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Thread: Up to 22% Dips Detected in Starlight 1,500 LY Away

  1. #781
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    Quote Originally Posted by Mudskipper View Post
    they can usually tell from the red-shift and blue-shift, of the sides of the star, if it is rotating, I think...not sure.
    Starlight is a point source. Suppose you were looking down at Ecuador. You could not tell from Doppler if the earth rotates from Chicago towards Quito, Quito to Chicago, the correct way (prograde), retrograde, or anything in between. Looking down at the pole you would not see a Doppler shift. Looking down at a point near the arctic circle you would see some Doppler but not much.

  2. #782
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    JPL News release:
    Wavelength dependent dimming points to micrometer sized dust particles as responsible for the long term dimming. A comet swarm remains the most likely cause of the larger, short-term dimming. These same comets could be a plausible source of the dust for the long-term dimming. More study (of course) is needed.

    https://www.jpl.nasa.gov/news/news.php?release=2017-258

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  3. #783
    Another study shows that the dimming might be asymmetric or if it symmetric it might have a ten year or longer period.
    https://arxiv.org/abs/1710.05000
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  4. #784
    looks likes like tabby star is up to ir again.
    http://www.wherestheflux.com/single-...9/tldr-DIPPING
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  5. #785
    I wonder if there is any interaction between the star wind or the magnetic fields of the star with the material.
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  6. #786
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    Could this be a synestia in orbit around this star? Synestia is some sort of dusty collision merger between protoplanets.

    as per this thread:

    New-theory-on-Moon-formation
    Last edited by transreality; 2018-Mar-20 at 11:03 PM. Reason: add thread link

  7. #787
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    The timescale of this recent dip is only a couple of days. It is already returning to baseline.

    To me, this "quick dip" behaviour is not consistent with extended debris clouds in wide orbits ?

  8. #788
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    Quote Originally Posted by kzb View Post
    The timescale of this recent dip is only a couple of days. It is already returning to baseline.

    To me, this "quick dip" behaviour is not consistent with extended debris clouds in wide orbits ?
    If the synestia is formed by the accretion of super earth it can be closer to the star, hotter, and therefore has a longer lifetime before it collapses. Parts of the synestia that pass out of the Roche limit can condense into proto-moons. Depending on the state of evolution of the synestia it could be quite lumpy, and depending on the orientation of the disc we might not see the main planetary condensation, instead just see the moonlets.

  9. #789
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    Quote Originally Posted by transreality View Post
    If the synestia is formed by the accretion of super earth it can be closer to the star, hotter, and therefore has a longer lifetime before it collapses. Parts of the synestia that pass out of the Roche limit can condense into proto-moons. Depending on the state of evolution of the synestia it could be quite lumpy, and depending on the orientation of the disc we might not see the main planetary condensation, instead just see the moonlets.
    Moonlets don't shield enough light to produce dips of the required magnitude. It has to be dust, to cover a large enough area.

    If that dust is close to this F-type star, within its Roche limit, it will be hot. I'm no expert but surely this would be detected in the IR?

    My question at the moment is we have a paper (see post #783) which says the period, if there is one, is ten years or more. This implies a wide orbit (that is, if we accept the idea these events are due to dust in orbit).

    Yet the duration of this latest dip is only about 4 or 5 days. I am asking if this can truly be rationalised via dust in 10-year orbit ?

  10. #790
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    Quote Originally Posted by kzb View Post
    Yet the duration of this latest dip is only about 4 or 5 days. I am asking if this can truly be rationalised via dust in 10-year orbit ?
    Whatever is going on it doesn't seem to be finished. It only stayed back at baseline for a day and now is down even farther than it was last week.

  11. #791
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    Can we gather anything from the shape of the curve?

    It does not look like a sine wave, nor the shadow of any solid object.

    It seems to arc down smoothly to a minimum but then bounce back up quite rapidly, making a curve akin to a bouncing ball.

    What phenomena would fit such a curve?

    Or am I reading too much in to the curve?

    tabbysstar.png

  12. #792
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    Quote Originally Posted by ExoZZ View Post
    Whatever is going on it doesn't seem to be finished. It only stayed back at baseline for a day and now is down even farther than it was last week.
    Yes I saw that as well. The time taken by the first dip is about a week. Surely this tells something about the orbital period.

    It returned to 100% flux very briefly and is now on its next dip.

  13. #793
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    Quote Originally Posted by DaveC426913 View Post
    Can we gather anything from the shape of the curve?

