First we saw black hole mergers. Then we saw two neutron stars collide. Now LIGO’s gearing up to reveal the secrets of the universe’s birth.
Source: www.cnet.com/news/gravitational-wave-detectors-upgraded-to-hunt-for-extreme-cosmic-events/’
Apparently our galaxy really likes to boogie. It has, on several occasions, enjoyed a Monster Mash; now it’s been caught doing the Twist. A new study has revealed that the Milky Way isn’t a nice, neat, flat disc – it’s seriously warped around the edg
Source: www.sciencealert.com/the-milky-way-s-disc-is-all-warped-and-twisted
ESO’s exquisitely sensitive GRAVITY instrument has added further evidence to the long-standing assumption that a supermassive black hole lurks in the centre of the Milky Way. New observations show clumps of gas swirling around at about 30% of the speed of light on a circular orbit just outside its event horizon — the first time material has been observed orbiting close to the point of no return, and the most detailed observations yet of material orbiting this close to a black hole.
Radio astronomers are increasingly using convolutional neural networks to sift through massive amounts of data
Last year’s mysterious outburst of deep-space light flashes was even more frenzied than previously thought, a new study reports.
Source: www.space.com/41775-breakthrough-listen-fast-radio-bursts.html
Astronomers are now able to detect a host of signals streaming through the universe. This newfound ability is like gaining new senses and it’s opening the door to understanding the cosmos.
Source: theconversation.com/new-era-of-astronomy-uncovers-clues-about-the-cosmos-100155
For decades, scientists have theorized that beyond the edge of the solar system, at a distance of up to 50,000 AU (0.79 ly) from the sun, there lies a massive cloud of icy planetesimals known as the Oort Cloud. Named in honor of Dutch astronomer Jan Oort, this cloud is believed to be where long-term comets originate from. However, to date, no direct evidence has been provided to confirm the Oort Cloud’s existence.
Source: phys-org.cdn.ampproject.org/c/s/phys.org/news/2018-08-oort-clouds-stars-visible-cosmic.amp
“It was a rare case in astronomy where two competing models … offered precisely opposite predictions,” said UCLA professor Steven Furlanetto.
Source: newsroom.ucla.edu/releases/astronomers-find-far-fewer-galaxies-than-they-expected
Nobody knows what these rare speedy electromagnetic spurts really are
Chile’s Very Large Telescope tracks S2 star as it reaches mind-boggling speeds by supermassive black hole
New findings are fueling an old suspicion that fundamental particles and forces spring from strange eight-part numbers called âoctonions.â
Source: www.quantamagazine.org/the-octonion-math-that-could-underpin-physics-20180720/
The Gaia Sausage: The Major Collision That Changed the Milky Way Galaxy on Simons Foundation
An international team of astronomers has discovered an ancient and dramatic head-on collision between the Milky Way and a smaller object, dubbed the “Sausage” galaxy. The cosmic crash was a defining event in the early history of the Milky Way and reshaped the structure of our galaxy, fashioning both its inner bulge and its outer halo, the astronomers report in a series of new papers.
The astronomers propose that around 8 billion to 10 billion years ago, an unknown dwarf galaxy smashed into our own Milky Way. The dwarf did not survive the impact: It quickly fell apart, and the wreckage is now all around us.
“The collision ripped the dwarf to shreds, leaving its stars moving in very radial orbits” that are long and narrow like needles, said Vasily Belokurov of the University of Cambridge and the Center for Computational Astrophysics at the Flatiron Institute in New York City. The stars’ paths take them “very close to the center of our galaxy. This is a telltale sign that the dwarf galaxy came in on a really eccentric orbit and its fate was sealed.”
The new papers in the Monthly Notices of the Royal Astronomical Society, The Astrophysical Journal Letters and arXiv.org outline the salient features of this extraordinary event. Several of the papers were led by Cambridge graduate student GyuChul Myeong. He and colleagues used data from the European Space Agency’s Gaia satellite. This spacecraft has been mapping the stellar content of our galaxy, recording the journeys of stars as they travel through the Milky Way. Thanks to Gaia, astronomers now know the positions and trajectories of our celestial neighbors with unprecedented accuracy.
