… Out of the cluster and out of town” While that’s a facetious description as to how binary stars end up losing their companions, it’s not entirely untrue. In practicing the field of astronomy, we’re quite aware that not all stars are single entities and at least half of the stellar population of the Milky Way consists of binaries. However, explaining just exactly why some are loners and others belong to multiple systems has been somewhat of a mystery. Now a team of astronomers from Bonn University and the Max-Planck-Institute for Radio astronomy think they have the answer…

The team recently published their results in a paper in the journal Monthly Notices of the Royal Astronomical Society. Apparently the environment that forms a particular group of stars plays a huge role in how many stars lead a lone existence – or have one or more companions. For the most part, star-forming nebulae produce binary stars in clustered groups. These groups then quickly disband into their parent galaxy and at least half of them become loners. But why do some double stars end up leading a solitary life? The answer might very well be how they interact gravitationally.

“In many cases the pairs are torn apart into two single stars, in the same way that a pair of dancers might be separated after colliding with another couple on a crowded dance floor”, explains Michael Marks, a PhD student and member of the International Max-Planck Research School for Astronomy and Astrophysics.

If this is the case, then single stars take on that state long before they spread out into a galaxy. Since conditions in star-forming regions vary widely in both appearance and population, science is taking a closer look at density. The more dense the region is, the more binary stars form – and the greater the interaction that splits them apart. Every cluster of stars has a different population, too.. And that population is dependant on the initial density. By using computer modeling, astronomers are able to determine what regions are most likely to contribute single stars are multiple systems to their host galaxy.

“Working out the composition of the Milky Way from these numbers is simple: We just add up the single and binary stars in all the dispersed groups to build a population for the wider galaxy”, says Kroupa. Michael Marks further explains how this concept applies universally: “This is the first time we have been able to compute the stellar content of a whole galaxy, something that was simply not possible until now. With our new method we can now calculate the stellar contents of many different galaxies and work out how many single and binary stars they have.”

Original Story Source: RAS News. For further reading: Notices of the Royal Astronomical Society. Animations of the interactions of binary stars.

Astronomers Witness Star Birth

Astronomers caught a glimpse of a future star just as it is being born out of the surrounding gas and dust, in a star-forming region similar to the one pictured above. (Spitzer Space Telescope image of DR21 in Infrared) Credit: A. Marston (ESTEC/ESA) et al., JPL, Caltech, NASA


Astronomers have glimpsed into the birth of a star, and have seen what could be the youngest known star at the very moment it is being born. “It’s very difficult to detect objects in this phase of star formation, because they are very short-lived and they emit very little light,” said Xuepeng Chen, from Yale University and lead author of a new paper. Not yet fully developed into a true star, the object is in the earliest stages of star formation and has just begun pulling in matter from a surrounding envelope of gas and dust. The team detected the faint light emitted by the nearby dust.

Using the Submillimeter Array in Hawaii and the Spitzer Space Telescope, the astronomers studied L1448-IRS2E, located in the Perseus star-forming region, about 800 light years away within our Milky Way galaxy.

Stars form out of large, cold, dense regions of gas and dust called molecular clouds, which exist throughout the galaxy. Astronomers think L1448-IRS2E is in between the prestellar phase, when a particularly dense region of a molecular cloud first begins to clump together, and the protostar phase, when gravity has pulled enough material together to form a dense, hot core out of the surrounding envelope.

Most protostars are between one to 10 times as luminous as the Sun, with large dust envelopes that glow at infrared wavelengths. Because L1448-IRS2E is less than one tenth as luminous as the Sun, the team believes the object is too dim to be considered a true protostar. Yet they also discovered that the object is ejecting streams of high-velocity gas from its center, confirming that some sort of preliminary mass has already formed and the object has developed beyond the prestellar phase. This kind of outflow is seen in protostars (as a result of the magnetic field surrounding the forming star), but has not been seen at such an early stage until now.

The team hopes to use the new Herchel space telescope, launched last May, to look for more of these objects caught between the earliest stages of star formation so they can better understand how stars grow and evolve. “Stars are defined by their mass, but we still don’t know at what stage of the formation process a star acquires most of its mass,” said Héctor Arce, also from Yale. “This is one of the big questions driving our work.”

Other authors of the paper include Qizhou Zhang and Tyler Bourke of the Harvard-Smithsonian Center for Astrophysics; and Ralf Launhardt, Markus Schmalzl and Thomas Henning of the Max Planck Institute for Astronomy.

The new study appears in the current issue of the Astrophysical Journal.

Read the team’s paper here.

Source: Yale University

Newly-Discovered Stellar Nurseries in the Milky Way

The Orion Nebula, one of the most brilliant star-forming regions in our galaxy. Other, newly-discovered regions like the Orion Nebula could help astronomers determing the chemical composition of our galaxy. Image Credit: APOD/Hubble Space Telescope


Our Milky Way churns out about seven new stars per year on average. More massive stars are formed in what’s called H II regions, so-named because the gas present in these stellar nurseries is ionized by the radiation of the young, massive stars forming there. Recently-discovered regions in the Milky Way that are nurseries for massive stars may hold important clues as to the chemical composition and structural makeup of our galaxy.

Thomas Bania, of Boston University, said in an NRAO press release, “We can clearly relate the locations of these star-forming sites to the overall structure of the Galaxy. Further studies will allow us to better understand the process of star formation and to compare the chemical composition of such sites at widely different distances from the Galaxy’s center.”

The announcement of these newly discovered regions was made in a presentation today at the American Astronomical Society meeting in Miami, Florida. The team of astronomers that collaborated on the search includes Thomas Bania of Boston University, Loren Anderson of the Astrophysical Laboratory of Marseille in France, Dana Balser of the National Radio Astronomy Observatory (NRAO), and Robert Rood of the University of Virginia.

H II regions that you may be familiar with include the Orion Nebula (M42), visible just South of Orion’s Belt with the naked eye, and the Horsehead Nebula, so famously imaged by the Hubble Space Telescope. For more information on other known regions (and lots of pictures), visit the 2Micron All-Sky Survey at IPAC.

By studying such regions in other galaxies, and our own, the chemical composition and distribution of a galaxy can be determined. H II regions form out of giant molecular clouds of hydrogen, and remain stable until a collision happens between two clouds, creating a shockwave, or the resulting shockwave from a nearby supernova collapses some of the gas to form stars. As these stars form and start to shine, their radiation strips the molecular hydrogen of its electrons.

The astronomers used both infrared and radio telescopes to see through the thick dust and gas that pervades the Milky Way. By combing surveys taken by the Spitzer Space Telescope’s infrared camera, and the Very Large Array (VLA) radio telescope, they identified “hot spots” that would be good candidates for H II regions. To further verify their findings, they used the Robert C. Byrd Green Bank Telescope (GBT), a sensitive radio telescope that allowed them to detect radio frequencies emitted by electrons as they rejoined protons to form hydrogen. This process of recombination to form hydrogen is a telltale sign of regions that contain ionized hydrogen, or H II.

The location of the regions is concentrated near the ends of the central bar of the Milky Way, and in its spiral arms. Over 25 of the regions discovered were further from the center of the galaxy than our own Sun – a more detailed study of these outlying regions could give astronomers a better understanding of the evolution and composition of our Milky Way.

“There is evidence that the abundance of heavy elements changes with increasing distance from the Galactic center,” Bania said. “We now have many more objects to study and improve our understanding of this effect.”

Source: NRAO Press Release