THE MOST!
Anybody else? Anybody? Seems like objects with the title of 'The Most' aren't so well known, are they?
Here's another:
The Most Luminous Object Ever Imaged:
Blazar 3C454.3.
Here's a paper about it: https://pos.sissa.it/063/037/pdf
Uploaded files:
Here's another paper on 3C454.3's mega outburst in 2005:
https://digital.library.unt.edu/ark:/67531/metadc893656/m1/1/
The most close (of the major galaxies):
...M31/ a.k.a. The Andromeda Galaxy.
Here's one article courtesy space.com
The Andromeda Galaxy (M31): Location, Characteristics & Images
The Andromeda galaxy, our Milky Way's closest neighbor, is the most distant object in the sky that you can see with your unaided eye — but only on a clear night from a location with a very dark sky. The galaxy is a beautiful spiral, but one fact you may not be aware of: We’re safe for a few billion years, but Andromeda is headed our way and on a collision course with the Milky Way.
Andromeda's close proximity to Earth — at only 2.5 million light-years away — makes it a convenient target to observe for extrapolations about other spiral galaxies. In recent years, scientists have done detailed studies of black holes, stars and other objects within the galaxy. This included a stunning mosaic of Andromeda galaxy images taken by the Hubble Space Telescope in 2015.
Location, location, location
The visible fuzzy patch of stars stretches about as long as the width of the full moon, and half as wide; only with significant magnification can you tell it stretches six times that length in fullness.
A spiral galaxy like the Milky Way, Andromeda contains a concentrated bulge of matter in the middle, surrounded by a disk of gas, dust, and stars and an immense halo. Though Andromeda contains approximately a trillion stars to the 250 billion in the Milky Way, our galaxy is actually more massive, because it is thought to contain more dark matter. [Andromeda Galaxy Photos: Amazing Pictures of M31]
Collision course
Andromeda and the Milky Way are heading on a collision course that will alter the structure of the two galaxies forever. The galaxies are rushing closer to one another at about 70 miles per second (112 kilometers per second). Astronomers estimate that Andromeda will collide with the Milky Way in 4 billion years, with the merger concluding 6 billion years from now. By that time, the sun will have swollen into a red giant and swallowed up the terrestrial planets, so Earth will have other things to worry about. [Milky Way Galaxy's Head-On Crash with Andromeda in Pictures (Gallery)]
Still, the fresh influx of dust should boost star formation in the new "Milkomeda" galaxy, and the Earthless sun may well leave the Milky Way for good. After a messy phase, where arms project crazily from the combined pair, the two should settle into a smooth elliptical galaxy.
Galaxy collisions are a normal part of the universe's evolution. In fact, both Andromeda and the Milky Way bear signs of having already crashed into other galaxies. Andromeda boasts a large ring of dust in its center, giving it an interesting shape. Astronomers believe this dust may have formed when it swallowed an existing galaxy.
Early observational history
In 964, the Persian astronomer Abd al-Rahman al-Sufi described the galaxy as a "small cloud" in his "Book of Fixed Stars," the first known report of our nearest neighbor. When Charles Messier labeled it M31 in 1764, he incorrectly credited the discovery of what was then called a nebula to the German astronomer, Simon Marius, who provided the first telescopic observation of the object. The first photographs of Andromeda were taken in 1887, by Isaac Roberts.
In the 1920s, the distant galaxy became part of the Great Debate between American astronomers Harlow Shapley and Heber Curtis. At the time, astronomers thought the Milky Way composed the whole universe, and the strange patches known as nebulae lay inside of them. Curtis had spotted various novae in Andromeda, and argued instead that it was a separate galaxy.
The discussion wasn't concluded until 1925, when Edwin Hubble identified a special kind of star known as a Cepheid variable — a star whose characteristics allow for precise measurements of distance — within Andromeda. Because Shapley had previously determined that the Milky Way was only 100,000 light-years across, Hubble's calculations revealed that the fuzzy patch was too far away to lie within the Milky Way.
