Small Solar System objects on highly inclined orbits

Abstract

Context. Less than one percent of the discovered small Solar System objects have highly inclined orbits (i > 60°), and revolve around the Sun on near-polar or retrograde orbits. The origin and evolutionary history of these objects are not yet clear. Aims. In this work we study the surface properties and orbital dynamics of selected high-inclination objects. Methods. BVRI photometric observations were performed in 2019–2020 using the 2.0 m telescope at the Terskol Observatory and the 2.6 m telescope at the Crimean Astrophysical Observatory. Additionally, we searched for high-inclination objects in the Sloan Digital Sky Survey and Pan-STARRS. The dynamics of the selected objects was studied using numerical simulations. Results. We obtained new photometric observations of six high-inclination objects (468861) 2013 LU28, (517717) 2015 KZ120, 2020 EP, A/2019 U5 (A/PanSTARRS), C/2018 DO4 (Lemmon), and C/2019 O3 (Palomar). All of the objects have similar B−V, V −R, R−I colours, which are close to those of moderately red TNOs and grey Centaurs. The photometric data that were extracted from the all-sky surveys also correspond to moderately red surfaces of high-inclination objects. No signs of ultra-red material on the surface of high-inclination asteroids were found, which supports the results of previous works. The comet C/2018 DO4 (Lemmon) revealed some complex morphology with structures that could be associated with particles that were ejected from the cometary nucleus. Its value of the parameter Afρ is around 100 cm for the aperture size of 6000 km. The value of Afρ for the hyperbolic comet C/2019 O3 (Palomar) is much larger, and is in the range from 2000 to 3700 cm for the aperture sizes from 25 000 to 60 000 km. For objects 2013 LU28, 2015 KZ120, and 2020 EP we estimated future and past lifetimes on their orbits. It appears that the orbits of considered objects are strongly chaotic, and with the available accuracy of the orbital elements no reliable predictions can be made about their distant past or future. The lifetimes of high-inclination objects turned out to be highly non-sensitive to the precision of the orbital elements, and to the Yarkovsky orbital drift.

Near-UV Reddening Observed in the Reflectance Spectrum of High-inclination Centaur 2012 DR30

“…Both observing runs were conducted under clear (sky 90% cloudless at elevation >30°, transmission variation <10%) or photometric (sky cloudless, transmission variation <2%) conditions as defined by ESO; as a result, we expect the continuum colors of our spectra to be minimally affected by clouds, and therefore accurate. As in previously reported observational epochs (Kiss et al 2013;Szabó et al 2018;Hromakina et al 2021), 2012 DR 30 was found to be inactive both times we observed it.…”

“…In Figure 2 we present our optical reflectance spectra of 2012 DR 30 in comparison to all published optical photometric and spectroscopic reflectance data where such data cover 0.6 μm, enabling consistent scaling between data sets (literature data sets include those reported by Kiss et al 2013;Szabó et al 2018;Hromakina et al 2021). Optical photometric colors were converted to coarse reflectance spectra using methods described by Hainaut & Delsanti (2002) and were scaled relative to the reflectance value at 0.6 μm on a line drawn between the two data points on either side of that wavelength.…”

“…As a collection, the optical colors reported for 2012 DR 30 so far suggest that its color varies significantly between observational epochs (Kiss et al 2013;Szabó et al 2018;Hromakina et al 2021).…”

“…To date, multiband photometry has been the main technique used for characterization of the surfaces of HiHq Centaurs, and half of those currently known have published optical colors. 127546 (2002 XU 93 ), 528219 (2008 KV 42 ), 2010 WG 9 , and 2012 DR 30 have all been reported to have gray to moderately red optical colors similar to those of cometary nuclei, the Damocloids, the Trojan asteroids of Jupiter and Neptune, the less-red trans-Neptunian objects (TNOs), and the primitive Xand D-type asteroids (Sheppard 2010;Hainaut et al 2012;Kiss et al 2013;Rabinowitz et al 2013;Jewitt 2015;Szabó et al 2018;Hromakina et al 2021). The similarity between the colors of these minor planet populations and those of HiHq Centaurs suggests that the HiHq Centaurs are likely to have dark and carbonaceous surfaces that may have experienced significant irradiation and thermal evolution (e.g., Sheppard 2010).…”

Early Kyiv Observations of Asteroids: Analysis and New Reduction With Tycho-2 and Gaia Catalogs

“…The data obtained with reprocessed observations of asteroids for this long-term period are highly useful for a more detailed study of the dynamics and modern orbital parameters of asteroids (see, for example, Savanevych et al 2015;Savanevych et al 2018;Hromakina et al 2021;Vavilova et al 2022) as well as the obtained photometric parameters are very complementary with present-day data for studying changes in brightness and light curves (see, for example, Marzari, 2020).…”