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| Space news roundup! Cool cloud around A*, etc | Aug 07, 2019 8:56 PM PDT | url |
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Added 1 new A* page:Space news rrrroundup!
- Spektr-RG: powerful X-ray telescope launches to map cosmos (BBC): This Russian/German space telescope "will map X-rays across the entire sky in unprecedented detail"; "Spektr-RG is expecting to detect perhaps three million super-massive black holes during its service life."
- A Cool Accretion Disk around the Galactic Centre Black Hole (arXiv): A scientific research paper describes a relatively cool, disc-shaped cloud of hydrogen gas, about 1.5 trillion miles in diameter (~ a quarter of a light year), rotating at about 2,000 km/s around the supermassive black hole at the center of our galaxy, the radio source designated "Sagittarius A*." Hydrogen gas at less than 10 million degrees K does not produce X-rays, which had enabled much of this mostly ~10,000 K cloud to escape prior detection; the scientists spotted it with the ALMA radio telescope array. The paper includes a pretty nifty diagram showing the known structures around Sgr A*, including a radial cloud of stars weighing a total of about 1 million solar masses of stars within 1 parsec (3.26 light years) of the black hole—imagine 1 million stars the size of the Sun, all within 3/4th of the distance from Earth to Earth's next closest star, Alpha Centauri! It also mentions that the black hole seems to control the movements of stars within one light year of it. They estimate the black hole would swallow the current cloud within about 120 years, if it was not being replenished ("we think that replenishing is more likely a continuous process as the Galactic Center is a complex region with no shortage of gas supply either hot or cold"). They describe the density of the cloud, estimated (I think) at 100,000 to 1,000,000 atoms of hydrogen per cubic meter, as "tenuous," having "minimal" effect on the velocity of major bodies—actual dense gas clouds, or stars—passing through it ("roughly equivalent [in the case of dense cloud object G2, and if the hydrogen gas is a thin, even layer] to an aluminium ball 1 cm in diameter passing through a 1mm layer of water"). Overall, this paper is far and away the most detailed description of the galactic core I've ever come across! Sent in by @n1vus, from a tweet by @JossBlandHawtho, showing that diagram of the galactic core.
- The Marines’ New Drone-Killer Aces Its First Real World Test (Wired): US Marines used a powerful signal jammer—it emits blasts of radio waves—to fry the circuits of an Iranian drone that approached a US warship in the Persian Gulf; this constitutes "the first-ever 'kill' by a US directed-energy weapon." From a tweet by @PaulHChadwick.
- LightSail-2 Mission Shows Solar Sailing’s Potential for Spaceflight (NYT): A nonprofit's Earth-orbiting craft, with a gossamer sail "roughly the area of a boxing ring," demonstrated it could use the pressure of sunlight across the whole surface of the sail ("the equivalent of the weight of a paper clip pushing down on your hand") to adjust its orbit slightly: raising one side of its orbit by a mile over the course of four days.
- Milky Way galaxy is warped and twisted, not flat (BBC): Turns out that as you move to the outer parts of the galaxy, the "disc" of stars becomes warped and twisted, with the arrangement of stars curving significantly above or below the flat-ish "galactic plane" arrangement followed by stars closer to the core. Kind of a big deal. : o
- Tardigrades: 'Water bears' stuck on the moon after crash (BBC): An Israeli spacecraft that crashed on the Moon in April—its mission was to land there, but it suffered an engine failure—carried a supply of dehydrated, amber-encased "water bears": little microscopic organisms that can survive extreme conditions. So in theory, if they get cracked out of their artificial amber casing, and get a little heat and moisture—dehydration put them in stasis—they'll spring to life. Nice knowing you, Moon.
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