TY  - JOUR
T1  - A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea
A1  - Vernazza, P.
A1  - Jorda, L.
A1  - Ševeček, P.
A1  - Brož, M.
A1  - Viikinkoski, M.
A1  - Hanuš, J.
A1  - Carry, B.
A1  - Drouard, A.
A1  - Ferrais, M.
A1  - Marsset, M.
A1  - Marchis, F.
A1  - Birlan, M.
A1  - Podlewska-Gaca, E.
A1  - Jehin, E.
A1  - Bartczak, P.
A1  - Dudziński, G.
A1  - Berthier, J.
A1  - Castillo-Rogez, J.
A1  - Cipriani, F.
A1  - Colas, F.
A1  - DeMeo, F.
A1  - Dumas, C.
A1  - Ďurech, J.
A1  - Fetick, R.
A1  - Fusco, T.
A1  - Grice, J.
A1  - Kaasalainen, M.
A1  - Kryszczynska, A.
A1  - Lamy, P.
A1  - Le Coroller, H.
A1  - Marciniak, A.
A1  - Michalowski, T.
A1  - Michel, P.
A1  - Rambaux, N.
A1  - Santana-Ros, T.
A1  - Tanga, P.
A1  - Vachier, F.
A1  - Vigan, A.
A1  - Witasse, O.
A1  - Yang, B.
A1  - Gillon, M.
A1  - Benkhaldoun, Z.
A1  - Szakats, R.
A1  - Hirsch, R.
A1  - Duffard, R.
A1  - Chapman, A.
A1  - Maestre, J. L.
JA  - Nature Astronomy
Y1  - 2020
SP  - 136
EP  - 141
SN  - 2397-3366
UR  - https://ui.adsabs.harvard.edu/abs/2020NatAs...4..136V
N2  - (10) Hygiea is the fourth largest main belt asteroid and the only known asteroid whose surface composition appears similar to that of the dwarf, planet (1) Ceres, suggesting a similar origin for these, two objects. Hygiea suffered a giant impact more than 2 Gyr, ago that is at the origin of one of the largest asteroid, families. However, Hygeia has never been observed with sufficiently high, resolution to resolve the details of its surface or to constrain its, size and shape. Here, we report high-angular-resolution imaging, observations of Hygiea with the VLT/SPHERE instrument ( 20 mas at 600 nm) that reveal a basin-free nearly spherical shape with a volume-, equivalent radius of 217 ± 7 km, implying a density of 1,944 ± 250 kg.m^3. In addition, we have determined a new, rotation period for Hygiea of 13.8 h, which is half the currently, accepted value. Numerical simulations of the family-forming event show, that Hygiea's spherical shape and family can be explained by a collision, with a large projectile (diameter 75-150 km). By comparing Hygiea's, sphericity with that of other Solar System objects, it appears that, Hygiea is nearly as spherical as Ceres, opening up the possibility for, this object to be reclassified as a dwarf planet.
ER  -