Hubble went on to use his measurements of the Doppler shifts of the galaxies to determine that the universe was expanding. The calculated distance to Andromeda doubled in the 1940s when Walter Baade was the first to observe individual stars in the central region of the galaxy, and found two different types of Cepheid variables. Radio maps of Andromeda followed in the 1950s, after radio emissions were detected by Hanbury Brown and Cyril Hazard at Jodrell Bank Observatory.
Recent Andromeda discoveries
Our understanding of the size of the Andromeda galaxy has grown bigger in recent years. In 2015, observations from the Hubble Space Telescope found that a halo of material surrounding Andromeda is six times larger and 1,000 times more massive than what was previously measured. (At the time, astronomers said the Milky Way may have a halo as well — and perhaps the two galaxies' halos are already starting to merge.) This follows on from revised size estimates in 2005 and 2007, based on observing stars and star motions.
In 2015, scientists released the most detailed photo of Andromeda ever using a mosaic of images from the Hubble Space Telescope. The image included 7,398 exposures taken over 411 pointings of the telescope. The image revealed more than 100 million stars within the galaxy, as well as dust structures and other features. At the time, scientists said the images would help with extrapolating the structure of spiral galaxies that are even farther from Earth, making them more difficult to view in such detail.
Black hole activities within Andromeda also came under scrutiny. In late 2017, scientists unexpectedly found two supermassive black holes closely orbiting each other. At the time, the research team said these black holes were likely the "most tightly coupled" of any supermassive ones known.
A search using NASA's Chandra X-Ray Telescope yielded 26 black hole candidates in Andromeda in 2013, making this the biggest catch of such candidates ever found in another galaxy besides our own Milky Way. Another 40 black holes were tracked down in 2016 using NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which specializes in X-ray observations.
Scientists tracked down a probable pulsar — a dead star that spins rapidly — in Andromeda in 2017. The X-ray source was first cataloged by NASA's Swift satellite as object Swift J0042.6+4112, and then characterized by NuSTAR. The newer observations found that this object's spectrum of light appears similar to pulsars in the Milky Way.
Other miscellaneous discoveries in Andromeda include tracking star birth and death in infrared wavelengths in 2011; discovering gamma-ray radiation in 2017 that could be an indication of dark matter, a substance that is only known through its effects on "ordinary" matter such as galaxies; and spotting a ring of dwarf galaxies around Andromeda in 2013 — something that could also be present around the Milky Way.
Additional reporting by Elizabeth Howell, Space.com contributor
Correction: This article was updated on March 11, 2019 to include the correct estimated number of stars in the Milky Way.
Here's an image of M31, The Andromeda Galaxy- THE MOST Close Major Galaxy.
Uploaded files:
Fastest 'star' (a radio source believed to be a 'neutron star':
Uploaded files:
The most empty parts of space? Voids!
Cosmic voids are vast spaces between filaments (the largest-scale structures in the universe), which contain very few or no galaxies. Voids typically have a diameter of 10 to 100 megaparsecs; particularly large voids, defined by the absence of rich superclusters, are sometimes called supervoids. They have less than one tenth of the average density of matter abundance that is considered typical for the observable universe. They were first discovered in 1978 in a pioneering study by Stephen Gregory and Laird A. Thompson at the Kitt Peak National Observatory.[1]
Voids are believed to have been formed by baryon acoustic oscillations in the Big Bang, collapses of mass followed by implosions of the compressed baryonic matter. Starting from initially small anisotropies from quantum fluctuations in the early universe, the anisotropies grew larger in scale over time. Regions of higher density collapsed more rapidly under gravity, eventually resulting in the large-scale, foam-like structure or "cosmic web" of voids and galaxy filaments seen today. Voids located in high-density environments are smaller than voids situated in low-density spaces of the universe.[2]
Voids appear to correlate with the observed temperature of the cosmic microwave background (CMB) because of the Sachs–Wolfe effect. Colder regions correlate with voids and hotter regions correlate with filaments because of gravitational redshifting. As the Sachs–Wolfe effect is only significant if the universe is dominated by radiation or dark energy, the existence of voids is significant in providing physical evidence for dark energy.[3][4]
source: wikipedia.org
Largest explosion... EVAH!