The paths of the stars from the galactic merger earned them the moniker “the Gaia Sausage,” explained Wyn Evans of Cambridge. “We plotted the velocities of the stars, and the sausage shape just jumped out at us. As the smaller galaxy broke up, its stars were thrown onto very radial orbits. These Sausage stars are what’s left of the last major merger of the Milky Way.”
The Milky Way continues to collide with other galaxies, such as the puny Sagittarius dwarf galaxy. However, the Sausage galaxy was much more massive. Its total mass in gas, stars and dark matter was more than 10 billion times the mass of our sun. When the Sausage crashed into the young Milky Way, its piercing trajectory caused a lot of mayhem. The Milky Way’s disk was probably puffed up or even fractured following the impact and would have needed to regrow. And Sausage debris was scattered all around the inner parts of the Milky Way, creating the ‘bulge’ at the galaxy’s center and the surrounding ‘stellar halo.’
Numerical simulations of the galactic mashup can reproduce these features, said Denis Erkal of the University of Surrey. In simulations run by Erkal and colleagues, stars from the Sausage galaxy enter stretched-out orbits. The orbits are further elongated by the growing Milky Way disk, which swells and becomes thicker following the collision.
Evidence of this galactic remodeling is seen in the paths of stars inherited from the dwarf galaxy, said Alis Deason of Durham University. “The Sausage stars are all turning around at about the same distance from the center of the galaxy.” These U-turns cause the density in the Milky Way’s stellar halo to decrease dramatically where the stars flip directions. This discovery was especially pleasing for Deason, who predicted this orbital pileup almost five years ago. The new work explains how the stars fell into such narrow orbits in the first place.
The new research also identified at least eight large, spherical clumps of stars called globular clusters that were brought into the Milky Way by the Sausage galaxy. Small galaxies generally do not have globular clusters of their own, so the Sausage galaxy must have been big enough to host a collection of clusters.
“While there have been many dwarf satellites falling onto the Milky Way over its life, this was the largest of them all,” said Sergey Koposov of Carnegie Mellon University, who has studied the kinematics of the Sausage stars and globular clusters in detail.
Deputy President of the Republic of South Africa, Mr David Mabuza, today officially inaugurated the MeerKAT radio telescope. After a decade in design and construction, this project of South Africa’s Department of Science and Technology has now begun science operations. At the launch event, a panorama obtained with the new telescope was unveiled that reveals extraordinary detail in the region surrounding the supermassive black hole at the centre of our Milky Way Galaxy. This is one of several very exciting new views of the Universe already observed by the telescope.
“We wanted to show the science capabilities of this new instrument”, says Fernando Camilo, chief scientist of the South African Radio Astronomy Observatory (SARAO), which built and operates MeerKAT in the semi-arid Karoo region of the Northern Cape. “The centre of the galaxy was an obvious target: unique, visually striking and full of unexplained phenomena – but also notoriously hard to image using radio telescopes”, according to Camilo. The centre of the Milky Way, 25,000 light-years away from Earth and lying behind the constellation Sagittarius (the “Teapot”), is forever enshrouded by intervening clouds of gas and dust, making it invisible from Earth using ordinary telescopes. However, infrared, X-ray, and in particular, radio wavelengths penetrate the obscuring dust and open a window into this distinctive region with its unique 4 million solar mass black hole. “Although it’s early days with MeerKAT, and a lot remains to be optimised, we decided to go for it – and were stunned by the results.”
“This image is remarkable”, says Farhad Yusef-Zadeh of Northwestern University in Evanston, Illinois, one of the world’s leading experts on the mysterious filamentary structures present near the central black hole but nowhere else in the Milky Way. These long and narrow magnetised filaments were discovered in the 1980s using the Very Large Array (VLA) radio telescope in New Mexico, but their origin has remained a mystery. “The MeerKAT image has such clarity”, continues Yusef-Zadeh, “it shows so many features never before seen, including compact sources associated with some of the filaments, that it could provide the key to cracking the code and solve this three-decade riddle”.
Yusef-Zadeh adds that “MeerKAT now provides an unsurpassed view of this unique region of our galaxy. It’s an exceptional achievement, congratulations to our South African colleagues. They’ve built an instrument that will be the envy of astronomers everywhere and will be in great demand for years to come”.
New data from the Gaia mission has revealed a surprise hidden among main-sequence stars.
Source: aasnova.org/2018/07/11/3796/
