Author Topic: Boyajians Star Updates And Discussion  (Read 46152 times)

Offline Johnnyhinbos

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Re: Boyajians Star Updates And Discussion
« Reply #100 on: 01/23/2017 01:47 PM »
I'll add again that we're looking at 1,400 years in the past. Who knows, even if there's a Dyson sphere out there, it could be a smoldering ruin by now. Or perhaps the next thing we see is an occlusion of a near star in line but only a 100 light years from us - or perhaps we see a new star 10 light years from us and it's blue shifted, as in something's headed our way...
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline Ben the Space Brit

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Re: Boyajians Star Updates And Discussion
« Reply #101 on: 01/23/2017 02:12 PM »
That assumes that there IS a way to move FTL. It may be so that laws of physics simply don't allow it.

I don't know how current this is but I did see on one text book that the famous Feynman diagram suggests that travelling FTL is as easy as travelling STL; the thing forbidden by orthodox solutions of General Relativity is crossing the v=c barrier in either direction.
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Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #102 on: 03/05/2017 08:30 PM »
Technical overview.

The strange star discovered by Planet Hunters

http://physicstoday.scitation.org/doi/10.1063/PT.3.3504

Offline M.E.T.

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Re: Boyajians Star Updates And Discussion
« Reply #103 on: 03/16/2017 06:11 PM »
So if I recall correctly, the next big dip is expected to recur around April/May 2017, is that correct? And if it does recur, would that go some way in reducing the number of options for a potential solution to the mystery?

For example, if it does recur as predicted, am I right in saying that this would pretty much dismiss the idea that the blockage was caused by something in the interstellar medium? Because surely nothing in the interstellar medium would be rotating around the star in this manner? Instead some interstellar dust cloud would drift randomly, with a non-reptitive dimming pattern, right?

Also, my understanding is that with the number of telescopes now focused on this star, the next dimming event will be better analysed, with additional data gathering capabilities, allowing us to better understand the shape and substance of the intervening object?

In short, my understanding is that the mere fact that the dimming pattern repeats itself in April/May will tell us a whole lot, and then the data gathered from this dimming event (if it occurs) will provide further answers on top of that.

Am I correct?
« Last Edit: 03/16/2017 06:12 PM by M.E.T. »

Offline gospacex

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Re: Boyajians Star Updates And Discussion
« Reply #104 on: 03/16/2017 06:24 PM »
That's possible. New data usually gives some new ideas.

Offline M.E.T.

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Re: Boyajians Star Updates And Discussion
« Reply #105 on: 03/16/2017 06:29 PM »
That's possible. New data usually gives some new ideas.

My point is that there is rather a lot riding on this dimming event actually occuring as predicted. If it doesn't it would pretty much be a death blow to the idea of a locally orbiting object, and significantly strengthen the idea of a blockage in the interstellar medium instead.

So it is much more significant than just an opportunity to gather more data to form some new ideas.
« Last Edit: 03/16/2017 06:33 PM by M.E.T. »

Online hop

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Re: Boyajians Star Updates And Discussion
« Reply #106 on: 03/16/2017 07:23 PM »
So if I recall correctly, the next big dip is expected to recur around April/May 2017, is that correct?
IMHO "expected" is probably too strong a word. The case for the events being periodic is not very compelling.

Dr Boyajian's email newsletter to backers on Feb 22 addressed this:
Quote
The big dip "birthday" was Feb 21, 2017.  This date was calculated from the time difference the deepest dips in Kepler data occurred: dip on day 1519 minus dip on day 792 equals a "period" of 727 days. We then use 1519 (+ 727 + 727) to predict this event happening on Feb 21, 2017. Note: the dips on day 792 and 1519 look nothing like each other, they only have similar depths. 

Just wanted to send a short note to say that observations on Feb 21 and Feb 22 show no variation in the star's brightness.

This information, while not as exciting as detecting a dip, is still useful. It does not rule out the presence of any object in orbit, just any object with an orbital period of 727 days. In fact, if an object was on a 727 day orbital period, it would have meant that we would have seen a large dip in the start of the Kepler mission, and we did not.

Looking ahead, the dip at day 1519 was accompanied by dozens of other dips spanning at least 100 days, we may still see the star dip in the coming months and we are keeping a close eye on it.

