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Mars Base

For the first time, astronomers have measured the radius of a black hole - 0 views

phys.org/...onomers-radius-black-hole.html

scibyte65 black holes

shared by Mars Base on 30 Sep 12 - No Cached
  • an international team
  • , has for the first time measured the radius of a black hole at the center of a distant galaxy—the closest distance at which matter can approach before being irretrievably pulled into the black hole.
  • scientists linked together radio dishes in Hawaii, Arizona and California to create a telescope array called the "Event Horizon Telescope" (EHT) that can see details 2,000 times finer than what's visible to the Hubble Space Telescope.
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  • , the team observed the glow of matter near the edge of this black hole—a region known as the "event horizon."
  • , not everything can cross the event horizon to squeeze into a black hole
  • "cosmic traffic jam" in which gas and dust build up, creating a flat pancake of matter known as an accretion disk
  • disk of matter orbits the black hole at nearly the speed of light, feeding the black hole a steady diet of superheated material
  • Over time, this disk can cause the black hole to spin in the same direction as the orbiting material
  • Caught up in this spiraling flow are magnetic fields, which accelerate hot material along powerful beams above the accretion disk
  • resulting high-speed jet, launched by the black hole and the disk, shoots out across the galaxy, extending for hundreds of thousands of light-years
  • jets can influence many galactic processes, including how fast stars form.
  • . Because M87's jet is magnetically launched from this smallest orbit,
  • astronomers can estimate the black hole's spin through careful measurement of the jet's size as it leaves the black hole
  • Until now, no telescope has had the magnifying power required for this kind of observation
  • team used a technique called Very Long Baseline Interferometry, or VLBI, which links data from radio dishes located thousands of miles apart.
  • , taken together, create a "virtual telescope" with the resolving power of a single telescope as big as the space between the disparate dishes
  • enables scientists to view extremely precise details in faraway galaxies.
  • Using the technique
  • team measured the innermost orbit of the accretion disk to be only 5.5 times the size of the black hole event horizon
  • According to the laws of physics, this size suggests that the accretion disk is spinning in the same direction as the black hole
  • first direct observation to confirm theories of how black holes power jets from the centers of galaxies
  • The team plans to expand its telescope array, adding radio dishes in Chile, Europe, Mexico, Greenland and Antarctica, in order to obtain even more detailed pictures of black holes in the future.
  • www.eventhorizontelescope.org/
Mars Base

Astronomers Watch as a Black Hole Eats a Rogue Planet - 0 views

www.universetoday.com/...black-hole-eats-a-rogue-planet

scibyte89 BlackHole

shared by Mars Base on 03 Apr 13 - No Cached
  • Astronomers using the Integral space observatory were able to watch as the planet was eaten by a black hole that had been inactive for decades
  • The observation was
  • from a galaxy that has been quiet for at least 20–30 years
  • ...14 more annotations...
  • the event is a preview of a similar feeding event that is expected to take place with the black hole at the center of our own Milky Way Galaxy
  • galaxy NGC 4845, 47 million light-years away
  • Astronomers were using Integral to study a different galaxy when they noticed a bright X-ray flare coming from another location in the same wide field-of-view
  • the origin was confirmed as NGC 4845, a galaxy never before detected at high energies
  • the emission was traced from its maximum in January 2011, when the galaxy brightened by a factor of a thousand, and then as it subsided over the course of the year
  • By analyzing the characteristics of the flare, the astronomers could determine that the emission came from a halo of material around the galaxy’s central black hole as it tore apart and fed on an object of 14–30 Jupiter masses, and so the astronomers say the object was either a super-Jupiter or a brown dwarf
  • This object appears to have been ‘wandering,’ which would fit the description of recent studies
  • The black hole in the center of NGC 4845 is estimated to have a mass of around 300,000 times that of our own Sun
  • This is the first time where we have seen the disruption of a substellar object by a black hole
  • estimate that only its external layers were eaten by the black hole, amounting to about 10% of the object’s total mass, and that a denser core has been left orbiting the black hole
  • The flaring event in NGC 4845 might be similar to what is expected to happen with the supermassive black hole at the center of our own Milky Way Galaxy
  • these events will tell astronomers more about what happens to the demise of different types of objects as they encounter black holes of varying sizes
  • Estimates are that events like these may be detectable every few years in galaxies around us
  • the emission brightened and decayed shows there was a delay of 2–3 months between the object being disrupted and the heating of the debris in the vicinity of the black hole.
Mars Base

