Haumea could have organics....

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Spot Discovered On Dwarf Planet Haumea Shows Up Red And Rich With Organics

ScienceDaily (Sep. 26, 2009) — A dark red area discovered on the dwarf planet Haumea appears to be richer in minerals and organic compounds than the surrounding icy surface.

The discovery will be presented at the European Planetary Science Congress in Potsdam by Dr Pedro Lacerda on Wednesday 16 September.

The spot was discovered by measuring changes in its brightness as it rotates. The origin of the spot is unknown, however its “light curve”, which describes variations in its brightness over time, is not exactly the same shape in all wavelengths. Small but persistent differences indicate that the dark spot is slightly redder in visible light and slightly bluer at infrared wavelengths.
Possible interpretations of these measurements are that the spot is richer in minerals and organic compounds, or that it contains a higher fraction of crystalline ice. If the spot is a scar of a recent impact onto Haumea then the spot material might resemble the composition of the impactor, perhaps mixed with material from the inner layers of Haumea.



Dr Lacerda had already published on this topic end 2007/beginning 2008. Why the media pay attention to his 2009 presentation at EPSC instead of the ones in 2008 will remain a mystery.

But beyond my mean remark, it's indeed very interesting. They still do not know whether it is a slightly reddish entire hemisphere (or to be more accurate hemi-ellipsoid) or a very red concentrated spot. The nature of the organic deposits calls too for investigation. What is strange is that it seems to be (if we believe the lightcurve) on the smallest equatorial diameter (hence closer to the rocky core) whereas one might expect an endogenic organic layer to be on top of the water ice layer, so where it is the thickest. I would expect the water ice layer (quite thin in absolute terms given the large density of Haumea) to be thicker at the points of largest altitude (at the largest equatorial diameter) and the temperature to be coldest at these points (so attractors for chemical species with a very low solidification temperature). Since Haumea is thought to have lost most of its volatiles during a huge collision some time ago, may be then this is exogenic (brought by another more recent impactor). Another possibility is that there is thermal segregation like on Iapetus. Or transient liquid flow? With its 3D-shape, the surface gravity field and the surface thermal conditions are likely to be quite bizarre. May be this is inducing strange migrations of species on the surface. Haumea is such a source of speculation...

I still wonder btw whether they have not misestimated the period by a factor of 2, which is frequent when there is some symmetry and when several periods have not been observed in a row (and this is the case for Haumea if you look at their quite short elementary observation records). In that case there would be two red spots more or less symmetrical longitude-wise, which would make sense if they resulted from thermal segregation or from an endogenic source.

Lacerda plans new observations in 2010 with the VLT. Let's hope they will get more. There is too a program for observing TNOs in Infrared with the largest space telecope ever (Herschel), for which Lacerda is co-investigator. See

The observations have begun for their Herschel TNO program. Haumea is in the list but have they observed it yet? It will be interesting to compare the VLT and Herschel performances with each other.

Best regards.
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