Author Topic: Boyajians Star Updates And Discussion  (Read 185408 times)

Offline Stan-1967

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Re: Boyajians Star Updates And Discussion
« Reply #900 on: 12/08/2017 11:36 PM »
His claims are becoming more modest & aligned to observation, at least the regarding the orbital period part. I did note this quote:

"The presence of a BD in an eccentric 1601 day orbit could be detectable in 2017 October and November through radial velocity (RV) observations with a potential amplitude of ~1–2 km s−1."

Also, I found this paper by B.Gary dating back to August.  I don't recall seeing it [posted here, but it is the same as the Iopscience link.
https://arxiv.org/ftp/arxiv/papers/1711/1711.07472.pdf

With a radial shift of 1-2 km/sec, this should be easy to test, as that is a huge velocity shift.  Props to them for the prediction.  An interesting follow would be "what is the explanation if no radial shift is found, or if it is much smaller, say near detection limit of 1 m s-1?    Seeing that we are past the date where they predicted the shift, we should expect another paper soon.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #901 on: 12/09/2017 08:24 AM »
His claims are becoming more modest & aligned to observation, at least the regarding the orbital period part. I did note this quote:

"The presence of a BD in an eccentric 1601 day orbit could be detectable in 2017 October and November through radial velocity (RV) observations with a potential amplitude of ~1–2 km s−1."

Also, I found this paper by B.Gary dating back to August.  I don't recall seeing it [posted here, but it is the same as the Iopscience link.
https://arxiv.org/ftp/arxiv/papers/1711/1711.07472.pdf

With a radial shift of 1-2 km/sec, this should be easy to test, as that is a huge velocity shift.  Props to them for the prediction.  An interesting follow would be "what is the explanation if no radial shift is found, or if it is much smaller, say near detection limit of 1 m s-1?    Seeing that we are past the date where they predicted the shift, we should expect another paper soon.

What interested me is the claim that the huge ring system would only be a transient phenomenon. What could have caused that, disrupted moon?

Offline Stan-1967

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Re: Boyajians Star Updates And Discussion
« Reply #902 on: 12/09/2017 04:40 PM »

What interested me is the claim that the huge ring system would only be a transient phenomenon. What could have caused that, disrupted moon?
 
That is the weakness of all the propositions beyond the orbital period.   From his earlier paper & statements (post #895):

'As models are developed for natural structures that can
account for the observed fades (such as ring systems and
comas) there will be a parallel effort needed for the
development of the physical mechanisms that can
produce such structures."


I think it was J.Wright who said the uniqueness of this star makes it allowable to invoke 1, or maybe 2 extraordinary conditions to explain it.  I'm beginning to move to the side that it's going to take more than 1 or 2, & I can't fault B.Gary for at least trying to think it through, but he has gotten ahead of himself, even though he admits it will take a long time & many continued observations to solve the riddle.

1.  He makes a solid testable hypothesis regarding the periodicity,
2.  but rather than waiting to confirm the periodicity, he then makes suppositions as to the nature of the occulting material being in the same orbit, which then leads him to constrain the primary object needing to be a massive BD type object.
3.  He predicts the massive BD also have an easily detectable radial velocity shift.  Also testable, & to date, unsupported.
4.   Since he invokes a massive BD object, he then thinks he can invoke chaotic transient conditions with moon & comets inside the BD's Hill Sphere.

He could have played it safe & stopped at point #1 to wait for confirming periodicity.  Expanding to #2 is a reach, but perhaps understandable given the lengths of the dips, the orbital mechanics do constrain what else can be orbiting close by & impact the light curve.

I don't see it being useful to him to move beyond #2 until more is known.   Developing physical mechanism for chaotic transients built on 2 as yet unproven hypotheses is not likely to hold up & the paper unnecessarily devolves from there.


Offline Mongo62

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Re: Boyajians Star Updates And Discussion
« Reply #903 on: 12/09/2017 11:26 PM »

Offline RotoSequence

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Re: Boyajians Star Updates And Discussion
« Reply #904 on: 12/10/2017 09:15 AM »
I think it was J.Wright who said the uniqueness of this star makes it allowable to invoke 1, or maybe 2 extraordinary conditions to explain it.  I'm beginning to move to the side that it's going to take more than 1 or 2, & I can't fault B.Gary for at least trying to think it through, but he has gotten ahead of himself, even though he admits it will take a long time & many continued observations to solve the riddle.

