(24835) 1995 SM55
Trans-Neptunian object (TNO)
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(24835) 1995 SM55 (provisional designation 1995 SM55) is an icy trans-Neptunian object and member of the Haumea family that resides in the Kuiper belt, located in the outermost region of the Solar System. It was discovered on 19 September 1995, by American astronomer Nichole Danzl of the Spacewatch program at Kitt Peak National Observatory near Tucson, Arizona, in the United States.[2] Stellar occultation observations in 2025 show that it has highly reflective surface and a diameter of about 200 km (120 mi). This highly reflective surface is typical for Haumea family Kuiper belt objects,[8] which are believed to be icy fragments of the dwarf planet Haumea.[11][12]
| Discovery[1][2] | |
|---|---|
| Discovered by | N. Danzl |
| Discovery site | Spacewatch Kitt Peak National Obs. |
| Discovery date | 19 September 1995 |
| Designations | |
| (24835) 1995 SM55 | |
| 1995 SM55 | |
| Orbital characteristics[1] | |
| Epoch 5 May 2025 (JD 2460800.5) | |
| Uncertainty parameter 2 | |
| Observation arc | 42.31 yr (15,455 days) |
| Aphelion | 46.823 AU |
| Perihelion | 37.448 AU |
| 42.135 AU | |
| Eccentricity | 0.1112 |
| 273.51 yr (99,902 days) | |
| 342.25° | |
| 0° 0m 13.32s / day | |
| Inclination | 27.015° |
| 20.974° | |
| â 7 June 2040[7] ±5 days | |
| 70.087° | |
| Physical characteristics | |
| Dimensions | (212±4) à (184±24) à (152±20) km[8] |
| 181±12 km (volume-equivalent)[8] | |
| 52.52±0.02 h or 26.26±0.01 h (ambiguous, but 52.52 h is preferred[8]) | |
| 0.80±0.04[8] | |
| BBb (suspected)[9] · C[10] (Neutral) BâV = 0.65[10] VâR = 0.37[10] VâI = 0.710[10] | |
| 4.55±0.03[8] 4.57[1] | |
Origin
1995 SM55 has a high geometric albedo of 0.80 in visible light[8] and a similar orbit to the dwarf planet Haumea, which means that it must be a member of the Haumea family.[3][8] The Haumea family is a population of bright, water ice-rich Kuiper belt objects that are believed to have broken off from Haumea after a giant collision over 4 billion years ago.[12][11] Members of the Haumea family include 1996 TO66, 2002 TX300, 2003 OP32 and 2005 RR43.[12][11] Based on the differences between the orbits of 1995 SM55 and Haumea, the object was likely ejected from the dwarf planet at a relatively high speed of 123.3 m/s.[11]
Physical characteristics
Because 1995 SM55 has a high albedo, it appears much brighter than other Kuiper belt objects.[13] Because its high brightness, astronomers initially believed that 1995 SM55 could have a very large size, with a diameter up to 700 km (430 mi) if it had a dark, low-albedo surface.[14] However, further analysis of 1995 SM55's thermal emission and orbit showed that it should be much smaller with a more reflective surface.[13]
On 25 February 2024, 1995 SM55 passed in front of a star and occulted it.[8] This stellar occultation was observed by numerous astronomers at 40 different locations, with 7 of them reporting positive detections of the occultation.[8] The occultation observations revealed that 1995 SM55 is a roughly elliptical object that is 212 km à 184 km à 152 km (132 mi à 114 mi à 94 mi) in diameter (volume-equivalent diameter 181 km or 112 mi).[8]
Naming
As of January 2025, this minor planet has not been named by the Minor Planet Center.[2] Suggestions for names are open to the public.
