Photometric survey of 55 near-earth asteroids

¹ LESIA, Observatoire de Paris, Université PSL CNRS, Université de Paris, Sorbonne Université, 5 place Jules Janssen, 92195 Meudon, France
e-mail: tetiana.hromakina@obspm.fr
² V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine
³ IMCCE, Observatoire de Paris, CNRS UMRO 8028, PSL Research University, 77 Av. Denfert Rochereau, 75014 Paris Cedex, France
e-mail: Mirel.Birlan@obspm.fr
⁴ Astronomical Institute of the Romanian Academy, 5 Cutitul de Argint, 040557, sector 4, Bucharest, Romania
⁵ Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris Cedex 05, France
⁶ Vasile Urseanu Astronomical Observatory, bd. Lascar Catargiu 21, 010661, Bucharest, Romania
⁷ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone, Italy

Received: 21 June 2021
Accepted: 9 September 2021

Abstract

Context. Near-earth objects (NEOs), thanks to their proximity, provide a unique opportunity to investigate asteroids with diameters down to dozens of meters. The study of NEOs is also important because of their potential hazard to the Earth. The investigation of small NEOs is challenging from Earth as they are observable only for a short time following their discovery and can sometimes only be reached again years or decades later.

Aims. We aim to derive the visible colors of NEOs and perform an initial taxonomic classification with a main focus on smaller objects and recent discoveries.

Methods. Photometric observations were performed using the 1.2 m telescope at the Haute-Provence observatory and the 1.0 m telescope at the Pic du Midi observatory in broadband Johnson-Cousins and Sloan photometric systems.

Results. We present new photometric observations for 55 NEOs. Our taxonomic classification shows that almost half (43%) of the objects in our sample are classified as S+Q-complex members, 19% as X-complex, 16% as C-complex, 12% as D-types, and finally 6% and 4% as A- and V-types, respectively. The distribution of the observed objects with H > 19 and H ≤ 19 remains almost the same. However, the majority of the objects in our dataset with D < 500 m belong to the “silicate” group, which is probably a result of an observational bias towards brighter and more accessible objects. “Carbonaceous” objects are predominant among those with a Jovian Tisserand parameter of Tj < 3. These bodies could be dormant or extinct comets. The median values of the absolute magnitude for “carbonaceous” and “silicate” groups are H = 18.10 ± 0.95 and H = 19.50 ± 1.20, whereas the estimated median diameters are D = 1219 ± 729 m and D = 344 ± 226 m, respectively. “Silicate” objects have a much lower median Earth’s minimum orbit intersection distance (MOID) and a somewhat lower orbital inclination in comparison to “carbonaceous” objects. About half of the observed objects are potentially hazardous asteroids and are mostly (almost 65%) represented by “silicate” objects.