    It does not look like a sine wave, nor the shadow of any solid object.

    It seems to arc down smoothly to a minimum but then bounce back up quite rapidly, making a curve akin to a bouncing ball.

    What phenomena would fit such a curve?

    Or am I reading too much in to the curve?

    tabbysstar.png

    Speaking as a complete novice, this latest episode does not look like a solid body transit. Or should I say that probability is low.

    I would say it fits with a translucent cloud, perhaps densest in the middle.

    A planet transit shape is a rapid dip down to a level, staying close to horizontal for a while and then returning to baseline quickly as the planet clears the limb. This is not like that.

    It is possible for a planetary body to produce a sharp curve shape, if the orbit just clips the edge of the stellar disk, as seen from here. On its own that may be a possibility.

    BUT, the magnitude of the dip (current one is -5%) is too big for a planet. It's an order of magnitude larger than even a Hot Jupiter would produce. So that would seem to negate the clipping of the stellar disk theory.
    Last edited by kzb; 2018-Mar-27 at 12:29 PM.

  14. #794
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    The flux is on its way back up again. If it continues like this, it will be another sharp pointy dip, like the last one.

  15. #795
    Yes the dip is a lot more now about the same as before.
    https://phys.org/news/2018-03-tabby-star-dims.html
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  16. #796
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    The second dip has returned to baseline.

    Interestingly, this was a symmetrical dip, -5% at peak and lasting about a week. Followed by a tail of about -0.5% before return to baseline.

    So this cloud (if that is what it is) has a tail. A spherically symmetric cloud with a short tail ?

  17. #797
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    May I suggest we move this topic over to Astronomy? I never "got" the Life in Space angle, as there was only ever a vanishingly small probability that anything "living" was responsible for the phenomenon (though it was brilliant from a PR perspective).

    CJSF
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  18. #798
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    Quote Originally Posted by CJSF View Post
    May I suggest we move this topic over to Astronomy? I never "got" the Life in Space angle, as there was only ever a vanishingly small probability that anything "living" was responsible for the phenomenon (though it was brilliant from a PR perspective).

    CJSF
    Still weird tho

  19. #799
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    Quote Originally Posted by alromario View Post
    Still weird tho
    Yes, it is weird. A strange astronomical phenomenon under current observation, research, and review.

    CJSF
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    If you were incorrect
    A fact is just a fantasy
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  20. #800
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    Latest...

    https://arxiv.org/abs/1806.09911

    The KIC 8462852 Light Curve From 2015.75 to 2018.18 Shows a Variable Secular Decline

    Bradley E. Schaefer, Rory O. Bentley, Tabetha S. Boyajian, Phillip H. Coker, Shawn Dvorak, Franky Dubois, Emery Erdelyi, Tyler Ellis, Keith Graham, Barbara G. Harris, John E. Hall, Robert James, Steve J. Johnston, Grant Kennedy, Ludwig Logie, Katherine M. Nugent, Arto Oksanen, John J. Ott, Steve Rau, Siegfried Vanaverbeke, Rik van Lieshout, Mark Wyatt
    (Submitted on 26 Jun 2018)

    The star KIC 8462852 (Boyajian's Star) displays both fast dips of up to 20% on time scales of days, plus long-term secular fading by up to 19% on time scales from a year to a century. We report on CCD photometry of KIC 8462852 from 2015.75 to 2018.18, with 19,176 images making for 1,866 nightly magnitudes in BVRI. Our light curves show a continuing secular decline (by 0.023 +- 0.003 mags in the B-band) with three superposed dips with duration 120-180 days. This demonstrates that there is a continuum of dip durations from a day to a century, so that the secular fading is seen to be by the same physical mechanism as the short-duration Kepler dips. The BVRI light curves all have the same shape, with the slopes and amplitudes for VRI being systematically smaller than in the B-band by factors of 0.77 +- 0.05, 0.50 +- 0.05, and 0.31 +- 0.05. We rule out any hypothesis involving occultation of the primary star by any star, planet, solid body, or optically thick cloud. But these ratios are the same as that expected for ordinary extinction by dust clouds. This chromatic extinction implies dust particle sizes going down to ~0.1 micron, suggesting that this dust will be rapidly blown away by stellar radiation pressure, so the dust clouds must have formed within months. The modern infrared observations were taken at a time when there was at least 12.4% +- 1.3% dust coverage (as part of the secular dimming), and this is consistent with dimming originating in circumstellar dust.
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  21. #801
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    Quote Originally Posted by Roger E. Moore View Post
    Latest...

