accretion disks

And here we see @why-animals-do-the-thing stealing all my spotlight by reblogging one of my posts, the fiend. The small orange node in the bottom left is my root post, the huge node in the middle is them. It’s like an accretion disk of popularity.

Curse you, blackguard! How dare you reblog my post and generate me more views! Just kidding, I love you forever.

anonymous asked:

hey what the hell is a quasar

A quasar is a Quasi-Stellar Object meaning it shines like a star, but when you take spectrographic data of it, it’s mad fucked up my dude so it can’t be a star (hence the name) so people were like “what the heck dude” and now we know it’s actually the center of a galaxy called an “Active Galactic Nuclei” and you know how black holes will fucking wreck a star? Well mid-wreckage they form an accretion disk of star stuff around it and as the star stuff falls closer to the black hole, it releases a bunch of energy that comes to us looking like a star, but it’s actually a star being eaten alive and torn to shreds at an atomic level. Fucked up huh.

Black Holes: A Summary

I got asked this lovely question yesterday afternoon and instead of just answering it, I wanted to write a comprehensive post about black holes and their many intricacies.  So, here we go: let’s talk about black holes!

Assumptions

We’re going to work with General Relativity (mostly) because it simplifies these concepts down into something a lot more understandable.  General Relativity is the perception of gravity as not an inherent force, but instead caused by the curvature of spacetime, a two-dimensional interpretation of the four dimensions of Minkowski spacetime (space in x, y and z directions and time).  The extent of the curvature of spacetime is directly related to the mass of the object.  Quantum theory will come up briefly, but not in the creation of black holes nor in the analysis of their properties.  

We’re also going to assume that the black holes discussed are gravitational, static and eternal.  This means that the black holes have gravity generated by their mass, do not spin and do not deteriorate over time.  I will discuss black hole deterioration in a separate section, but that concept won’t be relevant in the earlier sections.  

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Framing a bright emission region, this telescopic view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the reddish glowing cloud of interstellar gas and dust is also found in the1959 catalog by astronomer Stewart Sharplessas Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms at the center of this composite image. Ultraviolet radiation from young energetic stars at the edge of the Cygnus OB3 association, including O star HDE 227018,ionizes the atoms and powers the emission from the Tulip Nebula. HDE 227018 is the bright star near the center of the nebula. Also framed in the field of view is microquasar Cygnus X-1, one of the strongest X-ray sources in planet Earth’s sky. Driven by powerful jets from a black hole accretion disk, its fainter visible curved shock front lies above and right, just beyond the cosmic Tulip’s petals.

Image Credit &Copyright:Ivan Eder

Time And Space

Jupiter is the Oldest Planet  in our Solar System

An international group of scientists has found that Jupiter is the oldest planet in our solar system.

By looking at tungsten and molybdenum isotopes on iron meteorites, the team, made up of scientists from Lawrence Livermore National Laboratory and Institut für Planetologie at the University of Münsterin Germany, found that meteorites are made up from two genetically distinct nebular reservoirs that coexisted but remained separated between 1 million and 3-4 million years after the solar system formed.

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Black Holes: Monsters in Space

This artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. (Smaller black holes also exist throughout galaxies.) In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity.

Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole’s spin. The regions near black holes contain compact sources of high energy X-ray radiation thought, in some scenarios, to originate from the base of these jets. This high energy X-radiation lights up the disk, which reflects it, making the disk a source of X-rays. The reflected light enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole’s spin rate.

Image credit:
NASA/JPL-Caltech

ASTROPHYSICISTS FROM THE LOMONOSOV MOSCOW STATE UNIVERSITY
HAVE STUDIED THE “REJUVENATING” PULSAR IN A NEIGHBORING GALAXY

Lomonosov Moscow State University scientists have published in the Astrophysical Journal the results of a study of the unique ultraslow pulsar XB091D. This neutron star is believed to have captured a companion only a million years ago and, since then, has been slowly restoring its rapid rotation. The young pulsar is located in one of the oldest globular star clusters in the Andromeda galaxy, where the cluster may once have been a dwarf galaxy.

Massive stars die young, exploding as bright supernovae. In this process, their outer layers of material are thrown off, and the core shrinks, usually becoming a compact and super-dense neutron star. Strongly magnetized, they rotate rapidly, making hundreds of revolutions per second, but they lose their rotational energy and slow down, emitting narrow beams of particles. They radiate a focused radio emission that periodically passes the Earth, creating the effect of a regularly pulsating source, often with a millisecond period.

