We studied a sample of 93 asteroid pairs, i.e., pairs of genetically related asteroids that are on highly similar heliocentric orbits. We estimated times elapsed since separation of pair members (i.e., pair age) that are between 7 × 10 3 yr and a few 10 6 yr. With photometric observations, we derived the rotation periods P 1 for all the primaries (i.e., the larger members of asteroid pairs) and a sample of secondaries (the smaller pair members). We derived the absolute magnitude differences of the studied asteroid pairs that provide their mass ratios q. For a part of the studied pairs, we refined their WISE geometric albedos and collected or estimated their taxonomic classifications. For 17 asteroid pairs, we also determined their pole positions. In two pairs where we obtained the spin poles for both pair components, we saw the same sense of rotation for both components and constrained the angles between their original spin vectors at the time of their separation. We found that the primaries of 13 asteroid pairs in our sample are actually binary or triple systems, i.e., they have one or two bound, orbiting secondaries (satellites). As a by-product, we found also 3 new young asteroid clusters (each of them consisting of three known asteroids on highly similar heliocentric orbits). We compared the obtained asteroid pair data with theoretical predictions and discussed their implications. We found that 86 of the 93 studied asteroid pairs follow the trend of primary rotation period vs mass ratio that was found by Pravec et al. (2010). Of the 7 outliers, 3 appear insignificant (may be due to our uncertain or incomplete knowledge of the three pairs), but 4 are high mass ratio pairs that were unpredicted by the theory of asteroid pair formation by rotational fission. We discuss a (remotely) possible way that they could be created by rotational fission of flattened parent bodies followed by re-shaping of the formed components. The 13 asteroid pairs with binary primaries are particularly interesting systems that place important constraints on formation and evolution of asteroid pairs. We present two hypotheses for their formation: The asteroid pairs having both bound and unbound secondaries could be "failed asteroid clusters", or they could be formed by a cascade primary spin fission process. Further studies are needed to reveal which of these two hypotheses for formation of the paired binary systems is real.

Aims. We studied the rotational properties of the dwarf planet Makemake. Methods. The photometric observations were carried out at different telescopes between 2006 and 2017. Most of the measurements were acquired in BVRI broad-band filters of a standard Johnson-Cousins photometric system. Results. We found that Makemake rotates more slowly than was previously reported. A possible lightcurve asymmetry suggests a double-peaked period of P = 22.8266±0.0001 h. A small peak-to-peak lightcurve amplitude in R-filter A = 0.032±0.005 mag implies an almost spherical shape or near pole-on orientation. We also measured BVRI colours and the R-filter phase-angle slope and revised the absolute magnitudes. The absolute magnitude of Makemake has remained unchanged since its discovery in 2005. No direct evidence of a newly discovered satellite was found in our photometric data; however, we discuss the possible existence of another larger satellite.

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.

The dwarf planet (136472) Makemake is one of the largest trans-Neptunian objects discovered to date. Noteworthy, the size and surface temperature of this celestial body put it in a transition region where nitrogen is preferentially lost, while the less volatile methane is retained. Indeed, literature spectra clearly show that the surface of Makemake is dominated by methane ice, though the presence of nitrogen and of irradiation products of methane has been inferred by several authors and a debate is still open about the eventual rotational variability of the surface composition. In this work, we present new visible and near-infrared spectra of Makemake obtained with the TNG telescope (La Palma, Spain) in the time span 2006-2013. Our data sample different rotational phases, covering about 80 per cent of the surface. All of the obtained spectra look very similar, suggesting an overall homogeneous composition. No secular variations appear when comparing our data to literature results (as expected, considering the quite short orbital arc travelled by Makemake since its discovery in 2005). The presence of methane diluted in nitrogen is evidenced by the shift of the observed absorption bands with respect to those of pure methane, with a dilution state looking homogeneous over the surface. We modelled a complete visible and near-infrared spectrum of Makemake using the Shkuratov formalism, and found that adding irradiation products of methane like ethane and ethylene seems indeed improving the fit of the synthetic spectrum to our data. We found no hints of a localized/temporary atmosphere.