Physical and dynamical properties of the unusual V-type asteroid (2579) Spartacus

Abstract

Context. Asteroid (2579) Spartacus is a small V-type object located in the inner main belt. This object shows spectral characteristics unusual for typical Vestoids, which may indicate an origin deeper than average within Vesta or an origin from an altogether different parent body. Aims. Our main goal is to study the origin of Spartacus. We derive the spin of Spartacus and a convex shape model of Spartacus in order to increase the knowledge of the body’s physical properties. The rotational parameters are then used to investigate dynamical evolution of the object as well as to distinguish regions sampled by spectral observations to determine whether its surface displays heterogeneity. Methods. We collected lightcurves available from the literature (oppositions of 2009, 2012) and obtained additional photometric observations at various telescopes in 2016, 2017, and 2018. We used the lightcurve inversion method to derive a spin and convex shape model. We have collected spectral observations over two rotational periods of Spartacus and determined its spectral parameters using the modified Gaussian model (MGM). We then dynamically integrated the orbital elements of Spartacus, taking into account existing information, including its thermal properties, size and the derived spin axis orientation. Results. We find two models for (2579) Spartacus: (a) λ = 312° ± 5°, β = −57° ± 5° and (b) λ = 113° ± 5°, β = −60° ± 5° both retrograde. We find that the drift direction for Spartacus is consistent with separation from Vesta, and after a backward integration of 1 Gyr the asteroid reaches the boundary of the family. We did not observe spectral variations with rotation, thus the body most likely has a homogeneous surface. Additionally, new spectral analysis indicates that the 1.0 and 2.0 μm band centers are within ranges that are typical for Vestoids while the area ratio of these bands is about half that of typical Vestoids. Conclusions. The asteroid (2579) Spartacus is in retrograde rotation and has a drift direction consistent with an origin from Vesta. The revised spectral band centers are within ranges typical for Vestoids, while band area ratio (BAR) is unusually low compared to that of other V-types. The dynamical model shows that the asteroid could have migrated to its current location from the edges of the Vesta family within 1 Gyr, but an origin from an earlier impact on Vesta could also be plausible.

Spectral analysis of basaltic asteroids observed by the Gaia space mission

“…However, these findings were not confirmed by Ieva et al (2016Ieva et al ( , 2018. Only one asteroid in the inner main belt, (2579) Spartacus, shows an unusually low band area ratio (BAR, ratio of the areas encompassed by the 1.0-and 2.0-µm absorption bands) compared to Vesta family members (Burbine et al 2001;Moskovitz et al 2010;Oszkiewicz et al 2019). However, backward dynamical integration shows that the object could well originate from the Vesta family.…”

Physical Properties of “Hot Population” Objects in the Kuiper Belt

“…The obtained refined physical parameters of our objects will be used in further work. Numerical simulation (Troianskyi & Bazyey, 2018;Oszkiewicz et al, 2019;Troianskyi et al, 2022) of orbits on − 4 Gy to must confirm the theory of "hot population" migration from the region of Neptune (Levison et al, 2021).…”

Dynamical evolution of basaltic asteroids outside the Vesta family in the inner main belt

“…In order to apply an appropriate dynamical model to the longterm numerical integration, we adopted a very similar approach as in our previous work on the asteroid (2579) Spartacus (Oszkiewicz et al 2019) and asteroids from the Flora region (Oszkiewicz et al 2015). The main tool was the SWIFT_RMVSY software developed by Brož (2006), which is a modification of the SWIFT_RMVS method from the SWIFT package (Duncan et al 1998 [1,2] Fugitive (1914) Hartbeespoortdam 12.09 2.406 0.139 0.0848 pro.…”

“…However, up-to-date spectral observations do not show a large number of distinct V-types (parts of mantles of the differentiated bodies) across the Solar System. Most V-types reside in the inner main belt in the vicinity of the fossil planetesimal (4) Vesta and are therefore considered related (Binzel & Xu 1993;Bus & Binzel 2002;DeMeo et al 2009;Moskovitz et al 2008bMoskovitz et al , 2010Popescu et al 2018;Oszkiewicz et al 2019Oszkiewicz et al , 2020. Most are parts of the Vesta family or considered Vesta fugitives, that is, objects that escaped the borders of the family through the combination of the Yarkovsky effect and dynamical resonances (Nesvornỳ 2015;Nesvorný et al 2008).…”