Early Black Holes were Grazers Rather than Glutonous Eaters - 0 views

www.universetoday.com/...s-rather-than-glutonous-eaters

scibyte52 black holes

shared by Mars Base on 21 Jun 12 - No Cached
  • Black holes powering distant quasars in the early Universe grazed on patches of gas or passing galaxies rather than glutting themselves in dramatic collisions according to new observations from NASA’s Spitzer and Hubble space telescopes
  • A black hole doesn’t need much gas to satisfy its hunger and turn into a quasar
  • Quasars are distant and brilliant galactic powerhouses. These far-off objects are powered by black holes that glut themselves on captured material; this in turn heats the matter to millions of degrees making it super luminous
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  • team studied 30 quasars with NASA’s orbiting telescopes Hubble and Spitzer
  • These quasars, glowing extremely bright in the infrared images
  • telltale sign that resident black holes are actively scooping up gas and dust into their gravitational whirlpool
  • formed during a time of peak black-hole growth between eight and twelve billion years
  • supports evidence that the creation of the most massive black holes in the early Universe was fueled not by dramatic bursts of major mergers but by smaller, long-term events
  • found 26 of the host galaxies
  • about the size of our own Milky Way Galaxy, showed no signs of collisions
  • Quasars that are products of galaxy collisions are very bright
  • the process powering the quasars and their black holes lies below the detection of Hubble
  • prime targets for the upcoming James Webb Space Telescope, a large infrared orbiting observatory scheduled for launch in 2018
Mars Base

Supermassive Black Hole Swallows Star | Hungry Black Holes | Space.com - 0 views

www.space.com/-black-hole-swallows-star.html

scibyte45 black holes star

shared by Mars Base on 03 May 12 - No Cached
  • star whose death may ultimately provide more clues on the inner workings of the enigmatic gravitational monster that devoured it.
  • In June 2010, the researchers spotted a bright flare from the previously dormant black hole at the center of a galaxy approximately 2.7 billion light-years away.
  • The flare of light reached peak brightness a month after it was detected, then slowly faded over the next 12 months
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  • By measuring the rise of the flare's brightness, the scientists calculated the rate at which the star's gas was getting sucked into the black hole
  • helped reveal at what point and time the black hole had begun disrupting the star, revealing how powerful its gravitational field was and thus its mass.
  • estimate the black hole's mass to be 3 million suns
  • like we are gathering evidence from a crime scene
  • analyzed the spectrum of the ejected gas — that is, the specific colors making up its light
  • using data from the Multiple Mirror Telescope Observatory on Mount Hopkins in Arizona
  • and the spectrum of the gas revealed it was mostly helium.
  • unique spectral fingerprint
  • fact there was mostly helium and very little hydrogen in the gas suggests "the slaughtered star had to have been the helium-rich core of a stripped star
  • This likely happened when the star went through the red giant phase, where it expanded to 100 times its original radius
  • it puffed up like that, it became vulnerable to the gravitational tidal forces of the black hole, and it would have been very easy to strip off the tenuous hydrogen envelope
  • the star then had to approach much closer, 100 times closer in, before it was completely disrupted by the black hole
Mars Base

A Star Is Torn - Science News - 0 views

www.sciencenews.org/...A_star_is_torn

scibyte45 black holes star

shared by Mars Base on 03 May 12 - No Cached
  • In spring 2010, NASA’s orbiting Galaxy Evolution Explorer and the ground-based Pan-STARRS telescope observed a suspicious brightening around a supermassive black hole parked more than 2 billion light-years from Earth
  • Over the next few months, the flare continued increasing in brightness — then it dimmed
  • Scientists now suggest that the light show was evidence of the black hole PS1-10jh shredding a star that wandered too close
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  • analysis presented online May 2 in Nature indicates that at the time of engulfment, the star was just a helium-rich core, the remainder of a former red giant
  • The black hole
  • weighing about 3 million solar masses, had probably already snacked on the star’s outer layers during a previous close encounter.
  • the black hole spat some of the stellar material into space
  • followed elongated orbits that eventually dumped them back into the black hole, producing the observed, months-long flare.
  • Such disruption events are rare, thought to occur only once every 10,000 years per galaxy
  • can help astronomers spot otherwise hidden black holes.
Mars Base

