A Lonely, Wandering Hermit of a Galaxy

Tells astronomers a thing or two about star birth throughout the cosmos 

A mysterious hermit
Credit: NASA/ESA/STScI

Space news (astrophysics: irregular dwarf galaxies; the formation of new stars) – a lonely, undefined looking galaxy an estimated 4.2 million light-years from Earth, approximately 2.3 million light-years from Leo A –  

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The Sagittarius Dwarf Irregular Galaxy (SagDIG) is a metal-poor galaxy from the dawn of the cosmos. Almost as old as the universe, SagDIG is showing us things about the evolution of everything we see during our journey to the beginning of space and time. Spanning about 1,500 light-years, this ancient star wanderer is about 3.5 million light-years distant toward the constellation Sagittarius.

Astronomers think the chaotic, unusual looking smaller island universe seen in the Hubble Space Telescope image here hasn’t merged with any other galaxies lately. Classified as an irregular dwarf galaxy, UGC 4879 has no obvious form and lacks the magnificent whirl of a spiral galaxy or the coherence of an elliptical. Approximately 1.36 million parsecs from Earth this lonely, wandering hermit of a galaxy is showing astronomers new, interesting things about star birth in the universe

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Irregular dwarf galaxy Leo A seen here has a much more complicated formation history than astronomers first thought. The simple structure astrophysicists were expecting isn’t what we see here. Instead, Leo A shows hints of an evolution just as chaotic and unpredictable as larger island universes. 

Spectral data of UGC 4879 indicates radial velocities for different sections of the galaxy, which could indicate the presence of a stellar disk. This lonely, isolated wanderer is studied closely and intensely by astronomers because of its history of few interactions with other galaxies. This isolation makes it less complicated to piece together its history of star birth and an ideal laboratory for study. 

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Dwarf irregular galaxy NGC 1569 seen here underwent a brief starburst period about 25 million years ago. Hidden within the chaos are monstrous, gigantic supermassive stars and envelopes of gas expelled by huge stars that recently went supernova. Only 11 million light-years away in the long-necked constellation Camelopardalis and spanning 8,000 light-years, the blue, white hot young stars within are perfect for study. Credit: NASA/ESA/STScI/Hubble Heritage

Study of UGC 4879 indicates during the first 4 billion years after the beginning of the universe new stars were being born at a pretty fast rate. The next nine billion years of relative inactivity followed by a recent starburst about 1 billion years ago is a puzzle for astronomers. They continue to study this hermit of a galaxy hoping to find out more about both its history and the complex riddles of sun birth across the cosmos.  

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Irregular dwarf galaxy NGC 4449 seen here is undergoing an intense period of starburst, with young, blue-white stars being created at an amazing rate and pinkish star forming regions in this deep colour image. Only 12.5 million light-years away in Canes Venatici, the constellation of the Hunting Dogs, NGC 4449’s the first such galaxy to have an identified star stream in the lower right composed mainly of supermassive red giant stars. These types of galaxies are thought to have a significant dark matter halo, which is a chance for astronomers to study the dark side’s role in the evolution and formation of galaxies. Credit: NASA/ESA/STScI 

Read about one of the most massive black holes ever discovered residing in a backwater part of the cosmos.

For the first time in space history the first moments of a supernova caught in visible light.

Read about Chandra observing the supermassive black hole in galaxy Pictor A having a little meal.

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Read a paper on the star formation history of irregular dwarf galaxy UGC 4879 here.

