Characterisation of the new target of the NASA Lucy mission: asteroid 152830 Dinkinesh (1999 VD57)

TL;DR

This study characterizes asteroid 152830 Dinkinesh, recently added to the NASA Lucy mission target list, using multi-observatory spectral and photometric data to determine its composition, size, and physical properties.

Contribution

The paper provides the first detailed physical characterization of asteroid Dinkinesh, including spectral type, size, and albedo, aiding mission planning and scientific understanding.

Findings

Dinkinesh is an S-type asteroid mainly composed of silicates and metals.

Estimated diameter of Dinkinesh is approximately 900 meters.

Dinkinesh has a geometric albedo of about 0.223.

Abstract

The NASA Lucy mission is aimed at the study of the very interesting population of Jupiter Trojans, considered as time capsules from the origin of our solar system. During its journey, the mission will pass near a main belt asteroid, Donaldjohanson. Recently, NASA has announced that a new asteroid in the belt will also be visited by Lucy: 152830 Dinkinesh (1999 VD57). The main goal of this work is to characterise this newly selected target, asteroid Dinkinesh, in order to provide critical information to the mission team. To achieve it, we have obtained visible spectra, colour photometry, and time-series photometry of Dinkinesh, using several telescopes located at different observatories. For the spectra we used the 10.4m Gran Telescopio Canarias (GTC), in the island of La Palma (Spain); for the colour photometry the 4.3m Lowell Discovery Telescope (LDT), near Happy Jack, Arizona (USA) was used; and for the time-series photometry we used the 82cm IAC80 telescope located in the island of Tenerife (Spain). Both visible spectrum and reflectance values computed from colour photometry show that Dinkinesh is an S-type asteroid, i.e., it is composed mainly of silicates and some metal. According to observations done by the NEOWISE survey, S-type asteroids have typical geometric albedo of $p_V$ = 0.223 $\pm$ 0.073. From our time-series photometry, we obtained an asteroid mean magnitude $r'$ = 19.99 $\pm$ 0.05, which provides an absolute magnitude $H_{r'}$ = 17.53 $\pm$ 0.07 assuming $G$ = 0.19 $\pm$ 0.25 for S-types. Using our colour-photometry, we transformed $H_{r'}$ to $H_V$ = 17.48 $\pm$ 0.05. This value of absolute magnitude combined with the geometric albedo provides a mean diameter for Dinkinesh of $\sim$900 m, ranging between a minimum size of 542 m and a maximum size of 1309 m.