Boom! Scientists spot the biggest known explosion in the universe
Astronomers have spotted a cosmic blast that dwarfs all others.
A gargantuan explosion tore through the heart of a distant galaxy cluster, releasing about five times more energy than the previous record holder, a new study reports.
"In some ways, this blast is similar to how the eruption of Mt. St. Helens in 1980 ripped off the top of the mountain," study lead author Simona Giacintucci, of the Naval Research Laboratory in Washington, D.C., said in a statement. "A key difference is that you could fit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster's hot gas."
Related: Our expanding universe: Age, history and other facts
The explosion occurred in the Ophiuchus cluster, which lies about 390 million light-years from Earth. Giacintucci and her colleagues think the source was a supermassive black hole in one of the cluster's constituent galaxies — specifically, jets of radiation and material spewing from the light-gobbling monster, which are powered by inflowing gas and dust.
The possibility of an incredibly powerful Ophiuchus explosion was first raised in 2016 in a study led by Norbert Werner, which examined images captured by NASA's Chandra X-ray Observatory. Werner and his colleagues reported a strangely curved edge in the cluster, which could be part of the wall of a cavity formed by a blast. And what a blast it would be: The scientists calculated that it would take about 5 times 10^54 joules of energy to create such a cavity. (For perspective, humanity's total global energy consumption each year is about 6 times 10^20 joules.)
But the 2016 study didn't establish that an explosion actually was responsible for that curved edge. Giacintucci and her colleagues just made that determination, after analyzing additional X-ray data from Chandra and Europe's XMM-Newton space telescope, as well as radio information gathered by the Murchison Widefield Array in Australia and the Giant Metrewave Radio Telescope in India.
The combined data show that the curved edge is indeed part of a cavity wall, because it borders an area rich in radio emission. That emission likely resulted when the black hole's outburst accelerated electrons to nearly the speed of light, the researchers said.
"The radio data fit inside the X-rays like a hand in a glove," study co-author Maxim Markevitch, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in the same statement. "This is the clincher that tells us an eruption of unprecedented size occurred here."
The energy released by the Ophiuchus blast is hundreds of thousands of times greater than explosions typically seen in galaxy clusters, the researchers said. And it's about five times higher than the previous record holder, an eruption in the cluster MS 0735.6+7421.
The Ophiuchus fireworks appear to be over, by the way; the radio data show no evidence for ongoing jet activity, the scientists said.
The Chandra data reveal just one region of radio emission. That's a bit odd, because black-hole jets usually go off in two different directions. It's possible that the jet-feeding gas on the other side — the one opposite the detected cavity — was less abundant and the radio emission there dissipated more quickly as a result, the researchers said.
The new study was published in the Feb. 27 issue of The Astrophysical Journal. You can read a preprint of the paper for free via arXiv.org.
Record-Breaking, Gargantuan Black Hole Eruption – Biggest Explosion Seen in the Universe
This extremely powerful eruption occurred in the Ophiuchus galaxy cluster, which is located about 390 million light-years from Earth. Galaxy clusters are the largest structures in the Universe held together by gravity, containing thousands of individual galaxies, dark matter, and hot gas. Credit: X-ray: NASA/CXC/Naval Research Lab/Giacintucci, S.; XMM:ESA/XMM; Radio: NCRA/TIFR/GMRTN; Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF
The biggest explosion seen in the universe has been found. This record-breaking, gargantuan eruption came from a black hole in a distant galaxy cluster hundreds of millions of light-years away.
“In some ways, this blast is similar to how the eruption of Mt. St. Helens in 1980 ripped off the top of the mountain,” said Simona Giacintucci of the Naval Research Laboratory in Washington, DC, and lead author of the study. “A key difference is that you could fit fifteen Milky Way galaxies in a row into the crater this eruption punched into the cluster’s hot gas.”
Astronomers made this discovery using X-ray data from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton, and radio data from the Murchison Widefield Array (MWA) in Australia and the Giant Metrewave Radio Telescope (GMRT) in India.
The unrivaled outburst was detected in the Ophiuchus galaxy cluster, which is about 390 million light-years from Earth. Galaxy clusters are the largest structures in the Universe held together by gravity, containing thousands of individual galaxies, dark matter, and hot gas.
