1. Results from a triple chord stellar occultation and far-infrared photometry of the trans-Neptunian object (229762) 2007 UK126
- Author
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Jerry Bardecker, Julio Camargo, Thomas Müller, Alfred Krabbe, Jürgen Wolf, Aart M. Olsen, Dave Herald, Felipe Braga-Ribas, Jose Luis Ortiz, Karsten Schindler, Csaba Kiss, European Commission, Hungarian Scientific Research Fund, Junta de Andalucía, German Academic Exchange Service, Universities Space Research Association (US), European Space Agency, and National Research, Development and Innovation Office (Hungary)
- Subjects
Rotation period ,010504 meteorology & atmospheric sciences ,Kuiper belt objects: individual: (229762) 2007 UK126 ,FOS: Physical sciences ,Astrophysics ,individual: (229762) 2007 UK126 [Kuiper belt objects] ,Ellipse ,01 natural sciences ,Occultation ,Photometry (optics) ,Far infrared ,Planet ,Geometric albedo ,Methods: data analysis ,0103 physical sciences ,Trans-Neptunian object ,data analysis [Methods] ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Astronomy and Astrophysics ,Radiation mechanisms: thermal ,13. Climate action ,Space and Planetary Science ,thermal [Radiation mechanisms] ,Occultations ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Schindler, K. et. al., Context. A stellar occultation by a trans-Neptunian object (TNO) provides an opportunity to probe the size and shape of these distant solar system bodies. In the past seven years, several occultations by TNOs have been observed, but mostly from a single location. Only very few TNOs have been sampled simultaneously from multiple locations. Sufficient data that enable a robust estimation of shadow size through an ellipse fit could only be obtained for two objects. Aims. We present the first observation of an occultation by the TNO 2007 UK126 on 15 November 2014, measured by three observers, one nearly on and two almost symmetrical to the shadow's centerline. This is the first multi-chord dataset obtained for a so-called detached object, a TNO subgroup with perihelion distances so large that the giant planets have likely not perturbed their orbits. We also revisit Herschel/PACS far-infrared data, applying a new reduction method to improve the accuracy of the measured fluxes. Combining both datasets allows us to comprehensively characterize 2007 UK126. Methods. We use error-in-variable regression to solve the non-linear problem of propagating timing errors into uncertainties of the ellipse parameters. Based on the shadow's size and a previously reported rotation period, we expect a shape of a Maclaurin spheroid and derive a geometrically plausible size range. To refine our size estimate of 2007 UK126, we model its thermal emission using a thermophysical model code. We conduct a parametric study to predict far-infrared fluxes and compare them to the Herschel/PACS measurements. Results. The favorable geometry of our occultation chords, combined with minimal dead-time imaging, and precise GPS time measurements, allow for an accurate estimation of the shadow size (best-fitting ellipse with axes 645.80 +/- 5.68 km x 597.81 +/- 12.74 km) and the visual geometric albedo (p(V) = 15.0 +/- 1.6%). By combining our analyses of the occultation and the far-infrared data, we can constrain the effective diameter of 2007 UK126 to d(eff) = 599-629 km. We conclude that subsolar surface temperatures are in the order of approximate to 50 55 K., K.S. has been supported financially by a one-year fellowship from the German Academic Exchange Service (DAAD) during his stay at NASA Ames Research Center, CA as part of his Ph.D. research. K.S. would also like to thank the Universities Space Research Association (USRA) for their support throughout his thesis. T.M., C.K. and J.L.O. have received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378. C.K. has been supported by the PECS grant # 4000109997/13/NL/KML of the Hungarian Space Office and the European Space Agency, the K-104607 grant of the Hungarian Research Fund (OTKA), and the GINOP-2.3.2-15-2016 00003 grant of the National Research, Development and Innovation Office of Hungary (NKFIH). J.L.O. acknowledges support from Proyecto de Excelencia J.A. 2012-FQM1776.
- Published
- 2017