Author Topic: Boyajians Star Updates And Discussion  (Read 87908 times)

Offline as58

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Re: Boyajians Star Updates And Discussion
« Reply #40 on: 12/11/2016 02:49 PM »
I think the (possible) companion star is a bit too faint for Gaia.

Offline Star One

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Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #42 on: 12/13/2016 10:37 AM »
I think the (possible) companion star is a bit too faint for Gaia.

Very likely, which is a shame: we'd be much more likely to be able to see the orbital motion on the M companion than on the A3V primary (if they're bound) ...

--- Tony

Offline as58

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Re: Boyajians Star Updates And Discussion
« Reply #43 on: 12/13/2016 10:58 AM »
I think the (possible) companion star is a bit too faint for Gaia.

Very likely, which is a shame: we'd be much more likely to be able to see the orbital motion on the M companion than on the A3V primary (if they're bound) ...

--- Tony

A3V?

Online jgoldader

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Re: Boyajians Star Updates And Discussion
« Reply #44 on: 12/13/2016 12:14 PM »
I think the (possible) companion star is a bit too faint for Gaia.

Very likely, which is a shame: we'd be much more likely to be able to see the orbital motion on the M companion than on the A3V primary (if they're bound) ...

--- Tony

A3V?

Spectral type A3, luminosity class 5 (main sequence dwarf).  The Sun is G2V.  The spectral type sequence reflects temperature, and goes (from hottest to coldest) OBAFGKM (I am not including the brown dwarfs).  Each spectral type goes from subtype 0 to 9 (e.g., G0 is warmer than G1, etc., then G9, then K0).  Luminosity classes go from I to V, in order of decreasing luminosity.  It depends on the temperature and radius of the star.  Supergiants are the class I, dwarfs (normal core hydrogen burning stars) are V.

How we ended up with those letters (OBAFGKM) is a fascinating story, but way beyond the scope of this post!
Recovering astronomer

Offline as58

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Re: Boyajians Star Updates And Discussion
« Reply #45 on: 12/13/2016 12:49 PM »

Spectral type A3, luminosity class 5 (main sequence dwarf).  The Sun is G2V.  The spectral type sequence reflects temperature, and goes (from hottest to coldest) OBAFGKM (I am not including the brown dwarfs).  Each spectral type goes from subtype 0 to 9 (e.g., G0 is warmer than G1, etc., then G9, then K0).  Luminosity classes go from I to V, in order of decreasing luminosity.  It depends on the temperature and radius of the star.  Supergiants are the class I, dwarfs (normal core hydrogen burning stars) are V.

How we ended up with those letters (OBAFGKM) is a fascinating story, but way beyond the scope of this post!

I meant that I didn't think the primary is an A star and now that I've checked, it seems to be F3V.

Not that there's anything wrong with your explanation ;)

Online jgoldader

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Re: Boyajians Star Updates And Discussion
« Reply #46 on: 12/13/2016 01:49 PM »


I meant that I didn't think the primary is an A star and now that I've checked, it seems to be F3V.


Yer right, I didn't catch that.  D'oh.

Nothing to see here everyone, carry on, carry on.
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Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #47 on: 12/19/2016 08:07 PM »
Short documentary about this subject.

« Last Edit: 12/19/2016 08:08 PM by Star One »

Offline Mongo62

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Re: Boyajians Star Updates And Discussion
« Reply #48 on: 12/20/2016 01:03 AM »
Mysterious eclipses in the light-curve of KIC8462852: a possible explanation

ABSTRACT:

Apart from thousands of 'regular' exoplanet candidates, Kepler satellite has discovered a few stars exhibiting peculiar eclipse-like events. They are most probably caused by disintegrating bodies transiting in front of the star. However, the nature of the bodies and obscuration events, such as those observed in KIC8462852, remain mysterious. Swarm of comets or artificial alien mega-structures have been proposed as an explanation for the latter object.

We explore the possibility that such eclipses are caused by the dust clouds associated with massive parent bodies orbiting the host star.

