Abstract
Abstract The Latitude Density Search utilized the Hyper Suprime-Cam on the Subaru Telescope to discover 60 moving objects in the outer solar system, 54 of which have semimajor axes beyond 30 au. The images were acquired in exceptional seeing (0.″4) and reached a detection limit of m r ≃ 25.2. The two night arcs were used to calculate orbits that are poorly constrained; however, the distance and inclination are the parameters best constrained by short arcs, and a reasonable determination can be made of which objects are cold classical trans-Neptunian objects (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 point-spread function (PSF) subtraction method and identified one binary object with a separation of 0.″34 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 (471165) 2010 HE79, which has a dynamically excited orbit. Because of the excellent seeing, this search was sensitive to secondaries with 0.″34 separation and a brightness of ≥50% the primary brightness for seven objects, including one cold classical. This gives an intrinsic binary fraction of 17 − 10 + 19 % (one of six) for the dynamically excited objects within our detection limits. The trailed PSF subtraction method used in the Latitude Density Search to identify binaries, fit the two components, and determine the sensitivity limits is a useful tool that could be more broadly applied to identify binary TNOs and track known binary TNO orbits.
Highlights
Trans-Neptunian objects (TNOs) populate the distant icy solar system beyond Neptune, and the characteristics of these small icy bodies provide useful insights into the formation of planetesimals in the solar system
The two night arcs were used to calculate orbits that are poorly constrained; the distance and inclination are the parameters best constrained by short arcs, and a reasonable determination can be made of which objects are cold classical trans-Neptunian objects (TNOs) and which are dynamically excited
We searched all of the detections for binary sources using a trailed point-spread function (PSF) subtraction method and identified one binary object with a separation of 0 34 and a secondary with 17% the brightness of the primary (2.0 magnitudes fainter)
Summary
Trans-Neptunian objects (TNOs) populate the distant icy solar system beyond Neptune, and the characteristics of these small icy bodies provide useful insights into the formation of planetesimals in the solar system. The cold classical TNOs have distinct orbits (Brown 2001) and are thought to have formed in their current locations (e.g., Levison & Stern 2001). The difference in the binary fraction between the cold classicals and dynamically excited objects is likely linked to their different formation and evolutionary histories (Noll et al 2020). Understanding how the binary fraction of TNOs of different orbital classes varies with size can provide useful insight into how these objects formed and evolved. In this deep two-night search, the Latitude Density Search discovered 54 distant solar system objects 5 Hr 10.
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