Tag: Sagittarius A*

Stunning James Webb image shows the heart of our Milky Way | Digital Trends

tech FranklinWilbur

Stunning James Webb image shows the heart of our Milky Way | Digital Trends

A new image from the James Webb Space Telescope shows the heart of our galaxy, in a region close to the supermassive black hole at the center of the Milky Way, Sagittarius A*. The image shows a star-forming region where filaments of dust and gas are clumping together to give birth to new baby stars.

The image was captured using Webb’s NIRCam instrument, a camera that looks in the near-infrared portion of the electromagnetic spectrum with shorter wavelengths shown in blue and cyan and longer wavelengths shown in yellow and red.

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 center. An estimated 500,000 stars shine in this image of the Sagittarius C (Sgr C) region, along with some as-yet-unidentified features. NASA, ESA, CSA, STScI, S. Crowe (UVA)

This region is called Sagittarius C, and is located around 300 light-years away from the supermassive black hole Sagittarius A*. For reference, Earth is located much further away from the galactic center, at a distance of around 26,000 light years from Sagittarius A*.

There are thought to be as many as 500,000 stars in the Sagittarius C region, including many young protostars, some of which will go on to become main-sequence stars like our sun. As stars form, they give off powerful stellar winds which blow away nearby material and prevent more stars from forming very close to them.

These outflows are illuminated in the infrared wavelength, and the cyan-colored patches in the image are created by ionized gas. The young stars give off a great deal of energy, which ionizes the hydrogen gas around them and makes them glow in the infrared.

However, there are actually even more stars in this area than can be seen in the image. The pockets of darkness scattered throughout the image aren’t blank but are dense clouds that are dark in the infrared, including a large dense area in the heart of the region.

There are still some surprises to be found in the image too, with some features that scientists need to study in more depth. “Researchers say they have only begun to dig into the wealth of unprecedented high-resolution data that Webb has provided on this region, and many features bear detailed study,” Webb scientists write. “This includes the rose-colored clouds on the right side of the image, which have never been seen in such detail.”

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X-Ray telescope spots black hole slowly devouring a star

tech FranklinWilbur

X-Ray telescope spots black hole slowly devouring a star

On June 22, 2022, NASA’s Swift Observatory spotted something curious in a galaxy over 500 million light-years away. It was a routine outburst of gas that a team studying the data now believes is evidence of a black hole intermittently gobbling up a star each time the latter draws near.

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The black hole and its star are collectively named Swift J023017.0+283603, or Swift J0230. The two sit in a galaxy called 2MASX J02301709+2836050, in a constellation Triangulum. Swift J0230 was observed by—you guessed it—the Swift Observatory, which launched in 2004, thanks to a new way of analyzing the telescope’s X-ray data. Analysis of the dynamic duo—an admittedly imbalanced one—was published yesterday in Nature Astronomy.

“Swift’s hardware, software, and the skills of its international team have enabled it to adapt to new areas of astrophysics over its lifetime,” said Phil Evans, an astrophysicist at the University of Leicester in the United Kingdom and a member of the Swift team, in a NASA release. “Neil Gehrels, the mission’s namesake, oversaw and encouraged many of those transitions. Now, with this new ability, it’s doing even more cool science.”

Despite their stoic countenance in films and images, black holes are hardly inert. They are some of the densest objects in the universe, and the environments surrounding them are extremely energetic. Black holes accrete matter around them in disks and gorge themselves on the superheated material that falls into their event horizons, the region beyond which not even light can escape them.

Black Hole Snack Attack

When a star becomes gravitationally ensnared by a black hole, the black hole leeches material off the star every time it comes near. The black hole feeds over time, in what’s known as a repeating tidal disruption event. Swift J0230 appears to be such an event, though it’s hardly the first; another recently observed repeating tidal disruption was observed in the object ASASSN-14ko back in 2021. Stars unfortunate enough to get caught in a black hole’s orbit but too far to be quickly devoured get locked into a death spiral with the more massive object.

In Swift J0230’s case, a black hole over 200,000 times the mass of the Sun is prying off three Earth masses’ worth of the star each time the latter object swings past. But it may not be the end of the star; previously, astronomers have seen black holes upchucking stellar material they consumed years earlier.

More work needs to be done to distinguish tidal disruption events from the reinvigoration of active galactic nuclei, or AGNs, which are supermassive black holes at the cores of galaxies that emit massive jets of material in energetic outbursts. From a distance, the demise of an unfortunate star can look a lot like a black hole waking up after a long slumber.

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Astronomers surprised by a distant black hole roaring back to life

tech FranklinWilbur

Astronomers surprised by a distant black hole roaring back to life

Black holes often sit at the centers of galaxies, where they can gorge themselves on the superheated material that falls into their abyssal event horizons. Now, a team of astronomers have observed the beginning of one such meal.

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The feast was found in a galaxy a staggering 10 billion light-years from Earth. The meal itself—or what the astronomers think is a black hole’s meal—is a luminous transient, meaning an object that changes in brightness quickly. It was first discovered in 2019 and is called J221951-484240 (J221951 for short.)

To date, the event has been observed by the Swift Observatory, the Hubble Space Telescope, the South African Large Telescope, and ESO observatories including the Very Large Telescope.