How many extraordinary conditions does it take before you're allowed to invoke ETI as a simpler and more logical explanation?
« Last Edit: 12/10/2017 09:21 AM by RotoSequence »

Offline KelvinZero

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Re: Boyajians Star Updates And Discussion
« Reply #905 on: 12/10/2017 10:14 AM »
I think it was J.Wright who said the uniqueness of this star makes it allowable to invoke 1, or maybe 2 extraordinary conditions to explain it.  I'm beginning to move to the side that it's going to take more than 1 or 2, & I can't fault B.Gary for at least trying to think it through, but he has gotten ahead of himself, even though he admits it will take a long time & many continued observations to solve the riddle.
How many extraordinary conditions does it take before you're allowed to invoke ETI as a simpler and more logical explanation?
People have been trying to match to ETI explanations right from the beginning. So far, no good match.

There is no specific level of weirdness at which aliens become preferred. What you do is you compete theories to see which has the most explaining power. The default theory of "some unspecified natural phenomenon" beats "some undefined ETI phenomenon" even though both predict nothing, so to begin building a case for aliens you have to have a more specific theory for what they are doing, such as building a dyson sphere, starlifting, or perhaps show evidence that the light curve is matched by a cloud of hexagons in deep space between us and this star.. Those sorts of hypotheses could each be used to make all sorts of predictions.

..or we could find new evidence that they are sending out signals encoding prime numbers. Suddenly aliens would leap ahead as an explanation, though some portion of scientists would still no doubt have a go at trying to come up with a natural explanation for that. Good luck to them.

That is when aliens will become a serious contender. It won't just be "Weird! Aliens!" it will be a specific story about aliens that fits what we have so far and fits future tests that we perhaps wouldn't even have considered making without that story.

Another way of looking at it, is think of all the tests that could have strengthened the case for aliens already, but that have failed. It doesn't look like a conventional dyson swarm because we have found evidence that the occlusion is being cause by a specific grain size, for example, that just blocks light below a certain wavelength close to the grain size (I think. I might have the explanation wrong). Not large contiguous sheets then. Or what if the spectra had suggested certain unlikely chemistry, such as chlorophyl? As far as I know there is nothing like that, just these cold grains in space.
« Last Edit: 12/10/2017 10:19 AM by KelvinZero »

Offline RotoSequence

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Re: Boyajians Star Updates And Discussion
« Reply #906 on: 12/10/2017 10:40 AM »
We don't actually have enough data to say more than some of the dips are caused by ultra-fine dust particles that orbit the star too closely to persist without replenishment. Other than that, we know that a lot of unusually structured objects are orbiting the star, with simple integer relationships showing up in their relative locations and/or orbital periods. Much of the spectroscopic data that has been gathered for KIC8462852 remains unpublished.

Oh, and the star is getting dimmer over time.

I really wish Kepler could still see this star. While I'm wishing for it, a followup to Kepler that also performs continuous photometry and spectroscopy of stars.
« Last Edit: 12/10/2017 12:39 PM by RotoSequence »

Offline as58

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Re: Boyajians Star Updates And Discussion
« Reply #907 on: 12/10/2017 02:22 PM »
Other than that, we know that a lot of unusually structured objects are orbiting the star, with simple integer relationships showing up in their relative locations and/or orbital periods.

I have seen nothing convincing about "strange" integer relationships. If you try as hard as some people have tried with this star, you're sure to find all sorts of relationships.

Offline RotoSequence

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Re: Boyajians Star Updates And Discussion
« Reply #908 on: 12/10/2017 02:56 PM »
Other than that, we know that a lot of unusually structured objects are orbiting the star, with simple integer relationships showing up in their relative locations and/or orbital periods.

I have seen nothing convincing about "strange" integer relationships. If you try as hard as some people have tried with this star, you're sure to find all sorts of relationships.

I didn't say anything about strange integer relationships, just simple ones of a common multiple. It's the curve of the dimming events themselves that are strange! ;)

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #909 on: 12/10/2017 06:47 PM »
By the way SETI have been observing the star but I haven’t seen any recent data on that, unless someone has seen different?

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #910 on: 12/10/2017 09:32 PM »
Finally an update that seems worth posting.

Quote
Dip update 124/n
December 10, 2017
[Orig: Dec 10, 2017]
 
Hi everyone,
 
The past two days have shown some interesting changes to WTF's brightness.  Yesterday, data taken from both OGG and TFN (bad weather at ELP) showed the brightness has significantly dropped down, however, the data taken last night from TFN, ELP, and OGG show a brightening back up to normal levels.
 
