Summary for : (65803) Didymos

DynT.TT.BT T.L B T.DDensity (g/cm^3)Δρ/ρDiameter (km)ΔD/DMass (kg)ΔM/MRefAvg.M
NEA--- | --1.95 ± 0.62   (C)32 %0.8 ± 0.110.0 %5.24e+11 ± 5.24e+1010 %SEVM
NEA--- | --1.95 ± 0.62   (C)32 %0.8 ± 0.110.0 %5.24e+11 ± 5.24e+1010 %Sw.avg
NEA-1.90 ± 0.53   (C)28 %0.8 ± 0.110.0 %5.24e+11 ± 5.20e+1010 %C?

Average asteroid densities (g/cm^3):
C = 1.3 ± 0.6, B = 2.4 ± 0.5, S = 2.7 ± 0.5, M = 3.5 ± 1.0, P = 2.8 ± 1.6, X = 1.9 ± 0.8, Xc = 4.9 ± 0.9, Xk = 4.2 ± 0.7 (Ref)

Additional resources:
3D Model | JPL New Horizons | Minor Planet Center | Wikipedia (these auto-generated links might not work)

Note: The density estimates have been ranked from (A) to (E), corresponding to the relative error: (B) less than 20%, (C) between 20 and 50%, (D) between 50 and 100%, and (E) more than 100%. (A) stands for (presumably) reliable estimates (accuracy better than 20%), based on more than 5 mass estimates and 5 diameter estimates, or a spacecraft encounter. Apparently unrealistic densities (ρ > 8) are tagged with (X).

EVM: average by using the Expected Value Method (Ref). w.avg: weighted average (with w = 1/err^2).

T.T: Tholen Tax Class. T.B: Bus & Binzel Tax Class. T T.L: S3OS2 Lazarro (Tholen) Tax Class. T.L B: S3OS2 Lazarro (Bus & Binzel) Tax Class. T.D: DeMeo Tax Class.

Ref: S = SiMDA, C = Carry (2012)

(Indirect) density estimates

Density (g/cm^3)Δρ/ρMethodYearRefN
1.7 ± 0.4023.5 %PheMu2006BD7
2.1 ± 0.6028.6 %PheMu2006BD7
1.7 ± 0.5029.4 %PheMu2009BD11
2.1 ± 0.6531.0 %PheMu2009BD11

PheMu : Mutual eclipsing phenomena in binary systems.
References
BD7(2006):Pravec, P., Scheirich, P., Kusnirak, P., Sarounova, L., et al., 2006. Photometric survey of binary near-Earth asteroids. Icarus 181, 63-93.
BD11(2009):Scheirich, P., Pravec, P., 2009. Modeling of lightcurves of binary asteroids. Icarus 200, 531-547.

Diameter estimates

DesignationDiameter / Err (km)ΔD/DMethodYearRefNχ2Use
(65803) Didymos0.80 ± 0.0810.0 % Radar2010D66 0.00 1

Notes (N):
1: This estimate is discarded for the average diameter (and derived density) calculation in Carry (2012).
2: This estimate is discarded for the average diameter (and derived density) calculation in SiMDA (catalog).

Radar : Radar imaging.


00.511.520.750.80.85
Diameter estimates for : (65803) DidymosDiameter in km

EVM diam. average D = (0.8 ± 0.08) km   (ΔD/D = 10%, SNR = 10.00) Derived bulk density ρ = (1.95 ± 0.62) g/cm3   (Δρ/ρ = 32%, SNR = 3.2)


References
D66(2010):Benner, L.A.M., Margot, J., Nolan, M.C., Giorgini, J.D., Brozovic, M., Scheeres, D.J., Magri, C., Ostro, S.J., 2010. Radar Imaging and a Physical Model of Binary Asteroid 65803 Didymos, in: AAS/Division for Planetary Sciences Meeting Abstracts

Mass estimates

DesignationMass / Err (kg)ΔM/MMethodYearRefNχ2Use
(65803) Didymos5.24e+11 ± 5.24e+1010 %BinRad 2010M910.00 1

Notes (N):
1: This estimate is discarded for the average mass (and derived density) calculation in Carry (2012).
2: This estimate is discarded for the average mass (and derived density) calculation in SiMDA (catalog).
3: This estimate is an average of individual solutions listed before under the same reference (e.g. M125).

BinRad : Binary imaged with radar.


00.511.52480B500B520B540B560B580B
Mass estimates for : (65803) DidymosMass in kg

EVM mass average M = (5.240 ± 0.524) × 1011 kg   (ΔM/M = 10%, SNR = 10.0) Derived bulk density ρ = (1.95 ± 0.62) g/cm3   (Δρ/ρ = 32%, SNR = 3.2)


References
M91(2010):Benner, L.A.M., Margot, J., Nolan, M.C., Giorgini, J.D., Brozovic, M., Scheeres, D.J., Magri, C., Ostro, S.J., 2010. Radar Imaging and a Physical Model of Binary Asteroid 65803 Didymos, in: AAS/Division for Planetary Sciences Meeting Abstracts