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Across the Universe - Space Station View of Sun Over Earth From Space
Space Station View of Sun Over Earth From Space:
Thursday, June 14, 2018
Across The Universe- The Clash of NGC 3256
The Clash of NGC 3256:
Marked by an unusually bright central region, swirling dust lanes,
and far flung tidal tails, peculiar NGC 3256 is the aftermath of a
truly
cosmic collision.
The 500 million year old clash of two separate galaxies spans
some 100 thousand light-years in
this
sharp Hubble view.
Of course when two galaxies collide, individual stars rarely do.
Giant galactic clouds of
molecular gas
and dust do interact though, and produce spectacular bursts of
star formation.
In this
galaxy clash,
the two original spiral galaxies had similar masses.
Their disks are no longer distinct and the two galactic nuclei
are hidden by obscuring dust.
On the timescale of a few hundred million years the nuclei
will likely also merge
as
NGC 3256 becomes a single large elliptical galaxy.
NGC 3256 itself is nearly 100 million light-years distant toward
the southern sailing constellation Vela.
The frame includes many even more distant background galaxies and
spiky foreground stars.
Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.
2018 June 7
Explanation: Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.
2018 June 7
Marked by an unusually bright central region, swirling dust lanes,
and far flung tidal tails, peculiar NGC 3256 is the aftermath of a
truly
cosmic collision.
The 500 million year old clash of two separate galaxies spans
some 100 thousand light-years in
this
sharp Hubble view.
Of course when two galaxies collide, individual stars rarely do.
Giant galactic clouds of
molecular gas
and dust do interact though, and produce spectacular bursts of
star formation.
In this
galaxy clash,
the two original spiral galaxies had similar masses.
Their disks are no longer distinct and the two galactic nuclei
are hidden by obscuring dust.
On the timescale of a few hundred million years the nuclei
will likely also merge
as
NGC 3256 becomes a single large elliptical galaxy.
NGC 3256 itself is nearly 100 million light-years distant toward
the southern sailing constellation Vela.
The frame includes many even more distant background galaxies and
spiky foreground stars.
Across The Universe- The Cats Eye Nebula from Hubble
The Cats Eye Nebula from Hubble:
Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.
2018 June 10
The Cat's Eye Nebula from Hubble
Image Credit:
NASA,
ESA,
HEIC, and
The Hubble Heritage Team
(STScI/AURA)
Explanation:
To some, it may look like a cat's eye.
The
alluring Cat's Eye
nebula, however, lies three thousand light-years from Earth across interstellar space.
A classic
planetary
nebula, the Cat's Eye (NGC 6543) represents a final, brief
yet
glorious phase in the life of a sun-like star.
This nebula's dying central star may have produced the simple,
outer pattern of dusty
concentric shells
by shrugging off
outer
layers in a series of regular convulsions.
But the formation of the beautiful, more complex
inner structures is not well understood.
Seen so clearly in
this digitally sharpened Hubble Space Telescope image,
the truly cosmic eye is over half a
light-year across.
Of course,
gazing into this Cat's Eye,
astronomers may well be seeing
the fate of our sun, destined to enter its own
planetary nebula
phase of evolution ... in about 5 billion years.
Tomorrow's picture: a long time ago
<
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Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman
Specific rights apply.
NASA Web
Privacy Policy and Important Notices
A service of:
ASD at
NASA /
GSFC
& Michigan Tech. U.
Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.
2018 June 10
The Cat's Eye Nebula from Hubble
Image Credit:
NASA,
ESA,
HEIC, and
The Hubble Heritage Team
(STScI/AURA)
Explanation:
To some, it may look like a cat's eye.
The
alluring Cat's Eye
nebula, however, lies three thousand light-years from Earth across interstellar space.
A classic
planetary
nebula, the Cat's Eye (NGC 6543) represents a final, brief
yet
glorious phase in the life of a sun-like star.
This nebula's dying central star may have produced the simple,
outer pattern of dusty
concentric shells
by shrugging off
outer
layers in a series of regular convulsions.
But the formation of the beautiful, more complex
inner structures is not well understood.
Seen so clearly in
this digitally sharpened Hubble Space Telescope image,
the truly cosmic eye is over half a
light-year across.
Of course,
gazing into this Cat's Eye,
astronomers may well be seeing
the fate of our sun, destined to enter its own
planetary nebula
phase of evolution ... in about 5 billion years.
Tomorrow's picture: a long time ago
<
| Archive
| Submissions
| Index
| Search
| Calendar
| RSS
| Education
| About APOD
| Discuss
| >
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman
Specific rights apply.
