Another paperModelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation M. C. Wyatt, R. van Lieshout, G. M. Kennedy, T. S. Boyajian(Accepted for publication in MNRAS)QuoteThis paper shows how the dips and secular dimming in the KIC8462852 light curve can originate in circumstellar material distributed around a single elliptical orbit (e.g., exocomets). The expected thermal emission and wavelength dependent dimming is derived for different orbital parameters and geometries, including dust that is optically thick to stellar radiation, and for a size distribution of dust with realistic optical properties. We first consider dust distributed evenly around the orbit, then show how to derive its uneven distribution from the optical light curve and to predict light curves at different wavelengths. The fractional luminosity of an even distribution is approximately the level of dimming times stellar radius divided by distance from the star at transit. Non-detection of dust thermal emission for KIC8462852 thus provides a lower limit on the transit distance to complement the 0.6au upper limit imposed by 0.4day dips. Unless the dust distribution is optically thick, the putative 16% century-long secular dimming must have disappeared before the WISE 12micron measurement in 2010, and subsequent 4.5micron observations require transits at >0.05au. However, self-absorption of thermal emission removes these constraints for opaque dust distributions. The passage of dust clumps through pericentre is predicted to cause infrared brightening lasting 10s of days and dimming during transit, such that total flux received decreases at wavelengths <5micron, but increases to potentially detectable levels at longer wavelengths. We suggest that lower dimming levels than seen for KIC8462852 are more common in the Galactic population and may be detected in future transit surveys.I've only skimmed it, but it seems like a significant step to building a coherent model for the "exocomet" (in the broad sense of dusty things in elliptical orbit) theories that accounts for the IR observations, long term variability and dips.Note although Dr Boyajian is a co-author, this is not the anticipated paper on the recent dips. From the last kickstarter updateQuoteLastly, since activity has seemed to subside for a little bit, we have plans to move forward and publish the dip announcement paper, so stay tuned!
This paper shows how the dips and secular dimming in the KIC8462852 light curve can originate in circumstellar material distributed around a single elliptical orbit (e.g., exocomets). The expected thermal emission and wavelength dependent dimming is derived for different orbital parameters and geometries, including dust that is optically thick to stellar radiation, and for a size distribution of dust with realistic optical properties. We first consider dust distributed evenly around the orbit, then show how to derive its uneven distribution from the optical light curve and to predict light curves at different wavelengths. The fractional luminosity of an even distribution is approximately the level of dimming times stellar radius divided by distance from the star at transit. Non-detection of dust thermal emission for KIC8462852 thus provides a lower limit on the transit distance to complement the 0.6au upper limit imposed by 0.4day dips. Unless the dust distribution is optically thick, the putative 16% century-long secular dimming must have disappeared before the WISE 12micron measurement in 2010, and subsequent 4.5micron observations require transits at >0.05au. However, self-absorption of thermal emission removes these constraints for opaque dust distributions. The passage of dust clumps through pericentre is predicted to cause infrared brightening lasting 10s of days and dimming during transit, such that total flux received decreases at wavelengths <5micron, but increases to potentially detectable levels at longer wavelengths. We suggest that lower dimming levels than seen for KIC8462852 are more common in the Galactic population and may be detected in future transit surveys.
Lastly, since activity has seemed to subside for a little bit, we have plans to move forward and publish the dip announcement paper, so stay tuned!
Dip update 105/nOctober 18, 2017[Orig: Oct 18, 2017] Hi everyone, Below is the light curve as of a few hours ago. Note I have removed the TFN point from the night before because it didn't constrain diddly. More later, ~Tabby and team
The last g'-mag is the brightest measured during the past 12 months! I predict that during the first week of November this brightening will reach a level ~ 1.5 % higher than during the past summer months. The brightening currently underway was predicted on this web page Oct 10, and ~ 3 months ago in an e-mail by a colleague. Paper#3 will explain why it is brightening so fast right now (really simple once it's explained). We are hoping to submit paper#1 to MNRAS next week, and a week later post it at arXiv (and at this web page)."