In order to “return youth” and again accelerate its rotation, the pulsar can encounter an ordinary star. After teaming up to form a pair or a binary system, the neutron star begins to pull matter from the star, forming a hot accretion disk around itself. Closer to the neutron star, the gaseous disk is torn apart by the magnetic field of the neutron star, and the matter streams onto it, forming a “hot spot” – the temperature here reaches millions of degrees, and the spot radiates in X-rays. A rotating neutron star can then be seen as an X-ray pulsar as a beacon, while the matter that continues to fall on it gives an additional impulse, accelerating the rotation.

For some hundred thousand years – a mere blink in the history of the universe – the old pulsar, which has already slowed to one revolution every few seconds, can once again spin thousands of times faster. Such a rare moment was observed by a team of astrophysicists from the Lomonosov Moscow State University, jointly with colleagues from Italy and France. The X-ray pulsar known as XB091D, was discovered at the earliest stages of its “rejuvenation” and turns out to be the slowest rotating of all globular-cluster pulsars known to date. The neutron star completes one revolution in 1.2 seconds – more than ten times slower than the previous record holder. According to scientists, the acceleration of the pulsar began less than one million years ago.

The discovery was made using observations collected by the XMM-Newton space observatory between 2000 and 2013 and were combined by astronomers of the Lomonosov Moscow State University into an open online database. Access to information on approximately 50 billion X-ray photons has already allowed scientists from different countries to discover a number of previously unnoticed interesting objects. Among them was the pulsar XB091D, which was also noticed by another group of Italian astronomers who published their results several months ago. XB091D is only the second pulsar found outside of our galaxy and its nearest satellites, although two more such pulsars were subsequently detected using the same online catalog.

The results of the first complete analysis of the X-ray source XB091D are presented in an article published by Ivan Zolotukhin, a researcher at the Lomonosov Moscow State University, and his co-authors in The Astrophysical Journal.

“The detectors on XMM-Newton detect only one photon from this pulsar every five seconds. Therefore, the search for pulsars among the extensive XMM-Newton data can be compared to the search for a needle in a haystack, “ says Ivan Zolotukhin. – In fact, for this discovery we had to create completely new mathematical tools that allowed us to search and extract the periodic signal. Theoretically, there are many applications for this method, including those outside astronomy. “

Based on a total of 38 XMM-Newton observations, astronomers managed to characterize the XB091D system. The X-ray pulsar is about 1 million years old, the companion of the neutron star is an old star of moderate size (about four fifths the mass of the Sun). The binary system itself has a rotation period of 30.5 hours, and the neutron star spins once on its axis every 1.2 seconds. In about 50 thousand years, it will accelerate sufficiently to turn into a conventional millisecond pulsar.

However, it was not only orbital parameters that astronomers were able to observe, they were also able to determine the environment around XB091D. Ivan Zolotukhin and his colleagues showed that XB091D is located in the neighboring Andromeda galaxy, 2.5 million light-years away, amongst the stars of the extremely dense globular cluster B091D, where in a volume of only 90 light-years across, there are more millions of old faint stars. The cluster itself is estimated to be as much as 12 billion years old, so no recent supernovae resulting in the birth of a pulsar would have occurred.

“In our galaxy, no such slow X-ray pulsars are observed in hundred and fifty known globular clusters, because their cores are not big and dense enough to form close binary stars at sufficiently high rate” explains Ivan Zolotukhin. – This indicates that the B091D cluster core, with an extremely dense composition of stars in the XB091D is much larger than that of the usual cluster. So, we are dealing with a large and rather rare object – with a dense remnant of a small galaxy that the Andromeda galaxy once devoured. The density of the stars here, in a region that is about 2.5 light-years across, is about ten million times higher than in the vicinity of the Sun.”

According to scientists, it is the vast region of super-high density stars in the B091D cluster that allowed a neutron star to capture a companion about a million years ago and begin the process of acceleration and “rejuvenation.”

The beautiful spiral galaxy visible in the center of the image is known as RX J1140.1+0307, a galaxy in the Virgo constellation imaged by the NASA/ESA Hubble Space Telescope, and it presents an interesting puzzle. At first glance, this galaxy appears to be a normal spiral galaxy, much like the Milky Way, but first appearances can be deceptive!

The Milky Way galaxy, like most large galaxies, has a supermassive black hole at its center, but some galaxies are centered on lighter, intermediate-mass black holes. RX J1140.1+0307 is such a galaxy — in fact, it is centered on one of the lowest black hole masses known in any luminous galactic core. What puzzles scientists about this particular galaxy is that the calculations don’t add up. With such a relatively low mass for the central black hole, models for the emission from the object cannot explain the observed spectrum. There must be other mechanisms at play in the interactions between the inner and outer parts of the accretion disk surrounding the black hole.