We assume a massive object and a simple model of the dust cloud surrounding the object. Then, we use the numerical integration to simulate the evolution of the cloud, its parent body, and resulting light-curves as they orbit and transit the star.

It is found that it is possible to reproduce the basic features in the light-curve of KIC8462852 with only four objects enshrouded in dust clouds. The fact that they are all on similar orbits and that such models require only a handful of free parameters provide additional support for this hypothesis.

This model provides an alternative to the comet scenario. With such physical models at hand, at present, there is no need to invoke alien mega-structures into the explanation of these light-curves.

7. Conclusions

Our main findings and arguments are briefly summarized below.

1. It was demonstrated that it is possible to explain the complex morphology of the Kepler light-curve of KIC8462852 with a very simple model. Only four massive objects, each surrounded by a dust cloud can account for most of the observed features. The objects are apparently of a common origin i.e. a result of a break-up process of a single progenitor.

2. Most of the features may be represented by a simple, initially spherical dust cloud. Such clouds in eccentric orbits are observed to naturally vertically shrink and develop a leading tail as they approach periastron. The feature at 1 540 days seems to be special since it is best reproduced by an initially ring-like structure.

3. This scenario of 4 massive objects is further supported by the following arguments: the smooth shape of the 800 day feature which is difficult to assemble from a number of smaller objects such as comets; a tendency towards shallower ingress and steeper egress of the 800 day feature which is just the opposite of what is expected for the less massive objects such as comets; the 1 520 and 1 570-day features also show a gradual increase in strengths of individual ’sub-features’ and fast recovery what resembles the 800 day feature; the symmetric ’ring-like’ structure of the 1 540-day feature which would presume a non-negligible gravity of the object; the very existence of another symmetric structure at 1 210 days which is very similar to the above mentioned feature and which is difficult to understand within comet scenario or other models; the clustering of the obscuration features into 4 main events which naturally leads to the association with four objects; as well as by the fact that our solution indicates that all four bodies are on very similar eccentric orbits. Apart from that all best fits were for the P-R drag parameter β = 0.629 what indicates that also the dust particles may be similar in size and chemical composition.

4. It is not claimed that we found the only/best solution within this concept of 4 massive bodies. We rather state that we found a possible solution.

5. Iron or carbon grains smaller than about 0.1 micron experience a very strong radiative push which quickly disconnects them from the parent body and places them on hyperbolic orbits. Thus it is unlikely that such grains contribute significantly to the observed features.

6. Grains larger than about 100 microns experience small radiative accelerations and may remain bound to the massive object. Their opacity is small so they are not likely to contribute significantly to the obscuration events. However, they may act as a reservoir and produce smaller dust grains via collisions.

7. It is argued that 0.3−10 micron size dust grains are the best candidates to explain the obscuration events. Smaller grains, unless they were being replenished, would be easily expelled from the system while larger grains would have a relatively small opacity.

8. It was shown that the mutual interaction between the massive objects and their dust clouds within few astronomical units from the periastron can be neglected and that they can be treated independently of each other in this region.

9. If the two massive objects follow each other on identical eccentric orbits with a short enough time lag, a strong interaction between them and their dust clouds may happen at larger distances from the star which might disperse the clouds but, at the same time, also expose sub-surface volatile material, trigger outbursts and produce debris.
« Last Edit: 12/20/2016 01:04 AM by Mongo62 »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #49 on: 12/20/2016 07:37 PM »
Viewpoint: New Clues as to Why Boyajian’s Star is Dimming

A statistical analysis links a star’s mysterious brightness fluctuations to internal nonequilibrium phenomena, rather than structures orbiting around the star.

http://physics.aps.org/articles/v9/150

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #50 on: 12/21/2016 08:48 PM »

