(24835) 1995 SM55

Trans-Neptunian object (TNO) October 2019 yes (24835) 1995 SM 55 #C2E0FF AnimatedOrbitOf248351995SM55 N. Danzl SpacewatchKitt Peak National Obs. 19 September 1995 (24835) 1995 SM 55 TNO Haumea classical Scat-Ext distant 5 May 2025 (JD 2460800.5) 2 42.31 yr (15,455 days) 46.823 AU 37.448 AU ≈ 7 June 2040JPL Horizons Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 3-sigma.)±5 days 42.135 AU 0.1112 273.51 yr (99,902 days) 342.25° 0.0037 ms / day 27.015° 20.974° 70.087° (212 4) × (184 24) × (152 20) km 181 12 km (volume-equivalent) 52.52 0.02 h or 26.26 0.01 h(ambiguous, but 52.52 h is preferred) 0.80 0.04 BBb (suspected)C(Neutral)B–V 0.65V−R 0.37 0.05V−I 0.710 4.55 0.034.57 (24835) 1995 SM 55 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. Stellar occultation observations in 2025 show that it has a highly reflective surface and a diameter of about 200 km mi. This highly reflective surface is typical for Haumea family Kuiper belt objects, which are believed to be icy fragments of the dwarf planet Haumea. Origin thumb|left|upright=1.25|Diagram showing the orbits of 1995 SM 55 among other members of the Haumea family (colored gray) Haumea family 1995 SM 55 has a high geometric albedo of 0.80 in visible light and a similar orbit to the dwarf planet Haumea, which means that it must be a member of the Haumea family. 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. Members of the Haumea family include 19308 1996 TO 66, 55636 2002 TX 300, 120178 2003 OP 32 and 145453 2005 RR 43. Based on the differences between the orbits of 1995 SM 55 and Haumea, the object was likely ejected from the dwarf planet at a relatively high speed of 123.3 m/s. Physical characteristics Because 1995 SM 55 has a high albedo, it appears much brighter than other Kuiper belt objects. Because its high brightness, astronomers initially believed that 1995 SM 55 could have a very large size, with a diameter up to 700 km mi if it had a dark, low-albedo surface. However, further analysis of 1995 SM 55's thermal emission and orbit showed that it should be much smaller with a more reflective surface. On 25 February 2024, 1995 SM 55 passed in front of a star and occulted it. This stellar occultation was observed by numerous astronomers at 40 different locations, with 7 of them reporting positive detections of the occultation. The occultation observations revealed that 1995 SM 55 is a roughly elliptical object that is 212 × 184 × 152 km mi in diameter (volume-equivalent diameter 181 km mi or). The object has a high geometric albedo of 0.80 0.04. Naming As of January 2025, this minor planet has not been named by the Minor Planet Center. Suggestions for names are open to the public. References 2025-01-08 last obs. JPL Small-Body Database Browser: 24835 (1995 SM55) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2024835 Jet Propulsion Laboratory 14 August 2025 24835 (1995 SM55) Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=24835 8 February 2018 MPEC 2009-R09 :Distant Minor Planets (2009 SEPT. 16.0 TT) 2009-09-04 IAU Minor Planet Center http://www.cfa.harvard.edu/mpec/K09/K09R09.html 2009-10-04 Marc W. Buie Marc W. Buie 2004-11-02 using 119 of 123 observations Orbit Fit and Astrometric record for 24835 SwRI (Space Science Department) http://www.boulder.swri.edu/~buie/kbo/astrom/24835.html 2009-10-04 Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope 6 John Stansberry Will Grundy Mike Brown Dale Cruikshank John Spencer David Trilling Jean-Luc Margot astro-ph/0702538 2007 2008ssbn.book..161S C. Snodgrass B. Carry C. Dumas O. Hainaut February 2010 Characterisation of candidate members of (136108) Haumea's family Astronomy and Astrophysics 511 9 2010A&A...511A..72S 10.1051/0004-6361/200913031 0912.3171 62880843 The water ice rich surface of (145453) 2005 RR43: a case for a carbon-depleted population of TNOs? Pinilla-Alonso, N. Licandro, J. Gil-Hutton, R. Brunetto, R. Astronomy and Astrophysics June 2007 468 1 2007A&A...468L..25P 10.1051/0004-6361:20077294 L25 astro-ph/0703098 18546361 List of Known Trans-Neptunian Objects Johnston's Archive 15 October 2017 Johnston, Wm. Robert http://www.johnstonsarchive.net/astro/tnoslist.html 8 February 2018 How many dwarf planets are there in the outer solar system? California Institute of Technology Michael E. Brown http://web.gps.caltech.edu/~mbrown/dps.html 8 February 2018 24835 8 February 2018 W. M. Grundy K. S. Noll D. C. Stephens July 2005 Diverse albedos of small trans-neptunian objects Icarus 176 1 184–191 2005Icar..176..184G 10.1016/j.icarus.2005.01.007 astro-ph/0502229 118866288 Irina N. Belskaya Maria A. Barucci Marcello Fulchignoni Anatolij N. Dovgopol April 2015 Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo Icarus 250 482–491 2015Icar..250..482B 10.1016/j.icarus.2014.12.004 etal Jose L. Ortiz N. Morales B. Sicardy E. Fernandez-Valenzuela F. Braga-Ribas Y. Kilic A high geometric albedo and small size of the Haumea cluster member (24835) 1995 SM55 from a stellar occultation and photometric observations 18 Sep 2025 2509.15384 astro-ph.EP External links List of Transneptunian Objects, Minor Planet Center 24835 24835 (24835) 1995 SM 55 Category:Haumea family Category:Classical Kuiper belt objects 1995 SM55 19950919 Category:Objects observed by stellar occultation