(24835) 1995 SM55

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(24835) 1995 SM55
Discovery [1] [2]
Discovered by N. Danzl
Discovery site Spacewatch
Kitt Peak National Obs.
Discovery date19 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°
≈ 7 June 2040 [7]
±5 days
70.087°
Physical characteristics
Dimensions (212±4) × (184±24) × (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)
B–V = 0.65 [10]
V−R = 0.37 [10]
V−I = 0.710 [10]
4.55±0.03 [8]

    (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]

    Contents

    Origin

    Diagram showing the orbits of 1995 SM55 among other members of the Haumea family (colored gray) Haumea family orbits.png
    Diagram showing the orbits of 1995 SM55 among other members of the Haumea family (colored gray)

    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 × 184 km × 152 km (132 mi × 114 mi × 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.

    References

    1. 1 2 3 "JPL Small-Body Database Browser: 24835 (1995 SM55)" (2025-01-08 last obs.). Jet Propulsion Laboratory . Retrieved 14 August 2025.
    2. 1 2 3 4 "24835 (1995 SM55)". Minor Planet Center. Retrieved 8 February 2018.
    3. 1 2 Michael E. Brown. "How many dwarf planets are there in the outer solar system?". California Institute of Technology . Retrieved 8 February 2018.
    4. ↑ Johnston, Wm. Robert (15 October 2017). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 8 February 2018.
    5. ↑ "MPEC 2009-R09 :Distant Minor Planets (2009 SEPT. 16.0 TT)". IAU Minor Planet Center. 4 September 2009. Retrieved 4 October 2009.
    6. ↑ Marc W. Buie. "Orbit Fit and Astrometric record for 24835" (2004-11-02 using 119 of 123 observations). SwRI (Space Science Department). Retrieved 4 October 2009.
    7. ↑ JPL Horizons Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 3-sigma.)
    8. 1 2 3 4 5 6 7 8 9 10 11 Ortiz, Jose L.; Morales, N.; Sicardy, B.; Fernandez-Valenzuela, E.; Braga-Ribas, F.; Kilic, Y.; et al. (18 September 2025). "A high geometric albedo and small size of the Haumea cluster member (24835) 1995 SM55 from a stellar occultation and photometric observations". arXiv: 2509.15384 [astro-ph.EP].
    9. ↑ Belskaya, Irina N.; Barucci, Maria A.; Fulchignoni, Marcello; Dovgopol, Anatolij N. (April 2015). "Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo". Icarus. 250: 482–491. Bibcode:2015Icar..250..482B. doi:10.1016/j.icarus.2014.12.004.
    10. 1 2 3 4 "LCDB Data for (24835)". Asteroid Lightcurve Database (LCDB). Retrieved 8 February 2018.
    11. 1 2 3 4 Snodgrass, C.; Carry, B.; Dumas, C.; Hainaut, O. (February 2010). "Characterisation of candidate members of (136108) Haumea's family". Astronomy and Astrophysics. 511: 9. arXiv: 0912.3171 . Bibcode:2010A&A...511A..72S. doi:10.1051/0004-6361/200913031. S2CID   62880843.
    12. 1 2 3 Pinilla-Alonso, N.; Licandro, J.; Gil-Hutton, R.; Brunetto, R. (June 2007). "The water ice rich surface of (145453) 2005 RR43: a case for a carbon-depleted population of TNOs?". Astronomy and Astrophysics. 468 (1): L25. arXiv: astro-ph/0703098 . Bibcode:2007A&A...468L..25P. doi:10.1051/0004-6361:20077294. S2CID   18546361.
    13. 1 2 John Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; John Spencer; David Trilling; et al. (2007). Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope. arXiv: astro-ph/0702538 . Bibcode:2008ssbn.book..161S.
    14. ↑ Grundy, W. M.; Noll, K. S.; Stephens, D. C. (July 2005). "Diverse albedos of small trans-neptunian objects". Icarus. 176 (1): 184–191. arXiv: astro-ph/0502229 . Bibcode:2005Icar..176..184G. doi:10.1016/j.icarus.2005.01.007. S2CID   118866288.
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