A deep dive into Dip 792 (part I)
|The famous Dip of Day 792 at Boyajian Star (Data-Source: NASA Kepler Mission)|
What makes the Dip so unique?The first thing is, this dip is very deep, about 15% of the light of the star is invisible to the telescope during the peak of the dip. This is a very high number, when we compare that to a transit of a Jupiter like planet, which would absorb about 1% of the starlight and when we remember, that Jupiter is near to the maximum size of a planet.
The second thing is the shape, it is definitely not the shape of a planet, as has been shown by Ksanfomality , The asymmetric structure does not match with a high eccentric planet due to timing and absorption. The same is true for comets, the density of a comet and the homogeneity of the dip is not something we expect to see by well known comets analysed in our solar system.
The third mystery is the obvious smoothness of the dip, this is only possible, if a relatively simple shape or process is the cause of the dip. we should be very happy to have this dip 792 near the other much more complex and hard to understand dips later in the Kepler mission survey. If we understand D792, we might be able to take the hints to comprehend the other dips.
The fourth mystery is the total time of the dip, that is about 8 days. No massive object, even another star, would occlude this star for so long.
Analysing the shape
End and Start of the Dip
|Dip 792 end at day 794,85 within a well defined uncertainty of a few measurement points.|
The begin of the dip is much harder to define, due to the very smooth beginning of the dropping light intensity. It seems so, that the density of the absorbing object is fading away with no sharp border as seen in the high resolution image, be aware of the slightly wider time scale.
|Dip 792 starts with a very smooth slope of the signal at day 787.|
We might get a better understanding of this shape when we assume an exponential decay as shown later in this post.
|Missing data points were calculated by linear interpolation using the two data points at the border of the gap.|
|The symmetric assumption of the dip 792.|
We can now syntesis the basic dip and the fading part. First look at the basic dip:
|The basic dip is a artificial constructed dip using symmetric assumptions.|
The remaining Signal
|The remaining fading part, if we subtract the artificial basic dip from the measured data.|
|Log-plot of the absorption in the remaining signal after subtraction of basic dip. |
Different colors mark different slopes.
Here comes the second part.
2017 May 19: We have a new dip, I publish this, and wait for new results.
I have used this value for the start lifting model and have a quick view into the error of the right part:
|The shape of star lifting with 756 day period as suggested by the new dip in 2017|
|The simulated shape using a period of 725 days|
Periodic?Is the new dip periodic? If we assume, that d792 is the start of some periodic process and today, 20 May 2017 is dip day, then 2268 are in between. If the dip series around d1500 is related, then a 756 day period makes sense.
I plot this in my standard long time chart:
|Compare 726 and 756 day period|
That is not a day with a significant dip.
First data of new dip
|Latest data of the first dip that was observed after the Kepler mission. (20 May 2017)|
|More actual measured data, source: Boyajian.|
As Jason Wright mentions on twitter, the dip seems to be over.
Dataprocessing is now on.
|The new dip has a duration of seven days, very typical for dips at this star.|
Here comes the second part of the dip 792 analysis.
 Ksanfomality, L.V. Astron. Rep. (2017) 61: 347. doi:10.1134/S1063772917040114
 Eduard Heindl, Do we see Starlifting?
 Eduard Heindl, A physically inspired model of Dip d792 and d1519 of the Kepler light curve seen at KIC8462852, 2016, https://arxiv.org/abs/1611.08368