In the center of the Ophiuchus cluster, there is a large galaxy that contains a supermassive black hole. Researchers think that the source of the gigantic eruption is this black hole.
This extremely powerful eruption occurred in the Ophiuchus galaxy cluster, which is located about 390 million light-years from Earth. Galaxy clusters are the largest structures in the Universe held together by gravity, containing thousands of individual galaxies, dark matter, and hot gas. Credit: X-ray: NASA/CXC/Naval Research Lab/Giacintucci, S.; XMM:ESA/XMM; Radio: NCRA/TIFR/GMRTN; Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF
Although black holes are famous for pulling material toward them, they often expel prodigious amounts of material and energy. This happens when matter falling toward the black hole is redirected into jets, or beams, that blast outward into space and slam into any surrounding material.
Chandra observations reported in 2016 first revealed hints of the giant explosion in the Ophiuchus galaxy cluster. Norbert Werner and colleagues reported the discovery of an unusual curved edge in the Chandra image of the cluster. They considered whether this represented part of the wall of a cavity in the hot gas created by jets from the supermassive black hole. However, they discounted this possibility, in part because a huge amount of energy would have been required for the black hole to create a cavity this large.
The latest study by Giacintucci and her colleagues show that an enormous explosion did, in fact, occur. First, they showed that the curved edge is also detected by XMM-Newton, thus confirming the Chandra observation. Their crucial advance was the use of new radio data from the MWA and data from the GMRT archives to show the curved edge is indeed part of the wall of a cavity, because it borders a region filled with radio emission. This emission is from electrons accelerated to nearly the speed of light. The acceleration likely originated from the supermassive black hole.
“The radio data fit inside the X-rays like a hand in a glove,” said co-author Maxim Markevitch of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is the clincher that tells us an eruption of unprecedented size occurred here.”
The amount of energy required to create the cavity in Ophiuchus is about five times greater than the previous record holder, MS 0735+74, and hundreds and thousands of times greater than typical clusters.
MS 0735+74 was the previous record-holder for the most powerful eruption discovered in the universe. This Chandra image shows two vast cavities — each 600,000 light years in diameter — in the hot, X-ray emitting gas that pervades the galaxy cluster MS 0735.6+7421 (MS 0735 for short). Although the cavities contain very little hot gas, they are filled with a two-sided, elongated, magnetized bubble of extremely high-energy electrons that emit radio waves. Credit: NASA/CXC/Ohio U./B.McNamara
The black hole eruption must have finished because the researchers do not see any evidence for current jets in the radio data. This shutdown can be explained by the Chandra data, which show that the densest and coolest gas seen in X-rays is currently located at a different position from the central galaxy. If this gas shifted away from the galaxy it will have deprived the black hole of fuel for its growth, turning off the jets.
This gas displacement is likely caused by “sloshing” of the gas around the middle of the cluster, like wine sloshing around in a glass. Usually the merger of two galaxy clusters triggers such sloshing, but here it could have been set off by the eruption.
One puzzle is that only one giant region of radio emission is seen, as these systems usually contain two on opposite sides of the black hole. It is possible that the gas on the other side of the cluster from the cavity is less dense so the radio emission there faded more quickly.
“As is often the case in astrophysics we really need multiwavelength observations to truly understand the physical processes at work,” said Melanie Johnston-Hollitt, a co-author from International Centre for Radio Astronomy in Australia. “Having the combined information from X-ray and radio telescopes has revealed this extraordinary source, but more data will be needed to answer the many remaining questions this object poses.”
For more on this discovery, read Biggest Explosion in the History of the Universe Detected by Astronomers.
A paper describing these results appears in the February 27th issue of The Astrophysical Journal. In addition to Giacintucci, Markevitch, and Johnston-Hollitt, the authors are Daniel Wik (University of Utah), Qian Wang (University of Utah), and Tracy Clarke (Naval Research Laboratory). The 2016 paper by Norbert Werner was published in the Monthly Notices of the Royal Astronomical Society.
