“TNOs are Cool”: A survey of the trans-Neptunian region

Abstract

Context. Gravitationally bound multiple systems provide an opportunity to estimate the mean bulk density of the objects, whereas this characteristic is not available for single objects. Being a primitive population of the outer solar system, binary and multiple trans-Neptunian objects (TNOs) provide unique information about bulk density and internal structure, improving our understanding of their formation and evolution. Aims. The goal of this work is to analyse parameters of multiple trans-Neptunian systems, observed with Herschel and Spitzer space telescopes. Particularly, statistical analysis is done for radiometric size and geometric albedo, obtained from photometric observations, and for estimated bulk density. Methods. We use Monte Carlo simulation to estimate the real size distribution of TNOs. For this purpose, we expand the dataset of diameters by adopting the Minor Planet Center database list with available values of the absolute magnitude therein, and the albedo distribution derived from Herschel radiometric measurements. We use the 2-sample Anderson-Darling non-parametric statistical method for testing whether two samples of diameters, for binary and single TNOs, come from the same distribution. Additionally, we use the Spearman's coefficient as a measure of rank correlations between parameters. Uncertainties of estimated parameters together with lack of data are taken into account. Conclusions about correlations between parameters are based on statistical hypothesis testing. Results. We have found that the difference in size distributions of multiple and single TNOs is biased by small objects. The test on correlations between parameters shows that the effective diameter of binary TNOs strongly correlates with heliocentric orbital inclination and with magnitude difference between components of binary system. The correlation between diameter and magnitude difference implies that small and large binaries are formed by different mechanisms. Furthermore, the statistical test indicates, although not significant with the sample size, that a moderately strong correlation exists between diameter and bulk density.

VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis

“…Our density estimate of P-type (87) Sylvia (Carry et al 2021) as well as that of (107) Camilla (Pajuelo et al 2018) appear compatible with those of several D ≤ 300 km TNOs (Brown 2013;Kovalenko et al 2017) providing support for a direct link between P/D types and TNOs. However, the same applies for C-type asteroids.…”

“…Based on our density estimates for all C-complex bodies, we cannot discard a link between these asteroid types and current TNOs. We note the existence of a few TNOs with extremely low densities (Brown 2013;Kovalenko et al 2017) whose counterparts were not identified by our survey of main-belt asteroids.…”

“…9 and Schorghofer 2008) in addition to collisional erosion, which would naturally explain why we are currently observing the exposed aqueously altered C-type-like interiors of these bodies. The same could apply for Ceres (see above) whose density appears higher (2.16 g cm −3 ) than the typical density of large TNOs (1.8-2.0 g cm −3 ; Kovalenko et al 2017) and that may have lost a primordial ∼30-50 km thick icy shell following its implantation in the middle belt (see above). -The size distribution of TNOs does not reach its maximum at ∼270 km which corresponds to the diameter of the largest inner Solar System P/D-type (namely 87 Sylvia).…”

Discovery of a Satellite of the Large Trans-Neptunian Object (225088) 2007 OR10

“…As 2007 OR 10 is a fairly large object, internal porosity is likely negligible and a lower limit for the density can be set to 1.2 g cm −3 , a typical value for medium size TNOs (Brown 2013;Barr & Schwamb 2016;Kovalenko et al 2017). For an upper limit we use the densities of the largest dwarf planets Pluto and Eris, and adopt 2.5 g cm −3 .…”

JWST/NIRSpec Prospects on Transneptunian Objects

“…Cryovolcanism on mid-sized TNOs is an intriguing prospect, as these objects are generally deemed too small to sustain any geophysical activity. Models suggest that some TNOs may be differentiated owing to the right combination of size and density (Merk and Prialnik, 2006;McKinnon et al, 2008;Guilbert-Lepoutre et al, 2011;Shchuko et al, 2014; Malamud and Prialnik, 90377 Sedna Lykawka and Mukai, 2005;Trujillo et al, 2005;Emery et al, 2007;Stansberry et al, 2008;Barucci et al, 2010;Lellouch et al, 2013;Braga-Ribas et al, 2014225088 2007OR 10 Tancredi, 2010Brown et al, 2011aBrown et al, , 2012Santos-Sanz et al, 2012;Pál et al, 2016;Holler et al, 2017;Kiss et al, 201790482 Orcus Fornasier et al, 2004bde Bergh et al, 2005;Lykawka and Mukai, 2005;Trujillo et al, 2005;Brown and Suer, 2007;Barucci et al, 2008;Stansberry et al, 2008;Delsanti et al, 2010;DeMeo et al, 2010;Carry et al, 2011;Thirouin et al, 2014;Brown andButler, 2017, 2018;Kovalenko et al, 2017 50000 Quaoar Brown and Trujillo, 2004;Jewitt and Luu, 2004;Lykawka and Mukai, 2005;Brown and Suer, 2007;Schaller and Brown, 2007b;Stansberry et al, 2008;…”