 

Small Region of Sky Source of Mysterious, Energetic Blasts

Astronomers have identified source as a supermassive, unknown star cluster containing some of the most massive stars in the Milky Way 

Hidden within the region inset in the small square lie some of the rarest, most massive stars in the galaxy.
Hidden within the region inset in the small square lie some of the rarest, most massive stars in the galaxy. More than a dozen red supergiant stars. Credit: NASA/ESA/STScI

Space news (unknown X-ray and gamma-ray sources) – 2/3 of the way to the core of the Milky Way or 18,900 light-years (5,800 parsecs) from Earth toward the constellation Scutum in the Bermuda Triangle of the Milky Way – 

For years, astronomers studied a small region of the sky called the Bermuda Triangle known for mysterious, highly energetic blasts of X-rays and gamma rays looking for clues to the source. The identity of the source was finally determined around 2005 as an unknown, hefty star cluster containing some of the rarest and most massive stars in the Milky Way. More than a dozen red supergiant stars, supermassive stars that are destroyed when a star goes supernova, within a million years time.  

This color composite image compiled by the Spitzer Space Telescope highlights the colors of the cosmos. Credit: NASA/ESA/STScI
This color composite image compiled by the Spitzer Space Telescope highlights the dazzling color palette of the cosmos. Credit: NASA/ESA/STScI

Astronomers detected 14 gigantic, red supergiant stars bloated to beyond 100 times their original size hidden within a star cluster estimated to be over 20 times the average size. Their outer envelopes of hydrogen bloated to beyond bursting, these behemoth stars are destined to end their days in one of the most energetic events in the cosmos a supernova. Destined to spread the elements of creation throughout the galaxy in a titanic explosion more energetic than the output of the entire Milky Way. 

“Only the most massive clusters can have lots of red supergiants because they are the only clusters capable of making behemoth stars,” explains Don Figer led scientists for the study. “They are good signposts that allow astronomers to predict the mass of the cluster. This observation also is a rare chance to study huge stars just before they explode. Normally, we don’t get to see stars before they pop off.” 

This very colorful artist's impression of the stars within this unknown star cluster. CreditNASA/ESA/STScI
This very colorful artist’s impression of the 14 red supergiant stars within this unknown star cluster. CreditNASA/ESA/STScI

What’s next for the team?

Red supergiant stars were indeed rare during the human journey to the beginning of space and time. Only about 200 such titanic stars have been identified among the hundreds of millions detected in the Milky Way. Finding 14 of these behemoth stars relatively close to Earth is an opportunity for astronomers to study their life cycle in greater detail. An opportunity Figer and his team at the Space Telescope Science Institute (STScI) in Baltimore plan on taking full advantage of during the years ahead. 

At the same time, Figer and his team of space scientists plan on studying an additional 130 supermassive star cluster candidates from the newly found clusters compiled in the Two Micron All Sky Survey catalog. “We can only see a small part of our galaxy in visible light because a dusty veil covers most of our galaxy,” Figer said. “I know there are other massive clusters in the Milky Way that we can’t see because of the dust. My goal is to find them using infrared light, which penetrates the dusty veil.” 

“Mysterious X-ray and gamma ray source explained!” 

“Now, we search for new cosmic mysteries to unveil!”

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Read about astronomers discovering superstar binary systems like Eta Carinae are more common than first thought.

Kepler Captures Supernova Shockwave in Visible Light

Mining of Kepler space mission data reveals “supernova’s shockwave” in visible light

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Space news (massive supernovae) – 1.2 billion light-years from Earth –

An international team of scientists at the University of Notre Dame in Indiana mining three years of Kepler Space Telescope data for massive supernovae discovered something never seen during the human journey to the beginning of space and time. Buried in the Kepler data Peter Garnavich and team observed for the first time the brilliant flash of a massive supernova’s shockwave in visible light as it reached the surface of the exploding star.

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NASA scientists Peter Garnavich. Credit: NASA

“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich. “You don’t know when a supernova is going to go off, and Kepler’s vigilance allowed us to be a witness as the explosion began.”

Garnavich’s the leader of the Kepler Extragalactic Survey (KEGS) research team, which is currently mining NASA’s Kepler K2 mission data looking for massive supernovae. NASA’s repurposed planet hunter is expected to detect around a dozen more events during its mission to capture the light from hundreds of distant galaxies and trillions of stars.