Hubble directly observes the disc around a black hole - 0 views

www.physorg.com/...11-hubble-disc-black-hole.html

scibyte20 black holes quasar

shared by Mars Base on 06 Nov 11 - No Cached
  • Scientists have used the NASA/ESA Hubble Space Telescope to observe a quasar accretion disc -- a glowing disc of matter that is slowly being sucked into its galaxy's central black hole
  • Scientists have used the NASA/ESA Hubble Space Telescope to observe a quasar accretion disc -- a glowing disc of matter that is slowly being sucked into its galaxy's central black hole.
  • the team measured the disc's size and studied the colours (and hence the temperatures) of different parts of the disc
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  • Using the NASA/ESA Hubble Space Telescope, combined with the gravitational lensing effect of stars in a distant galaxy, the team measured the disc's size and studied the colours (and hence the temperatures) of different parts of the disc.
  • Until now, the minute apparent size of quasars has meant that most of our knowledge of their inner structure has been based on theoretical extrapolations, rather than direct observations.
  • show a level of precision equivalent to spotting individual grains of sand on the surface of the Moon
  • Quasars — short for quasi-stellar objects — are glowing discs of matter that orbit supermassive black holes, heating up and emitting extremely bright radiation as they do so.
  • These observations show a level of precision equivalent to spotting individual grains of sand on the surface of the Moon.
  • using the stars in an intervening galaxy as a scanning microscope to probe features in the quasar's disc that would otherwise be far too small to see
  • As these stars move across the light from the quasar, gravitational effects amplify the light from different parts of the quasar, giving detailed colour information for a line that crosses through the accretion disc.
  • the team were able to reconstruct the colour profile across the accretion disc
  • allowed the team to measure the diameter of the disc of hot matter, and plot how hot it is at different distances from the centre
  • Quasars' physical properties are not yet well understood
  • This new ability to obtain observational measurements is therefore opening a new window to help understand the nature of these objects."
Mars Base

Black Hole 'Bonanza': Millions Found by NASA Space Telescope | WISE | Space.com - 0 views

www.space.com/ound-nasa-space-telescope.html

scibyte61

shared by Mars Base on 30 Aug 12 - No Cached
  • A jackpot of previously unknown black holes across the universe has been discovered by the infrared eyes of a prolific NASA sky-mapping telescope
  • astronomers are still poring through this celestrial trove for discoveries.
  • These black holes aren't the average tiny, dense objects created by the collapse of dead stars, but rather humongous "supermassive" black holes that have been caught feasting on matter falling into them
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  • We expected that there should be this large population of hidden quasars in the universe, but WISE can now identify them across the sky
Mars Base

Move Over, Gravity: Black Hole Magnetic Fields May Have Powerful Pull - 0 views

www.universetoday.com/...-fields-may-have-powerful-pull

scibyte134 BlackHole

shared by Mars Base on 05 Jun 14 - No Cached
  • It’s oft-repeated that black holes are powerful gravity wells, because they represent a dense concentration of matter in one location
  • magnetic fields
  • A new study suggests that
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  • could be at least as strong as gravity in supermassive black holes, the singularities that lurk in the center of many galaxies
Mars Base

Quasar - Wikipedia, the free encyclopedia - 0 views

en.wikipedia.org/Quasar

scibyte69 quasar

shared by Mars Base on 26 Oct 12 - Cached
  • size is 10–10,000 times the Schwarzschild radius of the black hole
  • powered by an accretion disc around the black hole.
  • among the most luminous, powerful, and energetic objects known in the universe
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  • emit up to a thousand times the energy output of the Milky Way.
  • More than 200,000 quasars are known
Mars Base

'Runaway' Star Cluster Breaks Free from Distant Galaxy - 0 views

www.universetoday.com/...reaks-free-from-distant-galaxy

scibyte129 StarCluster

shared by Mars Base on 01 May 14 - No Cached
  • discovered dozens of so-called “hypervelocity stars” — single stars that break the stellar speed limit
  • The Virgo Cluster galaxy, M87, has ejected an entire star cluster, throwing it toward us at more than two million miles per hour.
  • Astronomers have found runaway stars before, but this is the first time we’ve found a runaway star cluster
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  • About one in a billion stars travel at a speed roughly three times greater than our Sun
  • at 220 km/s with respect to the galactic center
  • At a speed that fast, these stars can easily escape the galaxy entirely, traveling rapidly throughout intergalactic space.
  • this is the first time an entire star cluster has broken free
  • hypervelocity stars have puzzled astronomers for years. But by observing their speed and direction, astronomers can trace these stars backward, finding that some began moving quickly in the Galactic Center
  • Here, an interaction with the supermassive black hole can kick a star away at an alarming speed
  • Another option is that a supernova explosion propelled a nearby star to a huge speed
  • think M87 might have two supermassive black holes at its center
  • The star cluster wandered too close to the pair, which picked off many of the cluster’s outer stars while the inner core remained intact
  • The black holes then acted like a slingshot, flinging the cluster away at a tremendous speed
Mars Base

