(55636) 2002 TX300
| bgcolour=#FFFFC0 | name=(55636) 2002 TX300 | image = | caption = TX300 (apparent magnitude 19.4) as viewed with a 24" telescope | discovery=yes | discovery_ref =  | discoverer=Palomar Mountain/NEAT (644) | discovered=October 15, 2002 | mp_name=(55636) 2002 TX300 | alt_names=none | mp_category=Cubewano (MPC)
| orbit_ref = 
| epoch=August 27, 2011 (JD 2455800.5) | semimajor=43.530 AU | perihelion=38.1057 AU | aphelion=48.954 AU | eccentricity=0.12461 | period=287.20 a (104,901 d) | inclination=25.84118° | asc_node=324.5364° | arg_peri=343.104° | mean_anomaly=64.12° | physical_characteristics=yes | mean_radius=143±5 km (occultation)
(Spitzer two-band thermal model)
(55636) 2002 TX300 is a bright Kuiper belt object in the outer Solar System estimated to be about 286 km in diameter. It is a large member of the Haumea family, discovered on October 15, 2002, by the Near-Earth Asteroid Tracking (NEAT) program.
A variability of the visual brightness was also detected which could fit to 7.9 h or 15.8 h rotational period (the distinction between single or double-peaked curved could not be made with confidence). The changes in brightness are quite close to the error margin and could also be due to an irregular shape.
2002 TX300 is classified as a classical Kuiper belt object and follows an orbit very similar to that of Haumea: highly inclined (26°) and moderately eccentric (e ~0.12), far from Neptune’s perturbations (perihelion at ~37 AU). Other mid-sizes cubewanos follow similar orbits as well, notably 2002 UX25 and 2002 AW197.
The diagrams show polar and ecliptic views of the orbits of the two cubewanos. The perihelia (q) and the aphelia (Q) are marked with the dates of passage. The present positions (as of April 2006) are marked with the spheres illustrating relative sizes and differences in albedo (both objects appear neutral in the visible spectrum).
In 2004, the non-detection of IR thermal emissions put an upper limit of 709 km on its diameter and a lower limit on the albedo of 0.19. In a 2006 International Astronomical Union press release discussing the IAU 2006 draft proposal, a diagram suggested that TX300 could be as large as 50000 Quaoar. The artist's diagram was largely based on the concept that TX300 with an absolute magnitude (H) of 3.2 may have an albedo around 0.08, which resulted in an overly optimistic diameter estimate of around 1000 km.
Measurements by the Spitzer Space Telescope in 2007 showed it may be less than 641 km in diameter. In 2008, it was considered to be a dwarf planet based on the lightcurve amplititude analysis and the assumption that it was larger than 450 km in diameter. Since this object is a Haumea family fragment it was assumed to have an albedo of about 0.7, which would result in a diameter of about 360 km.
2002 TX300 occulted a relatively bright apparent magnitude 13.1 star in the constellation of Andromeda on October 9, 2009. This event was visible from Australia, possibly New Zealand, and the southern US and Mexico. The RA and dec for this event was about 00 37 13.64 +28 22 23.2.: detailed information for observers was made available. The occultation produced a diameter of 286 kilometers suggesting an albedo of about 0.88. Somewhere between a size of 200 km and 400 km, an icy body becomes rounded by its own gravity. All icy moons with diameters 400 km or more are known to be spherical. Mike Brown lists it as a possible dwarf planet.
The spectrum in the visible and near-infrared rages is very similar to that of Charon characterized by neutral to blue slope (1%/1000 Å) with deep (60%) water absorption bands at 1.5 and 2.0 μm). Mineralogical analysis indicates a substantial fraction of large ice (H2O) particles. The signal-to-noise ratio of the observations was insufficient to differentiate between amorphous or crystalline ice (crystalline ice was reported on Charon, Quaoar and Haumea). The proportion of highly processed organic materials (tholins), typically present on numerous trans-Neptunian objects, is very low. As suggested by Licandro et al. 2006, this lack of irradiated mantle suggest either a recent collision or comet activity.