References:
“Discovery of a Giant Radio Fossil in the Ophiuchus Galaxy Cluster” by S. Giacintucci, M. Markevitch, M. Johnston-Hollitt, D. R. Wik, Q. H. S. Wang and T. E. Clarke, 27 February 2020, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ab6a9d
arXiv: 2002.01291
“Deep Chandra study of the truncated cool core of the Ophiuchus cluster” by N. Werner, I. Zhuravleva, R. E. A. Canning, S. W. Allen; A. L. King; J. S. Sanders, A. Simionescu, G. B.Taylor, R. G. Morris and A. C. Fabian, 16 May 2016, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stw1171
NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science and flight operations from Cambridge and Burlington, Massachusetts.
Brightest star in observed brightness: Sirius.
Is Sirius the most luminous star?
It’s the brightest star in Earth’s sky, so spectacularly bright that you might see glints of different colors radiating from it. But is Sirius so bright because it’s an extremely powerful star?
View larger. | The three Belt stars of Orion pointing toward Sirius, the sky’s brightest star, via Tom Wildoner at Dark Side Observatory.
Look outside tonight, and you can’t miss Sirius, the brightest star in the nighttime sky. Is Sirius the most luminous star? No. To astronomers, the word luminous refers to a star’s intrinsic brightness.
Sirius, in the constellation Canis Major the Greater Dog, looks extraordinarily bright in Earth’s sky. It’s our sky’s brightest star. But its brightness stems primarily from the fact that it’s only 8.6 light-years away.
No matter where you live on Earth, just follow the three medium-bright stars in Orion’s Belt to locate Sirius.
If you’re not sure the bright star you’re seeing is Sirius, remember … Orion’s Belt always points to it.
Many people comment that they see Sirius flashing colors. It happens when you see Sirius low in the sky. The colors are just the ordinary rainbow colors in white starlight; all starlight is composed of this mixture of colors. We notice the sparkling colors of Sirius more readily, though, because Sirius is so much brighter than most stars!
The extra thickness of the Earth’s atmosphere near the horizon acts like a lens or prism, breaking up starlight into the colors of the rainbow. When you see Sirius low in the sky, you’re looking through more atmosphere than when the star is overhead.
If you watch, you’ll notice Sirius sparkling less, and appearing less colorful (more strictly white) when it appears higher in the sky.
Sirius is so bright that many notice it twinkling in different colors. Amanda Cross in England wrote: “This is Sirius twinkling different colors through the atmosphere. Images were taken deliberately out of focus, using a high ISO and low shutter speed to pick up the colors. There are 31 images taken 25 seconds apart and stacked using StarStaX.” Thank you, Amanda!
Mia asked EarthSky:
Isn’t there a brighter star than Sirius in absolute magnitude which appears dimmer because of its distance?
Yes, Mia, you’re right, of course. Many stars on the sky’s dome are intrinsically more luminous than Sirius but appear fainter because they lie farther away.
At least three stars in the constellation Canis Major are thought to be thousands of times more luminous than Sirius: Aludra, Wezen, and Omicron 2. Although the distances to these faraway stars are not known with precision, Aludra and Omicron 2 reside an estimated 3,000 light-years distant, and Wezen at about 2,000 light-years. That’s in contrast to Sirius’ distance of 8.6 light-years.
To get a better idea of a star’s true luminosity, astronomers like to list stars according to absolute magnitude. Absolute magnitude measures the brightness of the stars as if they were all an equal 32.6 light-years distant.
At 32.6 light-years away, our sun would barely be visible as a speck of light. In stark contrast, Aludra, Wezen, and Omicron 2 at 32.6 light-years away would outshine Sirius by some 100 to 200 times. At 32.6 light-years, Sirius would be about the same brightness as the Gemini star Castor (at its known distance of 52 light-years). So if all these stars were equally distant, these super-luminous stars in Canis Major – Aludra, Wezen and Omicron 2 – would be seen to shine thousands of times more brilliantly than Sirius.
Read more about stellar luminosity, the true brightnesses of stars
Sirius, from Matt Schulze in Santa Fe, New Mexico.
