So what to do? Today, Duncan Forbes at Swinburne University in Australia and Pavel Kroup at the University of Bonn in Germany put forward a novel solution. They outline the various characteristics that astronomers think about when classifying galaxies.
These include factors such as the presence of stars, so gas clouds can't be defined as galaxies; being gravitationally bound, so materials that has been stripped away by another galaxy wouldn't count; whether the system is stable or not; whether it hosts a good variety of different types of star, which excludes globular clusters which contain only similar stars; and whether it is held together by dark matter, which many galaxies seem to be.
There are other factors too, of course. (Although they do not include the presence of a black hole at the centre of a galaxy as a defining characteristic , which is odd given the growing interest in the link between galactic evolutoin and black holes.)
Forbes and Kroup go on to suggest that the best way to achieve consensus is to crowdsource the problem. In other works, they want to use the wisdom of the crowd to determine what factors are important what aren't.
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Scientists Just Found an "Impossible" Black Hole in The Milky Way Galaxy - 1 views
Welcome to the LISC web portal - LISC - LISA International Science Community - 0 views
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website features news, resources, and discussion boards about LISA (the Laser Interferometer Space Antenna), a space-based gravitational-wave observatory that will allow us to detect gravitational waves from massive black-hole mergers in the centers of galaxies, from the ultra-compact binary systems in our own Galaxy, and from many other sources. A joint ESA and NASA mission, LISA will create revolutionary research opportunities in astrophysics and fundamental physics.
Universe Sandbox a Steamen - 2 views
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Create and destroy on a scale you've never imagined with the ultimate space simulator. Harness the power to create black holes, collide galaxies, and manipulate gravity with just a few clicks. Inspired by the software astronomers use to unlock the mysteries of our universe, never before has astronomy been so interactive or so much fun.
Star Formation - 0 views
Heated gas stream at a cool star formation?In the inner regions of a galaxy cluster, astronomers found by Michael McDonald from the Massachusetts Institute of Technology in the USA further evidence...
Why Are Quark Stars So Strange? : Discovery News - 1 views
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First things first, neutron stars, quark stars and black holes are all born via the same mechanism: a supernova. But each of the three are progressively more massive, so they originate from supernovae produced by progressively more massive stars. So, what if a star exploded, producing something a little too massive to be called a neutron star? Well, neutron stars resist collapsing under their own gravitational pull by a characteristic of matter known as neutron degeneracy. This produces an outward force called neutron degeneracy pressure. What if the neutron star born after a supernova is too massive for this neutron degeneracy pressure to hold up against the neutron star's own gravity? In this case, it's up to the quarks that make up the neutrons to take over, preventing the body from collapsing any further. Single neutrons are composed of three quarks (two "down" quarks and one "up" quark). When quark degeneracy pressure kicks in, a quark star may be produced; the free "up" and "down" quarks get converted into "strange" quarks. Therefore, a quark star (also known as a "strange star") is made up of strange matter.
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Using what we know from the Standard Model of particle physics, a massive quark star may have enough gravitational energy to start 'burning' strange matter. The quarks inside the core of the quark star may be abused so badly by gravitational pressure that the quarks will be converted into pure energy and neutrinos.
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The fascinating thing with this scenario is that the quark star matter will be so dense that even the neutrinos cannot escape. However, this release of energy and generation of neutrinos creates an outward pressure countering the relentless inward gravitational pull.
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New Particle Collider Operating in Secret - NYTimes.com - 0 views
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"We may not have created a black hole, but it seems we may have discovered a way for elementary particles to shape the path of evolution. You just never know what you are going to find"
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I am no arbiter of humour, but I think this April Fool prank is fairly lame (unless there is truth in the unlikely twitter rumour that the NYT was pranked)
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Large Hadron Collider investigative journalism
Experimental Demonstration of space-time distortion - 0 views
Experimental Demonstration of space-time distortionAccording to the general theory of relativity deform very large rotating masses spacetime around him. This Frame-dragging was detected by the sate...
Experimental Demonstration of space-time distortion - 0 views
Experimental Demonstration of space-time distortionAccording to the general theory of relativity deform very large rotating masses spacetime around him. This Frame-dragging was detected by the sate...
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