Talk:(55637) 2002 UX25

Pancake + Crepe

• Pancake + crepe are like Pluto + Charon circa 1988. (or awfully close; need to confirm in morning) To know if 2002UX25+satellite are edge-on requires 3 pix from HST b4 March 2 (Mike Brown 2010-02-10)
• KBO 2002UX25+satellite probably eclipsed and occulted each other LAST YEAR (2009) but not again for 130 yrs. Grrr. (plutokiller 2010-02-12)
• 2002UX25, if edge on, turns out to be observed best in 2011. (Mike Brown 2010-02-22)
• Coming soon: Kozai cycling and tidal evolution of Kuiper belt satellites: the case of 2002 UX25

2012

• Observed by Mike Brown with Subaru Telescope on 2012-Jan-14.
• 2002 UX25. Moon isn't obvious but I think it's close and to the upper left.

"Not a dwarf planet"

[1] claims this object is not a dwarf planet. So the "probable dwarf planet" claim seems to be disputed. --Roentgenium111 (talk) 19:30, 21 September 2010 (UTC)

Maybe they are knocking it because the secondary is ~200km in diameter and they list the density as <0.2 which would be too low, but what is the source for their density calculation? Have they or someone else (Mike Brown?) made accurate measurements of the secondaries orbit? Spitzer2007 shows this object as 600+km in diameter. With a diameter >400km an icy object should be spherical. I need to know their reason/source before I think they are correct to exclude it. They should at least have a question mark after their statement. -- Kheider (talk) 20:54, 21 September 2010 (UTC)

Well, they published a paper on the question of which objects are dwarf planets: [2] Though I note that they indeed give this object's dwarf planet status as "No?" in that paper, citing contradicting evidence. So my above link may be a copying error. BTW, is it really scientific consensus that icy objects >400 km are in equilibrium? I know Mike Brown believes so, but the IAU seems to be uncertain about it, as they currently only classify those TNOs as dwarf planets which have a guaranteed diameter >800 km (i.e., H<1). Also, the non-spherical Proteus is close to being a counterexample to that claim....--Roentgenium111 (talk) 14:41, 22 September 2010 (UTC)

The IAU is definitely excessively conservative with their numbers because they never want another "Pluto". I have even read papers that suggest icy objects can become spherical around 150km, though they probably are not in true equilibrium. Proteus is a known exception since it is probably the rocky core of a spherical body that was destroyed when Triton was captured and de-stabilized the major moons of Neptune. Given the known binary nature of UX25, I think they might be a little quick to rule it out based on a generic light curve. But since I do not have access to their full paper, perhaps the binary nature is the very reason they want to rule it out. I have added their link to (42301) 2001 UR163. -- Kheider (talk) 15:04, 22 September 2010 (UTC)

See [3] for some calculations: 320 km / 10 Zg for water ice, 600 km / 340 Zg for silicates. That's for when the centre becomes fluid; he doesn't discuss how the fluid centre expands towards the surface. The IAU is not assuming that TNOs are icy (even if the surface might be), and the densities of Haumea and Quaoar validate them in that non-assumption, so I don't think they're being too conservative. Although I think they should have a second entry benchmark for system masses (determined from moons/binaries). A 400 km TNO might be icy and round, but a 600 km one could be a rocky potato, so 800 km is not that conservative. (Conversely, IAU shouldn't be naming anything that might be as much as 400 km, since it might be a dwarf -- get used to licence plates!) As to DPPH, from their web page it looks like they created an algorithm for determining whether or not something and are just presenting the results of the algorithm. It looks like their algorithm might be fooled by a splotchy albedo, but it could also be right and UX25 could be a close binary/multiple. Tbayboy (talk) 16:06, 24 September 2010 (UTC)

Brown agrees it could be albedo spots and it may also have color variations. -- Kheider (talk) 03:30, 15 January 2012 (UTC)

Dead link

During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!

• http://www.psi.edu/pds/asteroid/EAR_A_COMPIL_3_TNO_CEN_COLOR_V3_0/data/tnocencol.tab
  • In (119070) 2001 KP77 on 2011-05-20 21:17:27, 404 Not Found
  • In 20000 Varuna on 2011-05-25 06:57:38, 404 Not Found
  • In (119070) 2001 KP77 on 2011-05-31 04:11:44, 404 Not Found

--JeffGBot (talk) 04:15, 31 May 2011 (UTC)

Dead link 2

During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!

• http://www.cfa.harvard.edu/iauc/08800/08812.html
  • In (55637) 2002 UX25 on 2011-05-20 21:18:17, 404 Not Found
  • In (55637) 2002 UX25 on 2011-05-31 04:15:46, 404 Not Found

--JeffGBot (talk) 04:16, 31 May 2011 (UTC)

This link has been fixed by Fjörgynn in rev 437866434: https://en.wikipedia.org/w/index.php?title=%2855637%29_2002_UX25&diff=437866434&oldid=435791827 Camil7 (talk) 22:07, 25 January 2014 (UTC)

Dead link 3

During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!

• http://hamilton.dm.unipi.it/cgi-bin/astdys/astibo?objects:2002UX25;main
  • In (55637) 2002 UX25 on 2011-05-20 21:18:17, 403 Forbidden
  • In (55637) 2002 UX25 on 2011-05-31 04:15:55, 403 Forbidden

--JeffGBot (talk) 04:16, 31 May 2011 (UTC)

Updated link should have been http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.0&n=2002UX25 instead, but as that link is also in the references I removed it Camil7 (talk) 22:07, 25 January 2014 (UTC)

New mass/density figures

See [4] (from Brown's blog [5]). It's not published yet, so I don't know if the numbers should be added here, yet. On the other hand, it's got to be better than the current assumed values. He got the orbit of the satellite, thence a system mass of .125 Yg. Depending on the UX52:sat albedos (hence diameters), the density is between .79 and .85 +/- .08. Tbayboy (talk) 02:32, 9 November 2013 (UTC)

We usually add results from papers published on arxiv. Ruslik_Zero 17:24, 9 November 2013 (UTC)

Okay, I updated the page with Brown`s upcoming paper. Somebody should double-check the surface gravity and escape velocity figures. Tbayboy (talk) 23:04, 9 November 2013 (UTC)

I am not sure if we should show the estimated size of 650km from that paper. It seems Brown gave that diameter estimate (actually 640km, see Cp.3) to be on the safe side with his claim of unusual low density, not because he thinks this is an accurate estimate. Camil7 (talk) 20:32, 11 January 2014 (UTC)

I agree; it is a secondary source. The paper is averaging or approximating the values of its references, not presenting any new determination of the size. Tbayboy (talk) 05:10, 12 January 2014 (UTC)

On the other hand the other size estimates come from observations in the infrared and thermal modeling and seem to include the moon while the estimate of 650km is the estimated diameter without the moon, so maybe it is useful extra information. I am not sure how to express the difference in the table, however. — Preceding unsigned comment added by Camil7 (talk • contribs) 22:31, 25 January 2014 (UTC)

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