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #51 on: 12/22/2016 07:12 PM »
Quote
Jason Wright ‏@Astro_Wright
Inaugural K-band #BreakthroughListen observations underway at 22 GHz at @GrnBnkTelescope. Target:@tsboyajian's Star. #SETI
Moist Chure
3h
Moist Chure ‏@MoistChure
@Astro_Wright @GrnBnkTelescope @tsboyajian How long till SETI analyzes the data?
Jason Wright
3h
Jason Wright ‏@Astro_Wright
@MoistChure @GrnBnkTelescope @tsboyajian First we have to get it to PSU, then I have to learn the software. Timescale is weeks to months.
Jason Wright
Jason Wright –  ‏@Astro_Wright

@MoistChure @GrnBnkTelescope @tsboyajian Timescale to publication much longer. Unless we see something obvious; then maybe not so long :)

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #52 on: 12/30/2016 02:07 PM »
Quote
Hello Backers,

Edit: Over the past week, a few papers were published on WTF. Jason Wright blogged about the first two, you can view that discussion here (including links to the original papers). The third paper has only been 'submitted' to the journal, meaning that it has not gone through the peer review process necessary for publication. We will discuss the contents on this once it has been accepted. Be sure to visit the sub-reddit (which now has over 4,000 subscribers) if you want to discuss more with the community. Updates to the Observations

As discussed in the last report, we have modified our observing strategies to optimize data quality. This was a concern because the image was saturating because the defocus command not properly executing. When this happened, the scatter increased in the light curve, an effect we want to minimize. To remedy this, we have now selected settings that will work whether the defocus command executes or not. Just after this change in the schedule request we were reviewing the data and saw something.

We saw the data points trending downwards - like the start of a dip. But this trend was not downwards enough to be a sure thing (it was too soon), especially if we considered the measurement errors (which is a must!). Furthermore, we only saw the downwards trend in one of the three filters at only at one of the observatory sites (what is plotted in the figure above). OK, so nothing significant, right? Right? Well, we weren't so confident about whether or not it was real because we couldn't explain what was causing the trend we observed. And if we couldn't explain the data, we couldn't let our guard down. So here we are frantically checking the LCO scheduler to see when new data was expected to be taken. If the dip trend continued at the same rate, it was the next observations that would confirm it.

At the same time we are asking ourselves hundreds of questions. Why would a trend like this appear only in one filter at one observing site? Was is astrophysical or instrumental? Did a thin layer of clouds roll in that affected the conditions? Did the image get contaminated by scattered moonlight? Did we just not understand our errors well enough? Is there some unknown source of correlated noise in the data?

And then Tyler triumphantly announced - this comparison star is BAD! It was one of the comparison stars that we have been using all along. But after the configuration change to address saturation, the conditions were just barely right (or wrong) enough to affect the one star enough to make it look like there was a dip in the data. Removing the bad comparison star fixed everything, and the data now lines up with the rest of the curve to reveal nothing but a flatline. I guess that is good. For now. We remain patient. This highlights the odd nature of astronomy (and science as a whole), occasionally things just don't work right even though they should.

On the management side of things, we are now set up with a new computer which we have named Toph. Tyler chose this name because we wanted a theme which is expandable if we ever need future computers and the computer generally won't have a monitor attached. Toph is from Avatar: The Last Airbender and is a blind, but fierce fighter. Blind, no monitor. Look, we're scientists first and good at naming things somewhere further down the list.

This is where all the data will be stored locally. Each image is about 7 megabytes in size, but throughout this campaign we will take thousands (possibly over ten thousand images). At the moment we almost have 20 GB of images! From these images we will have Toph automatically extract and produce the light curves and then email them to us and send alerts if a dipping event occurs. This is largely possible with the photometry code developed by Rachel Street and the other astronomers at LCO.

Happy holidays to you all,

~the entire WTF team Thank you once again for your support!

https://www.reddit.com/r/KIC8462852/comments/5kq58q/latest_kickstarter_post_wtf_star/

Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #53 on: 01/04/2017 08:38 AM »
I meant that I didn't think the primary is an A star and now that I've checked, it seems to be F3V.

