Summary for : (895) Helio

DynT.TT.BT T.L B T.DDensity (g/cm^3)Δρ/ρDiameter (km)ΔD/DMass (kg)ΔM/MRefAvg.M
MBAFCBB- | --4.15 ± 3.89   (D)94 %135.5 ± 13.710.1 %5.40e+18 ± 4.79e+1889 %SEVM
MBAFCBB- | --1.68 ± 8.28   (E)492 %129.6 ± 8.56.5 %1.92e+18 ± 9.42e+18491 %Sw.avg
MBAB5.76 ± 3.58   (D)62 %148.4 ± 5.03.4 %9.87e+18 ± 6.05e+1861 %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
(895) Helio141.89 ± 3.502.5 % STM2004D93 3.38 1
(895) Helio150.93 ± 2.531.7 % STM2010D64 37.39 2
(895) Helio155.12 ± 7.654.9 % NEATM2010D64 6.61 3
(895) Helio128.16 ± 1.781.4 % STM2011D8312 16.81 4
(895) Helio119.31 ± 1.541.3 % NEATM2011D7212 109.96 5

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).

NEATM : Near-Earth Asteroid Thermal Model. STM : Standard Thermal Model.


EVM diam. average D = (135.5 ± 13.68) km   (ΔD/D = 10%, SNR = 9.91) Derived bulk density ρ = (4.15 ± 3.89) g/cm3   (Δρ/ρ = 94%, SNR = 1.1)


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.
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.

Mass estimates

DesignationMass / Err (kg)ΔM/MMethodYearRefNχ2Use
(895) Helio6.88e+18 ± 1.39e+19202 %Deflec 2011M970.01 1
(895) Helio7.75e+18 ± 3.43e+1844 %Deflec 2011M970.47 2
(895) Helio8.21e+18 ± 3.41e+1842 %Deflec 2011M970.68 3
(895) Helio2.80e+19 ± 1.37e+1949 %Deflec 2011M9722.72 4
(895) Helio1.37e+18 ± 6.77e+1749 %Ephem 2019M12635.43 5

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.


EVM mass average M = (5.398 ± 4.795) × 1018 kg   (ΔM/M = 89%, SNR = 1.1) Derived bulk density ρ = (4.15 ± 3.89) g/cm3   (Δρ/ρ = 94%, SNR = 1.1)


References
M97(2011):Zielenbach, W., 2011. Mass Determination Studies of 104 Large Asteroids. Astronomical Journal 142, 120–128.
M126(2019):Fienga, A., et. al, 2019. INPOP19a planetary ephemeris. Notes Scientifiques et Techniques de l'Institut de mécanique céleste,