NASA Web
Privacy Policy and Important Notices
A service of:
ASD at
NASA /
GSFC
& Michigan Tech. U.
Across The Universe- Okay, Last Year’s Kilonova Did Probably Create a Black Hole
Okay, Last Year’s Kilonova Did Probably Create a Black Hole:
In August of 2017, another major breakthrough occurred when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected waves that were believed to be caused by a neutron star merger. Shortly thereafter, scientists at LIGO, Advanced Virgo, and the Fermi Gamma-ray Space Telescope were able to determine where in the sky this event (known as a kilonova) occurred.
This source, known as GW170817/GRB, has been the target of many follow-up surveys since it was believed that the merge could have led to the formation of a black hole. According to a new study by a team that analyzed data from NASA’s Chandra X-ray Observatory since the event, scientists can now say with greater confidence that the merger created a new black hole in our galaxy.
The study, titled “GW170817 Most Likely Made a Black Hole“, recently appeared in The Astrophysical Journal Letters. The study was led by David Pooley, an assistant professor in physics and astronomy at Trinity University, San Antonio, and included members from the University of Texas at Austin, the University of California, Berkeley, and Nazarbayev University’s Energetic Cosmos Laboratory in Kazakhstan.
Illustration of the kilonova merger (top), and the resulting object (left and right) over time. Credit: NASA/CXC/Trinity University/D. Pooley et al. Illustration: NASA/CXC/M.WeissFor the sake of their study, the team analyzed X-ray data from Chandra taken in the days, weeks, and months after the detection of gravitational waves by LIGO and gamma rays by NASA’s Fermi mission. While nearly every telescope in the world had observed the source, X-ray data was critical to understanding what happened after the two neutron stars collided.
While a Chandra observation two to three days after the event failed to detect an X-ray source, subsequent observations taken 9, 15, and 16 days after the event resulted in detections. The source disappeared for a time as GW170817 passed behind the Sun, but additional observations were made about 110 and 160 days after the event, both of which showed significant brightening.
While the LIGO data provided astronomers with a good estimate of the resulting object’s mass after the neutron stars merged (2.7 Solar Masses), this was not enough to determine what it had become. Essentially, this amount of mass meant that it was either the most massive neutron star ever found or the lowest-mass black hole ever found (the previous record holders being four or five Solar Masses). As Dave Pooley explained in a NASA/Chandra press release:
By comparing the Chandra observations with those by the NSF’s Karl G. Jansky Very Large Array (VLA), Pooley and his team were also able to deduce that the X-ray emission were due entirely to the shock wave caused by the merger smashing into surrounding gas. In short, there was no sign of X-rays resulting from a neutron star.
This strongly implies that the resulting object was in fact a black hole. If confirmed, these results would indicate that the formation process of a blackhole can sometimes be complicated. Essentially, GW170817 would have been the result of two stars undergoing a supernova explosion that left behind two neutron stars in a sufficiently tight orbit that they eventually came together. As Pawan Kumar explained:
If the remnant turns out to be a massive neutron star with a strong magnetic field after all, then the source should get much brighter in the X-ray and radio wavelengths in the coming years as the high-energy bubble catches up with the decelerating shock wave. As the shock wave weakens, astronomers expect that it will continue to become fainter than it was when recently observed.
Regardless, future observations of GW170817 are bound to provide a wealth of information, according to J. Craig Wheeler, a co-author on the study also from the University of Texas. “GW170817 is the astronomical event that keeps on giving,” he said. “We are learning so much about the astrophysics of the densest known objects from this one event.”
If these follow-up observations find that a heavy neutron star is what resulted from the merger, this discovery would challenge theories about the structure of neutron stars and how massive they can get. On the other hand, if they find that it formed a tiny black hole, then it will challenge astronomers notions about the lower mass limits of black holes. For astrophysicists, it’s basically a win-win scenario.
As co-author Bruce Grossan of the University of California at Berkeley added:
Further Reading: Chandra, The Astrophysical Journal Letters
The post Okay, Last Year’s Kilonova Did Probably Create a Black Hole appeared first on Universe Today.
In August of 2017, another major breakthrough occurred when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected waves that were believed to be caused by a neutron star merger. Shortly thereafter, scientists at LIGO, Advanced Virgo, and the Fermi Gamma-ray Space Telescope were able to determine where in the sky this event (known as a kilonova) occurred.
This source, known as GW170817/GRB, has been the target of many follow-up surveys since it was believed that the merge could have led to the formation of a black hole. According to a new study by a team that analyzed data from NASA’s Chandra X-ray Observatory since the event, scientists can now say with greater confidence that the merger created a new black hole in our galaxy.
