Summary for : (20) Massalia

DynT.TT.BT T.L B T.DDensity (g/cm^3)Δρ/ρDiameter (km)ΔD/DMass (kg)ΔM/MRefAvg.M
MBASS- | -S3.40 ± 1.01   (C)30 %141.2 ± 10.27.2 %5.01e+18 ± 1.03e+1821 %SEVM
MBASS- | -S3.78 ± 1.15   (C)31 %132.6 ± 9.97.5 %4.62e+18 ± 9.52e+1721 %Sw.avg
MBAS3.71 ± 1.05   (C)28 %137.0 ± 8.86.4 %5.00e+18 ± 1.04e+1821 %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)

Object is a Gaia target for mass determination !

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
(20) Massalia145.50 ± 9.306.4 % STM2004D93 0.21 1
(20) Massalia152.27 ± 7.194.7 % STM2010D64 2.37 2
(20) Massalia155.04 ± 9.626.2 % NEATM2010D64 2.07 3
(20) Massalia131.55 ± 1.150.9 % STM2011D832 70.26 4

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 = (141.2 ± 10.19) km   (ΔD/D = 7%, SNR = 13.85) Derived bulk density ρ = (3.40 ± 1.01) g/cm3   (Δρ/ρ = 30%, SNR = 3.3)


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.
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
(20) Massalia4.77e+18 ± 7.96e+1717 %Deflec 1998M160.09 1
(20) Massalia5.67e+18 ± 8.15e+1714 %Deflec 2008M720.66 2
(20) Massalia4.36e+18 ± 4.36e+1710 %Ephem 2009M862.20 3
(20) Massalia3.34e+18 ± 6.96e+1721 %Deflec 2011M9525.74 4
(20) Massalia5.88e+18 ± 1.46e+1825 %Deflec 2011M970.36 5
(20) Massalia5.67e+18 ± 1.14e+1820 %Deflec 2011M970.34 6
(20) Massalia6.03e+18 ± 1.13e+1819 %Deflec 2011M970.82 7
(20) Massalia7.07e+18 ± 1.68e+1824 %Deflec 2011M971.51 8
(20) Massalia4.77e+18 ± 1.99e+174 %OrbFitN 2014M1231.39 9
(20) Massalia5.91e+18 ± 1.23e+1821 %Deflec 2017M12520.53 10
(20) Massalia8.15e+18 ± 2.60e+1832 %Deflec 2017M12521.46 11
(20) Massalia3.52e+18 ± 1.29e+1837 %Deflec 2017M12521.33 12
(20) Massalia3.96e+18 ± 1.92e+1849 %Deflec 2017M12520.30 13
(20) Massalia4.93e+18 ± 7.72e+1716 %Deflec 2017M12530.01 14
(20) Massalia1.71e+18 ± 6.85e+1740 %Ephem 2019M126223.12 15

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 = (5.007 ± 1.029) × 1018 kg   (ΔM/M = 21%, SNR = 4.9) Derived bulk density ρ = (3.40 ± 1.01) g/cm3   (Δρ/ρ = 30%, SNR = 3.3)


References
M16(1998):Bange, J., 1998. An estimation of the mass of asteroid 20-Massalia derived from the HIPPARCOS minor planets data. Astronomy and Astrophysics 340, L1–L4.
M72(2008):Baer, J., Milani, A., Chesley, S.R., Matson, R.D., 2008. An Observational Error Model, and Application to Asteroid Mass Determination, in: Bulletin of the American Astronomical Society, p. 493.
M86(2009):Folkner, W.M., Williams, J.G., Boggs, D.H., 2009. The planetary and lunar ephemeris de 421. IPN Progress Report 42, 1–34.
M95(2011):Baer, J., Chesley, S.R., Matson, R.D., 2011. Astrometric Masses of 26 Asteroids and Observations on Asteroid Porosity. Astronomical Journal 141, 143–155.
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.
M125(2017):Baer, J., Chesley, S.R., 2017. Simultaneous Mass Determination for Gravitationally Coupled Asteroids. The Astronomical Journal, Volume 154, Issue 2, article id. 76, 11 pp.
M126(2019):Fienga, A., et. al, 2019. INPOP19a planetary ephemeris. Notes Scientifiques et Techniques de l'Institut de mécanique céleste,