Bottom line: Sirius is our sky’s brightest star (although not as bright as the planets Jupiter and Venus), but not the most luminous star in the sky. In other words, it’s an ordinary star that only appears bright to us because it is relatively nearby.
source: earthsky.org
Most energetic stellar winds ever measured...
Team discovers quasar tsunamis capable of preventing stars from forming
Team discovers quasar tsunamis capable of preventing stars from forming
Using the unique capabilities of NASA's Hubble Space Telescope, a team of astronomers led by Virginia Tech's Nahum Arav has discovered the most energetic outflows ever witnessed in the universe.
The outflows emanate from quasars and tear across interstellar space similar to tsunamis on Earth, wreaking havoc on the galaxies in which the quasars reside. Quasars are the brilliant, compact cores of distant galaxies that can shine 1,000 times brighter than their host galaxies of hundreds of millions of stars. Their central engines are supermassive black holes that are engorged with infalling dust, gas, and stars, said Arav, a professor in the Department of Physics, part of the Virginia Tech College of Science.
Quasars are created when a black hole devours matter, thus emitting intense radiation. Driven by the blistering radiation pressure from the black hole, concussive blasts push material away from the galaxy's center into outflows that accelerate to breathtaking velocities that are a few percent of the speed of light, Arav said.
"These outflows are crucial for the understanding of galaxies' formation," Arav said. "They are pushing hundreds of solar masses of material each year. The amount of mechanical energy that these outflows carry is up to several hundreds of times higher than the luminosity of the entire Milky Way galaxy."
The findings appear in the March issue of Astrophysical Journal Supplements. Arav's research team includes post-doctorate researcher Timothy Miller and doctoral student Xinfeng Xu, both from Virginia Tech, as well as Gerard Kriss and Rachel Plesha of the Space Telescope Science Institute in Baltimore, Maryland.
The quasar winds disseminate across the galaxy's disc, violently sweeping material that otherwise would have formed new stars. Radiation pushes the gas and dust for far greater distances than scientists previously thought, creating a galaxy-wide event, according to the study.
As this cosmic tsunami slams into interstellar material, its temperature spikes to billions of degrees, where material glows largely in X-rays, but also widely across the light spectrum. Anyone witnessing this event would see a fantastic show of fireworks. "You'll get lots of radiation first in X-rays and gamma rays, and afterwards it will percolate to visible and infrared light," Arav said. "You'd get a huge light show, like Christmas trees all over the galaxy."
Numerical simulation of galaxy evolution suggest that such outflows can explain some important cosmological puzzles, such as why astronomers observe so few large galaxies in the universe and why there is a relationship between the mass of the galaxy and the mass of its central black hole. This study show that such powerful quasar outflows should be prevalent in the early universe.
"Both theoreticians and observers have known for decades that there is some physical process that shuts off star formation in massive galaxies, but the nature of that process has been a mystery. Putting the observed outflows into our simulations solves these outstanding problems in galactic evolution," said Jeremiah P. Ostriker, an eminent cosmologist at Columbia and Princeton universities. (Ostriker was not involved with this study.)
Aside from measuring the most energetic quasars ever observed, the team also discovered another outflow accelerating faster than any other. The outflow increased from nearly 43 million miles per hour to roughly 46 million miles per hour in a three-year period. The scientists believe its acceleration will continue to increase as time passes.
"There were so many discoveries in the data that I felt like a kid in a candy store," Miller added.
Astronomers were able to clock the breakneck speed of gas being accelerated by the quasar wind by looking at spectral "fingerprints" of light from the glowing gas. The Hubble ultraviolet data shows that these absorption features were shifted in the spectrum because of the fast motion of the gas across space. This is due to the Doppler effect, where the motion of an object compresses or stretches wavelengths of light depending on whether it is approaching or receding from us. Only Hubble has the ultraviolet sensitivity to obtain the necessary observations leading to this discovery, according to NASA.
More information: Nahum Arav et al. HST/COS Observations of Quasar Outflows in the 500–1050 Å Rest Frame. I. The Most Energetic Outflows in the Universe and Other Discoveries, The Astrophysical Journal Supplement Series (2020). DOI: 10.3847/1538-4365/ab66af
