Author Topic: Boyajians Star Updates And Discussion  (Read 295852 times)

Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #400 on: 05/28/2017 11:38 pm »
I though the M dwarf was deemed as too distant and that it's recent movements have been calculated in that respect.
Do you have a reference for this? I would be surprised if we had much constraint on its actual motion, AFAIK the only thing we know is the angular separation. It took followup with Keck AO to even confirm as a distinct source from KIC 8462852, so we don't have long term knowledge of its motion.

From the original Boyajian et al paper:
Quote
Assuming the fainter star is associated with the main F-star target, and the two stars that are separated by ~ 1.95", they are ~ 885 AU apart. At this separation, the second star cannot currently be physically affecting the behavior of the Kepler target star, though could be affecting bodies in orbit around it via long term perturbations. If such a star is unbound from KIC 8462852, but traveling through the system perpendicular to our line of sight, it would take only 400 years to double its separation if traveling at 10 km/s. So, the passage would be relatively short-lived in astronomical terms.
Emphasis mine. The odds of catching an encounter like this in the act may be uncomfortably low, but if we did, it seems compatible with a pass close enough to cause significant effects.

The time for the effects of the encounter to reach the inner part of the system might be troublesome, but without constraints on the closest approach and distance along the line of site there's a fair bit of wiggle room.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #401 on: 05/29/2017 05:29 am »
The distance of the M dwarf mostly just what Wright had tweeted in the past when asked about it.

Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #402 on: 05/30/2017 01:25 pm »
I though the M dwarf was deemed as too distant and that it's recent movements have been calculated in that respect.
Do you have a reference for this? I would be surprised if we had much constraint on its actual motion, AFAIK the only thing we know is the angular separation. It took followup with Keck AO to even confirm as a distinct source from KIC 8462852, so we don't have long term knowledge of its motion.

That's my understanding as well: we only know the angular separation.  The latest round of observations included both Kecks (and the LGS), so we may have got a new set of AO images.  If proper motion of the M dwarf is high enough, it may just be detectable.

--- Tony

Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #403 on: 05/31/2017 06:01 am »
Ballesteros et al posted an updated (still not reviewed / accepted) version of the Trojans pre-print discussed earlier https://arxiv.org/abs/1705.08427
Quote
Comments: 5 pages, 3 figures. v2: Corrected an error regarding the interpretation of the May 2017 event. Main conclusions unchanged. Revised version submitted to MNRAS Letters
The correction interprets the recent event as Hilda analogs rather than a secondary eclipse. Seems a bit contrived, but I guess if you are willing to accept enough trojans to cause a ~20% dip...

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #404 on: 06/05/2017 05:56 pm »

Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #405 on: 06/14/2017 05:57 am »
Apparently, KIC 8462852 might be dipping again.

Reported by Ben Montet on Twitter, citing observations by Bruce Gary.

https://twitter.com/benmontet/status/874748832357261313
http://www.brucegary.net/KIC846/#2017.06.13_V

Not heard any LCOGT confirmation yet.

--- Tony

Offline Alpha_Centauri

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Re: Boyajians Star Updates And Discussion
« Reply #406 on: 06/14/2017 08:18 am »
Notice the timing between this dip and the one in May. It's very close to the spacing of the complex of dips centred around D1540 in the Kepler data.  A coincidence or more evidence this is in orbit?
« Last Edit: 06/14/2017 08:19 am by Alpha_Centauri »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #407 on: 06/14/2017 08:27 am »
Notice the timing between this dip and the one in May. It's very close to the spacing of the complex of dips centred around D1540 in the Kepler data.  A coincidence or more evidence this is in orbit?

Someone on the relevant Reddit appears to have predicted this. It may indicate something in a 24.2 day orbit of the star.

https://www.reddit.com/r/KIC8462852/comments/6h3655/a_new_dip_has_started_now_at_10/
« Last Edit: 06/14/2017 08:34 am by Star One »

Offline Alpha_Centauri

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Re: Boyajians Star Updates And Discussion
« Reply #408 on: 06/14/2017 08:56 am »
If it were a 24 day orbit we would see them every* 24 days.  There would also be IR excess.

I was thinking perhaps multiple objects on roughly the same ~750d eccentric orbit that happen to cross our line of sight ~24d apart.





*well there are edge cases, but doubtful here.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #409 on: 06/14/2017 09:30 am »
According to what I've read on the same Reddit Tabby has confirmed a shallow dip. I should add I can't see anything about it on either her or Jason's Twitter feed.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #410 on: 06/14/2017 09:32 am »
If it were a 24 day orbit we would see them every* 24 days.  There would also be IR excess.

I was thinking perhaps multiple objects on roughly the same ~750d eccentric orbit that happen to cross our line of sight ~24d apart.





