Summary for : 81P/Wild 2

DynT.TT.BT T.L B T.DDensity (g/cm^3)Δρ/ρDiameter (km)ΔD/DMass (kg)ΔM/MRefAvg.M
COM--- | --1.44 ± 0.89   (D)62 %2.2 ± 0.420.4 %8.10e+12 ± 8.10e+1110 %SEVM
COM--- | --1.69 ± 2.96   (E)175 %2.1 ± 1.258.1 %8.10e+12 ± 8.10e+1110 %Sw.avg
COM-0.70 ± 0.10   (B)14 %2.1 ± 0.12.9 %8.10e+12 ± 8.10e+1110 %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:

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
0.7 ± 0.1014.3 %CNGF2006BD6

CNGF : Non-gravitational forces (comets).
References
BD6(2006):Davidsson, B.J.R., Gutierrez, P.J., 2006. Non-gravitational force modeling of Comet 81P/Wild 2. I. A nucleus bulk density estimate. Icarus 180, 224-242.

Diameter estimates

DesignationDiameter / Err (km)ΔD/DMethodYearRefNχ2Use
81P/Wild 22.08 ± 0.062.9 % FlyBy2004D17 4.40 1
81P/Wild 23.81 ± 0.7619.9 % H-mag2006D321 4.45 2

plot, average diameter and derived density

All

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).

FlyBy : Images from spacecraft encounter. H-mag : Crude estimate from absolute magnitude.


EVM diam. average D = (2.2 ± 0.45) km   (ΔD/D = 20%, SNR = 4.91) Derived bulk density ρ = (1.44 ± 0.89) g/cm3   (Δρ/ρ = 62%, SNR = 1.6)


References
D17(2004):Brownlee, D.E., Horz, F., Newburn, R.L., Zolensky, M., Duxbury, T.C., Sandford, S., Sekanina, Z., Tsou, P., Hanner, M.S., Clark, B.C., Green, S.F., Kissel, J., 2004. Surface of Young Jupiter Family Comet 81 P/Wild 2: View from the Stardust Spacecraft. Science 304, 1764–1769.
D32(2006):Tancredi, G., Fernández, J.A., Rickman, H., Licandro, J., 2006. Nuclear magnitudes and the size distribution of Jupiter family comets. Icarus 182, 527–549.

Mass estimates

DesignationMass / Err (kg)ΔM/MMethodYearRefNχ2Use
81P/Wild 28.10e+12 ± 8.10e+1110 %CNGF 2009M850.00 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).

CNGF : Non-gravitational forces (comets).


EVM mass average M = (8.100 ± 0.810) × 1012 kg   (ΔM/M = 10%, SNR = 10.0) Derived bulk density ρ = (1.44 ± 0.89) g/cm3   (Δρ/ρ = 62%, SNR = 1.6)


References
M85(2009):Sosa, A., Fernández, J.A., 2009. Cometary masses derived from nongravitational forces. Monthly Notices of the Royal Astronomical Society 393, 192–214.