"Similar Event Within 100 Light Years of Earth Would Be Catastrophic" --Astronomers...

For most of 2016, astronomers have been viewing a ball of hot gas billions of light years away that is radiating the energy of hundreds of billions of suns. At its heart is an object a little larger than 10 miles across. And astronomers are not entirely sure what it is. If, as they suspect, the gas ball is the result of a supernova, then it’s the most powerful supernova ever seen.

Most astronomers today believe that one of the plausible reasons we have yet to detect intelligent life in the universe is due to the deadly effects of local supernova explosions within 100 light years that wipe out all life in a given region of a galaxy. While there is, on average, only one supernova per galaxy per century, there is something on the order of 100 billion galaxies in the observable Universe. Taking 10 billion years for the age of the Universe (it's actually 13.7 billion, but stars didn't form for the first few hundred million), Dr. Richard Mushotzky of the NASA Goddard Space Flight Center, derived a figure of 1 billion supernovae per year, or 30 supernovae per second in the observable Universe! In June of 2015, this flaring spot of light was found by the All Sky Automated Survey for Supernovae (ASASSN) run by Ohio State astronomers and labelled ASASSN-15lh. Located about three billion light years distant, the source appears tremendously bright for anything so far away: roughly 200 times brighter than an average supernova, and temporarily 20 times brighter than all of the stars in our Milky Way Galaxy combined. The above-featured artist's illustration depicts a hypothetical night sky of a planet located across the host galaxy from the outburst.

“If you walked outside and saw a person who was six feet tall, and then someone who was six thousand feet tall, you would notice,” says team member Todd Thompson of Ohio State University. “You begin to question whether this is even a person.”

In the January 14, 2016 issue of the journal Science, the Ohio State team report that the object at the center could be a very rare type of star called a magnetar—but one so powerful that it pushes the energy limits allowed by physics.

Even in a discipline that regularly uses gigantic numbers to express size or distance, the case of this small but powerful mystery object in the center of the gas ball is so extreme that the team’s co-principal investigator, Krzysztof Stanek of The Ohio State University, turned to the movie This is Spinal Tap to find a way to describe it.

“If it really is a magnetar, it’s as if nature took everything we know about magnetars and turned it up to 11,” Stanek said. (For those not familiar with the comedy, the statement basically translates to “11 on a scale of 1 to 10.”)

The gas ball surrounding the object can’t be seen with the naked eye, because it’s 3.8 billion light years away. But it was spotted by the All Sky Automated Survey for Supernovae (ASAS-SN, pronounced “assassin”) collaboration. Led by Ohio State, the project uses a cadre of small telescopes around the world to detect bright objects in our local universe.

Though ASAS-SN has discovered some 250 supernovae since the collaboration began in 2014, the explosion that powered ASASSN-15lh stands out for its sheer magnitude. It is 200 times more powerful than the average supernova, 570 billion times brighter than our sun, and 20 times brighter than all the stars in our Milky Way Galaxy combined.

“We have to ask, how is that even possible?” said Stanek, professor of astronomy at Ohio State. “It takes a lot of energy to shine that bright, and that energy has to come from somewhere.”

“The honest answer is at this point that we do not know what could be the power source for ASASSN-15lh,” said Subo Dong, lead author of the Science paper and a Youth Qianren Research Professor of astronomy at the Kavli Institute for Astronomy and Astrophysics at Peking University.

He added that the discovery “may lead to new thinking and new observations of the whole class of superluminous supernova.” Todd Thompson, professor of astronomy at Ohio State, offered one possible explanation. The supernova could have spawned an extremely rare type of star called a millisecond magnetar, a rapidly spinning and very dense star with a very strong magnetic field.

To shine so bright, this particular magnetar would also have to spin at least 1,000 times a second, and convert all that rotational energy to light with nearly 100 percent efficiency, Thompson explained. It would be the most extreme example of a magnetar that scientists believe to be physically possible.

“Given those constraints,” he said, “will we ever see anything more luminous than this? If it truly is a magnetar, then the answer is basically no.”

The Hubble Space Telescope will help settle the question later this year, in part because it will allow astronomers to see the host galaxy surrounding the object. If the team finds that the object lies in the very center of a large galaxy, then perhaps it’s not a magnetar at all, and the gas around it is not evidence of a supernova, but instead some unusual nuclear activity around a supermassive black hole.

If so, then its bright light could herald a completely new kind of event, said study co-author Christopher Kochanek, professor of astronomy at Ohio State and the Ohio Eminent Scholar in Observational Cosmology. It would be something never before seen in the center of a galaxy.

“It’s worse than that. We haven’t even found another stellar system that resembles our own, which has effectively thrown their “nebular hypothesis” for planetary evolution into the trash bin.”

Actually, there are computer models which do show solar systems relatively like ours forming. The problem is that gas giants tend to shred such systems to bits. Something ... and this is more plausible than the use of vague language may suggest ... stopped Jupiter from descending into a very short orbit and pulled it back to a wider orbit. This knocks a few zeroes off any estimate acquired using Drake’s equation, but in no way disproves the nebular hypothesis.