*well there are edge cases, but doubtful here.

Yes you're right as that's been disputed in the same thread with mention of that 750 day orbit.

I believe someone else indicated with this that on the 17th July it should go into a major dip.
« Last Edit: 06/14/2017 11:22 am by Star One »

Offline Alpha_Centauri

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Re: Boyajians Star Updates And Discussion
« Reply #411 on: 06/14/2017 10:39 am »
Having said that, remember the spurious 48.4 day period from the original paper?  Well some of the shallower dips earlier on in the lightcurve that are usually glossed over fit cycles of 24.2 days.

The duration between the 22% dip at D1519.6 and dip 1 and 2 in the original paper is 57 or 52 ~24.2 day cycles respectively.  The duration between the other large dip near the end of the Kepler data at D1568.5 and these earlier dips is 59 or 54 cycles respectively.



Interesting aside, perhaps the 750 day period is spurious and that the shallower events are secondary eclipses?
« Last Edit: 06/14/2017 10:40 am by Alpha_Centauri »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #412 on: 06/14/2017 11:15 am »
Having said that, remember the spurious 48.4 day period from the original paper?  Well some of the shallower dips earlier on in the lightcurve that are usually glossed over fit cycles of 24.2 days.

The duration between the 22% dip at D1519.6 and dip 1 and 2 in the original paper is 57 or 52 ~24.2 day cycles respectively.  The duration between the other large dip near the end of the Kepler data at D1568.5 and these earlier dips is 59 or 54 cycles respectively.



Interesting aside, perhaps the 750 day period is spurious and that the shallower events are secondary eclipses?

Probably stating the very obvious here but probably what all observers need is one of the big dips, so that it clearly shows against the noise and error bars.

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #413 on: 06/14/2017 11:23 am »
I believe some indicated with this that on the 17th July it should go into a major dip.

Well, there we are. A line in the sand!

Can someone verify this date?

Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #414 on: 06/15/2017 06:00 am »
Still dipping ... apparently still ~1% down.

https://twitter.com/brettmor/status/875224630666993664

--- Tony

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #415 on: 06/15/2017 07:00 am »
Still dipping ... apparently still ~1% down.

https://twitter.com/brettmor/status/875224630666993664

--- Tony
Some confusing and contradictory data on the Reddit thread.

Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #416 on: 06/15/2017 07:11 am »
Some confusing and contradictory data on the Reddit thread.

I'm not too worried by that Reddit. First, detecting a 1% dip is beyond the capabilities of many on AAVSO (if nothing else because most don't have a continuous set of observations). Second, there are some pretty wild and unsubstantiated claims there ...

I'll go with the people with access to large instruments :-)

--- Tony

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #417 on: 06/15/2017 07:25 am »
Some confusing and contradictory data on the Reddit thread.

I'm not too worried by that Reddit. First, detecting a 1% dip is beyond the capabilities of many on AAVSO (if nothing else because most don't have a continuous set of observations). Second, there are some pretty wild and unsubstantiated claims there ...

I'll go with the people with access to large instruments :-)

--- Tony

Brett Morris Twitter.

https://mobile.twitter.com/brettmor/status/875243485661609985

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #418 on: 06/15/2017 09:26 am »
Quote
Update from Bruce:

Preliminary result for Jun 15 (after 1.7 hrs). The fade feature that began a couple days ago is slowly recovering.

KIC 8462852 Daily Normalized Flux, 2017 May 02 - Jun 15 - v7615

http://www.brucegary.net/KIC846/17.06.15%20KIC846%28V%29%20d7615%20May01-50%20Daily%20NFL%2005.jpg
« Last Edit: 06/15/2017 09:26 am by Star One »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #419 on: 06/15/2017 07:36 pm »
Here is a graph of the 11th June event from TRAPPIST-1 via Tabby.

https://drive.google.com/file/d/0B_LvagsQCx-cZHhDMVYyMDdpR2s/view

Also this.

Quote
Paul Thompson @trailrunnerlife

@Astro_Wright any update on when we might expect publication of GBT obs for Tabby's Star? Lots of hungry data scientists...
8:22 pm · 15 Jun 2017

Jason Wright @Astro_Wright
·
8m

Replying to @trailrunnerlife
It turns out transferring and collecting and organizing 610TB of data on a brand-new data center takes time! Much longer than I had hoped.

Jason Wright @Astro_Wright
·
7m

We're making slow progress.  We do hope to make snippets freely downloadable so others can chew on it and suggest analyses for us to run!

Paul Thompson @trailrunnerlife
·
4m

that's great news, thanks!

https://mobile.twitter.com/trailrunnerlife/status/875433474433437697
« Last Edit: 06/15/2017 07:38 pm by Star One »

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