Bruce Gary has made some revisions to his model. He cut his 1.5% prediction down to .8%.http://www.brucegary.net/ts4/
Quote from: Star One on 11/04/2017 10:33 amBruce Gary has made some revisions to his model. He cut his 1.5% prediction down to .8%.http://www.brucegary.net/ts4/Star One. I know you have followed this star's saga quite closely since the beginning.Would you be willing to give a summary of the latest prevailing theory, including what Bruce Gary's so called prediction is all about, and what it means for the likely solution to the mystery? With the dimming events seeming to be on hold for the time being, news on the star seems to have faded away (hehe) lately.While the dimming events were in full swing, I heard everything from the E.T. hypothesis having been disproven, to massive ringed planets bigger than Jupiter, to an invisible brown dwarf and everything inbetween.Essentially, what is being suggested as the reason behind the lack of any further 15-22% dips subsequent to Kepler's observations? And is an E.T. solution at all still on the cards?
Quote from: M.E.T. on 11/04/2017 12:37 pmQuote from: Star One on 11/04/2017 10:33 amBruce Gary has made some revisions to his model. He cut his 1.5% prediction down to .8%.http://www.brucegary.net/ts4/Star One. I know you have followed this star's saga quite closely since the beginning.Would you be willing to give a summary of the latest prevailing theory, including what Bruce Gary's so called prediction is all about, and what it means for the likely solution to the mystery? With the dimming events seeming to be on hold for the time being, news on the star seems to have faded away (hehe) lately.While the dimming events were in full swing, I heard everything from the E.T. hypothesis having been disproven, to massive ringed planets bigger than Jupiter, to an invisible brown dwarf and everything inbetween.Essentially, what is being suggested as the reason behind the lack of any further 15-22% dips subsequent to Kepler's observations? And is an E.T. solution at all still on the cards?Bruce Gary favours a rather complicated natural solution. That is a Brown Dwarf with rings that is also orbited by three Neptune class planets. These planets in turn have icy moons that sublimate material as the whole system approaches Boyajian’s star. The Brown Dwarf is in an highly eccentric orbit around Boyajian’s star, and the Brown Dwarf has an orbit that lasts 4.3 years.
Bruce Gary favours a rather complicated natural solution. That is a Brown Dwarf with rings that is also orbited by three Neptune class planets. These planets in turn have icy moons that sublimate material as the whole system approaches Boyajian’s star. The Brown Dwarf is in an highly eccentric orbit around Boyajian’s star, and the Brown Dwarf has an orbit that lasts 4.3 years.
The brightening continues to be consistent with a leveling off at a modest 0.8 % above the summer low (when all the dips were occurring).
I was rather hoping Bruce Gary & his mysterious collaborator would have published their paper by now.
Quote from: Star One on 12/11/2016 08:25 amMods on the relevant Reddit who I believe some of which are professional astronomers.https://m.reddit.com/r/KIC8462852/comments/5he29u/orbiting_planets_around_kic8462852/Thanks. I suspect that that QuoteThere probably are planets, but they aren't transiting (no surprise), and they are too small or too inclined to make a dent in the radial velocity measurements we have to dateis just meant in the general sense that most stars have planets, so this one probably does too.QuoteThere is a dwarf possibly in the system.presumably refers to the previously identified M dwarf, which may or may not be associated.
Mods on the relevant Reddit who I believe some of which are professional astronomers.https://m.reddit.com/r/KIC8462852/comments/5he29u/orbiting_planets_around_kic8462852/
There probably are planets, but they aren't transiting (no surprise), and they are too small or too inclined to make a dent in the radial velocity measurements we have to date
There is a dwarf possibly in the system.
Bruce Gary’s paper see what you think?https://arxiv.org/abs/1711.04205
"A recent dip reached a depth of 0.45 ± 0.10 % and has stayed at this depth for almost a week. I'm puzzled (as usual) by this fickle star! "