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

  1. #691
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    I understand that at least one astronomer observing KIC 8462852 was notified of the discovery of this supposed dip in light output some time ago, via Reddit. That seems to compensate for the 'overlooked' possibility.

    A lack of response there, even a negative one, in light of a former willingness to communicate, suggests that a simple refutation might not have been considered appropriate. Perhaps the question of the dip's significance can not be scientifically resolved at this time. Alternatively, perhaps something potentially significant was discerned, but requires further analysis, before speaking openly of it.

  2. #692
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    Quote Originally Posted by Ross 54 View Post
    I understand that at least one astronomer observing KIC 8462852 was notified of the discovery of this supposed dip in light output some time ago, via Reddit. That seems to compensate for the 'overlooked' possibility.
    I did notice that a few days ago. I believe that you were the person who brought it up, and you didn't really get a positive or negative response?

    Quote Originally Posted by Ross 54 View Post
    A lack of response there, even a negative one, in light of a former willingness to communicate, suggests that a simple refutation might not have been considered appropriate. Perhaps the question of the dip's significance can not be scientifically resolved at this time. Alternatively, perhaps something potentially significant was discerned, but requires further analysis, before speaking openly of it.
    I think we can agree that we can't make any definitive conclusions about it. So I think it's completely appropriate to discuss it in the context of "if this ends up being true, then..." I was a bit concerned (maybe wrongly so) that some people seemed to be discussing it as if it were a definite finding that had to be explained.
    As above, so below

  3. #693
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    Quote Originally Posted by Ross 54 View Post
    If one wants to consider technological possibilities, carbon is beginning to be recognized as a advanced construction material. I wouldn't be surprised to learn that stellar engineering, or megastructures, wherever they might exist, make use of carbon nanotubes in various forms.
    That might be true, but what you're doing it taking the latest early 21st century thing and projecting it into a future that seems a bit further along. So maybe there's something else, even better than carbon, that is being used at that time.
    As above, so below

  4. #694
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    Quote Originally Posted by Ross 54 View Post
    Particles that preferentially absorb green light should be around 510 to 550 nanometers in size. Since carbon nanotubes are on the order of 1 nanometer in diameter, complex structures built up from these could assume dimensions capable of preferentially obscuring green light.
    That may be true, but then you could say that for any size. Is there any reason that complex structures would be 510 to 550 instead of say 200 or 300 or 700? To me, that's like saying, "there is a building 100 feet long, and bricks are a foot long, so it must be a brick building."
    As above, so below

  5. #695
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    Quote Originally Posted by Jens View Post
    I did notice that a few days ago. I believe that you were the person who brought it up, and you didn't really get a positive or negative response?




    I think we can agree that we can't make any definitive conclusions about it. So I think it's completely appropriate to discuss it in the context of "if this ends up being true, then..." I was a bit concerned (maybe wrongly so) that some people seemed to be discussing it as if it were a definite finding that had to be explained.
    Yes, I brought the matter up on Reddit. A moderator then decided to bring it to the attention of Dr. Boyajian, who besides actively observing KIC 8462852, is also a moderator there. I am not aware that she has given any response.

    There is nothing definite about the supposed Nov.--Dec. 2016 dip in light output. It merely looked to me as if a reasonable case could be made for it, and that it was worth pursuing, in the absence of more obvious dips.
    Last edited by Ross 54; 2017-Mar-06 at 02:48 AM.

  6. #696
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    Quote Originally Posted by Jens View Post
    That might be true, but what you're doing it taking the latest early 21st century thing and projecting it into a future that seems a bit further along. So maybe there's something else, even better than carbon, that is being used at that time.
    Hard to know how long a given technology will remain useful. Humans discovered fire at least half a million years ago, and still find it has many valuable applications, some not so very different from the original ones.

  7. #697
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    Quote Originally Posted by Jens View Post
    That may be true, but then you could say that for any size. Is there any reason that complex structures would be 510 to 550 instead of say 200 or 300 or 700? To me, that's like saying, "there is a building 100 feet long, and bricks are a foot long, so it must be a brick building."
    I had been working with the suggested premise, that absorption of light from the star in the V band could be due to carbon compounds. It seemed unlikely that enough of these would be present in comets or the intervening interstellar medium to dim the star by 4 percent.

    With the idea of carbon still in mind, I recalled the work that has begun with carbon nanotubes. Seeing that they are much smaller than the wavelength of V band light, complex assemblies of them suggested itself. The connection with the original suggestion about the Swan bands of absorption by relatively simple carbon compounds is admittedly tenuous.

  8. #698
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    I (as a contributor) have just received a report on KIC 8462852 by Boyagian from Kickstarter.

  9. #699
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    Quote Originally Posted by Tom Mazanec View Post
    I (as a contributor) have just received a report on KIC 8462852 by Boyagian from Kickstarter.
    So what does it say?
    As above, so below

  10. #700
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    Quote Originally Posted by Jens View Post
    So what does it say?
    The report is supposed to be for the people who contributed money to the campaign...I just thought I'd give a heads up to people who don't follow their email much. I am one of those people, BTW, it is just a fluke that I was checking my email for something else a few minutes after the report arrived.
    I could copy and paste the report, but I'm not sure that would be "cricket".

  11. #701
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    My understanding (from the thread you started on reddit!) is that there was reference to a dip in 1978 (but I have no idea what the observational data is from), and also that they are requesting time on the HST to do imaging. Again I don't know what data they would get from the HST.
    As above, so below

  12. #702
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    In the last few weeks there were a couple articles on KIC 8462852 on Dream of the Open Channel:
    https://disownedsky.blogspot.com/

  13. #703
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    Quote Originally Posted by Tom Mazanec View Post
    In the last few weeks there were a couple articles on KIC 8462852 on Dream of the Open Channel:
    https://disownedsky.blogspot.com/
    Don't suppose you'd care to highlight some goodies?

