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A Deep Search for Binary TNOs

Presentation #307.04 in the session “Centaurs and Kuiper Belt Objects: Multiples”.

Published onOct 26, 2020
A Deep Search for Binary TNOs

The Latitude Density Search utilized Hyper Suprime-Cam on Subaru Telescope to discover 60 moving objects in the outer Solar System, 54 of which have semi-major axes beyond 30 AU. The images were acquired in exceptional seeing (0.4 arc seconds) and reached a detection limit of mr=25.2. The two night arcs were used to calculate orbits using the Bernstein & Khushalani orbit fitting procedure. The resulting orbits are highly uncertain and the current on-sky uncertainty of the discoveries is too large for easy recovery of these TNOs. However, the distance and inclination are the parameters best constrained by short arcs, so a reasonable determination can be made of which objects are cold classical TNOs and which are dynamically excited. We identify 10 objects as likely cold classical objects. We searched all of the detections for binary sources using a trailed PSF subtraction method (TRIPPy), and identified one binary object with a separation of 0.34 arc seconds and a secondary with 17% the brightness of the primary (2.0 magnitudes fainter). This is the brightest TNO in the sample, the previously known object 2010 HE79 (471165), which has a dynamically excited orbit. None of the likely cold classical objects were binary, although at least 5 are above our detection limits for a secondary with 50% the brightness of the primary and at least 1 pixel (0.17 arc seconds) separation. Although the cold classical sample is small, the lack of binary detections is consistent with previous studies which implied that the prevalence of binary trans-Neptunian objects with Solar System absolute magnitudes, Hr, between approximately 7.5 to 9 may be lower than for larger objects.

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