The study, titled “GW170817 Most Likely Made a Black Hole“, recently appeared in The Astrophysical Journal Letters. The study was led by David Pooley, an assistant professor in physics and astronomy at Trinity University, San Antonio, and included members from the University of Texas at Austin, the University of California, Berkeley, and Nazarbayev University’s Energetic Cosmos Laboratory in Kazakhstan.
Illustration of the kilonova merger (top), and the resulting object (left and right) over time. Credit: NASA/CXC/Trinity University/D. Pooley et al. Illustration: NASA/CXC/M.Weiss
While a Chandra observation two to three days after the event failed to detect an X-ray source, subsequent observations taken 9, 15, and 16 days after the event resulted in detections. The source disappeared for a time as GW170817 passed behind the Sun, but additional observations were made about 110 and 160 days after the event, both of which showed significant brightening.
While the LIGO data provided astronomers with a good estimate of the resulting object’s mass after the neutron stars merged (2.7 Solar Masses), this was not enough to determine what it had become. Essentially, this amount of mass meant that it was either the most massive neutron star ever found or the lowest-mass black hole ever found (the previous record holders being four or five Solar Masses). As Dave Pooley explained in a NASA/Chandra press release:
“While neutron stars and black holes are mysterious, we have studied many of them throughout the Universe using telescopes like Chandra. That means we have both data and theories on how we expect such objects to behave in X-rays.”If the neutron stars merged to form a heavier neutron star, then astronomers would expect it to spin rapidly and generate and very strong magnetic field. This would have also created an expanded bubble of high-energy particles that would result in bright X-ray emissions. However, the Chandra data revealed X-ray emissions that were several hundred times lower than expected from a massive, rapidly-spinning neutron star.
By comparing the Chandra observations with those by the NSF’s Karl G. Jansky Very Large Array (VLA), Pooley and his team were also able to deduce that the X-ray emission were due entirely to the shock wave caused by the merger smashing into surrounding gas. In short, there was no sign of X-rays resulting from a neutron star.
This strongly implies that the resulting object was in fact a black hole. If confirmed, these results would indicate that the formation process of a blackhole can sometimes be complicated. Essentially, GW170817 would have been the result of two stars undergoing a supernova explosion that left behind two neutron stars in a sufficiently tight orbit that they eventually came together. As Pawan Kumar explained:
“We may have answered one of the most basic questions about this dazzling event: what did it make? Astronomers have long suspected that neutron star mergers would form a black hole and produce bursts of radiation, but we lacked a strong case for it until now.”Looking ahead, the claims put forward by Pooley and his colleagues could be tested by future X-ray and radio observations. Next-generation instruments – like the Square Kilometer Array (SKA) currently under construction in South Africa and Australia, and the ESA’s Advanced Telescope for High-ENergy Astrophysics (Athena+) – would be especially helpful in this regard.
If the remnant turns out to be a massive neutron star with a strong magnetic field after all, then the source should get much brighter in the X-ray and radio wavelengths in the coming years as the high-energy bubble catches up with the decelerating shock wave. As the shock wave weakens, astronomers expect that it will continue to become fainter than it was when recently observed.
Regardless, future observations of GW170817 are bound to provide a wealth of information, according to J. Craig Wheeler, a co-author on the study also from the University of Texas. “GW170817 is the astronomical event that keeps on giving,” he said. “We are learning so much about the astrophysics of the densest known objects from this one event.”
If these follow-up observations find that a heavy neutron star is what resulted from the merger, this discovery would challenge theories about the structure of neutron stars and how massive they can get. On the other hand, if they find that it formed a tiny black hole, then it will challenge astronomers notions about the lower mass limits of black holes. For astrophysicists, it’s basically a win-win scenario.
As co-author Bruce Grossan of the University of California at Berkeley added:
“At the beginning of my career, astronomers could only observe neutron stars and black holes in our own galaxy, and now we are observing these exotic stars across the cosmos. What an exciting time to be alive, to see instruments like LIGO and Chandra showing us so many thrilling things nature has to offer.”Indeed, looking farther out into the cosmos and deeper back in time has revealed much about the Universe that was previously unknown. And with improved instruments being developed for the sole purpose of studying astronomical phenomena in greater detail and at even greater distances, there seems to be no limit to what we might learn. And be sure to check out this video of the GW170817 merger, courtesy of the Chandra X-ray Observatory:
Further Reading: Chandra, The Astrophysical Journal Letters
The post Okay, Last Year’s Kilonova Did Probably Create a Black Hole appeared first on Universe Today.
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