Back to your post:
Quote
For example, if it does recur as predicted, am I right in saying that this would pretty much dismiss the idea that the blockage was caused by something in the interstellar medium?
It would probably disfavor it, but not clear it would rule it out. There are plenty of astrophysical processes which produce things that are repetitive at various scales, so if you accept filaments in the interstellar medium as a plausible cause, having them repeat is not a huge stretch. As Dr Boyajian notes, the existing data doesn't really favor a really strictly periodic signal. A repetitive structure generating a quasi-periodic signal might be a better fit (to be clear, this is my interpretation, not from Dr Boyajian)

Quote
Also, my understanding is that with the number of telescopes now focused on this star, the next dimming event will be better analysed, with additional data gathering capabilities, allowing us to better understand the shape and substance of the intervening object?
The main thing is that with monitoring, more instruments can be brought to bear if a new dimming is detected. Getting spectra during a dip should narrow things down a lot, or even resolve the mystery completely.
« Last Edit: 03/16/2017 07:24 PM by hop »

Offline M.E.T.

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Re: Boyajians Star Updates And Discussion
« Reply #107 on: 03/16/2017 07:31 PM »
So if I recall correctly, the next big dip is expected to recur around April/May 2017, is that correct?
IMHO "expected" is probably too strong a word. The case for the events being periodic is not very compelling.

Dr Boyajian's email newsletter to backers on Feb 22 addressed this:
Quote
The big dip "birthday" was Feb 21, 2017.  This date was calculated from the time difference the deepest dips in Kepler data occurred: dip on day 1519 minus dip on day 792 equals a "period" of 727 days. We then use 1519 (+ 727 + 727) to predict this event happening on Feb 21, 2017. Note: the dips on day 792 and 1519 look nothing like each other, they only have similar depths. 

Just wanted to send a short note to say that observations on Feb 21 and Feb 22 show no variation in the star's brightness.

This information, while not as exciting as detecting a dip, is still useful. It does not rule out the presence of any object in orbit, just any object with an orbital period of 727 days. In fact, if an object was on a 727 day orbital period, it would have meant that we would have seen a large dip in the start of the Kepler mission, and we did not.

Looking ahead, the dip at day 1519 was accompanied by dozens of other dips spanning at least 100 days, we may still see the star dip in the coming months and we are keeping a close eye on it.

Back to your post:
Quote
For example, if it does recur as predicted, am I right in saying that this would pretty much dismiss the idea that the blockage was caused by something in the interstellar medium?
It would probably disfavor it, but not clear it would rule it out. There are plenty of astrophysical processes which produce things that are repetitive at various scales, so if you accept filaments in the interstellar medium as a plausible cause, having them repeat is not a huge stretch. As Dr Boyajian notes, the existing data doesn't really favor a really strictly periodic signal. A repetitive structure generating a quasi-periodic signal might be a better fit (to be clear, this is my interpretation, not from Dr Boyajian)

Quote
Also, my understanding is that with the number of telescopes now focused on this star, the next dimming event will be better analysed, with additional data gathering capabilities, allowing us to better understand the shape and substance of the intervening object?
The main thing is that with monitoring, more instruments can be brought to bear if a new dimming is detected. Getting spectra during a dip should narrow things down a lot, or even resolve the mystery completely.

Thank you. That clarifies a lot for me. I'm not sure where I got the April/May dip expectation from then. And if the dips are in fact not strictly repetitive, what type of orbiting body could produce such a pattern? Something that changes orbital speed? Or perhaps multiple overlapping objects that only align occasionally?

Anyway, it would be rather disappointing if no dips occur ever again. The whole thing would then just fizzle out and remain a mystery, similar to the SETI "WOW" signal some decades ago.

Online hop

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Re: Boyajians Star Updates And Discussion
« Reply #108 on: 03/16/2017 08:20 PM »
Thank you. That clarifies a lot for me. I'm not sure where I got the April/May dip expectation from then.
Dr. Boyajian gives a ~100 day window starting at the end of February, so April/May could have come from someone picking the midpoint or end instead. Again, the "period" is pretty fuzzy, because the episodes of dips last varying amounts of time and the boundaries aren't well defined.
Quote
And if the dips are in fact not strictly repetitive, what type of orbiting body could produce such a pattern? Something that changes orbital speed?
The existing data already rules out single or small numbers of solid objects with a very high degree of confidence.

The original comet swarm hypothesis might be able to do it: We might only see the activity when a particularly large one disintegrates, or they might be on a much longer orbit with the ~700 day interval produced by spacing between bodies sharing the orbit e.g. due to break up on a previous orbit.

The "alien megastructure" idea can do it, because aliens can do whatever they want... or less glibly, it assumes vast swarms of objects possibly under active control, so getting periodic but variable groupings is not a stretch.

