tokens: objects. Therefore, in the rest of this work, we consider the A-, B-, D-, Q-, and V-type objects as possible taxonomical interlopers and eliminate them from our family. Fig. 2 Top panel : projection in the ( a , e ) domain of 5523 AstDyS asteroids in the region of the Gefion family (orange) and of 2547 members of the Gefion HCM cluster (black). Bottom panel : projection in the ( a , sin i ) domain of the same asteroids. Other symbols are the same as in Fig. 1 . Fig. 3 An ( a , sin i ) projection of the 606 asteroids in the Gefion region with taxonomic information from the SDSS-MOC4 database. The inset figure legend indicates the meaning of the symbols. Open circles indicate asteroids in the background, while filled circles correspond to asteroids of the Gefion family. The Wide-field Infrared Survey Explorer (WISE) and near-Earth object WISE 4 ( Masiero et al. 2011 ; Mainzer et al. 2016 ) were also used in this work to revise asteroid diameters and albedosin the Gefion region. We identified 896 asteroids with geometric albedo ranging between 0.0278 ± 0.0104 and 0.6200 ± 0.1510. We found 658 of them without taxonomic information. About 57.8% of those last albedos are possibly associated with an S-type (they vary between 0.12 and 0.30 with a standard deviation of 0.05). The mean albedo found in the HCM group is 0.2609 and the median one is 0.2598 with an associated standard deviation of 0.17 ( Fig. 4 ). Fig. 4 An ( a , sin i ) projection of the 658 bodies in the Gefion region with albedo information from the WISE dataset. The inset figure legend provides the meaning of the symbols. Considering a simple model with a spherical shape and a uniform density varying according to each class ( DeMeo Carry 2013 ), we find that the effective diameters ( D ) of the members in the HCM group vary between 0.82 and 71.46 km. The total mass of the family is estimated to be 0.791± 0.54 × 10 18 kg. Assuming that the objects on the left-hand side of the family are lost in the 5J:-2A MMR, our family probably originates from the break-up of an S-type asteroid with a diameter D ≈ 128 km, which is inside the allowed diameter range of 100–150 km mentioned in Nesvorný et al. (2009) . 3 Dynamical map We started our numerical exploration on the Gefion family by constructing dynamical maps of synthetic proper elements for 19 000 massless particles in the ( a , sin i ) plane and for 18 360 particles in the ( a , e ) plane. These numbers are chosen to cover an equally spaced grid in each plan. We vary the initial semi-major axis in the interval [2.69463, 2.832] with a step size of 0.0017 au. In the ( a , e ) plane, we increase the initial values of e from 0 to 0.18 with a step of 0.0015, while the initial values of the other elements are fixed to those of (1272) Gefion at the modified Julian date of 57200, which corresponds to June 27, 2015, and are available in AstDyS database. We use the Swift package ( Levison Duncan 1994 ) to integrate the particles over 20 Myr with a
ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Database O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O B-Database I-Database O O O O O O O O O O O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O B-Telescope I-Telescope I-Telescope I-Telescope B-Telescope O B-CelestialObjectRegion O B-CelestialObject I-CelestialObject O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O B-Dataset I-Dataset O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O B-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O B-Database I-Database O O O B-Software I-Software O B-Citation I-Citation I-Citation O O O O O O O O O O