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The diagram illustrates the brightness of a supernova event relative to the sun as it unfolds. For the first time, a supernova shockwave has been observed in the optical wavelength or visible light as it reaches the surface of the star. This early flash of light is called a shock breakout. 

Astronomers call the brilliant flash of a supernova’s shockwave “a shock breakout”. This event only lasts around twenty minutes in the cases observed, so catching the flash as it happens is truly a milestone for astronomers studying supernovae. By piecing together individual moments of a supernova astronomers hope to learn more about the history of chemical complexity and the evolution of life.

“All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars,” said Steve Howell, project scientist for NASA’s Kepler and K2 missions at NASA’s Ames Research Center in California’s Silicon Valley. “Life exists because of supernovae.”

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NASA scientist Steve Howell. Credit: NASA

Massive supernovae and their less energetic brothers are the seeds of chemical complexity in the cosmos, spreading the elements of creation across the breadth of the universe. Understanding the physics behind these titanic events can help tell us how these elements of creation were spread across the universe.

Kepler observes two massive supernovae

The Kepler Space Telescope observed a type II supernova shockwave in visible light as it broke the surface of the star for the first time in history as supermassive red giant KSN 2011d went supernova in 2011. Containing roughly 500 times the mass of Sol, this supermassive star at the moment the shockwave from the supernova reached its surface was 130,000,000 times brighter than the Sun. Continuing to explode and grow, the star eventually reached a maximum brightness over 1 billion times greater than Sol 14 days later.

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This artist’s conception of the repurposed Kepler K2 spacecraft. Credit. NASA/Kepler K2

The Kepler Space Telescope also observed a second type II supernova in 2011. Red super massive star KSN 2011a contains 300 times as much mass as Sol and occupies a volume of space that would easily engulf the orbit of Earth around the Sun. Only 700 million light-years from Earth, astronomers weren’t able to observe a shock breakout in the data for this supernova, but they think it might be due to gas masking the shockwave as it reached the surface of the star.

“That is the puzzle of these results,” said Garnavich. “You look at two supernovae and see two different things. That’s maximum diversity.”

“While Kepler cracked the door open on observing the development of these spectacular events, K2 will push it wide open observing dozens more supernovae,” said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at Ames. “These results are a tantalizing preamble to what’s to come from K2!”

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Drawing of Tom Barclay. Credit: Tom Barclay.com

Watch this YouTube video on this event here.

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Polar Ring Galaxy NGC 660’s a Cosmic Anomaly

A single odd galaxy in a group of around a dozen or so extremely rare, bizarre island universes 

This new Hubble image shows a peculiar galaxy known as NGC 660, located around 45 million light-years away from us. NGC 660 is classified as a "polar ring galaxy", meaning that it has a belt of gas and stars around its centre that it ripped from a near neighbour during a clash about one billion years ago. The first polar ring galaxy was observed in 1978 and only around a dozen more have been discovered since then, making them something of a cosmic rarity. Unfortunately, NGC 660’s polar ring cannot be seen in this image, but has plenty of other features that make it of interest to astronomers – its central bulge is strangely off-kilter and, perhaps more intriguingly, it is thought to harbour exceptionally large amounts of dark matter. In addition, in late 2012 astronomers observed a massive outburst emanating from NGC 660 that was around ten times as bright as a supernova explosion. This burst was thought to be caused by a massive jet shooting out of the supermassive black hole at the centre of the galaxy.
The polar ring of NGC 660 isn’t visible in this Hubble Space Telescope image, but its central bulge looks strangely tilted. Astronomers are more interested in large amounts of invisible dark matter they think could be hidden within it. Studying the formation of its polar ring during galactic interactions and mergers has provided knowledge and understanding of the shape of dark matter halos around galaxies. 