Framing a bright emission region, this telescopic view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the reddish glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms at the center of this composite image. Ultraviolet radiation from young energetic stars at the edge of the Cygnus OB3 association, including O star HDE 227018, ionizes the atoms and powers the emission from the Tulip Nebula. HDE 227018 is the bright star near the center of the nebula. Also framed in the field of view is microquasar Cygnus X-1, one of the strongest X-ray sources in planet Earth’s sky. Driven by powerful jets from a black hole accretion disk, its fainter visible curved shock front lies above and right, just beyond the cosmic Tulip’s petals

What’s happened to giant star N6946-BH1? It was there just a few years ago – Hubble imaged it. Now there’s only a faint glow. What’s curiouser, no bright supernova occurred – although the star did brightened significantly for a few months. The leading theory is that, at about 25 times the mass of our Sun, N6946-BH1’s great gravity held much of the star together during its final tumultuous death throes, after which most the star sunk into a black hole of its own making. If so, then what remained outside of the black hole likely then formed an accretion disk that emits comparatively faint infrared light as it swirls around, before falling in. If this mode of star death is confirmed with other stars, it gives direct evidence that a very massive star can end its life with a whimper rather than a bang.

Image Credit: NASA, ESA, Hubble, C. Kochanek (OSU)

cosmic witchcraft 101: venusian magick ♀

Venus is the second planet from the Sun. Most likely the planet formed through disk accretion - gravitational forces drawing dust and particles together to form a rocky core, which gets big enough to capture the lighter elements that form the planet’s atmosphere. Astronomer Giovanni Cassini reported a moon on venus in the 1600′s, and many people claimed to see it over the next 200 years. Most of these sightings were proven to be nearby stars, but scientists believe Venus had a moon in our solar system’s earlier years. They hypothesize a huge impact on Venus created a moon billions of years ago, but 10 million years after its formation another huge impact reversed the planet’s spin direction and caused the moon to spiral inward until it collided with Venus.

Facts:

  • Venus is the 3rd brightest object in the sky after the Sun and Moon.
  • Incredibly thick, reflective clouds of sulfuric acid cause the planet to shine so brightly.
  • Due to its runaway greenhouse effect, Venus is the hottest planet in the solar system.
  • A Venusian day is 243 Earth days, 18 days longer than a Venusian year.
  • Venus spins backward compared to the other planets. From its surface, the Sun would appear to rise in the west and set in the east.
  • Venus is the most spherical of all the planets.

Magickal Correspondences*

Colors: red, pink, white, green, yellow, purple

Intents: love, self-love, glamors, balance, peace, creativity, attraction, beauty, justice, material comfort, finances, reversal of fortune

Herbs: vanilla, rose, poppy, peppermint, daffodil, juniper, hibiscus, heather, tansy, lilac, violet, myrrh, eucalyptus

Crystals: emerald, rose quartz, blue calcite, jade, green jasper, lapis lazuli, sodalite, turquoise, rhodonite, serpentine, celestite

*some of these correspondences are based on traditional associations and some are based on my personal associations

2

DISCOVERY IN THE EARLY UNIVERSE POSES BLACK HOLE GROWTH PUZZLE

** Abstract: Quasars are luminous objects with supermassive black holes at their centers, visible over vast cosmic distances. Infalling matter increases the black hole mass and is also responsible for a quasar’s brightness. Now, using the W. M. Keck observatory in Hawaii, astronomers led by Christina Eilers have discovered extremely young quasars with a puzzling property: these quasars have the mass of about a billion Suns, yet have been collecting matter for less than 100,000 years. Conventional wisdom says quasars of that mass should have needed to pull in matter a thousand times longer than that – a cosmic conundrum. The results have been published in the May 2 edition of the Astrophysical Journal. **

Within the heart of every massive galaxy lurks a supermassive black hole. How these black holes formed, and how they have grown to be as massive as millions or even billions of Suns, is an open question. At least some phases of vigorous growth are highly visible to astronomical observers: Whenever there are substantial amounts of gas swirling into the black hole, matter in the direct vicinity of the black hole emits copious amount of light. The black hole has intermittently turned into a quasar, one of the most luminous objects in the universe.

Now, researchers from the Max Planck Institute for Astronomy (MPIA) have discovered three quasars that challenge conventional wisdom on black hole growth. These quasars are extremely massive, but should not have had sufficient time to collect all that mass. The discovery, which is based on observations at the W. M. Keck observatory in Hawaii, glimpses into ancient cosmic history: Because of their extreme brightness, quasars can be observed out to large distances. The astronomers observed quasars whose light took nearly 13 billion years to reach Earth. In consequence, the observations show these quasars not as they are today, but as they were almost 13 billion years ago, less than a billion years after the big bang.

