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World & Current Events > The "Alien Megastructure" Strikes Again!

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message 1: by Matthew (new)

Matthew Williams (houseofwilliams) The subject of Tabby's Star has been a controversial one in the astronomical community since 2015, when it was first detected. Basically, this star exhibited a strange and significant drop in brightness, which astronomers spent the next two years tying to explain. The more imaginative (i.e. crazy) people suggested it was an alien megastructure passing the star. And now, its at it again! What do you think?

http://www.skyandtelescope.com/astron...


message 2: by Alex (new)

Alex (asato) cool, man.

of course, the data is there, but what's producing it is quite a bit more difficult to pin down. but it's always fun to speculate. it's an F class, so the goldilocks zone is farther out than we are. could be dyson ring in the making.


message 3: by Matthew (last edited May 23, 2017 09:40PM) (new)

Matthew Williams (houseofwilliams) That's what I would like to see. Not anything that proves that, that would be too much to ask for. But if all the studies at this point could fail to provide any natural explanation, that would leave all us nerds free to speculate!

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message 4: by Alex (last edited May 20, 2017 11:09PM) (new)

Alex (asato) nice pic.

even if the behavior is regular, it could still be artificial. unless the pattern is too complex, maybe?

the article did point to another article stating that the star was slowly dimming over the course of a century and if even states that it would take a huge number of comets to cause block the light from that star. so what are we left with? maybe there's a black hole nearby feeding on it?
Here, I provide a light curve of 1338 Johnson B-band magnitudes from 1890 to 1989 taken from archival photographic plates at Harvard. KIC8462852 displays a secular dimming at an average rate of 0.164+-0.013 magnitudes per century. From the early-1890s to the late-1980s, KIC8462852 faded by 0.193+-0.030 mag. The decline is not an artifact because nearby check stars have closely flat light curves. This century-long dimming is unprecedented for any F-type main sequence star. Thus the Harvard light curve provides the first confirmation (past the several dips seen in the Kepler light curve alone) that KIC8462852 has anything unusual. The century-long dimming and the day-long dips are both just extreme ends of a spectrum of timescales for unique dimming events. By Ockham's Razor, two such unique and similar effects are very likely produced by one physical mechanism. This one mechanism does not appear as any isolated catastrophic event in the last century, but rather must be some ongoing process with continuous effects. Within the context of dust-occultation models, the century-long dimming trend requires 10^4 to 10^7 times as much dust as for the deepest Kepler dip. Within the context of the comet-family idea, the century-long dimming trend requires an estimated 648,000 giant comets (each with 200 km diameter) all orchestrated to pass in front of the star within the last century.
(https://arxiv.org/abs/1601.03256)



message 5: by Nik (new)

Nik Krasno | 13758 comments A giant comet or a dusty clump as theorized by astronomers might be a trivial explanation, however it's clear that the outer space contains a lot of surprises and it's only so much we can decipher from afar...
Hope space travel is imminent


message 6: by Matthew (new)

Matthew Williams (houseofwilliams) Alex G wrote: "nice pic.

even if the behavior is regular, it could still be artificial. unless the pattern is too complex, maybe?

the article did point to another article stating that the star was slowly dimmin..."


This is true. There have been some very good and comprehensive explanations of what could account for this. My favorite so far has been this one, where a planet was being consumed:

https://arxiv.org/pdf/1612.07332v1.pdf


message 7: by Alex (new)

Alex (asato) Matthew wrote: "AThis is true. There have been some very good and comprehensive explanations of what could account for this. My favorite so far has been this one, where a planet was being consumed"

ah, that sounds more likely than a black hole and within the realm of reasonable plausability.


message 8: by P.K. (new)

P.K. Davies | 358 comments Don't understand much of this. But I question the theory of a planet being drawn into the star. Does this not question relativity? Once established are bodies not spacial-stable?


message 9: by Matthew (new)

Matthew Williams (houseofwilliams) Not necessarily. For instance, it has been theorized that during the process of planetary formation that large bodies can form farther out and then migrate towards a star.


message 10: by Ian (new)

