A Feline in the Heavens: The Smiling Cat Nebula

This is the Smiling Cat Nebula, aka Sh2-284. It's a stellar nursery of ionized hydrogen, powered by young stars in the center. If you can't see the cat, maybe you're more of a dog person. Image Credit: ESO/VPHAS+ team. Acknowledgement: CASU

A stellar nursery sounds like a placid place where baby stars go about their business undisturbed. But, of course, a stellar nursery is nothing like that. (Babies are noisy and cry a lot.) They’re dynamic places where powerful elemental forces rage mightily and bend the surroundings to their will. And this one, even though its name is the drowsy-sounding Smiling Cat Nebula, is no exception.

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Nancy Grace Roman Could Detect Supermassive Dark Stars

Artist view dark neutron star. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab

The first stars of the universe were very different than the stars we see today. They were made purely of hydrogen and helium, without heavier elements to help them generate energy in their core. As a result, they were likely hundreds of times more massive than the Sun. But some of the first stars may have been even stranger. In the early universe, dark matter could have been more concentrated than it is now, and it may have powered strange stellar objects known as dark stars.

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An Unfortunate Planet is Undergoing “Extreme Evaporation,” Melting Under the Extreme Heat From its Star

Illustration of a bursting planet about to flare. Credit: Sergei Nayakshin/Vardan Elbakyan, University of Leicester

FU Orionis is an unusual variable star. It was first seen as a magnitude 16 star in the early 1900s, but in the mid-1930s it rapidly brightened to a magnitude 9 star. The rapid brightening of a star was not unheard of, but in this case, FU Orionis did not fade to its original brightness. Since 1937 it has remained around magnitude 9, varying only slightly over time. For decades the mysterious star was thought to be unique, but in the 1970s similar stars were observed, and are now known as FU Orionis objects. Astronomers still had no real idea what could cause such a dramatic change, but a new study argues that it could be caused by a dying young planet.

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More Evidence of Massive First Generation Stars

Artist's rendition of massive, luminous first-generation stars in the Universe. When they died, their supernova explosions produced dust. Credit: NAOC
Artist's rendition of massive, luminous first-generation stars in the Universe. When they died, their supernova explosions produced dust. Credit: NAOC

A few days ago I wrote about the search for Population III stars. These stars were the first stars of the universe. Giant beasts hundreds of times more massive than the Sun, composed only of hydrogen and helium. These massive stars would have been very short-lived, exploding as brilliant supernovae in less than a million years. But Population III stars were so massive, their supernovae were uniquely different from the ones we see today, so our best way to find evidence of them is to look for their supernova remnants. And a recent study published in Nature may have found some.

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The Tarantula Nebula Shouldn’t Be Forming Stars. What’s Going On?

30 Doradus, also known as the Tarantula Nebula, is a region in the Large Magellanic Cloud. Streamlines show the magnetic field morphology from SOFIA HAWC+ polarization maps. These are superimposed on a composite image captured by the European Southern Observatory’s Very Large Telescope and the Visible and Infrared Survey Telescope for Astronomy. Credit: Background: ESO, M.-R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit. Streamlines: NASA/SOFIA

The Tarantula Nebula is a star formation region in the Large Magellanic Cloud (LMC). Tarantula is about 160,000 light-years away and is highly luminous for a non-stellar object. It’s the brightest and largest star formation region in the entire Local Group of galaxies.

But it shouldn’t be.

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Triggered Star Birth in the Nessie Nebula

A three-color composite of a portion of the Nessie Nebula that shows infrared observations from two Spitzer instruments. The bright red circular region in the center is the site of triggered star formation. Courtesy NASA/JPL.
A three-color composite of a portion of the Nessie Nebula that shows infrared observations from two Spitzer instruments. The bright red circular region in the lower center is the site of triggered star formation. Courtesy NASA/JPL.

Star formation is one of the oldest processes in the Universe. In the Milky Way and most other galaxies, it unfolds in cold, dark creches of gas and dust. Astronomers study sites of star formation to understand the process. Even though they know much about it, some aspects remain mysterious. That’s particularly true for the “Nessie Nebula” in the constellation Vulpecula. An international team led by astronomer James Jackson studies the nebula and its embedded star-birth regions. They found that it experienced a domino effect called “triggered star formation.”

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It Took Five Years and A Million Images to Make this Atlas of Stellar Nurseries

This image shows the HH 909 A object in the Chamaeleon constellation. New stars are born in the colourful clouds of gas and dust seen here. The infrared observations underlying this image reveal new details in the star-forming regions that are usually obscured by the clouds of dust. Image Credit: ESO/Meingast et al.

Star formation is an intricate process governed by a swarm of variables, and it all happens behind a thick veil of dust. Astrophysicists understand it to a certain degree. But this is nature, and nature doesn’t give up its intimate secrets without a concentrated effort.

To learn more about the star formation process, astronomers imaged five star-forming regions in the southern hemisphere with the ESO’s VISTA telescope. It took five years and over one million images, and the result is the VISIONS survey.

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Newborn Star Surrounded By Planet-Forming Disks at Different Angles

This artist's concept is based on Hubble Space Telescope images of gas-and-dust disks around the newborn star TW Hydrae. HST images show shadows sweeping across the disks encircling the system. These shadows are probably from slightly inclined inner disks that block starlight from reaching the outer disk. The disks are slightly inclined to each other due to the gravitational pull of unseen planets warping the disk structure. Credits ARTWORK: NASA, AURA/STScI for ESA, Leah Hustak (STScI)
This artist's concept is based on Hubble Space Telescope images of gas-and-dust disks around the newborn star TW Hydrae. HST images show shadows sweeping across the disks encircling the system. These shadows are probably from slightly inclined inner disks that block starlight from reaching the outer disk. The disks are slightly inclined to each other due to the gravitational pull of unseen planets warping the disk structure. Credits ARTWORK: NASA, AURA/STScI for ESA, Leah Hustak (STScI)

One of the great questions about our solar system is: what was it like as it formed? We know that a protosolar nebula birthed the Sun and planets. And, we know planets in our solar system have slightly different orbital inclinations, probably due to some interesting dynamics in the birth crèche. Why is that? The answer may be in a slightly weird-looking protoplanetary disk circling the newborn star TW Hydrae.

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Mother of Dragons: Astronomers Peer Inside the “Dragon Cloud”

The inner core of the "dragon cloud" complex. Image credit: Barnes et al.
The inner core of the "dragon cloud" complex. Image credit: Barnes et al.

How did the most massive stars form? Astronomers have debated their origins for decades. One of the biggest problems facing these theories is the lack of observations. Massive stars are relatively rare, and so it’s hard to catch them in the act of formation. But new observations of the so-called Dragon cloud may hold the clue to answering this mystery.

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When Clouds Collide, Destruction and Creation Go Hand-in-Hand

New stars seen by the Hubble Space Telescope in the Orion Nebula. ESA/Hubble & NASA, J. Bally; Acknowledgment: M. H. Özsaraç.

All stars are born from the collapse of clouds of dust and gas. But triggering star formation is a tricky process, because these gas clouds can just hang out doing nothing for billions of years. A pair of researchers have found a precise recipe for getting gas clouds to trigger star formation. It involves a lot of collision.

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