The quasars in question have about a billion times the mass of the Sun. All current theories of black hole growth postulate that, in order to grow that massive, the black holes would have needed to collect infalling matter, and shine brightly as quasars, for at least a hundred million years. But these three quasars proved to be have been active for a much shorter time, less than 100,000 years. “This is a surprising result,” explains Christina Eilers, a doctoral student at MPIA and lead author of the present study. “We don’t understand how these young quasars could have grown the supermassive black holes that power them in such a short time.”

To determine how long these quasars had been active, the astronomers examined how the quasars had influenced their environment – in particular, they examined heated, mostly transparent “proximity zones” around each quasar. “By simulating how the light from quasars ionizes and heats gas around them, we can predict how large the proximity zone of each quasar should be,” explains Frederick Davies, a postdoctoral researcher at MPIA who is an expert in the interaction between quasar light and intergalactic gas. Once the quasar has been “switched on” by infalling matter, these proximity zones grow very quickly. “Within a lifetime of 100,000 years, quasars should already have large proximity zones.”

Surprisingly, three of the quasars had very small proximity zones – indicating that the active quasar phase cannot have set in more than 100,000 years earlier. “No current theoretical models can explain the existence of these objects,” says Professor Joseph Hennawi, who leads the research group at MPIA that made the discovery. “The discovery of these young objects challenges the existing theories of black hole formation and will require new models to better understand how black holes and galaxies formed.”

The astronomers have already planned their next steps. “We would like to find more of these young quasars,” says Christina Eilers, “While finding these three unusual quasars might have been a fluke, finding additional examples would imply that a significant fraction of the known quasar population is much younger than expected.” The scientists have already applied for telescope time to observe several additional candidates. The results, they hope, will constrain new theoretical models about the formation of the first supermassive black holes in the universe – and, by implication, help astronomers understand the history of the giant supermassive black holes at the center of present-day galaxies like our own Milky Way.


TOP IMAGE….Basic set-up of the quasar observations: Light from a quasar (right) is absorbed by gas. Absorption is much less in the quasar’s proximity zone, which is shown in green for an older quasar, in yellow for a younger quasar. The extent of the proximity zone can be read off the spectrum (bottom). The quasar itself is a central black hole, surrounded by a disk of swirling matter, and possibly sending out particles in two tightly focussed jets (inset, top right).
Image: A. C. Eilers & J. Neidel, MPIA


LOWER IMAGE….Artists’ impression of a quasar: black hole (center) surrounded by a hot accretion disk, with two jets consisting of extremely fast particles perpendicularly to the disk.
Image: J. Neidel / MPIA

vimeo

This short clip of a rounded ring of ice spinning on the Middle Fork Snoqualmie River in Washington was one of the most popular videos shared on Social Media this week. Ice disks like these are thought to form either by ice that gets caught in an eddy in a river and is compacted into a circle while the water swirls, or ice that gets caught in an eddy as a sheet and then is rounded by collision with surrounding ice. The fact that there is an outer layer on this disk makes me think that outer layer has been accreted to the spinning disk as ice fell into a stationary eddy in this case. 

6

Cosmic ‘Spitballs’ Released From Milky Way’s Black Hole

“Black holes don’t just provide gravity, absorb incoming matter and prevent anything from escaping. They also gravitationally pull on and tear matter that passes nearby, including stars. In a surprising find, a new study out of Harvard shows that torn-apart stars aren’t merely reduced into gas, but they form dense streams that re-condense into planets in just year-long timescales. Moving rapidly away from the central black hole, these 'cosmic spitballs’ represent a brand new population of rogue planets, and are potentially the most catastrophic objects from space careening through our galaxy.”

Imagine you’re a star passing too close to a black hole. What’s going to happen to you? Yes, you’ll be tidally disrupted and eventually torn apart. Some of the matter will be swallowed, some will wind up in an accretion disk, and some will be accelerated and ejected entirely. But quite surprisingly, the ejected matter doesn’t just come out in the form of hot gas, but it condenses into large numbers of rapidly-moving planets. This population should make up approximately one out of every 1000 rogue planets, but should be uniquely identifiable. The vast majority will move at incredible speeds of around 10,000 km/s, be approximately the mass of Jupiter but will be made out of shredded star material, rather than traditional planetary material. As the next generation of infrared telescopes come online, these ‘cosmic spitballs’ should be one of the most exciting novel discoveries of all.