End of the World: 10 Disasters That Could End It All At Any Given Second - Best of the ... - 0 views

botw.org/endworld.html

scibyte75 End-of-the-World

shared by Mars Base on 13 Dec 12 - Cached
  • Gamma-Ray Burst
  • Gamma-ray bursts are extremely powerful, estimated to have 10 quadrillion times more energy than our sun
  • They are created by the collision of two collapsed stars
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  • it is almost impossible to visualize collapsed stars making it even more difficult to predict the location of a gamma-ray burst
  • A burst 1,000 light years from the earth (further away than most of our stars) would create an explosion as bright as our sun and bring a hasty destruction to earth
  • atmosphere and the ozone would provide protection at first it would soon be cooked away by the radiation. UV rays would kill the photosynthetic plankton in the ocean, which provide most of the earth's oxygen
  • At least one burst can be seen each day when watching our sky with gamma-ray vision; it can't be too long before there is one closer to home
  • earth's atmosphere and magnetic field protect us from the consequences of these potentially lethal flares
  • The sun emits solar flares, also known as coronal mass ejections, towards earth frequently
  • These flares are large magnetic outbursts which contain high-speed subatomic particles
  • evidence has been found that sun-like stars far from our solar system can briefly increase in brightness by 20 times
  • hypothesized that these increases are caused by super-flares, which are millions of times more powerful than the common solar flare
  • If our sun were to emit one of these super-flares it would literally fry the earth
  • if our sun's activity were to decrease by a mere 1% (which has been known to happen to many sun-like stars) we would be flung back into another ice age
  • Solar Activity (Super-Flares and Decreased Activity)
  • Particle Accelerators
  • When electric fields are used to accelerate protons they could collide at speed fast enough to create black holes or bits of altered matter
  • These small black holes would slowly engulf our planet
  • pieces of altered matter, called strangeletes, would destroy any ordinary matter they came in contact with, eventually annihilating the entire planet
  • most scientists assure that none of the particle accelerators being used at the present are strong enough to bring about these events
Mars Base

Quasar may be embedded in unusually dusty galaxy - 0 views

phys.org/...ed-unusually-dusty-galaxy.html

scibyte69 quasar

shared by Mars Base on 24 Oct 12 - No Cached
  • Quasars (short for quasi-stellar object) are the brilliant cores of galaxies where infalling material fuels a super-massive black hole
  • black hole is so engorged that some of the energy escapes as powerful blasts of radiation from the surrounding disk of accreting material
  • can appear as a jet-like feature
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  • If the beam shines in Earth's direction
  • can appear as a quasar that can outshine its surrounding galaxy a hundred or a thousand times.
  • first identified in the Sloan Digital Sky Survey (SDSS).
  • Only a handful of these very distant ultra-luminous quasars were found by the SDSS in about one quarter of the whole sky
Mars Base

Hubble Space Telescope Passes Major Science Milestone | Hubble 10,000th Science Paper |... - 0 views

www.space.com/cope-10000-science-papers.html

scibyte25

shared by Mars Base on 09 Dec 11 - No Cached
  • Hubble Space Telescope has crossed a major milestone, accumulating 10,000 science papers based on its observations
  • After 21 years
  • it's actually in the best shape of its life
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  • last space shuttle servicing mission was in May 2009.
  • Papers describing discoveries in nearly every field of astronomy and cosmology have been published based on data gathered by the Hubble Space Telescope.
  • conducted by scientists in more than 35 countries
  • most papers written by researchers in the United States, the United Kingdom, Germany, Italy, France, and Spain
  • Hubble's top five most referenced papers are on
  • The search for distant supernovas used to characterize dark energy
  • The precise measurement of the universe's rate of expansion
  • The apparent link between galaxy mass and central black hole mass
  • Early galaxy formation in the Hubble Deep Field
  • The evolutionary models for low-mass stars and brown dwarfs
  • 10,000th Hubble science paper
  • announces the discovery of the faintest supernova ever associated with a cosmic explosion called a long-duration gamma-ray burst, which spews high-energy radiation into space when a star dies
  • The first science paper based on Hubble data came about six months after the telescope's launch
  • a paper on observations of the center of galaxy NGC 7457, where scientists suspected a huge black hole lurked
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