The astronomers studying the object believe it was caused by one of two events; either a star passed too close to the black hole, and the latter ripped material away from the former, or a dormant black hole at the center of its galaxy suddenly began feeding. The team’s research is set to publish in the Monthly Notices of the Royal Astronomical Society and is currently hosted on the preprint server arXiv.

“J221951 is one of the most extreme examples yet of a black hole taking us by surprise,” said Matt Nicholl, an astronomer at Queen’s University Belfast and a co-author of the research, in an Royal Astronomical Society release. “Continued monitoring of J221951 to work out the total energy release might allow us to work out whether this is a tidal disruption of a star by a fast-spinning black hole, or a new kind of AGN switch on.”

AGN, an acronym for active galactic nuclei, have jet- and wind-emitting supermassive black holes at their cores. An ultraviolet spectrum of the object suggested to the research team that material was pushed outwards by some energetic outburst. A black hole suddenly deciding to feed could effectively “switch on” a galactic nucleus, and may be the situation at play in J221951.

Tidal disruption events occur when a star passes close—too close—to a black hole, causing it to yield at least some of its material to the abyss. But often, the black hole’s intense gravity pulls the entire star apart, an event called spaghettification.

Once spaghettified, the stellar material tends to orbit the black hole, rather than being swept immediately into the inky black. The orbiting stellar material heats up, allowing astronomers to detect the event. Last year, astronomers even found a black hole that did the cosmic equivalent of chundering when it puked up stellar material that it consumed at least three years earlier.

“In the future we will be able to obtain important clues that help distinguish between the tidal disruption event and active galactic nuclei scenarios,” said Samantha Oates, an astronomer at the University of Birmingham and the new study’s lead author, in the same release. “For instance, if J221951 is associated with an AGN turning on we may expect it to stop fading and to increase again in brightness, while if J221951 is a tidal disruption event we would expect it to continue to fade.”

“We will need to continue to monitor J221951 over the next few months to years to capture its late-time behavior,” Oates added.

Black holes only have a vacant demeanor if you peer into their lightless shadows. Observing their effects on surrounding matter reveals that black holes are some of the most dynamic objects in the universe. Just this week, astronomers using the Webb Space Telescope announced the discovery of the most distant active supermassive black hole, which dates back to around 570 million years after the Big Bang.

Whether it was an unfortunate star or a hungry, hungry hole—or both!—in J221951, the truth may help astronomers understand black hole behavior, and the sort of conditions that might cause such a behemoth to suddenly decide to “eat.”

The cosmos has plenty of many mysteries strewn across space and time. With just a few telescopes and some more observations, astronomers might clarify what went down in that ancient galaxy some 10 billion light-years away.

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Astronomers See Largest Explosion in Space Yet

tech FranklinWilbur

Astronomers See Largest Explosion in Space Yet

Astronomers have seen the most energetic cosmic explosion yet, which they believe resulted from a gas cloud being disrupted by a supermassive black hole.

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The explosion (dubbed AT2021lwx) happened billions of light-years away and was first spotted in 2020. But now it’s lasted over three years, indicating the sheer amount of material involved in the event. The team’s research describing the explosion was published today in Monthly Notices of the Royal Astronomical Society.

“Once you know the distance to the object and how bright it appears to us, you can calculate the brightness of the object at its source,” said Sebastian Hönig, an astronomer at the University of Southampton and a co-author of the paper, in a university release. “Once we’d performed those calculations, we realized this is extremely bright.”

The gargantuan explosion dwarfs that of the BOAT (or the Brightest of All Time), a gamma-ray burst spotted last year. The BOAT is still the brightest-known explosion, but it was fleeting compared to the multi-year outburst of AT2021lwx.

The explosion is as bright as a quasar—an active galactic nucleus with a supermassive black hole at its core, which appears very bright in the sky. But unlike a quasar, AT2021lwx only recently appeared in the sky. The team believes the event was caused by the interactions between a cloud and a supermassive black hole.

Black holes are the densest objects in the universe. Their gravitational pull is so immense that not even light can escape their event horizons. Once merely the realm of theory (the enigmatic objects were first predicted by Einstein), black hole shadows have since been imaged by massive radio telescopes, clueing researchers in to details of their extreme physics.

The recent astronomical team thinks the explosion was caused by wayward gas (or dust) from a cloud orbiting the black hole, which fell into the superdense object. From our perspective, the material is still falling into the black hole, but the explosion happened nearly 8 billion years ago.

“With new facilities, like the Vera Rubin Observatory’s Legacy Survey of Space and Time, coming online in the next few years, we are hoping to discover more events like this and learn more about them,” said Philip Wiseman, also an astronomer at the University of Southampton and the paper’s lead author, in the same release. “It could be that these events, although extremely rare, are so energetic that they are key processes to how the centers of galaxies change over time.”

The Legacy Survey of Space and Time will make use of the world’s largest digital camera to image the night sky every 15 seconds, giving astronomers around the world a newly dynamic view of a constantly changing universe.

The team plans to collect X-ray data on the explosion, among other wavelengths of light, to better understand the origins of the gargantuan blast.

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