More later!
 
~Tabby and team

http://www.wherestheflux.com/single-post/2017/12/10/Dip-update-124n

Offline the_other_Doug

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Re: Boyajians Star Updates And Discussion
« Reply #911 on: 12/12/2017 07:11 PM »
I think it was J.Wright who said the uniqueness of this star makes it allowable to invoke 1, or maybe 2 extraordinary conditions to explain it.  I'm beginning to move to the side that it's going to take more than 1 or 2, & I can't fault B.Gary for at least trying to think it through, but he has gotten ahead of himself, even though he admits it will take a long time & many continued observations to solve the riddle.

How many extraordinary conditions does it take before you're allowed to invoke ETI as a simpler and more logical explanation?

I think you have to have done six impossible things before breakfast... :D
-Doug  (With my shield, not yet upon it)

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #912 on: 12/15/2017 08:13 PM »
Reddened Dimming of Boyajian's Star Supports Internal Storage of Its "Missing" Flux

Quote
The F star KIC 8462852 ("Boyajian's star") has attracted attention by its deep dimming episodes lasting days to weeks (Boyajian et al. 2016) superposed on slower dimming events sometimes lasting for years (Montet & Simon 2016; Schaefer 2016). Originally, it was assumed (e.g., Wright & Sigurdsson 2016) that storage of blocked heat flux inside the star could not explain this behavior, although such internal storage has long been recognized as the mechanism responsible for the photometric variation of magnetically active stars, including the Sun (Spruit 1982; Foukal et al. 1983).

Recently, we pointed out that such blocking by star-spots might be generalized to other, possibly non-magnetic, obstructions to heat flow in convective stars (Foukal 2017). For example, location of the star near the transition between convective and radiative transport might cause sporadic decreases in heat flux. Alternatively, differential rotation and dynamo action are found to modulate convection in an F star rotating much faster than the Sun (e.g., Augustson et al. 2013).

We show here that such an explanation of the photometric behavior of KIC 8462852 seems to be supported by the star's reddening during two of its sporadic irradiance dips, observed in recent multi-color photometry.

Quote
In conclusion, the most plausible explanation of the reddening of KIC 8462852 during its brief dimmings appears to be photospheric cooling. Together with other evidence on possible reddening of the slower dimmings and on their timing following the brief dips, it favors interpretation as a transient reduction of the star's heat transport efficiency (Foukal 2017 see also Sheikh et al. 2016). MHD modeling of heat flow variability in early F stars (e.g., Augustson et al. 2013) could help to identify the specific mechanism of the heat flow blocking.

Rest on the link.

http://iopscience.iop.org/article/10.3847/2515-5172/aaa130/meta
« Last Edit: 12/15/2017 08:18 PM by Star One »

Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #913 on: 12/15/2017 09:02 PM »
Another recent paper: The GALEX View of "Boyajian's Star" (KIC 8462852) - (James. R. A. Davenport et al)

Quote
The enigmatic star KIC 8462852, informally known as "Boyajian's Star", has exhibited unexplained variability from both short timescale (days) dimming events, and years-long fading in the Kepler mission. No single physical mechanism has successfully explained these observations to date. Here we investigate the ultraviolet variability of KIC 8462852 on a range of timescales using data from the GALEX mission that occurred contemporaneously with the Kepler mission. The wide wavelength baseline between the Kepler and GALEX data provides a unique constraint on the nature of the variability. Using 1600 seconds of photon-counting data from four GALEX visits spread over 70 days in 2011, we find no coherent NUV variability in the system on 10-100 second or months timescales. Comparing the integrated flux from these 2011 visits to the 2012 NUV flux published in the GALEX-CAUSE Kepler survey, we find a 3% decrease in brightness for KIC 8462852. We find this level of variability is significant, but not necessarily unusual for stars of similar spectral type in the GALEX data. This decrease coincides with the secular optical fading reported by Montet & Simon (2016). We find the multi-wavelength variability is somewhat inconsistent with typical interstellar dust absorption, but instead favors a RV = 5.0 ± 0.9 reddening law potentially from circumstellar dust.

Also, an update from Boyajian mentioned their paper about the current dips is in review.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #914 on: 12/24/2017 07:48 PM »
According to one of its authors this paper has now been revised and updated following feedback.

