Snaps supersonic outflow of young star

Herbig-Haro (HH) objects are luminous regions surrounding newborn stars, formed when stellar winds or jets of gas spewing from these newborn stars form shock waves colliding with nearby gas and dust at high speeds. This image of HH 211 from NASA's James Webb Space Telescope reveals an outflow from a Class 0 protostar, an infantile analog of our Sun when it was no more than a few tens of thousands of years old and with a mass only 8% of the present-day Sun (it will eventually grow into a star like the Sun).

Infrared imaging is powerful in studying newborn stars and their outflows, because such stars are invariably still embedded within the gas from the molecular cloud in which they formed. The infrared emission of the star's outflows penetrates the obscuring gas and dust, making a Herbig-Haro object like HH 211 ideal for observation with Webb's sensitive infrared instruments. Molecules excited by the turbulent conditions, including molecular hydrogen, carbon monoxide, and silicon monoxide, emit infrared light that Webb can collect to map out the structure of the outflows.

The image showcases a series of bow shocks to the southeast (lower-left) and northwest (upper-right) as well as the narrow bipolar jet that powers them. Webb reveals this scene in unprecedented detail -- roughly 5 to 10 times higher spatial resolution than any previous images of HH 211. The inner jet is seen to "wiggle" with mirror symmetry on either side of the central protostar. This is in agreement with observations on smaller scales and suggests that the protostar may in fact be an unresolved binary star.

Earlier observations of HH 211 with ground-based telescopes revealed giant bow shocks moving away from us (northwest) and moving towards us (southeast) and cavity-like structures in shocked hydrogen and carbon monoxide respectively, as well as a knotty and wiggling bipolar jet in silicon monoxide. Researchers have used Webb's new observations to determine that the object's outflow is relatively slow in comparison to more evolved protostars with similar types of outflows.

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Hubble sees possible runaway black hole creating a trail of stars

There's an invisible monster on the loose, barreling through intergalactic space so fast that if it were in our solar system, it could travel from Earth to the Moon in 14 minutes. This supermassive black hole, weighing as much as 20 million Suns, has left behind a never-before-seen 200,000-light-year-long "contrail" of newborn stars, twice the diameter of our Milky Way galaxy. It's likely the result of a rare, bizarre game of galactic billiards among three massive black holes.

Rather than gobbling up stars ahead of it, like a cosmic Pac-Man, the speedy black hole is plowing into gas in front of it to trigger new star formation along a narrow corridor. The black hole is streaking too fast to take time for a snack. Nothing like it has ever been seen before, but it was captured accidentally by NASA's Hubble Space Telescope.

"We think we're seeing a wake behind the black hole where the gas cools and is able to form stars. So, we're looking at star formation trailing the black hole," said Pieter van Dokkum of Yale University in New Haven, Connecticut. "What we're seeing is the aftermath. Like the wake behind a ship we're seeing the wake behind the black hole." The trail must have lots of new stars, given that it is almost half as bright as the host galaxy it is linked to.

The black hole lies at one end of the column, which stretches back to its parent galaxy. There is a remarkably bright knot of ionized oxygen at the outermost tip of the column. Researchers believe gas is probably being shocked and heated from the motion of the black hole hitting the gas, or it could be radiation from an accretion disk around the black hole. "Gas in front of it gets shocked because of this supersonic, very high-velocity impact of the black hole moving through the gas. How it works exactly is not really known," said van Dokkum.

"This is pure serendipity that we stumbled across it," van Dokkum added. He was looking for globular star clusters in a nearby dwarf galaxy. "I was just scanning through the Hubble image and then I noticed that we have a little streak. I immediately thought, 'oh, a cosmic ray hitting the camera detector and causing a linear imaging artifact.' When we eliminated cosmic rays we realized it was still there. It didn't look like anything we've seen before."

Because it was so weird, van Dokkum and his team did follow-up spectroscopy with the W. M. Keck Observatories in Hawaii. He describes the star trail as "quite astonishing, very, very bright and very unusual." This led to the conclusion that he was looking at the aftermath of a black hole flying through a halo of gas surrounding the host galaxy.

