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Optical polarimetry of KIC 8462852 in 2017 May–August
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Steele, I. A., Copperwheat, C. M., Jermak, H. E., Kennedy, Grant M. and Lamb, G. P. (2017) Optical polarimetry of KIC 8462852 in 2017 May–August. Monthly Notices of the Royal Astronomical Society: Letters, 473 (1). L26-L30. doi:10.1093/mnrasl/slx145 ISSN 1745-3933.
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Official URL: http://dx.doi.org/10.1093/mnrasl/slx145
Abstract
Boyajian et al. (2016) presented a Kepler lightcurve of KIC 8462852 (TYC-3162-665-1, Boyajian's Star) which showed a number of irregularly shaped, aperiodic dips in ux of up to 20 per cent and duration 5- to 80-d from 2009 May until the end of monitoring in 2013 May. Over the same time period the source appeared to fade by 3% (Montet & Simon 2016). Boyajian et al. (2016) also presented spectroscopy which showed the source is an apparently normal
F3V star and shows no radial velocity variations. They discussed various possible interpretations of the dips. Intrinsic variability is ruled out since the detailed light curve behaviour and spectral type of the source are not consistent with any known variable source that shows aperiodic dips
(principally R Coronae Borealis and Be Stars). The most likely scenario is therefore some form of extrinsic variability, i.e. occultation by circumstellar or interstellar material. UX Ori and AA Tau systems show similar dipping optical lightcurves. However these are young stars with a strong infrared excess which is not present in KIC 8462852 (Lisse
et al. 2015; Meng et al. 2017). More generally the large dip amplitudes indicate that the occulting source is unlikely to be a solid body and is most likely associated with some form of clumpy/dusty material in either a distant, optically thin region or part of multiple isolated objects such as (possibly broken up) comets or planetesimals (Lecavelier Des Etangs et al. 1999; Boyajian et al. 2016). The relatively small wavelength
dependence of the long term dimming (compared to
the galactic extinction law) reported by Meng et al. (2017)
indicates any dusty material is likely to be circumstellar
rather than interstellar. Wright & Sigurdsson (2016) showed that the timing of the Kepler dips was consistent with them being randomly
distributed. They investigated a family of plausible explanations
and concluded that explanations associated with structure
in the interstellar medium or an intervening disk were most likely. On the other hand Bodman & Quillen (2016) investigated the transit of a large comet family in detail. They found that a single comet of similar size to those in our solar system produces a transit depth of the order of 10.3 lasting less than a day which is much smaller and shorter than observed. However a large ( 100) cluster of comets could fit
the observed depths and durations.
Item Type: | Journal Article | |||||||||
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Subjects: | Q Science > QB Astronomy | |||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||
Library of Congress Subject Headings (LCSH): | Optical measurements, Stars | |||||||||
Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society: Letters | |||||||||
Publisher: | Oxford University Press | |||||||||
ISSN: | 1745-3933 | |||||||||
Official Date: | 22 September 2017 | |||||||||
Dates: |
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Volume: | 473 | |||||||||
Number: | 1 | |||||||||
Page Range: | L26-L30 | |||||||||
DOI: | 10.1093/mnrasl/slx145 | |||||||||
Status: | Peer Reviewed | |||||||||
Publication Status: | Published | |||||||||
Access rights to Published version: | Open Access (Creative Commons) | |||||||||
Date of first compliant deposit: | 20 November 2017 | |||||||||
Date of first compliant Open Access: | 21 November 2017 | |||||||||
RIOXX Funder/Project Grant: |
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