Physical characterization of 2020 AV2, the first known asteroid orbiting inside Venus orbit

Abstract

The first known asteroid with the orbit inside that of Venus is 2020~AV${}_2$. This may be the largest member of a new population of small bodies with the aphelion smaller than 0.718~au, called Vatiras. The surface of 2020~AV${}_2$ is being constantly modified by the high temperature, by the strong solar wind irradiation that characterizes the innermost region of the Solar system, and by high-energy micrometeorite impacts. The study of its physical properties represents an extreme test-case for the science of near-Earth asteroids. Here, we report spectroscopic observations of 2020~AV${}_2$ in the 0.5-1.5~$\mu m$ wavelength interval. These were performed with the Nordic Optical Telescope and the William Herschel Telescope. Based on the obtained spectra, we classify 2020~AV${}_2$ as a Sa-type asteroid. We estimate the diameter of this Vatira to be $1.50_{-0.65}^{+1.10}$ km by considering the average albedo of A-type and S-complex asteroids ($p_V=0.23_{-0.08}^{+0.11}$), and the absolute magnitude (H=$16.40\pm 0.78$ mag). The wide spectral band around 1~$\mu m$ shows the signature of an olivine rich composition. The estimated band centre $BIC=1.08\pm 0.02\mu m$ corresponds to a ferroan olivine mineralogy similar to that of brachinite meteorites.

arXiv commentAccepted for publication in MNRAS. 10 pages, 5 figures,

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