SPOT DISCOVERED ON DWARF PLANET HAUMEA SHOWS UP RED AND RICH WITH ORGANICS AND MINERALS
A dark red area discovered on 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.
“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.
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.
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. One of the most surprising characteristics of Haumea is its very fast rotation, with one day lasting only 3.9 Earth hours. No other large object in the solar system spins as fast as Haumea. The rapid spin deforms Haumea into an elongated ellipsoid, 2000 km by 1600 km by 1000 km, whose shape balances gravitational and rotational accelerations. It is believed that Haumea was spun up by a massive impact more than a billion years ago.
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.
IMAGES
Composite image of computer model frames showing Haumea’s red spot as the dwarf planet rotates. Credit: P Lacerda
Still from computer model showing Haumea’s dark spot as the dwarf planet rotates. Credit: P Lacerda
Still from computer model showing Haumea’s dark spot as the dwarf planet rotates. Credit: P Lacerda
Still from computer model showing Haumea’s dark spot as the dwarf planet rotates. Credit: P Lacerda
ADDITIONAL INFORMATION
http://star.pst.qub.ac.uk/~pl/drs_pr.html
High Precision Photometry of Extreme KBO 2003 EL61, by Pedro Lacerda, David Jewitt and Nuno Peixinho, The Astronomical Journal, May 2008
Time-Resolved Near-Infrared Photometry of Extreme Kuiper Belt Object Haumea, by Pedro Lacerda,
The Astronomical Journal, February 2009
EUROPEAN PLANETARY SCIENCE CONGRESS (EPSC) 2009
EPSC 2009 is organised by Europlanet, a Research Infrastructure funded under the European Commission’s Framework 7 Programme, in association with the European Geosciences Union. It is the major meeting in Europe for planetary scientists. The programme comprises 37 sessions and workshops covering a wide range of planetary topics.
EPSC 2009 is taking place at the Kongresshotel am Templiner See, Potsdam, Germany from Sunday 13 September to Friday 18 September 2009.
For further details, see the meeting website:
http://meetings.copernicus.org/epsc2009/
EUROPLANET RESEARCH INFRASTRUCTURE (RI)
Europlanet Research RI is a major (€6 million) programme co-funded by the European Union under the Seventh Framework Programme of the European Commission.
Europlanet RI brings together the European planetary science community through a range of Networking Activities, aimed at fostering a culture of cooperation in the field of planetary sciences, Transnational Access Activities, providing European researchers with access to a range of laboratory and field site facilities tailored to the needs of planetary research, as well as on-line access to the available planetary science data, information and software tools, through the Integrated and Distributed Information Service. These programmes are underpinned by Joint Research Activities, which are developing and improving the facilities, models, software tools and services offered by Europlanet
Europlanet Project website: http://www.europlanet-ri.eu/
Europlanet Outreach/Media website: http://www.europlanet-eu.org/
