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Published January 20, 2018 | Submitted + Published
Journal Article Open

The First Post-Kepler Brightness Dips of KIC 8462852

Abstract

We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%–2.5% dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor," which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale ≪1 μm, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process.

Additional Information

© 2018 The American Astronomical Society. Received 2017 November 28; revised 2017 December 22; accepted 2017 December 22; published 2018 January 19. The LCOGT observations used in this project were made possible by the collective effort of 1762 supporters as part of the Kickstarter campaign "The Most Mysterious Star in the Galaxy." The authors gratefully acknowledge and humbly extend a special thanks for substantial support from Las Cumbres Observatory, Glenn Klakring, Fred Boyajian and Bobbie Staley, Alex Mazingue, The Bible Family, Claudio Bottaccini, Joachim De Lombaert, Amity and Brigid Williams, Kevin Fischer, William Hopkins, Milton Bosch, Zipeng Wang, T.J., D.R., and C.C. The authors thank Peter Foukal for helpful conversations. A.T. wishes to acknowledge her mother, Celeste, for all her love and efforts to help her become an astronomer. A.T. also wishes to thank the Boyajian's Star Kickstarter team for electing to name dip "Celeste" after her mom who passed away in 2017 June. Mom would have been pleased and would have "got it." H.D. acknowledges support from grant ESP2015-65712-C5-4-R of the Spanish Secretary of State for R&D&i (MINECO). This research made use of data acquired with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. J.B. acknowledges the support from the VEGA 2/0031/18 and APVV 15-0458 grants. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. E.H.L.B.'s research was supported by an appointment to the NASA Postdoctoral Program with the Nexus for Exoplanet System Science, administered by Universities Space Research Association under contract with NASA. A.V.F.'s group is grateful for financial assistance from the TABASGO Foundation, the Christopher R. Redlich Fund, Gary and Cynthia Bengier (T.d.J. is a Bengier Postdoctoral fellow), and the Miller Institute for Basic Research in Science (U.C. Berkeley). This project was supported by the National Research, Development and Innovation Fund of Hungary, financed under the K_16 funding scheme (project No. NKFIH K-115709). The research leading to these results has received funding from the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation. M. Gillon is Research Associate at the Belgian Fonds de la Recherche Scientifique (F.R.S.-FNRS). B.D.S. acknowledges support from the National Aeronautics and Space Administration (NASA) through Einstein Postdoctoral Fellowship Award Number PF5-160143 issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. E.H. and I.R. acknowledge support by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Fondo Europeo de Desarrollo Regional (FEDER) through grant ESP2016-80435-C2-1-R, as well as the support of the Generalitat de Catalunya/CERCA programme. A.A.R., H.S.N., and M.J.M.G. acknowledge financial support by the Spanish Ministry of Economy and Competitiveness through projects AYA2014-60476-P and AYA2014-60833-P. F.J.P.R is supported by Marie Curie CO-FUND fellowship, co-founded by the University of Liège and the European Union. F.P.N. is supported by grants 950/15 from the Israeli Science Foundation (ISF) and 3555/14-1 from the Deutsche Forschungsgemeinschaft (DFG). A major upgrade of the Kast spectrograph on the Shane 3 m telescope at Lick Observatory was made possible through generous gifts from William and Marina Kast as well as the Heising-Simons Foundation. Research at Lick Observatory is partially supported by a generous gift from Google. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration (NASA); the observatory was made possible by the generous financial support of the W. M. Keck Foundation. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by NASA. This publication also makes use of data products from NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the Planetary Science Division of NASA. Software: emcee (Foreman-Mackey et al. 2013).

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Published - Boyajian_2018_ApJL_853_L8.pdf

Submitted - 1801.00732.pdf

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Additional details

Created:
August 19, 2023
Modified:
October 18, 2023