Not that there's anything wrong with your explanation ;)

Doh!  Why I wrote "A" eludes me ... I know it's an F.  Senility can't be ruled out :-)

--- Tony

Offline jebbo

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Re: Boyajians Star Updates And Discussion
« Reply #54 on: 01/04/2017 08:41 AM »
Another theory:

Quote
Secular Dimming of KIC 8462852 Following its Consumption of a Planet

Quote
The Kepler-field star KIC 8462852, an otherwise apparently ordinary F3 main-sequence star, showed several highly unusual dimming events of variable depth and duration. Adding to the mystery was the discovery that KIC 8462852 faded by 14% from 1890 to 1989, as well as by another 3% over the 4 year Kepler mission. Following an initial suggestion by Wright & Sigurdsson, we propose that the secular dimming behavior is the result of the inspiral of a planetary body or bodies into KIC 8462852, which took place ~10 to 1e4 years ago (depending on the planet mass). Gravitational energy released as the body inspirals into the outer layers of the star caused a temporary and unobserved brightening, from which the stellar flux is now returning to the quiescent state. The transient dimming events could then be due to obscuration by planetary debris from an earlier partial disruption of the same inspiraling bodies, or due to evaporation and out-gassing from a tidally detached moon system. Alternatively, the dimming events could arise from a large number of bodies comet- or planetesimal-mass bodies placed onto high eccentricity orbits by the same mechanism (e.g. Lidov-Kozai oscillations due to the outer M-dwarf companion) responsible for driving the more massive planets into KIC 8462852. The required high occurrence rate of KIC 8462852-like systems which have undergone recent major planet inspiral event(s) is the greatest challenge to the model, placing large lower limits on the mass of planetary systems surrounding F stars and/or requiring an unlikely probability to catch KIC 8462852 in its current state.

https://arxiv.org/abs/1612.07332

--- Tony

Offline Star One

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Re: Boyajians Star Updates And Discussion
« Reply #55 on: 01/04/2017 10:21 AM »
Thing is we can keep coming up with theories on this forever but only more data is going to resolve it. So let's hope we see another dip this year or something comes out of Jason Wright's et al observing campaign.
« Last Edit: 01/04/2017 10:22 AM by Star One »

Offline savuporo

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Re: Boyajians Star Updates And Discussion
« Reply #56 on: 01/04/2017 12:37 PM »
Thing is we can keep coming up with theories on this forever but only more data is going to resolve it. ..
Not really. More data is going to refine the hypothesis, not resolve anything definitely
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Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #57 on: 01/05/2017 03:01 AM »
Wright's commentary on the "swallowed a planet" paper posted above http://sites.psu.edu/astrowright/2017/01/03/metzger-shen-and-stone/

It still has some loose ends, but ends up with higher marks than he gave the idea in his paper:
Quote
I’m glad to see this scenario fleshed out so well. I suspect that there are ways to save the model by finding ways to make sort of event occur more frequently—perhaps by making the merging/dips more frequent by getting a chain of material from a single massive object—so I’m optimistic there’s more to this.  I’d say this paper has moved the “post-merger return to normal” scenario from “unclear” plausibility to something like “less plausable,” or even higher.

Offline TakeOff

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Re: Boyajians Star Updates And Discussion
« Reply #58 on: 01/13/2017 07:22 PM »
Yeah, like a planet, swallowed or crushed or whatever, covers 22% of the star's light. A star 50% larger than the Sun. Very desperate. (Please accept that it is a peryton until confirmed by a second observatory)
« Last Edit: 01/13/2017 07:24 PM by TakeOff »

Offline hop

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Re: Boyajians Star Updates And Discussion
« Reply #59 on: 01/13/2017 08:55 PM »
Yeah, like a planet, swallowed or crushed or whatever, covers 22% of the star's light.
You should probably read the paper (or at least Wright's blog post) because that's not the mechanism proposed.

edit:
And FWIW, a disrupted planet would have no trouble blocking ~22% of the stars output, the problem is doing it without infra red excess.
« Last Edit: 01/14/2017 04:35 PM by hop »

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