    https://arxiv.org/abs/1806.09911

    ... Our light curves show a continuing secular decline (by 0.023 +- 0.003 mags in the B-band) with three superposed dips with duration 120-180 days... This demonstrates that there is a continuum of dip durations from a day to a century, so that the secular fading is seen to be by the same physical mechanism as the short-duration Kepler dips. The BVRI light curves all have the same shape, with the slopes and amplitudes for VRI being systematically smaller than in the B-band by factors of 0.77 +- 0.05, 0.50 +- 0.05, and 0.31 +- 0.05... This chromatic extinction implies dust particle sizes going down to ~0.1 micron, suggesting that this dust will be rapidly blown away by stellar radiation pressure, so the dust clouds must have formed within months. The modern infrared observations were taken at a time when there was at least 12.4% +- 1.3% dust coverage (as part of the secular dimming), and this is consistent with dimming originating in circumstellar dust... [electronic shrieking taking over EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE]


    Can someone break this down into layperson's terms???

    CJSF
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    If you were incorrect
    A fact is just a fantasy
    Unless it can be checked
    Make a test
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  22. #802
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    Itís dust, specifically new dust?


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  23. #803
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    Quote Originally Posted by Extravoice View Post
    It’s dust, specifically new dust?
    Yup.

    Not to mention ruling out a star, planet, solid body, or "optically thick" cloud.

    So, no alien superstructure.

  24. #804
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    Quote Originally Posted by DaveC426913 View Post
    So, no alien superstructure.
    I'm not at all surprised by this. But, maybe just a little bit disappointed.
    Conserve energy. Commute with the Hamiltonian.

  25. #805
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    If that was an alien civilization with a fully or even partially built Dyson sphere, we would be in sooooooooooooooooooooo much trouble. We would be in more trouble than the Hispaniola islanders when Columbus landed. More trouble than dodos. If we ran we would die tired. No alien Dyson spheres for me, thank you.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    ó Mark Twain, Life on the Mississippi (1883)

  26. #806
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    Quote Originally Posted by Roger E. Moore View Post
    If that was an alien civilization with a fully or even partially built Dyson sphere, we would be in sooooooooooooooooooooo much trouble.
    I donít know where that logic comes from. The star we are talking about here is 1,500 light years away. It would take an incredible amount of time to cross that distance, unless FTL is possible. Do you have knowledge that FTL is possible, or do you mean that they would come after us even if it took millennia of travel?


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  27. #807
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    Quote Originally Posted by Jens View Post
    I donít know where that logic comes from. The star we are talking about here is 1,500 light years away. It would take an incredible amount of time to cross that distance, unless FTL is possible. Do you have knowledge that FTL is possible, or do you mean that they would come after us even if it took millennia of travel?
    What we don't know could kill us.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    ó Mark Twain, Life on the Mississippi (1883)

  28. #808
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    I will endeavor to put it in better terms.

    We don't know very much at all about FTL travel, or interstellar travel, or what a Kardashev Type II civilization might do if it encountered us. I sure don't know. None of us know.

    However, in the arena of thought on what might happen if two civilizations of intelligent beings were to meet, one of them very far below the other in technological ability, I use human history as my guide. Humans meet humans... and one side goes by the wayside. Or you could use humans and whales. Or humans and octopi. Or humans and great apes.

    Or humans and dodos.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    ó Mark Twain, Life on the Mississippi (1883)

  29. #809
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    Quote Originally Posted by Roger E. Moore View Post
    However, in the arena of thought on what might happen if two civilizations of intelligent beings were to meet, one of them very far below the other in technological ability, I use human history as my guide. Humans meet humans... and one side goes by the wayside. Or you could use humans and whales. Or humans and octopi. Or humans and great apes.
    What I'm disputing here is the equivalence of "an alien race 1,500 light years away having a Dyson sphere" and "two civilizations meeting." To me, 1,500 light years is a mighty long way, and if there is no FTL then I would argue that we have nothing to fear. But you weren't saying "we could be in so much trouble," you were asserting "we would be in so much trouble." If you are willing to modify that to, "we could be in so much trouble," then I have no problem with what you wrote. I completely agree that we can't rule FTL out. I'm personally very skeptical, but not certain that it is impossible.
    As above, so below

  30. #810
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    Quote Originally Posted by Roger E. Moore View Post
    What we don't know could kill us.
    Yes, could, not would.
    As above, so below

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