Surface Heterogeneity, Physical, and Shape Model of Near-Earth Asteroid (52768) 1998 OR2

0584081 - ASÚ 2025 RIV US eng J - Journal Article
Devogèle, M. - McGilvray, A. - MacLennan, E. - Pravec, Petr … Total 40 authors
Surface Heterogeneity, Physical, and Shape Model of Near-Earth Asteroid (52768) 1998 OR2.
The Planetary Science Journal. Roč. 5, č. 2 (2024), č. článku 44. E-ISSN 2632-3338
Institutional support: RVO:67985815
Keywords : radar observations * lightcurve inversion * spectroscopic survey
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 3.4, year: 2022
Method of publishing: Open access

On 2020 April 29, the near-Earth object (52768) 1998 OR2 experienced a close approach to Earth at a distance of 16.4 lunar distances (LD). 1998 OR2 is a potentially hazardous asteroid of absolute magnitude H = 16.04 that can currently come as close to Earth as 3.4 LD. We report here observations of this object in polarimetry, photometry, and radar. Our observations show that the physical characteristics of 1998 OR2 are similar to those of both M- and S-type asteroids. Arecibo's radar observations provide a high radar albedo of sigma OC= 0.29 +/- 0.08, suggesting that metals are present in 1998 OR2 near-surface. We find a circular polarization ratio of mu c = 0.291 +/- 0.012, and the delay-Doppler images show that the surface of 1998 OR2 is a top-shape asteroid with large-scale structures such as large craters and concavities. The polarimetric observations display a consistent variation of the polarimetric response as a function of the rotational phase, suggesting that the surface of 1998 OR2 is heterogeneous. Color observations suggest an X-complex taxonomy in the Bus-DeMeo classification. Combining optical polarization, radar, and two epochs from the NEOWISE satellite observations, we derived an equivalent diameter of D = 1.80 +/- 0.1 km and a visual albedo p v = 0.21 +/- 0.02. Photometric and radar data provide a sidereal rotation period of P = 4.10872 +/- 0.00001 hr, a pole orientation of (332.degrees 3 +/- 5 degrees, 20.degrees 7 +/- 5 degrees), and a shape model with dimensions of (2.08-0.10+0.10,1.93-0.10+0.10,1.60-0.05+0.05) km.
Permanent Link: https://hdl.handle.net/11104/0353171