Summary for : (85) Io

DynT.TT.BT T.L B T.DDensity (g/cm^3)Δρ/ρDiameter (km)ΔD/DMass (kg)ΔM/MRefAvg.M
MBAFCBC | CbC1.45 ± 0.81   (D)56 %159.6 ± 6.44.0 %3.10e+18 ± 1.68e+1854 %SEVM
MBAFCBC | CbC1.68 ± 0.73   (C)43 %155.2 ± 4.12.6 %3.29e+18 ± 1.41e+1843 %Sw.avg
MBACb1.31 ± 0.77   (D)59 %155.0 ± 6.03.9 %2.57e+18 ± 1.48e+1858 %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)


Diameter estimates

DesignationDiameter / Err (km)ΔD/DMethodYearRefNχ2Use
(85) Io154.78 ± 3.792.4 % STM2004D93 1.63 1
(85) Io155.24 ± 5.093.3 % STM2010D64 0.74 2
(85) Io168.01 ± 10.566.3 % NEATM2010D64 0.63 3
(85) Io169.63 ± 23.0013.6 % Occ2011D95 0.19 4
(85) Io163.00 ± 15.009.2 % MDM:LO2011D78 0.05 5
(85) Io150.66 ± 1.911.3 % STM2011D832 22.02 6
(85) Io163.00 ± 18.6411.4 % NEATM2011D72 0.03 7
(85) Io165.00 ± 3.001.8 % ADAM2017D100 3.21 8

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).

ADAM : All-Data Asteroid Modeling. MDM:LO : Multi-Data Modeling: Lightcurves + Occultations. NEATM : Near-Earth Asteroid Thermal Model. Occ : Stellar occultation. STM : Standard Thermal Model.



EVM diam. average D = (159.6 ± 6.43) km   (ΔD/D = 4%, SNR = 24.83) Derived bulk density ρ = (1.45 ± 0.81) g/cm3   (Δρ/ρ = 56%, SNR = 1.8)



References
D64(2010):Ryan, E.L., Woodward, C.E., 2010. Rectified Asteroid Albedos and Diameters from IRAS and MSX Photometry Catalogs. Astronomical Journal 140, 933–943.
D72(2011):Masiero, J.R., Mainzer, A.K., Grav, T., Bauer, J.M., Cutri, R.M., Dailey, J., Eisenhardt, P.R.M., McMillan, R.S., Spahr, T.B., Skrutskie, M.F., Tholen, D., Walker, R.G., Wright, E.L., DeBaun, E., Elsbury, D., Gautier, IV, T., Gomillion, S., Wilkins, A., 2011. Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters. Astrophysical Journal 741, 68.
D78(2011):Ďurech, J., Kaasalainen, M., Herald, D., Dunham, D., Timerson, B., Hanuš, J., Frappa, E., Talbot, J., Hayamizu, T., Warner, B.D., Pilcher, F., Galád, A., 2011. Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes. Icarus 214, 652–670.
D83(2011):Usui, F., Kuroda, D., Müller, T.G., Hasegawa, S., Ishiguro, M., Ootsubo, T., Ishihara, D., Kataza, H., Takita, S., Oyabu, S., Ueno, M., Matsuhara, H., Onaka, T., 2011. Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey. Publications of the Astronomical Society of Japan 63, 1117–1138.
D93(2004):Tedesco, E.F., Noah, P.V., Noah, M.C., Price, S.D., 2004. IRAS Minor Planet Survey. NASA Planetary Data System. IRAS-A-FPA-3-RDR-IMPS-V6.0.
D95(2011):Dunham, D.W., Herald, D., Frappa, E., Hayamizu, T., Talbot, J., Timerson, B., 2011. Asteroid Occultations. NASA Planetary Data System. EAR-A-3-RDR-OCCULTATIONS-V9.0.
D100(2017):Hanuš, J., Viikinkoski, M., Marchis, F., et al., 2017. Volumes and bulk densities of forty asteroids from ADAM shape modeling. Astronomy and Astrophysics 601, A114 (2017). DOI: 10.1051/0004-6361/201629956


Mass estimates

DesignationMass / Err (kg)ΔM/MMethodYearRefNχ2Use
(85) Io3.32e+17 ± 3.45e+181039 %Deflec 2011M970.64 1
(85) Io3.87e+18 ± 2.68e+1869 %Deflec 2011M970.08 2
(85) Io3.49e+18 ± 2.64e+1876 %Deflec 2011M970.02 3
(85) Io1.40e+18 ± 6.33e+18452 %Deflec 2011M970.07 4
(85) Io2.39e+18 ± 5.97e+1725 %OrbFitN 2014M1231.41 5
(85) Io5.95e+18 ± 9.87e+1717 %Ephem 2019M1268.34 6

plot, average mass and derived density

All

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).

Deflec : Orbital deflection (close encounter) of one or several test asteroids (classical LSQ). Ephem : Planetary ephemeris solution. OrbFitN : Simultaneous multi-asteroid astrometric orbit solution (similar to 'Ephem').



EVM mass average M = (3.096 ± 1.683) × 1018 kg   (ΔM/M = 54%, SNR = 1.8) Derived bulk density ρ = (1.45 ± 0.81) g/cm3   (Δρ/ρ = 56%, SNR = 1.8)



References
M97(2011):Zielenbach, W., 2011. Mass Determination Studies of 104 Large Asteroids. Astronomical Journal 142, 120–128.
M123(2014):Goffin, E., 2014. Astrometric asteroid masses: a simultaneous determination. Astronomy & Astrophysics, Volume 565, id.A56, 8 pp.
M126(2019):Fienga, A., et. al, 2019. INPOP19a planetary ephemeris. Notes Scientifiques et Techniques de l'Institut de mécanique céleste,