Author Topic: Boyajians Star Updates And Discussion  (Read 75270 times)

Offline M.E.T.

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Re: Boyajians Star Updates And Discussion
« Reply #600 on: 07/14/2017 07:11 AM »
Question.

If the star has been long term dimming, what is the 100% flux level they are using as the benchmark? The latest updates show 99.5% flux or thereabouts, but what is that measured against? The flux when Kepler first started observing the star? The flux from May? Because presumably this benchmark level should have been steadily declining, if the star is gradually dimming.

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #601 on: 07/14/2017 08:05 AM »
Question.

If the star has been long term dimming, what is the 100% flux level they are using as the benchmark? The latest updates show 99.5% flux or thereabouts, but what is that measured against? The flux when Kepler first started observing the star? The flux from May? Because presumably this benchmark level should have been steadily declining, if the star is gradually dimming.

You're not the first to ask this question and I can only say that this seems to vary on who the observer is. In the case of Professor Boyajian's team I confess I don't know how they've worked this out. I am sure someone will know though.
« Last Edit: 07/14/2017 08:05 AM by Star One »

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #602 on: 07/14/2017 07:13 PM »
« Last Edit: 07/14/2017 07:14 PM by Star One »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #603 on: 07/16/2017 12:12 AM »


Plus another update with the star remaining steady at its current level.

http://www.wherestheflux.com/single-post/2017/07/15/Dip-update-33n
« Last Edit: 07/16/2017 12:15 AM by Star One »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #604 on: 07/17/2017 08:00 AM »
Quote
Tabetha Boyajian @tsboyajian

Downloaded new data just before wifi fail (so no blog post today). here are the latest #TabbysStar obs

https://mobile.twitter.com/tsboyajian/status/886634761917214720

Offline TakeOff

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Re: Boyajians Star Updates And Discussion
« Reply #605 on: 07/17/2017 11:45 AM »
About the 15 July report. Flux looks pretty constant (with a 100 days gap) before day 500 after which it gets lower. But after day 600 the overwhelming majority of observation s are above the fitted curve. Is it really warranted to fit one decreasing curve over the entire period? There's no astrophysical model motivating fitting this particular "functional form" of smooth dimming.

Online high road

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Re: Boyajians Star Updates And Discussion
« Reply #606 on: 07/17/2017 12:21 PM »
About the 15 July report. Flux looks pretty constant (with a 100 days gap) before day 500 after which it gets lower. But after day 600 the overwhelming majority of observation s are above the fitted curve. Is it really warranted to fit one decreasing curve over the entire period? There's no astrophysical model motivating fitting this particular "functional form" of smooth dimming.

The fact that no astrophysical model fits the data is what makes this star so intriguing.

They've been trying to predict the star's behaviour. That's all they're doing now too. If it follows this curve, we need to find out why, meaning creating a new astrophysical model based on the observations. If it doesn't, one more prediction tested and disproved. Excellent points for falsifiability.

Ticking off the wrong theories one by one is a great and exciting way to do science. I love being able to follow this up so closely.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #607 on: 07/17/2017 10:35 PM »
Quote
Hi everyone,
 
Below is the graph with today's update. 
 
Note: on June 26 (~45 on the x-axis) and after, there have been two 40cm telescopes at each of the LCO stations (OGG and TFN) taking observations of our star (instead of one at each station).  Previously posted light curves were generated without this data taken from the second set of telescopes. However, we have now collected enough data to verify that there is consistency with the two new telescopes compared to the ones that we have been using.  So the light curve below now includes the "new", old data, combined with the data set that you are accustomed to seeing.   
 
The most recent data (there has been bad weather at OGG) look to be fairly consistent with normal brightness (i.e., the error bars on the two, right-most, blue points touch the dotted horizontal line at 1.0). This seems to indicate that the ~2 week long, 0.5% dip is nearing its end.  However, given the unpredictable nature of this object, I hesitate to make that official call just yet. Im also torn on whether we should christen these small 0.5% dips, or save the names for just the bigger ones. We'll have to make a decision on this before too long though!     
 
Lastly, we continue to work on the Elsie detection paper.  Alas, these things (science in general) always take longer than expected.  I hope it is not terribly discouraging to you, and I promise that you will be the first to hear when things finalize.
 
~Tabby and team

http://www.wherestheflux.com/single-post/2017/07/17/Dip-update-34n

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #608 on: 07/19/2017 12:26 AM »

Offline Star One

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Boyajians Star Updates And Discussion
« Reply #609 on: 07/20/2017 05:46 PM »
This 0.5% dip seems to be a unique feature especially for the length of time it's lasting, as I don't remember seeing anything like it in the Kepler data.

Quote
[Orig: July, 20 2017]
 
Hi everyone,
 
Below is the newest light curve.  Again, the weather was bad at OGG, but observations at TFN continue.  I had previously commented that the two TFN observations ~70 on the x-axis could indicate a return to normal (the error bars crossing the dotted line at 1.0).  However, perhaps this was a premature conclusion, as they are also in agreement with the 0.5% flux decrement over the past few weeks (note that compared to other measurements, the error bars on these points are somewhat larger). 
 
Got to run for now, more later!     
 