Space news (galactic interactions: rare galaxy types; polar ring galaxies) – 45 million light-years from Earth, swimming in the cosmic seas of the constellation Pisces – 

One of the most enigmatic objects discovered during the human journey to the beginning of space and time, polar ring galaxies are a cosmic anomaly. Containing a belt of gas and stars orbiting its center that it tore from another galaxy during a collision around one billion years ago, polar ring galaxies are composed of two distinct systems. One of the rarest and oddest galaxy types classified, astronomers study the formation mechanisms of polar ring galaxies in order to try to grasp more knowledge and understanding of the evolution of galaxies.  

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NGC 660 is classified as a “polar ring galaxy”, meaning that it has a belt of gas and stars around its centre that it ripped from a near neighbour during a clash about one billion years ago. The first polar ring galaxy was observed in 1978 and only around a dozen more have been discovered since then, making them something of a cosmic rarity. Credit: Gemini North Telescope

A large, elliptical galaxy about 300 million light years from Earth.
Astronomers studying dark matter halos observe galaxies like NGC 4555 because it hasn’t interacted much with other galaxies, which makes it easier to dark matter they started with. Chandra has shown this galaxy is embedded in a cloud of 10-million-degree Celcius gas (left) with a diameter of 40,000 light-years, more than twice that of NGC 4445. (left). A dark matter halo ten times the combined mass of the stars in the galaxy (right) and 300 times the mass of the gas cloud would be required to gravitationally hold it. is difficult to determine how much dark matter they originally possessed. Chandra’s observations of NGC 4555 confirms that an isolated, elliptical galaxy can possess a dark matter halo of its own.

Studying dark matter halos

The study of the formation history of unique polar-ring spiral galaxy NGC 660 has been even more useful in the detection and shape of the galaxy’s otherwise unseen dark matter halo. The only island universe of this kind detected, so far, a team of astronomers at the Paris Observatory has been studying the formation of its polar ring during interactions and mergers between galaxies. In order to gain insight into the shape of dark matter halos around the thousands of galaxies viewed during our journey. 

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Polar Ring Galaxy NGC 660 Credit: AstronomyTrek

 

The disk of NGC 660 has a flat rotation curve and a rising polar ring astronomers find intriguing and rather puzzling. Scientists are studying its flatness and haven’t reached a conclusion, but they have determined it has a massive polar ring. It does raise a few difficulties in measuring the polar ring and disk velocities since they can’t be measured at the same radius. But astronomers have observed this in previous dark matter studies using polar ring galaxies. 

NGC 660’s also of interest to astronomers because late in 2012 they observed a massive burst emanating from this polar ring galaxy. An energetic outburst estimated to be nearly ten times as bright as a supernova event, they attribute to a massive jet shooting out of the supermassive black hole believed to reside at its core. This island universe’s a one-of-a-kind galaxy astronomers study looking for clues to its unique structure and formation history. A uniqueness that both intrigues and puzzles their inquisitive natures’. 

Learn about the things astronomers have determined about polar ring galaxies here

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A Titanic Supermassive Black Hole Residing in a Galactic Backwater

Makes astronomers think they need to rethink theory on black hole formation 

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Scientists generated this computer simulation showing a supermassive black hole lurking at the center of a massive galaxy. The black sphere seen here at the core of the galaxy is its event horizon, beyond which not even light can escape the gravitational grip of this monster. A gravitational force that distorts spacetime near it and stretches and smears light from background stars as it travels past the black hole. Image credit: NASA/STSci/ESA

Space news (Black hole formation theory) – 200 million light-years from Earth in the direction of the constellation Eridanus –

Astronomers working on current black hole formation theory have detected a supermassive black hole at the center of a galaxy in a region of space and time they didn’t expect to find such a monster. A very hungry monster containing the mass of over 17 billion suns, residing in an out-of-the-way galactic backwater town.
Previously, astronomers detected titanic supermassive black holes at the center of huge, very massive galaxies in parts of space and time with a greater density of large galaxies. The very crowded Coma galaxy cluster has over 1,000 galaxies and is home to the biggest monster supermassive black hole recorded with an estimated mass of 21 billion times that of Sol.

