We have made the first attempt to derive the chemical properties of the Galactic disc at its very central part using high-resolution infrared spectroscopic observations of four classical Cepheids. Those stars are located at Galactocentric distances smaller than 1 kpc. All investigated stars show near-to-solar elemental abundances. By combining these new data with our previous studies, this result suggests that the radial distribution of iron abundance on a logarithmic scale gradually increases from the outskirts of the Galactic disc to Galactocentric distances of about 2-4 kpc, reaching there a maximal value of about +0.4 dex, and then declines sharply to about the solar value at the Galactic Center.

Context. Basaltic V-type asteroids play a crucial role in studies of Solar System evolution and planetesimal formation. Comprehensive studies of their physical, dynamical, and statistical properties provide insight into these processes. Thanks to wide surveys, currently there are numerous known V-type and putative V-type asteroids, allowing a detailed statistical analysis. Aims. Our main goal is to analyze I corrected for US language conventions in this paper the currently available large sample of V-type spin rates, to find signatures of the non-gravitational Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect among the different V-type populations, and to estimate the spin barrier and critical density for V-type asteroids. Our intention is to increase the pool of information about the intriguing V-types. Methods. We collected rotational periods from the literature for spectrally confirmed V-types, putative V-types, and Vesta family members. Through spectroscopic observations we confirmed their taxonomic type and verified the high confirmation rates of the putative V-types. We combined the collected periods with periods estimated in this manuscript and produced rotational frequency distributions. We determined the spin barrier in the frequency–light curve amplitude space for V-type asteroids. Results. We analyzed rotational periods of 536 asteroids in our sample. As expected, due to the small size of the objects analyzed, the frequency distributions for the Vesta family and the V-types outside the family are inconsistent with a Maxwellian shape. The Vesta family shows an excess of slow-rotators. V-types outside the family show an excess of both slow and fast rotators. Interestingly, we found that the population of V-types outside the Vesta family shows a significant excess of fast rotators compared to the Vesta family. The estimated critical density for V-type asteroids exceeds ρc = 2.0 g cm−3, which surpasses the previous estimates. Conclusions. We demonstrated that V-type asteroids have been influenced by the thermal radiation YORP effect and that their critical spin rate is higher than for C-type asteroids. The population of V-types outside the Vesta family shows a significant excess of fast rotators compared to the Vesta family. We hypothesize that the objects that evolved from the Vesta family though the Yarkovsky drift are also more susceptible to the YORP effect. Objects for which YORP has not yet had enough time to act and those that are more YORP resistant will be left in the family, which explains the relatively small proportion of fast rotators being left. The YORP timescale must thus be similar to the migration timescale for those objects.

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