>> Correct, although most scientists refuse to acknowledge this and cling to the “cosmological principle”, an assumption that contradicts the evidence. <<

Well, the Hercules-Corona Borealis Great Wall apparently contradicts the cosmological principle, but that’s actually irrelevant. It’s a quirk of relativity that no matter where you are, you are at the center of the universe. Not that you seem to be relatively in the middlish region of the universe, but the exact center to as precise a degree as can ever be measured. So it’s not coincidental that we’re at the oldest part of the universe, but it’s not meaningless, either. Further portions of the universe are shown to have galaxies composed mostly of star systems with very low levels of heavy elements, demonstrating that they are younger, and therefore lack the prerequisites of life.

>> The only thing I’m wondering is, does temporal distortion kick in if the motion is due to the expansion of space itself? <<

Wow... I have to retrace all my thinking on this. (Which is based purely on following the logic of the physics; I don’t have near the math skills to know any real, math-based physics.) The quick, sloppy answer, which I’m not sure is right, is that to catch up the matter, you’d have to go travel faster than light, which would mean you’d go backwards in time. If you simply always were at a distant part of the universe, you’d be going closer to the speed of light, relative to earth, and so you’d be age slower, and so again, the universe would be younger. But if you warped time-space, I guess you’d be on a time-space island of old universe surrounded by younger universe? But any light (or any form of entropy) reaching you would be the same light reaching the younger universe, so you’d still appear to be at the center of the universe, with nothing but your advanced age to suggest otherwise?

>> Seems like an optimistic estimate to me even so. If we didn’t know there was life on at least one planet, I would say the probability was effectively zero. Since there is life on at least one planet, then either it’s due to some extraordinary circumstance (like divine intervention), or we hit the biggest lottery drawing ever held. <<

Well, the anthropological principle would say that if there’s going to be life on any planet in the universe, and you’re life, you’re going to be on that planet. I think applying the anthropological principle to the multiverse is a copout, until the dimensions past four are somehow proven to be substantially thick... but it’s not like you’re going to pop into sentience on the wrong planet and then say, “Oh no! Wrong planet!” and die.

Another factor not in the Drake equation:

You need tides for life. That means you need a massive moon, relative to the host planet. Earth, so far, has the only such massive moon. There are moons on Jupiter larger than ours, but Jupiter is so much massive, that they are puny relative to Jupiter, and as such were simple for Jupiter to catch. Earth catching the moon by gravity might be something like sinking a hole in one from 10,000 yards without hitting the grass. The present theory for the existence of such a massive moon around such a modestly-sized planet is that it’s the result of a direct (yet glancing) collision.

But a collision with what?

“Actually, there are computer models which do show solar systems relatively like ours forming.”

A computer model can be made to show you anything you want to see though. In the real world observations of systems with exoplanets, we haven’t found any resembling our configuration yet.

We’ll never be able to actually witness a system forming over a long enough timescale to confirm or deny the nebular hypothesis, so you cannot test the models that way. However, we have predictions from the models BEFORE exoplanets were observed, and that precludes scientists from having done any funny business to force their algorithms to fit observations when they produced those predictions. The predictions were a failure, and that should doom the hypothesis, as far as I’m concerned. I wouldn’t trust any new predictions to not simply be the result of tweaking the algorithm to produce the results they want.

“The quick, sloppy answer, which I’m not sure is right, is that to catch up the matter, you’d have to go travel faster than light, which would mean you’d go backwards in time.”

This can’t be right, because anything with mass can’t even reach the speed of light, much less go faster. I’m thinking that temporal distortion must happen regardless of whether you are moving or the space expanding is moving you though, because according to relavity, the cause of the motion wouldn’t matter, only the rate of motion from whichever frame of reference you pick.

“I think applying the anthropological principle to the multiverse is a copout, until the dimensions past four are somehow proven to be substantially thick... but it’s not like you’re going to pop into sentience on the wrong planet and then say, “Oh no! Wrong planet!” and die.”

I think the whole multiverse stuff is silly... it isn’t wholly illogical, but it’s also not really science, since the nature of the proposition makes it impossible we could ever prove or disprove it by scientific means. So it’s more philosophy dressed up like science than science.

>> A computer model can be made to show you anything you want to see though. <<

Weeeellll, yeah. You can model to the point of simply showing a computer portrayal of your assumptions, and this is basic critique of global-warming models. But I’m referring to computer-based simulations of the behavior of gasses and distinct particles with very little inputs besides mass and momentum.

>> This can’t be right, because anything with mass can’t even reach the speed of light, much less go faster. <<

Yes, you can regard it as a thought exercise.

And I agree vis-a-vis multiverses. An intellectual copout.

Note: this topic is from 07/28/2016. Thanks LibWhacker.

Most astronomers today believe that one of the plausible reasons we have yet to detect intelligent life in the universe is due to the deadly effects of local supernova explosions within 100 light years that wipe out all life in a given region of a galaxy. While there is, on average, only one supernova per galaxy per century, there is something on the order of 100 billion galaxies in the observable Universe. Taking 10 billion years for the age of the Universe (it's actually 13.7 billion, but stars didn't form for the first few hundred million), Dr. Richard Mushotzky of the NASA Goddard Space Flight Center, derived a figure of 1 billion supernovae per year, or 30 supernovae per second in the observable Universe!



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