Come get the whole story on cosmic spitballs, fresh from the AAS meeting!

The Milky Way’s close neighbor, Andromeda, features a dominant source of high-energy X-ray emission, but its identity was mysterious until now. As reported in a new study, NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission has pinpointed an object responsible for this high-energy radiation.

The object, called Swift J0042.6+4112, is a possible pulsar, the dense remnant of a dead star that is highly magnetized and spinning, researchers say. This interpretation is based on its emission in high-energy X-rays, which NuSTAR is uniquely capable of measuring. The object’s spectrum is very similar to known pulsars in the Milky Way.

It is likely in a binary system, in which material from a stellar companion gets pulled onto the pulsar, spewing high-energy radiation as the material heats up.

“We didn’t know what it was until we looked at it with NuSTAR,” said Mihoko Yukita, lead author of a study about the object, based at Johns Hopkins University in Baltimore. The study is published in The Astrophysical Journal.

This candidate pulsar is shown as a blue dot in a NuSTAR X-ray image of Andromeda (also called M31), where the color blue is chosen to represent the highest-energy X-rays. It appears brighter in high-energy X-rays than anything else in the galaxy.

The study brings together many different observations of the object from various spacecraft. In 2013, NASA’s Swift satellite reported it as a high-energy source, but its classification was unknown, as there are many objects emitting low energy X-rays in the region. The lower-energy X-ray emission from the object turns out to be a source first identified in the 1970s by NASA’s Einstein Observatory. Other spacecraft, such as NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton had also detected it. However, it wasn’t until the new study by NuSTAR, aided by supporting Swift satellite data, that researchers realized it was the same object as this likely pulsar that dominates the high energy X-ray light of Andromeda.

Traditionally, astronomers have thought that actively feeding black holes, which are more massive than pulsars, usually dominate the high-energy X-ray light in galaxies. As gas spirals closer and closer to the black hole in a structure called an accretion disk, this material gets heated to extremely high temperatures and gives off high-energy radiation. This pulsar, which has a lower mass than any of Andromeda’s black holes, is brighter at high energies than the galaxy’s entire black hole population.

Even the supermassive black hole in the center of Andromeda does not have significant high-energy X-ray emission associated with it. It is unexpected that a single pulsar would instead be dominating the galaxy in high-energy X-ray light.

“NuSTAR has made us realize the general importance of pulsar systems as X-ray-emitting components of galaxies, and the possibility that the high energy X-ray light of Andromeda is dominated by a single pulsar system only adds to this emerging picture,” said Ann Hornschemeier, co-author of the study and based at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

Andromeda is a spiral galaxy slightly larger than the Milky Way. It resides 2.5 million light-years from our own galaxy, which is considered very close, given the broader scale of the universe. Stargazers can see Andromeda without a telescope on dark, clear nights.

“Since we can’t get outside our galaxy and study it in an unbiased way, Andromeda is the closest thing we have to looking in a mirror,” Hornschemeier said.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

For

cosmic witchcraft 101: martian magick ♂

Mars is the fourth planet from the Sun and the second smallest planet in our solar system. Like the other terrestrial planets, Mars likely formed via disk accretion (gravitational forces drawing dust and particles together to form a rocky core which captures the lighter elements to form the planet’s atmosphere) and probably suffered a tremendous impact as well. Scientists hypothesize a Pluto-sized object struck the red planet and left behind Valles Marineris, a gigantic crack in Mars’ surface approximately ten times longer and wider than the Grand Canyon.

Facts:

  • Mars’s brilliant red color comes from iron oxide/rust on the planet’s surface.
  • A Martian year is 687 Earth days; however, a Martian day is almost identical to an Earth day in length at 24 hours and 37 minutes.
  • The red planet has two small, irregularly shaped moons named Phobos and Deimos.  
  • Mars has the largest volcano in the solar system, Olympus Mons.
  • In a few million years, Phobos is expected to collide with Mars.
  • Mars is so cold the ice caps on the Northern and Southern poles get a coating of dry ice during the winter.

Magickal Correspondences*

Colors: red, brown, white

Intents: courage, strength, power, protection, success, force, conflict, passion, energy, drive, lust, stamina

Herbs: onion, thyme, basil, black pepper, acacia, aloe, dandelion, ginger, cardamom, chives, nettles, turmeric

Crystals: red jasper, ruby, carnelian, red labradorite, red beryl, bloodstone, garnet, red spinel, red zircon, tiger’s eye, agate, fire opal, red tourmaline, hematite, sardonyx, red coral

*some of these correspondences are based on traditional associations and some are based on my personal associations