154 Bertha

Bertha (minor planet designation: 154 Bertha) is a main-belt asteroid. It was discovered by the French brothers Paul Henry and Prosper Henry on 4 November 1875, but the credit for the discovery was given to Prosper. It is probably named after Berthe Martin-Flammarion, sister of the astronomer Camille Flammarion.[8]

154 Bertha
Discovery[1]
Discovered byP. M. Henry
Discovery date4 November 1875
Designations
(154) Bertha
Pronunciation/ˈbɜːrθə/[2]
Main belt
Orbital characteristics[3][4]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc130.75 yr (47758 d)
Aphelion3.44394 AU (515.206 Gm)
Perihelion2.94994 AU (441.305 Gm)
3.19694 AU (478.255 Gm)
Eccentricity0.077261
5.72 yr (2087.9 d)
16.63 km/s
125.046°
0° 10m 20.734s / day
Inclination20.9724°
36.7441°
159.722°
Earth MOID1.95152 AU (291.943 Gm)
Jupiter MOID1.53096 AU (229.028 Gm)
TJupiter3.087
Physical characteristics
Dimensions184.93±3.6 km[3]
186.85 ± 1.83 km[5]
Mass(9.19 ± 5.20) × 1018 kg[5]
Mean density
2.69 ± 1.52 g/cm3[5]
Equatorial surface gravity
0.0517 m/s²
Equatorial escape velocity
0.0978 km/s
25.224 h (1.0510 d)[3][6]
0.0480±0.002[3]
0.0483 ± 0.0107[7]
Temperature~156 K
C[7]
7.58,[3] 7.530[7]

    Observations performed at the Palmer Divide Observatory in Colorado Springs, Colorado in during 2007 produced a light curve with a period of 22.30 ± 0.03 hours and a brightness range of 0.10 ± 0.02 in magnitude. A 1998 measurement gave a value of 27.6 hours, which doesn't fit the PDO data.[9] In 2011, observations from the Organ Mesa Observatory in Las Cruces, New Mexico were used to determine a rotation period of 25.224 ± 0.002 hours with a brightness variability of 0.10 ± 0.01 magnitude, ruling out previous studies.[6]

    This is classified as a C-type asteroid[7] and it has an estimated diameter of about 187 km.[5]

    References
    1. "Discovery Circumstances: Numbered Minor Planets". International Astronomical Union - Minor Planet Center.
    2. "Bertha". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (Subscription or UK public library membership required.)
    3. Yeomans, Donald K., "154 Bertha", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
    4. "The Asteroid Orbital Elements Database". astorb. Lowell Observatory.
    5. Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
    6. Pilcher, Frederick (April 2012), "Rotation Period Determinations for 31 Euphrosyne, 65 Cybele, 154 Bertha 177 Irma, 200 Dynamene, 724 Hapag, 880 Herba, and 1470 Carla", The Minor Planet Bulletin, 39 (2), pp. 57–60, Bibcode:2012MPBu...39...57P.
    7. Pravec, P.; et al. (May 2012), "Absolute Magnitudes of Asteroids and a Revision of Asteroid Albedo Estimates from WISE Thermal Observations", Asteroids, Comets, Meteors 2012, Proceedings of the conference held May 16–20, 2012 in Niigata, Japan (1667), Bibcode:2012LPICo1667.6089P. See Table 4.
    8. Schmadel, Lutz D. (2012), Dictionary of Minor Planet Names (6th ed.), Springer, p. 27, ISBN 3642297188.
    9. Warner, Brian D. (September 2007), "Asteroid Lightcurve Analysis at the Palmer Divide Observatory", The Minor Planet Bulletin, Bibcode:2007MPBu...34...72W.


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