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]
Discovery[1] | |
---|---|
Discovered by | P. M. Henry |
Discovery date | 4 November 1875 |
Designations | |
(154) Bertha | |
Pronunciation | /ˈbɜːrθə/[2] |
A875 VD | |
Main belt | |
Orbital characteristics[3][4] | |
Epoch 31 July 2016 (JD 2457600.5) | |
Uncertainty parameter 0 | |
Observation arc | 130.75 yr (47758 d) |
Aphelion | 3.44 AU (515.21 Gm) |
Perihelion | 2.95 AU (441.30 Gm) |
3.20 AU (478.26 Gm) | |
Eccentricity | 0.077261 |
5.72 years (2,087.9 d) | |
Average orbital speed | 16.63 km/s |
125.046° | |
0° 10m 20.734s / day | |
Inclination | 20.9724° |
36.7441° | |
159.722° | |
Earth MOID | 1.95 AU (291.94 Gm) |
Jupiter MOID | 1.53 AU (229.03 Gm) |
TJupiter | 3.087 |
Physical characteristics | |
Dimensions | 184.93±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]