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Summary for : (31) Euphrosyne

Dyn	T.T	T.B	T T.L B	T.D	Density (g/cm^3)	Δρ/ρ	Diameter (km)	ΔD/D	Mass (kg)	ΔM/M	Ref	Avg.M
MBA	C	Cb	- \| -	-	1.49 ± 0.82 (D)	55 %	273.5 ± 13.6	5.0 %	1.59e+19 ± 8.44e+18	53 %	S	EVM
MBA	C	Cb	- \| -	-	1.13 ± 0.87 (D)	77 %	274.6 ± 9.7	3.5 %	1.22e+19 ± 9.36e+18	77 %	S	w.avg
MBA	C				1.18 ± 0.61 (D)	52 %	272.9 ± 8.9	3.2 %	1.27e+19 ± 6.50e+18	51 %	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

Designation	Diameter / Err (km)	ΔD/D	Method	Year	Ref	χ²	Use
(31) Euphrosyne	255.89 ± 11.50	4.5 %	STM	2004	D93	2.35	1
(31) Euphrosyne	265.94 ± 7.00	2.6 %	STM	2010	D64	1.18	2
(31) Euphrosyne	286.91 ± 12.54	4.4 %	NEATM	2010	D64	1.14	3
(31) Euphrosyne	276.48 ± 2.85	1.0 %	STM	2011	D83	1.07	4
(31) Euphrosyne	280.00 ± 60.77	21.7 %	NEATM	2011	D72	0.01	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 = (273.5 ± 13.60) km (ΔD/D = 5%, SNR = 20.12) Derived bulk density ρ = (1.49 ± 0.82) g/cm³ (Δρ/ρ = 55%, 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.
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

Designation	Mass / Err (kg)	ΔM/M	Method	Year	Ref	N	χ²	Use
(31) Euphrosyne	1.87e+19 ± 1.03e+19	55 %	Deflec	2004	M42		0.07	1
(31) Euphrosyne	6.23e+18 ± 1.17e+18	19 %	Deflec	2008	M72		68.63	2
(31) Euphrosyne	5.95e+19 ± 1.35e+19	23 %	Ephem	2009	M80	12	10.42	3
(31) Euphrosyne	1.71e+19 ± 1.71e+18	10 %	Ephem	2009	M86		0.47	4
(31) Euphrosyne	5.81e+19 ± 1.97e+19	34 %	Deflec	2011	M95	12	4.58	5
(31) Euphrosyne	1.85e+19 ± 1.13e+19	61 %	Deflec	2011	M97		0.05	6
(31) Euphrosyne	2.31e+19 ± 9.44e+18	41 %	Deflec	2011	M97		0.58	7
(31) Euphrosyne	2.69e+19 ± 9.10e+18	34 %	Deflec	2011	M97		1.46	8
(31) Euphrosyne	1.39e+19 ± 1.27e+19	91 %	Deflec	2011	M97		0.03	9
(31) Euphrosyne	8.75e+18 ± 3.98e+18	45 %	Ephem	2011	M100		3.25	10
(31) Euphrosyne	1.73e+19 ± 1.39e+18	8 %	OrbFitN	2014	M123		0.98	11
(31) Euphrosyne	8.52e+18 ± 2.77e+18	33 %	Ephem	2019	M126		7.14	12

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 = (1.592 ± 0.844) × 10¹⁹ kg (ΔM/M = 53%, SNR = 1.9) Derived bulk density ρ = (1.49 ± 0.82) g/cm³ (Δρ/ρ = 55%, SNR = 1.8)

References

M42	(2004):	Kochetova, O.M., 2004. Determination of Large Asteroid Masses by the Dynamical Method. Solar System Research 38, 66–75.
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.
M80	(2009):	Fienga, A., Laskar, J., Morley, T., Manche, H., Kuchynka, P., Le Poncin-Lafitte, C., Budnik, F., Gastineau, M., Somenzi, L., 2009. INPOP08, a 4-D planetary ephemeris: from asteroid and time-scale computations to ESA Mars Express and Venus Express contributions. Astronomy and Astrophysics 507, 1675–1686.
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.
M100	(2011):	Fienga, A., Kuchynka, P., Laskar, J., Manche, H., Gastineau, M., 2011. Asteroid mass determinations with INPOP planetary ephemerides. EPSC-DPS Joint Meeting 2011 , 1879.
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,

Size, Mass and Density of Asteroids (SiMDA)

Summary for : (31) Euphrosyne

Diameter estimates

Mass estimates