The impact crater at the origin of the Julia family detected with VLT/SPHERE?
| Type of publication: | Article |
| Citation: | |
| Publication status: | Published |
| Journal: | Astronomy and Astrophysics |
| Volume: | 618 |
| Year: | 2018 |
| Month: | oct |
| Pages: | A154 |
| ISSN: | 0004-6361 |
| URL: | https://ui.adsabs.harvard.edu/... |
| Abstract: | Context. The vast majority of the geophysical and geological constraints |
| Userfields: | ={(e.g., internal structure, cratering history) for main-belt asteroids, have so far been obtained via dedicated interplanetary missions (e.g.,, ESA Rosetta, NASA Dawn). The high angular resolution of SPHERE/ZIMPOL,, the new-generation visible adaptive-optics camera at ESO VLT, implies, that these science objectives can now be investigated from the ground, for a large fraction of D ≥ 100 km main-belt asteroids. The sharp images, acquired by this instrument can be used to accurately constrain the, shape and thus volume of these bodies (hence density when combined with, mass estimates) and to characterize the distribution and topography of D, ≥ 30 km craters across their surfaces. Aims: Here, via several, complementary approaches, we evaluated the recently proposed hypothesis, that the S-type asteroid (89) Julia is the parent body of a small, compact asteroid family that formed via a cratering collisional event., Methods: We observed (89) Julia with VLT/SPHERE/ZIMPOL throughout, its rotation, derived its 3D shape, and performed a reconnaissance and, characterization of the largest craters. We also performed numerical, simulations to first confirm the existence of the Julia family and to, determine its age and the size of the impact crater at its origin., Finally, we utilized the images/3D shape in an attempt to identify the, origin location of the small collisional family. Results: On the, one hand, our VLT/SPHERE observations reveal the presence of a large, crater (D 75 km) in Julia's southern hemisphere. On the other hand, our, numerical simulations suggest that (89) Julia was impacted 30-120 Myrs, ago by a D 8 km asteroid, thereby creating a D ≥ 60 km impact crater at, the surface of Julia. Given the small size of the impactor, the, obliquity of Julia and the particular orientation of the family in the, (a,i) space, the imaged impact crater is likely to be the origin of the, family. Conclusions: New doors into ground-based asteroid, exploration, namely, geophysics and geology, are being opened thanks to, the unique capabilities of VLT/SPHERE. Also, the present work may, represent the beginning of a new era of asteroid-family studies. In the, fields of geophysics, geology, and asteroid family studies, the future, will only get brighter with the forthcoming arrival of 30-40 m class, telescopes like ELT, TMT, and GMT. Based on observations made with, ESO Telescopes at the Paranal Observatory under program ID 199.C-0074, (PI: P. Vernazza).The reduced images are only available available at the, CDS via anonymous ftp to |
| Keywords: | asteroids: individual: (89) Julia, methods: numerical, methods: observational, minor planets, techniques: high angular resolution |
| Authors | |
| Added by: | [JoH] |
| Total mark: | 0 |
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