A 1574-day periodicity of transits orbiting KIC 8462852

Quote
Observations of the main sequence F3 V star KIC 8462852 (also known as Boyajian's star) revealed extreme aperiodic dips in flux up to 20% during the four years of the Kepler mission. Smaller dips (< 2%) were also observed with ground-based telescopes between May and September 2017. We investigated possible correlation between recent dips and the major dips in the last 100 days of the Kepler mission. We compared Kepler light curve data, 2017 data from two observatories (TFN, OGG) which are part of the Las Cumbres Observatory (LCO) network and Sternberg observatory archival data, and determined that observations are consistent with a 1,574-day (4.31 year) periodicity of a transit (or group of transits) orbiting Boyajian's star within the habitable zone. It is unknown if transits that have produced other major dips as observed during the Kepler mission (e.g. D792) share the same orbital period. Nevertheless, the proposed periodicity is a step forward in guiding future observation efforts.

https://arxiv.org/abs/1710.01081

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #915 on: 12/29/2017 06:21 AM »
Professor Boyajian’s next paper is out on 03/01/2018 along with a press release at 9am central time.

Quote
The paper will be introduced to the rest of the world on January 3, 2017 (any sooner and it would get lost in the holiday mix), and we are planning a press release for 9am central time. I request that you respect this embargo and not share the paper openly until this time.

https://www.reddit.com/r/KIC8462852/comments/7mcrkq/mod_announcement_please_respect_the_3_january/

This info only appears on the Reddit not on her Twitter account.
« Last Edit: 12/29/2017 06:31 AM by Star One »

Online Johnnyhinbos

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Re: Boyajians Star Updates And Discussion
« Reply #916 on: 12/29/2017 11:06 AM »
Um, if my date math is correct, Jan 3, 2017 has long come and gone...
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #917 on: 12/29/2017 11:41 AM »
Um, if my date math is correct, Jan 3, 2017 has long come and gone...

Yeah they mean 2018.

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #918 on: 12/29/2017 08:39 PM »
A new post from Jason Wright.

Quote
To answer some questions:

Yes, Tabby meant 2018.

The press release is because, as you may have noticed, the media finds this story very interesting. We were confident that we would learn a lot if we could catch the star in the act, and now that we have caught it it's important to share what we've learned.

But it's not obvious what we've learned from a quick look; you have to really analyze it. We've had lots of discussions, data analysis, mistakes, false leads, and blind alleys. It's a huge author list and there have been many people putting eyes on it, making it better, catching mistakes, and refining the conclusions before we submitted.

Then the referee had a lot of good suggestions, and we had to follow those up and do another round with the authors.

Since we know that the media will want to know what's going on, we have to make sure we give them what they need to get it right. This means press releases in multiple languages, and discussions among the authors about who is available to chat with the press, and making sure we're all on the same page about what the conclusions are.

Finally, there's timing. The holidays are a tough time because lots of academics travel between semesters and visit family (I'm in the basement of a relative's house now, editing a press release while the family gets lunch ready) and we don't want to just let the news dribble out when people are so busy. Tabby's already being flooded with interview requests.

So, we've aimed for January 3 which is after the holidays but before the AAS meeting on Jan 8 (which will dominate astronomy news for the week). This gives the press time to get the story right, us time to give them quotes and help them get the story right, and is fair to the various media outlets (no one who plays by the rules gets left out).

To be clear, the embargo is enforced by our institutions with press releases, not by the journal in this case. It's a handshake deal to keep science journalism accurate and timely.

We have a unique situation because we've shared the paper with our Kickstarter backers, so it's "out there", meaning an unscrupulous reporter could potentially get a copy without agreeing to the embargo. Then they could scoop the responsible journalists that are interviewing us to make sure they have it right with their own inexpert take on the paper. That's not good for anyone involved, so we appreciate our backers' efforts (and those of the mod here) to keep the paper private until Jan. 3.

https://www.reddit.com/r/KIC8462852/comments/7mcrkq/mod_announcement_please_respect_the_3_january/

Allegedly the paper has 199 co-authors.
« Last Edit: 12/29/2017 08:45 PM by Star One »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #919 on: 01/01/2018 10:02 PM »
Additional commentary commentary from Jason Wright will be found on the link below once the embargo lifts.

 http://sites.psu.edu/astrowright/2018/01/01/why-my-lasts-2-posts-are-private/

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