  14. #704
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    Quote Originally Posted by DaveC426913 View Post
    Don't suppose you'd care to highlight some goodies?
    He does a lot of data analysis with the AAVSO observations. There seems to be some statistical basis for a slight dimming over the time the AAVSO has been observing this star, but there needs to be more data to confirm it, so he plans to update the results in a few months.

  15. #705
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    Tabetha Boyajian and Jason Wright are reporting on Twitter that the star has dipped in brightness again (2% light loss in the R band as of last plot). So folks set up for accurate relative photometry with CCDs, there it is... Folks set up for spectroscopy, there it really is...

  16. #706
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    You beat me to it! Hopefully some useful spectra or interesting time detail data will limit the models of what's happening there.
    Forming opinions as we speak

  17. #707
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    If I remember correctly, last year, were they not predicting a dip in May of this year? Does this mean that an object/material is orbiting at predictable period now?

  18. #708
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    If the dimming is caused by a solar energy collector orbiting the star in 750 days, what Kardashev level does this imply? I think about 1.4...am I right?

  19. #709
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    So what area of the star, would that exclude? About half a million km across square?
    Formerly Frog march..............

    “One is never alone with a rubber duck.” The Golgafrinchan Ark B captain

  20. #710
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    When should I expect to hear results of the current dimming? Especially if its spectrum is achromatic?

  21. #711
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    Tabby's Star has started to do its thing again.

    https://www.universetoday.com/135644...maybe-dimming/

    The first indications that the star was dimming again were reported late last month by the Fairborn Observatory in Arizona. The robotic telescope spotted what might be a dip in brightness on April 24th, 2017. Within a week, the brightness returned to normal levels, but the event (known as “Event 1” in the star’s light curve, shown below) caught the interest of astronomers around the world.

    Then on May 18th, a more significant drop began, which prompted the observatory’s scientists to put out the call to observatories around the world to begin turning their telescopes to Tabby’s Star. According to the alert issued by the Observatory, the star had already dimmed by 2% after just one night of observation. As soon as the Sun set in their respective regions, observatories around the world began monitoring the star and recording its light curve.


    “[At] about 4 a.m. this morning I got a phone call from [Tabitha Boyajian] that Fairborn Observatory in Arizona had confirmed that the star was 3 percent dimmer than it normally is. That is enough that we are absolutely confident that this is no statistical fluke. We’ve now got it confirmed at multiple observatories, I think.”

  22. #712
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    The dimming seems to be achromatic:
    http://www.astronomerstelegram.org/?read=10406
    This would support the ETI hypothesis.

  23. #713
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    Quote Originally Posted by Tom Mazanec View Post
    The dimming seems to be achromatic:
    http://www.astronomerstelegram.org/?read=10406
    This would support the ETI hypothesis.
    Sorry, I'm not familiar with the term. Does achromatic mean that the dimming takes place through all wavelengths equally?
    As above, so below

  24. #714
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    Quote Originally Posted by Jens View Post
    Sorry, I'm not familiar with the term. Does achromatic mean that the dimming takes place through all wavelengths equally?
    Yes.

  25. #715
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    Achromatic -- wavelength-independent.

    Starspots are not achromatic -- that's been used to estimate their temperatures.

    Dust and gases make non-achromatic extinction, at least if the dust particles are not much larger than a few microns. That's from diffraction and Rayleigh scattering. That's what makes interstellar reddening.

    Larger dust particles on up may make achromatic extinction, at least if their reflectance is non-achromatic (gray).

  26. #716
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    One of the possibilities being considered is that it is an intrinsic dimming. For example, it ate a planet and is now returning to baseline. Would that produce an achromatic dimming?
    As above, so below

  27. #717
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    Quote Originally Posted by Jens View Post
    One of the possibilities being considered is that it is an intrinsic dimming. For example, it ate a planet and is now returning to baseline. Would that produce an achromatic dimming?
    Over the decades, but not the dips every couple years, is my understanding.

  28. #718
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    Quote Originally Posted by lpetrich View Post
    Achromatic -- wavelength-independent.

    Starspots are not achromatic -- that's been used to estimate their temperatures.

    Dust and gases make non-achromatic extinction, at least if the dust particles are not much larger than a few microns. That's from diffraction and Rayleigh scattering. That's what makes interstellar reddening.

    Larger dust particles on up may make achromatic extinction, at least if their reflectance is non-achromatic (gray).
    Would you expect to see infra red excess though?

    Any material in orbit, whether natural or ETI in origin, must re-emit absorbed light energy as IR ? And given the scale of some of the previous dips it must be quite a sizeable IR emission.

  29. #719
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    And if this putative dust is in a 750 day orbit around a F3 star it has to be warm enough to emit quite a bit of IR anyway.

  30. #720
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    Latest rumor is that there is "color" after all
    From my post on the Reddit:
    Planets as they migrate can collide (a dust ring around an old star was attributed to this a few years ago, and some simulations have this happening in the inner Solar System billions of years from now). So say about a couple centuries ago two planets collided in the KIC 8462852 system. Big cloud of debris formed. Gradually, it starts spreading out. As the dust starts to form a ring, the star begins to dim, while the cloud still orbits in the ring like a diamond on a wedding band. So the star slowly dims, with a dip every orbit, Could this work?

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