Haumea Hot Spot
Spot Discovered on Dwarf Planet Haumea Shows Up Red and Rich with Organics and Minerals
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.
“Our very first measurements of Haumea told us there was a spot on the surface. The two brightness maxima and the two minima of the light curve are not exactly equal, as would be expected from a uniform surface. This indicates the presence of a dark spot on the otherwise bright surface. But Haumea’s light curve has told us more and it was only when we got the infrared data that were we able to begin to understand what the spot might be,” said Dr. Pedro Lacerda, Newton Fellow at Queen's University Belfast.
Haumea orbits the sun beyond Neptune, in a region known as the Kuiper belt. It is the fourth largest known Kuiper belt object (KBO) after Eris, Pluto and Makemake. These large KBOs, together with main-belt asteroid Ceres, are known as dwarf planets.
Because of its large distance from the Earth, Haumea is visible only as a rather uninformative point of light. Most of what we know about this object was derived from its brightness variations, or “light curve”. Because of its rotation and elongated shape, Haumea brightens and dims periodically as it reflects more and less sunlight. The extent of this variation tells us how elongated Haumea is, and the time between each brightening and dimming is a measure of the rotation period. The precise Haumea shape and spin period imply that it has a density 2.5 times that of water. Since we know from spectroscopic observations that Haumea is covered in water ice, this high density implies Haumea must have a rocky interior, in contrast with its bright icy surface.
New observations of this spot are planned for early 2010 using the ESO Very Large Telescope. “Now we will get detailed spectroscopy of the spot to hopefully identify its chemical composition and solve the puzzle of its origin” Lacerda concluded. Understanding the chemical inventory of objects in the solar system can help astrobiologists understand what types of molecules could have been delivered to the early Earth to play a role in the origins of life.