Common physical characteristics with the dwarf planet Haumea together with similar orbit elements led to suggestion that 2002 TX300 is a member of the Haumean collisional family. The object, together with other members of the family ((19308) 1996 TO66, (24835) 1995 SM55, (120178) 2003 OP32, and (145453) 2005 RR43), would be created from ice mantle ejected from the proto-Haumea as result of a collision with another large (~1660 km) body.
- "JPL Small-Body Database Browser: 55636 (2002 TX300)". 2009-07-31 last obs. Retrieved 2008-06-12.
- "MPEC 2009-R09 :Distant Minor Planets (2009 SEPT. 16.0 TT)". IAU Minor Planet Center. 2009-09-04. Retrieved 2009-10-04.
- Marc W. Buie (2009-07-31 using 303 observations). "Orbit Fit and Astrometric record for 55636". SwRI (Space Science Department). Retrieved 2009-10-04.
- Elliot, J. L.; Person, M. J. et al. (2010). "Size and albedo of Kuiper belt object 55636 from a stellar occultation". Nature 465 (7300): 897–900. Bibcode:2010Natur.465..897E. doi:10.1038/nature09109. PMID 20559381.
- John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". arXiv:astro-ph/0702538 [astro-ph].
- J. L. Ortiz, A. Sota, R. Moreno, E. Lellouch, N. Biver, A. Doressoundiram, P. Rousselot, P. J. Gutiérrez, I. Márquez, R. M. González Delgado and V. Casanova A study of Trans-Neptunian object (55636) 2002 TX300, Astronomy & Astrophysics, 420 (2004), Issue 1, pp. 383–388. Abstract.
- Grundy, W. M; Noll, K; Stephens, D (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. (Preprint on arXiv.)
- O. Gingerich (2006). "The Path to Defining Planets". Harvard-Smithsonian Center for Astrophysics and IAU EC Planet Definition Committee chair. Archived from the original on 6 March 2007. Retrieved 2007-03-13.
- Dan Bruton. "Conversion of Absolute Magnitude to Diameter for Minor Planets". Department of Physics & Astronomy (Stephen F. Austin State University). Archived from the original on 23 March 2010. Retrieved 2009-12-27.
- Gonzalo Tancredi and Sofía Favre (13-Oct-2008?). "Dwarf Planet & Plutoid Headquarters". Portal Uruguayo de Astronomía. Retrieved 2010-09-22. (Which are the dwarfs in the Solar System?)
- Mike Brown (2009-12-29). "A ghost of Christmas past". Mike Brown's Planets (blog). Archived from the original on 2 January 2010. Retrieved 2009-12-29.
- Steve Preston. "(55636) 2002 TX300 / UCAC2 41650964 event on 2009 Oct 09, 10:28 UT". Archived from the original on 2009-10-08. Retrieved 2009-10-05.
- "55636.20091009 Occultation October 09, 2009". Retrieved 2009-10-09.
- Mike Brown. "The Dwarf Planets". Archived from the original on 9 January 2010. Retrieved 2009-12-28.
- Michael E. Brown (Sep 23, 2011). "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Retrieved 2012-01-05.
- J.Licandro, L. di Fabrizio, N. Pinilla-Alonso, J. de León, and E. Oliva Trans-Neptunian object (55636) 2002 TX300, a fresh icy surface in the outer Solar System. 2006, A&A, 457, 329–333 Abstract
- Pinilla-Alonso, N.; Licandro, J.; Campins, H. Mineralogical analysis of two different kinds of icy surfaces in the trans-neptunian belt, TNOs (50000) Quaoar and 2002 TX300, American Astronomical Society, DPS meeting #36, #11.07 (2004). Abstract.
- 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.
- Michael E. Brown, Kristina M. Barkume, Darin Ragozzine & Emily L. Schaller, A collisional family of icy objects in the Kuiper belt, Nature, 446, (March 2007), pp 294–296.
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