This intergalactic skyrocket is likely the result of multiple collisions of supermassive black holes. Astronomers suspect the first two galaxies merged perhaps 50 million years ago. That brought together two supermassive black holes at their centers. They whirled around each other as a binary black hole.

Then another galaxy came along with its own supermassive black hole. This follows the old idiom: "two's company and three's a crowd." The three black holes mixing it up led to a chaotic and unstable configuration. One of the black holes robbed momentum from the other two black holes and got thrown out of the host galaxy. The original binary may have remained intact, or the new interloper black hole may have replaced one of the two that were in the original binary, and kicked out the previous companion.

When the single black hole took off in one direction, the binary black holes shot off in the opposite direction. There is a feature seen on the opposite side of the host galaxy that might be the runaway binary black hole. Circumstantial evidence for this is that there is no sign of an active black hole remaining at the galaxy's core. The next step is to do follow-up observations with NASA's James Webb Space Telescope and the Chandra X-ray Observatory to confirm the black hole explanation.

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Webb Space Telescope reveals previously shrouded newborn stars

Rice University astronomer Megan Reiter and colleagues took a "deep dive" into one of the first images from NASA's James Webb Space Telescope and were rewarded with the discovery of telltale signs from two dozen previously unseen young stars about 7,500 light years from Earth.

The published research in the December issue of the Monthly Notices of the Royal Astronomical Society offers a glimpse of what astronomers will find with Webb's near-infrared camera. The instrument is designed to peer through clouds of interstellar dust that have previously blocked astronomers' view of stellar nurseries, especially those that produce stars similar to Earth's sun.

Reiter, an assistant professor of physics and astronomy, and co-authors from the California Institute of Technology, the University of Arizona, Queen Mary University in London and the United Kingdom's Royal Observatory in Edinburgh, Scotland, analyzed a portion of Webb's first images of the Cosmic Cliffs, a star-forming region in a cluster of stars known as NGC 3324.

"What Webb gives us is a snapshot in time to see just how much star formation is going on in what may be a more typical corner of the universe that we haven't been able to see before," said Reiter, who led the study.

Located in the southern constellation Carina, NGC 3324 hosts several well-known regions of star formation that astronomers have studied for decades. Many details from the region have been obscured by dust in images from the Hubble Space Telescope and other observatories. Webb's infrared camera was built to see through dust in such regions and to detect jets of gas and dust that spew from the poles of very young stars.

Reiter and colleagues focused their attention on a portion of NGC 3324 where only a few young stars had previously been found. By analyzing a specific infrared wavelength, 4.7 microns, they discovered two dozen previously unknown outflows of molecular hydrogen from young stars. The outflows range in size, but many appear to come from protostars that will eventually become low-mass stars like Earth's sun.

"The findings speak both to how good the telescope is and to how much there is going on in even quiet corners of the universe," Reiter said.

Within their first 10,000 years, newborn stars gather material from the gas and dust around them. Most young stars eject a fraction of that material back into space via jets that stream out in opposite directions from their poles. Dust and gas pile up in front of the jets, which clear paths through nebular clouds like snowplows. One vital ingredient for baby stars, molecular hydrogen, gets swept up by these jets and is visible in Webb's infrared images.

"Jets like these are signposts for the most exciting part of the star formation process," said study co-author Nathan Smith of the University of Arizona. "We only see them during a brief window of time when the protostar is actively accreting."

The accretion period of early star formation has been especially difficult for astronomers to study because it is fleeting -- usually just a few thousand years in the earliest portion of a star's multimillion-year childhood.

Study co-author Jon Morse of the California Institute of Technology said jets like those discovered in the study "are only visible when you embark on that deep dive -- dissecting data from each of the different filters and analyzing each area alone.

"It's like finding buried treasure," Morse said.

Reiter said the size of the Webb telescope also played a role in the discovery.

"It's just a huge light bucket," Reiter said. "That lets us see smaller things that we might have missed with a smaller telescope. And it also gives us really good angular resolution. So we get a level of sharpness that allows us to see relatively small features, even in faraway regions."

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