None of this is particularly satisfactory, but it's not completely unphysical ;)

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #109 on: 03/20/2017 07:34 PM »
K2 finds 23 more stars with unusual dips in their light curves.

Quote
The primary Kepler mission provided light curves for over 100,000 stars, and its continuation K2 is observing another 20,000 stars every three months. As we enter an era where these enormous photometric data sets become commonplace — Gaia will obtain photometry for millions of stars, and LSST billions — it’s crucial that we understand the different categories of variability observed in these stars.

The authors find three different types of light curves among their 23 unusual stars. Scallop-shell curves (top) show many undulations; persistent flux-dip class curves (middle) have discrete triangularly shaped flux dips; transient, narrow dip class curves (bottom) have only one dip that is variable in depth. The authors speculate a common cause for the scallop-shell and persistent flux-dip stars, and a different cause for the transient flux-dip stars. [Stauffer et al. 2017]
After filtering out the stars with planets, those in binary systems, those with circumstellar disks, and those with starspots, a number of oddities remain: a menagerie of stars with periodic variability that can’t be accounted for in these categories. Some of these stars are now famous (for instance, Boyajian’s star); some are lesser known. But by continuing to build up this sample of stars with unusual light curves, we have a better chance of understanding the sources of variability.

http://aasnova.org/2017/03/17/more-unusual-light-curves-from-kepler

Offline Ben the Space Brit

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Re: Boyajians Star Updates And Discussion
« Reply #110 on: 03/21/2017 12:34 PM »
If these other objects turn out to have the same family of spectral type, similar light curves and the same overall behaviour, I desperately hope that the IAU calls them 'Tabby-class Variables'.
« Last Edit: 03/21/2017 12:35 PM by Ben the Space Brit »
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Online jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #111 on: 03/22/2017 08:41 AM »
Unlikely, the group of 23 stars are all very very young and the dips are consistent with still-forming systems.
Tabby's star is respectably middle aged and these causes are pretty much ruled out.

But a nice thought :-)

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Offline Proponent

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Re: Boyajians Star Updates And Discussion
« Reply #112 on: 03/22/2017 10:10 AM »
For the same reason we require extraordinary evidence that some phenomenon on Earth is caused by little elf people and not some more mundane physical explanation.

That's an extremely poor comparison being as little elf people definitely don't exist but intelligent aliens possible do. And seemingly typically of the narrow thinking some take on this.

ISTM it's ultimately an application of Occam's Razor.  An explanation involving intelligence introduces a huge number of degrees of freedom and limits predictive power.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #113 on: 03/22/2017 10:29 AM »
For the same reason we require extraordinary evidence that some phenomenon on Earth is caused by little elf people and not some more mundane physical explanation.

That's an extremely poor comparison being as little elf people definitely don't exist but intelligent aliens possible do. And seemingly typically of the narrow thinking some take on this.

ISTM it's ultimately an application of Occam's Razor.  An explanation involving intelligence introduces a huge number of degrees of freedom and limits predictive power.

That's an ineffective argument against it though as it saying because this is hard to predict then it cannot be the answer.

Offline Proponent

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Re: Boyajians Star Updates And Discussion
« Reply #114 on: 03/22/2017 10:57 AM »
I'm not saying the difficulty in predicting the phenomenon in the first place is the problem, I'm saying that it's difficult to make testable predictions on the basis of an explanation involving intelligent life, because if a prediction doesn't pan out, you can probably say, "Oh well, I guess they made a different decision than the one I expected."  There are too many degrees of freedom.

To put it another way, given a large number of free variables, I can fit just about any model to any set of observations.  So, the fact that I've managed to fit a very complicated model to the observations give me very little confidence in the model.  Life, especially intelligent life, involves a very large number of degrees of freedom, so we should be very skeptical of the likelihood of an explanation involving intelligent life, unless the data are truly overwhelming.

In the context of the scientific method, simpler theories and those with greater predictive are to be preferred.  One reason for preferring predictive power is that it makes theories more testable, and testability is central to the scientific method.

A more practical reason for a scientist to prefer natural explanations is that explanations involving extraterrestrial life have poor track records:

* The canals of Mars;
* The vegetation hypothesis for the seasonal changes in Mars' coloration;
* The suggestion that Mars' moons were artificial, because the large decay rates of their orbits (which were inaccurately determined) implied very low densities;
* The LGM hypothesis for pulsars; and
* The suggestion that quasars were the exhaust plumes of starship engines (the lack of blue-shifted quasars be explained by the paucity of UV observations at the time).