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NGC 1600 is a massive, isolated elliptical galaxy with one of the biggest recorded monster residing at its core. A supermassive black hole estimated to contain the matter found within 17 million suns like our own. Credit: NASA, ESA, Digital Sky Survey 2

“The newly discovered supersized black hole resides in the center of a massive elliptical galaxy, NGC 1600, located in a cosmic backwater, a small grouping of 20 or so galaxies,” said lead discoverer Chung-Pei Ma, a University of California-Berkeley astronomer and head of the MASSIVE Survey, a study of the most massive galaxies and supermassive black holes in the local universe. “While finding a gigantic black hole in a massive galaxy in a crowded area of the universe is to be expected – like running across a skyscraper in Manhattan – it seemed less likely they could be found in the universe’s small towns.”
“There are quite a few galaxies the size of NGC 1600 that reside in average-size galaxy groups,” Ma said. “We estimate that these smaller groups are about 50 times more abundant than spectacular galaxy clusters like the Coma cluster. So the question now is, ‘Is this the tip of an iceberg?’ Maybe there are more monster black holes out there that don’t live in a skyscraper in Manhattan, but in a tall building somewhere in the Midwestern plains.”

Ground-based view of NGC 1600
This is an image of lonely, wandering NGC 1600 taken by ground-based telescopes. Credit: NASA/ESA/Digitized Sky Survey 2

Astrophysicists studying NGC 1600 detected a supermassive black hole at least ten times more massive than current theory predicted at its center. Scientists previously thought the more massive the central bulge of a galaxy, proportionally more massive the supermassive black hole at its center should be, but this throws a wrench in previous correlations between the mass of a supermassive black hole and its central bulge of suns.

“It appears that that relation does not work very well with extremely massive black holes; they are a larger fraction of the host galaxy’s mass,” Ma said.

What could cause this smaller galaxy in a cosmic backwater to have such a titanic supermassive black hole at its core? It could be NGC 1600 merged with another galaxy hundreds of millions of years ago when such collisions were more common in this region of spacetime. Computer simulations show the central supermassive black holes of two merging galaxies fall into the center of the recently formed galaxy and begin orbiting each other in a slowly diminishing radius. Stars and other stellar objects that fall into the core steal momentum from the twirling monsters and in the process are often flung from the center of the galaxy. This transfer of momentum causes the supermassive black holes to slowly move closer together and eventually merge to form a super monster. A super monster that continues to grow by devouring gas drawn into the center of the galaxy by collisions and gravity.

In the words of Ma, “To become this massive, the black hole would have had a very voracious phase during which it devoured lots of gas.”

Astronomers continue to watch

Is it possible constant merging of NGC 1600 with galactic neighbors is one reason it lives in a cosmic backwater, with relatively few nearby galactic neighbors? It’s the brightest galaxy in town, more than three times brighter than any member of its galactic group. This difference in brightness has rarely been observed in other galactic groups. Maybe lots of galactic mergers resulted in one of the most titanic supermassive black holes ever recorded, residing in a small, cosmic backwater town.

The super monster lurking at the center of NGC 1600 is currently sleeping, but astronomers are watching for signs of its next meal going down. While they wait, they’re working on updating current theory on the formation of black holes, using the data obtained by studying NGC 1600 and similar galaxies. Current theory that will likely need to be revamped once new data comes in during our journey to the beginning of space and time.

The tide of science may rise and fall, but it always seeks truth in the facts. 

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Learn more about NGC 1600.

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Learn more about the things astronomers learn by looking at the light from distant, young stars.

Supermassive black holes engulf any mass coming to close, and often burp after a meal.

Read about the weird light signal given off by two black holes that are destined to merge.