~Tabby and team

http://www.wherestheflux.com/single-post/2017/07/20/Dip-update-37n
« Last Edit: 07/20/2017 05:50 PM by Star One »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #610 on: 07/21/2017 07:36 PM »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #611 on: 07/21/2017 10:19 PM »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #612 on: 07/23/2017 06:58 PM »
Still depressed at the same level, three weeks now.

Quote
[Orig: July, 23 2017]
 
Hi everyone,
 
Excuse the break in frequent posts, Ive been traveling.  I also forgot to hit "publish" for the last update (38/n), so this is the updated post with the newest light curve as of 2 hours ago. 
 
More later!
 
 
~Tabby and team

http://www.wherestheflux.com/single-post/2017/07/23/Dip-update-38an

Offline Mongo62

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Re: Boyajians Star Updates And Discussion
« Reply #613 on: 07/23/2017 11:34 PM »

Offline meekGee

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Re: Boyajians Star Updates And Discussion
« Reply #614 on: 07/24/2017 04:25 AM »
I just watched those clips for the first time.

If I'm following correctly, then I don't agree with the methodology.   He's discounting short dips as mere "transients" that should be ignore, but looking at a somewhat longer-term decrease and inferring from it a "longer term accelerated dimming".  So basically extrapolating the second derivative.

That's a giant leap in logic.

Especially since on the 600 day view (two clips up) it's apparent that there are only two clusters of data points, so really statistically all we have is that the flux today, if you low-pass the shorter "weekish" events, is lower than it was some 300 days ago.

There is no reason to think that this is part of downward trend, and doubly no reason to think that this is part of an accelerating downward trend.

And I wish the videos were not anonymous but rather attributed to someone.  "That's all we have for you today" - who's "we"?
« Last Edit: 07/26/2017 05:21 AM by meekGee »
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Offline Star One

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Boyajians Star Updates And Discussion
« Reply #615 on: 07/24/2017 05:46 AM »
They aren't anonymous as they are all posted on his channel, him being Fredric Parker.

I didn't post that last video myself as though I did see the video, it was mostly concerned with promoting his own theory which I don't agree with.
« Last Edit: 07/24/2017 09:22 AM by Star One »

Online high road

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Re: Boyajians Star Updates And Discussion
« Reply #616 on: 07/24/2017 10:35 AM »
I agree it's too early to conclude there's a clear trend without cherrypicking the desired points. Considering the last measurements seem to have stabilized, I hope this week we'll see whether the star returns back towards normal, stays at a current level, or continues to dim.

However, should the measurements follow the 'accelerated dimming' graph, how long would it take for that hypothesis (or does the inferred formula make it a theory?) to be credible enough to warrant time on the bigger telescopes for a detailed study over many wavelengths to see if there's more dimming in certain wavelengths?

The previous request was rejected because Tabby's team was unable to specify the specific time of the measurements. If a new proposal would ask to take measurements now, and again in six months for comparison, that might be specific enough to be accepted.

Considering we're probably in for the long haul, does anyone know if there's a limit on how long the two observatories can take measurements with the available funding? Or was the funding required for Tabby's team and not for time on these two telescopes?

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #617 on: 07/24/2017 01:01 PM »
I agree it's too early to conclude there's a clear trend without cherrypicking the desired points. Considering the last measurements seem to have stabilized, I hope this week we'll see whether the star returns back towards normal, stays at a current level, or continues to dim.

However, should the measurements follow the 'accelerated dimming' graph, how long would it take for that hypothesis (or does the inferred formula make it a theory?) to be credible enough to warrant time on the bigger telescopes for a detailed study over many wavelengths to see if there's more dimming in certain wavelengths?

The previous request was rejected because Tabby's team was unable to specify the specific time of the measurements. If a new proposal would ask to take measurements now, and again in six months for comparison, that might be specific enough to be accepted.

Considering we're probably in for the long haul, does anyone know if there's a limit on how long the two observatories can take measurements with the available funding? Or was the funding required for Tabby's team and not for time on these two telescopes?

Their Kickstarter funding for their observation campaign lasts for a year. Hopefully now the star has started acting up again they shouldn't have too much trouble raising more money from another Kickstarter.

Offline Mongo62

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Re: Boyajians Star Updates And Discussion
« Reply #618 on: 07/24/2017 08:50 PM »
Especially since on the 600 day view (two clips up) it's apparent that there are only two cluster of data points, so really statistically all we have is that the flux today, if you low-pass the shorter "weekish" events, is lower than it was some 300 days ago.

There is no reason to think that this is part of downward trend, and doubly no reason to think that this is part of an accelerating downward trend.

Well, there IS the long-term gradual dimming on the order of 20%, between ~1900 and ~1970, recorded on photographic survey plates. And the measured secular dimming (1 or 2 percent?) over the full run of Kepler photometry.

Not that I am endorsing the theory propounded in the videos, that seems far too early to be justified in my opinion. But secular dimming does seem to be happening on a yearly to decadal time scale, the question is how quickly.

Offline meekGee

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Re: Boyajians Star Updates And Discussion
« Reply #619 on: 07/24/2017 08:55 PM »
Could be, and clearly something is abnormal here, but if you were to extrapolate the theorized accelerating trend he goes on about to a 70 year extent, where would the star be?
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