(Can anybody think of any more examples?)

Explanations involving life are emotionally appealing, and there's nothing wrong with discussing them.  But I think we need guard against that appeal clouding our judgments as to their likelihoods.
« Last Edit: 03/22/2017 02:40 PM by Proponent »

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #115 on: 03/22/2017 03:07 PM »
I'm not saying the difficulty in predicting the phenomenon in the first place is the problem, I'm saying that it's difficult to make testable predictions on the basis of an explanation involving intelligent life, because if a prediction doesn't pan out, you can probably say, "Oh well, I guess they made a different decision than the one I expected."  There are too many degrees of freedom.

To put it another way, given a large number of free variables, I can fit just about any model to any set of observations.  So, the fact that I've managed to fit a very complicated model to the observations give me very little confidence in the model.  Life, especially intelligent life, involves a very large number of degrees of freedom, so we should be very skeptical of the likelihood of an explanation involving intelligent life, unless the data are truly overwhelming.

In the context of the scientific method, simpler theories and those with greater predictive are to be preferred.  One reason for preferring predictive power is that it makes theories more testable, and testability is central to the scientific method.

A more practical reason for a scientist to prefer natural explanations is that explanations involving extraterrestrial life have poor track records:

* The canals of Mars;
* The vegetation hypothesis for the seasonal changes in Mars' coloration;
* The suggestion that Mars' moons were artificial, because the large decay rates of their orbits (which were inaccurately determined) implied very low densities;
* The LGM hypothesis for pulsars; and
* The suggestion that quasars were the exhaust plumes of starship engines (the lack of blue-shifted quasars be explained by the paucity of UV observations at the time).

(Can anybody think of any more examples?)

Explanations involving life are emotionally appealing, and there's nothing wrong with discussing them.  But I think we need guard against that appeal clouding our judgments as to their likelihoods.

But then that still is ineffective argument because that then creates an inherent bias towards natural explanations. An effective argument should have no bias at all in the scientific method. There was an interesting discussion recently that scientific papers that came in from SETI were seemingly being rejected more often from publication and the argument put forward by some to explain this was there is an inherent bias by editors to anything that might include any kind of discussion of ETI.
« Last Edit: 03/22/2017 03:11 PM by Star One »

Offline JasonAW3

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Re: Boyajians Star Updates And Discussion
« Reply #116 on: 03/22/2017 07:55 PM »
Odd thought here;

      Is it possible that what we are seeing with the dips in luminosity are from multiple clouds of debris, in different orbits and with different orbital inclinations?

      In other words; is it possible that the big dip we saw the last time was a coincidental alignment of multiple debris clouds in different orbits, that just happened to align together between us and Boyajian's star?  This would explain a semi-periodic nature of the various dips we are seeing.

      But it does pose another interesting question;  If the dips are caused by multiple debris clouds in different orbits, what caused the debris clouds to form in the first place?
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Offline CuddlyRocket

Re: Boyajians Star Updates And Discussion
« Reply #117 on: 03/22/2017 09:40 PM »
There was an interesting discussion recently that scientific papers that came in from SETI were seemingly being rejected more often from publication and the argument put forward by some to explain this was there is an inherent bias by editors to anything that might include any kind of discussion of ETI.

Too many kooks have spoiled the broth!

Offline Proponent

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Re: Boyajians Star Updates And Discussion
« Reply #118 on: 03/23/2017 09:23 AM »
But then that still is ineffective argument because that then creates an inherent bias towards natural explanations. An effective argument should have no bias at all in the scientific method. There was an interesting discussion recently that scientific papers that came in from SETI were seemingly being rejected more often from publication and the argument put forward by some to explain this was there is an inherent bias by editors to anything that might include any kind of discussion of ETI.

If you follow the scientific paradigm, the repeating cycle of hypothesis and test, it is rational to prefer simple explanations.  To put it in more colloquial terms, extraordinary claims require extraordinary evidence.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #119 on: 03/23/2017 09:24 AM »
But then that still is ineffective argument because that then creates an inherent bias towards natural explanations. An effective argument should have no bias at all in the scientific method. There was an interesting discussion recently that scientific papers that came in from SETI were seemingly being rejected more often from publication and the argument put forward by some to explain this was there is an inherent bias by editors to anything that might include any kind of discussion of ETI.

If you follow the scientific paradigm, the repeating cycle of hypothesis and test, it is rational to prefer simple explanations.  To put it in more colloquial terms, extraordinary claims require extraordinary evidence.

Which again is just a form of moving the goalposts.

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