Sonneberg Plate Photometry for Boyajian's Star in Two Passbands

Hippke, Michael; Kroll, P.; Matthai, F.; Angerhausen, Daniel; Tuvikene, T.; Stassun, Keivan G.; Roshchina, E. A.; Vasil’eva, T. A.; Izmailov, I. S.; Samus, N. N.; Pastukhova, E. N.; Bryukhanov, I. S.; Lund, Michael B.

doi:10.3847/1538-4357/aa615d

Cited by 39 publications

(16 citation statements)

References 30 publications

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“…While these models can potentially account for the dipping activ-ity without violating the infrared constraints, they were severely challenged by the finding by Schaefer (2016) that Boyajian's Star appears to have been monotonically fading since the late 19th century, with a total change in its brightness of 0.16 mag from 1890 to 1989. The interpretation of the archival photographic measurements for the star has been controversial (Hippke et al 2016(Hippke et al , 2017, but Montet & Simon (2016) demonstrated using Kepler full-frame images that the star's brightness did steadily decline by a total of ∼ 3% over the four years of Kepler 's main mission. Further complicating the situation, Makarov & Goldin (2016) used astrometry from Kepler to show that the variability detected by Boyajian et al (2016) in the Kepler long-cadence light curve must originate from at least two distinct sources.…”

Section: Introductionmentioning

confidence: 99%

Where Is the Flux Going? The Long-term Photometric Variability of Boyajian’s Star

Simon

Shappee

Pojmański

et al. 2018

ApJ

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We present ∼ 800 days of photometric monitoring of Boyajian's Star (KIC 8462852) from the AllSky Automated Survey for Supernovae (ASAS-SN) and ∼ 4000 days of monitoring from the All Sky Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian's Star has steadily decreased at a rate of 6.3 ± 1.4 mmag yr −1 , such that the star is now 1.5% fainter than it was in February 2015. Moreover, the longer time baseline afforded by ASAS suggests that Boyajian's Star has also undergone two brightening episodes in the past 11 years, rather than only exhibiting a monotonic decline. We analyze a sample of ∼ 1000 comparison stars of similar brightness located in the same ASAS-SN field and demonstrate that the recent fading is significant at 99.4% confidence. The 2015 − 2017 dimming rate is consistent with that measured with Kepler data for the time period from 2009 to 2013. This long-term variability is difficult to explain with any of the physical models for the star's behavior proposed to date.

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Section: Introductionmentioning

confidence: 99%

Where Is the Flux Going? The Long-term Photometric Variability of Boyajian’s Star

Simon

Shappee

Pojmański

et al. 2018

ApJ

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“…Such behavior is virtually unique among normal main-sequence stars (Schlecker 2016). Archival data have also been used to suggest a decline in stellar brightness over the past century with an average rate of −0.151±0.012% yr −1 (Schaefer 2016), though the existence and significance of the century-long trend are disputed (Hippke et al 2016a(Hippke et al , 2017Lund et al 2016). In addition, adaptive optics-corrected images in the JHK bands reveal a nearby source 2 from the primary star, with brightness and color consistent with a M2 V companion at a projected distance of ∼800 AU (Boyajian et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Extinction and the Dimming of KIC 8462852

Meng

Rieke

Dubois³

et al. 2017

ApJ

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To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star over a wide wavelength range from the UV to the mid-infrared from October 2015 through December 2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period reported is 22.1 ± 9.7 milli-mag yr −1 in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2 mmag yr −1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at 3 σ by three different observatories operating from the UV to the IR. The presence of long-term secular dimming means that previous SED models of the star based on photometric measurements taken years apart may not be accurate. We find that stellar models with T ef f = 7000 -7100 K and A V ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of the fading favors a relatively neutral color (i.e., R V 5, but not flat across all the bands) compared with the extinction law for the general ISM (R V = 3.1), suggesting that the dimming arises from circumstellar material.

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“…Typical exposure times are 30 to 60 minutes. Our reduction pipeline is described in-depth in Hippke et al (2017). In brief, we perform an astrometric solution (Lang et al 2010) using a list of coordinates of the brightest sources as an input and the Tycho-2 catalog as a reference.…”

Section: Plate Photometry 1956-1994mentioning

confidence: 99%

The PDS 110 observing campaign – photometric and spectroscopic observations reveal eclipses are aperiodic

Osborn

Kenworthy

Rodriguez

et al. 2019

Monthly Notices of the Royal Astronomical Society

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PDS 110 is a young disk-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a closed periodic orbit. In this paper we present data from a ground-based observing campaign designed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in September 2017. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscuration. We also searched for RV oscillations caused by any hypothetical companion and can rule out close binaries to 0.1 M s . A search of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 years, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and shorter-duration than those of UX Ori variables, but may have a similar mechanism.

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Sonneberg Plate Photometry for Boyajian's Star in Two Passbands

Cited by 39 publications

References 30 publications

Where Is the Flux Going? The Long-term Photometric Variability of Boyajian’s Star

Where Is the Flux Going? The Long-term Photometric Variability of Boyajian’s Star

Extinction and the Dimming of KIC 8462852

The PDS 110 observing campaign – photometric and spectroscopic observations reveal eclipses are aperiodic

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