General Post 1:
How does the result of the first imaged Black Hole relate to our galaxy? Write more than a simple statement of fact.
https://www.nytimes.com/2019/04/10/science/black-hole-picture.html
https://eventhorizontelescope.org/
The image of the black hole came from Messier 87 (abbreviated as M87), a galaxy in the constellation Virgo, located 55 million light-years away from Earth. The data was collected by a large telescope virtually the size of Earth, the Event Horizon Telescope. The telescope is comprised of a network of eight radio observatories, precisely synchronized together using atomic clocks. This observation technique is called very-long-baseline interferometry (VLBI), which leverages the rotation of the Earth to form a huge telescope which observes at a wavelength of 1.3 mm, giving an angular resolution of 20 micro-arcseconds. VLBI can be used to observe other things as well; for example the Event Horizon Telescope also recorded data from our Milky Way galaxy, where there is source of radio noise called Sagittarius A*, likely the location of another black hole. However, it is much smaller than M87, making it harder to image. The Event Horizon Telescope is at work imaging the black hole in our galaxy.
Furthermore, the image of M87 also enables astronomers to measure the radius of the black hole, as it provides a clear, circular shadow. Using the radius, we can estimate the mass of the black hole. This measurement yielded an estimated mass of 6.5 billion solar masses, and can be generalized across other black hole. Since it is heavier than most other estimates, it suggests that the masses of other black holes may be underestimated.
Finally, the image confirms Einstein's theory of general relativity, which predicts that when too much matter or energy is crammed into a small enough volume, space-time would collapse, leading to an eternal gravity trap from which light cannot even escape. The black hole casts a shadow by creating a dark region when immersed in a bright region such as a disc of glowing gas. The circular shadow is caused by the gravitational bending and capture of light by the event horizon of the black hole.
https://eventhorizontelescope.org/
The image of the black hole came from Messier 87 (abbreviated as M87), a galaxy in the constellation Virgo, located 55 million light-years away from Earth. The data was collected by a large telescope virtually the size of Earth, the Event Horizon Telescope. The telescope is comprised of a network of eight radio observatories, precisely synchronized together using atomic clocks. This observation technique is called very-long-baseline interferometry (VLBI), which leverages the rotation of the Earth to form a huge telescope which observes at a wavelength of 1.3 mm, giving an angular resolution of 20 micro-arcseconds. VLBI can be used to observe other things as well; for example the Event Horizon Telescope also recorded data from our Milky Way galaxy, where there is source of radio noise called Sagittarius A*, likely the location of another black hole. However, it is much smaller than M87, making it harder to image. The Event Horizon Telescope is at work imaging the black hole in our galaxy.
Furthermore, the image of M87 also enables astronomers to measure the radius of the black hole, as it provides a clear, circular shadow. Using the radius, we can estimate the mass of the black hole. This measurement yielded an estimated mass of 6.5 billion solar masses, and can be generalized across other black hole. Since it is heavier than most other estimates, it suggests that the masses of other black holes may be underestimated.
Finally, the image confirms Einstein's theory of general relativity, which predicts that when too much matter or energy is crammed into a small enough volume, space-time would collapse, leading to an eternal gravity trap from which light cannot even escape. The black hole casts a shadow by creating a dark region when immersed in a bright region such as a disc of glowing gas. The circular shadow is caused by the gravitational bending and capture of light by the event horizon of the black hole.
General Post 2:
http://www.astronomy.com/news/2019/04/a-new-neutron-star-merger-is-caught-on-x-ray-cameraWhen neutron stars collide, they give off powerful signals, both on the electromagnetic spectrum and as gravitational waves. Back in October 2017, the first gravitational waves were detected from the merger of two neutron stars. This event was also the advent of multi-messenger astronomy, in which many telescopes observed a single event as different types of signals, including optical light, X-rays, and gamma rays. Now, a second neutron star merger has been detected in the form of an X-ray signal named XT2. The signal originated from a galaxy 6.6 billion light years away, in which two neutron stars combined into a single, heavier neutron star. This body is called a magnetar, because of its extremely strong magnetic field This is a completely new way to detect a neutron star merger, using X-rays instead of gravity waves. The X-ray signal matched astronomer’s predictions for this kind of event.
A neutron star is the final stage of some massive stars, formed after a supernova, when the star’s core collapses into dense, hot ball of neutrons about 20 meters in diameter. These neutron stars spin very quickly and possess very strong magnetic fields, trillions of times that of Earth. Magnetars, as their name suggests, are neutron stars with particularly strong magnetic fields, on the order of thousands of times that of regular neutron stars, or a quadrillion that of Earth. They are very rare, as only 30 of them are known. Their behavior can’t be replicated in a lab, so they need to be observed in order to learn more about them. For example, in the collision and merger of two neutron stars, a heavy neutron star emerges, which indicated that their structure is relatively resilient.
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