Request this item to view in the Library's reading rooms using your library card. To learn more about how to request items watch this short online video.
You can view this on the NLA website. Login Register.
- Naval History and Heritage Command;
- Echoes from Space?
- Prokrastiniert Euch (German Edition).
- Ians Gang - Straight Out Of Hell.
- Half Bad!
Advanced search Search history. Browse titles authors subjects uniform titles series callnumbers dewey numbers starting from optional. See what's been added to the collection in the current 1 2 3 4 5 6 weeks months years.
Your reader barcode: Your last name:. Cite this Email this Add to favourites Print this page. You must be logged in to Tag Records. The new film "Earth to Echo" — which follows a group of kids on a fictional journey to help save a small alien robot — might have a bit of extraterrestrial truth at its core, one alien-hunting astronomer says. As it turns out, writer Henry Gayden's "Zombie Roadkill," the upcoming "Children of the Lamp" depiction of a small, owl-like alien robot might be a more likely candidate for first contact than most people would expect, said Seth Shostak , a senior astronomer at the SETI Institute in Mountain View, California.
Given the dynamics of interstellar travel, robots make sense, he said.
That is just decades away. Cybernetic brains seem to be the way to go when traversing the huge distances between stars, Shostak added.
Machines are not stuck with Darwin. In his role with SETI, Shostak not only oversees much of the science underpinning the sprawling project, but also spends a lot of time pondering the implications. That makes sense. Given the distances and physics involved in traveling vast distances across space, Shostak thinks that extraterrestrial visitors are likely to be both artificial and small.
Neurons of all species are about the same size. So if you can build smart things that are small, it makes sense to do so.
Scientists detect radio echoes of a black hole feeding on a star | MIT News
Of course, smaller is also cuter. While the last statement has a humorous bent, animal researchers have suggested that the eye size and spacing of baby mammals are traits that evolved, in part, to make them cute, because cute animals are more likely to be nurtured by their parents and, therefore, survive. The source of the X-ray emissions is thought to be ultrahot material in the innermost regions of the accretion disk, which is just about to fall into the black hole. Optical and ultraviolet emissions likely arise from material further out in the disk, which will eventually be pulled into the black hole.
However, what gives rise to radio emissions during a tidal disruption flare has been up for debate. Some scientists propose that, in the moments after the stellar explosion, a shockwave propagates outward and energizes the plasma particles in the surrounding medium, in a process that in turn emits radio waves. In such a scenario, the pattern of emitted radio waves would look radically different from the pattern of X-rays produced from infalling stellar debris.
Soon after the initial discovery, multiple electromagnetic telescopes focused on the event, which astronomers coined ASASSNli.
Tonight's Sky — Change location
Pasham and van Velzen perused radio data from three telescopes of the event over days. The researchers looked through the compiled radio data and discovered a clear resemblance to patterns they had previously observed in X-ray data from the same event. When they fit the radio data over the X-ray data, and shifted the two around to compare their similarities, they found the datasets were most similar, with a 90 percent resemblance, when shifted by 13 days.
That is, the same fluctuations in the X-ray spectrum appeared 13 days later in the radio band. From this same data, Pasham and van Velzen calculated the size of the X-ray-emitting region to be about 25 times the size of the sun, while the radio-emitting region was about , times the solar radius. The team proposes that the radio waves were produced by a jet of high-energy particles that began to stream out from the black hole shortly after the black hole began absorbing material from the exploded star.
Because the region of the jet where these radio waves first formed was incredibly dense tightly packed with electrons , a majority of the radio waves were immediately absorbed by other electrons. Thus, they say, the strength of the jet must be controlled by the accretion rate, or the speed at which the black hole is consuming X-ray-emitting stellar debris. Ultimately, the results may help scientists better characterize the physics of jet behavior — an essential ingredient in modeling the evolution of galaxies.
Related Echoes Among the Stars: A Short History of the U.S. Space Program
Copyright 2019 - All Right Reserved