Ian Miller | 9737 comments Needless to say, my view is different from most others :-). However, in 2011 I published "Planetary Formation and Biogenesis" which started with a review of the topic (over 600 references, then an analysis from which I put forward my theory. To summarise, I predicted that in certain cases there will be a failed Venus. My argument is that rocky bodies, when they collide, either bounce off each other, creating a little dust, or sit beside each other, but if the latter, another collision knocks them away. The difficulty is, there are no collisions until the bodies generate some orbital eccentricity, and then the collisions tend to get violent, at least some of the time. (The debris in the film "Gravity" did not make dynamical sense.) Now, for the rocky debris to stick together, they need something to hold them, and that is cement, basically calcium aluminosilicates but also possibly magnesium silicates, set by gaseous water in the disk. Water can set cements up to about 550 degrees C but it gets increasingly difficult. In this concept the, it is the aluminosilicate cements that make the feldsic/granitic continents. If I am right, the small cratons that make Ishtar and Aphrodite terra on Venus will be the only significant granitic/feldsic masses outside Earth in this solar system. Unfortunately, getting samples is difficult. That is also why Earth has so much water, and Venus does not. Then material that made Mars never got hot enough to make significant aluminosilicates, which is why there is no significant granite on Mars, and just a very limited amount of plagioclase.

Thus there are two critical temperature profiles: the initial star formation when the disk processes the dust to a significant temperature, and to get Earth, you need it to get to about 1550 degrees C at 1 AU (to melt iron and form the aluminosilicates) and later, the temperature when the cements set the rocks, which here was about 0 degrees C at 1 AU plus or minus a fair bit. If the two temperature profiles do not match so well, and the Earth type planet can only form closer to the star, interior to that will be a boulder belt. The chances of seeing that are quite low (same as eclipsing planets, except this option seems to be inherently rare.) So, in my opinion, Tabby's star matches on of my predictions. Of course it still could be because of something else, but I still like my choice.


message 11: by Baz (new)

Baz MW (bazcatt) Matthew wrote: "That's what I would like to see. Not anything that proves that, that would be too much to ask for, But if all the studies at this point could fail to provide any natural explanation, that would lea..."

If this is it, I'll trade places any day! (Provided I can bring my cat)


message 12: by Matthew (new)

Matthew Williams (houseofwilliams) Ian wrote: "Needless to say, my view is different from most others :-). However, in 2011 I published "Planetary Formation and Biogenesis" which started with a review of the topic (over 600 references, then an ..."

Your view is different and you have a theory of your own? You don't say! ;)


message 13: by Ian (new)

Ian Miller | 9737 comments Actually, yes, I thought I did say :-) Or at least write :-)


message 14: by Ian (new)

Ian Miller | 9737 comments And on top of that, big surprise, I think it is a good theory :-)


message 15: by P.K. (new)

P.K. Davies | 358 comments For my part I am grateful for that science, Ian. Does your chemical knowledge get us nearer to finding the magic formula for life?


message 16: by Ian (new)

Ian Miller | 9737 comments P.P., if you mean where you might find land-based life in the Universe, it requires a planet around a G type star (our sun is one) or a heavy K type star (the next smallest down) and that star had to get rid of its accretion disk quickly after formation, otherwise the planets get too big. Certain red dwarfs might have life on water worlds but I doubt it. It is most likely to form only on an earth type planet, where you get feldsic continents, because only then do you get enough water to keep the process going long enough. My guess is there won't have been life on Mars because possible conditions did not last long enough, BUT something might have got started and because many of the different water systems were not connected, some may have made more progress than others, so Mars might offer "chemical fossils" that outline what the process was. This is conditional on there also being nitrogen buried on Mars. You need water for life, but you also need other things, nitrogen being one of them. There will be no life under the ice of Europa because all evidence is there is no significant nitrogen on the Jovian moons (the ebook shows why) and also there is no mechanism to make phosphate esters there. Phosphate esters are critical, because they are the ONLY chemical group that can make three linkages that can be changed tolerably easily, and that is needed for reproduction. Thus nucleic acids have two links to hold them together, and one function to change their solubility - i.e. do they form intertwined chains, or do they separate. You can't reproduce without the ability to be in both states.


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