Astronomy and Astrophysics
Aims: 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. This information includes the most likely surface composition, albedo, and size of the asteroid, which will be used to better plan the data acquisition strategy at the time of the fly-by.
Methods: To this end, we obtained visible spectra, colour photometry, and time-series photometry for Dinkinesh using several telescopes located at different observatories. For the spectra, we used the 10.4 m Gran Telescopio Canarias (GTC) on the island of La Palma (Spain); for the colour photometry, we used the 4.3 m Lowell Discovery Telescope (LDT) near Happy Jack, Arizona (USA); and for the time-series photometry, we used the 82 cm IAC80 telescope located on the island of Tenerife (Spain). We used the visible reflectance spectrum to obtain the taxonomical class of the asteroid in order to constrain its albedo value. Colour and time-series photometry were used to compute the absolute magnitude of Dinkinesh, which was used in conjunction with an albedo estimation to constrain its size.
Results: Both the visible spectrum and reflectance values computed from colour photometry show that Dinkinesh is an S-type asteroid; that is, it is composed mainly of silicates and some metal. According to observations carried out as part of the NEOWISE survey, S-type asteroids have a typical geometric albedo of pV = 0.223 ± 0.073. From our time-series photometry, we obtain an asteroid mean magnitude of r' = 19.99 ± 0.05, which provides an absolute magnitude Hr' = 17.53 ± 0.07 assuming G = 0.19 ± 0.25 for S-types. Using our colour-photometry, we transformed Hr' to HV = 17.48 ± 0.05. This value of absolute magnitude combined with the geometric albedo provides a mean diameter for Dinkinesh of ~900 m, ranging between a minimum size of 542 m and a maximum size of 1309 m.
Este Proyecto estudia las propiedades físicas y composicionales de los llamados pequeños cuerpos del Sistema Solar, que incluyen asteroides, objetos helados y cometas. Entre los grupos de mayor interés destacan los objetos trans-neptunianos (TNOs), incluyendo los objetos más lejanos detectados hasta la fecha (Extreme-TNOs o ETNOs); los cometas, y