Dwarf planet Haumea shines with crystalline ice

May 12, 2011
Dwarf planet Haumea shines with crystalline ice
This is an illustration of Haumea and its two satellites (Hi’iaka and Namaka). Credit: SINC/José Antonio Peñas

The fifth dwarf planet of the Solar System, Haumea, and at least one of its two satellites, are covered in crystalline water-ice due to the tidal forces between them and the heat of radiogenic elements. This is the finding of an international research study using observations from the VLT telescope at the European Southern Observatory in Chile.

The tiny and strange planet Haumea moves beyond the orbit of Neptune. It has the shape of a flattened rugby ball and is around 2,000 km long. It spins completely in less than four hours, at one of the fastest rotation speeds in the . The crystallised water that covers this planet and its two satellites (Hi'iaka and Namaka) makes them shine in the darkness of space.

Now an international research team has confirmed that 75% of Haumea and 100% of Hi'iaka (which is around 400 km in diameter) are covered with crystallised water-ice (with an ordered structure) and not, as would have been expected, with amorphous ice disorganised due to . The study suggests that the planet is made up of a frozen outer layer and an internal section made up of between 88% and 97% rock (with a density of 3.5 g/cm3).

"Since solar radiation constantly destroys the crystalline structure of ice on the surface, energy sources are required to keep it organised. The two that we have taken into consideration are that able to generate radiogenic elements (potassium-40, thorium-232 and ) from the inside, and the tidal forces between Haumea and its satellites (as seen between the Earth and the Moon)", Benoit Carry, co-author of the study and a researcher at the ESAC Centre of the European Space Agency (ESA) in Madrid (Spain), tells SINC.

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This is Haumea and its two satellites (Hi’iaka and Namaka). Credit: SINC/José Antonio Peñas

The researcher also highlights other peculiarities of Haumea: "Its orbital plane is inclined at 28º with respect to the usual plane of planets in the Solar System, the orbits of its satellites are not on the same plane either – which is very unusual – and the entire system belongs to a single family within the frozen objects in the Kuiper Belt (at a distance of between 4.5 billion and more than 15 billion kilometres from the Sun)".

According to the scientists, the two satellites could have been created by another object smashing into Haumea, which could also have originated the rapid rotation of the (3.9 hours) and have moulded it into its rugby ball shape. Some numerical models have demonstrated that this could be caused by a fairly tangential impact.

Observations from the SINFONI instrument of the Very Large Telescope (VLT), the enormous telescope of the European Southern Observatory (ESO) in Chile, were used in order to carry out the study, which has been published in the journal Astronomy & Astrophysics. ESO astronomer Christophe Dumas led this study from the observatory.

"SINFONI is an integral field spectrometer that provides 'data cubes' in which two of the dimensions are spatial (like those of any flat image), while the third is spectral, meaning that each layer of the cube is an image taken with a different wave size", explains Carry.

The mystery and polemic of Haumea

The scientist acknowledges that the precise orbits and sizes of the dwarf planet are still not known (they are operating with approximate scales of around 2,000 x 1,500 x 1,000 km) nor are those of its satellites. In reality, these are two very distant bright points of light, the data for which are obtained indirectly.

In the case of the tiny Namaka (around 200 km in diameter), the signal at the time it was observed was so weak that it was impossible to obtain information about its surface, although new data on its orbit were gathered. Meanwhile, the models for the tidal forces of this strange system are also improving.

Another of the mysteries of Haumea is the presence of a dark, reddish spot, which contrasts with the whitish colour of the planet. "My interpretation of the infrared photometry is that this area could be a richer source of crystalline than the rest of the surface", Pedro Lacerda, co-discoverer of the spot and an astronomer at Queen's University in Belfast (United Kingdom), tells SINC. The researcher does not rule out the possibility of some kind of irradiated mineral or organic matter having caused this colouration.

Haumea is the fifth dwarf planet in the Solar System along with Pluto, Ceres, Eris and Makemake. Its existence was confirmed in 2005, when it was called 2003 EL61 (from the international nomenclature code: year of first observation, half and order number).

Two teams of astronomers contested the discovery. The first group was led by the Spanish researcher José Luis Ortiz Moreno from the Institute of Astrophysics of Andalusia (CSIC), while the other was led by the astrophysicist Michael E. Brown from the California Institute of Technology (Caltech, USA).

In the end, the International Astronomical Union decided to accept the discovery by the Spanish team, but named the strange dwarf planet and its satellites according to names suggested by the American team. In Hawaiian mythology, Haumea is the goddess of fertility and birth, and Hi'iaka and Namaka are two of her daughters.

Explore further: Astronomer confirms a new "Super-Earth" planet

More information: Christophe Dumas, Benoit Carry, Daniel Hestroffer, Frederic Merlin. "High-contrast observations of (136108) Haumea. A crystalline water-ice multiple system". Astronomy & Astrophysics 528: A105, abril de 2011. DOI: 10.1051/0004-6361/201015011

Provided by FECYT - Spanish Foundation for Science and Technology

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that_guy
5 / 5 (3) May 12, 2011
Sort of an interesting thought, not exactly on topic to the article. Haumea was found by comparing its movement to background stars, but it moves very slowly.

Wouldn't it be easier to find all these objects if we dropped a telescope over in lagrange points 4 and 5 - and compare those pictures, rather than trying to detect a snail's pace in motion?

The perspective would set anything in system off from the background stars, and it would be easy to range them geometrically...or are these objects just too far for that to be easily done?
71STARS
1 / 5 (3) May 12, 2011
@that guy: Please remember that this piece of rock given the name Haumea is within the Kuiper Belt; hardly a place to "drop a telescope" now or in the forseeable future. Hope this answers your question.
SemiNerd
5 / 5 (1) May 13, 2011
@that guy: Please remember that this piece of rock given the name Haumea is within the Kuiper Belt; hardly a place to "drop a telescope" now or in the forseeable future. Hope this answers your question.


Actually, a telescope at L4 or L5 could be combined with a telescope like the new James Web telescope to give a telescope with an effective resolution of the radius of the earths orbit (L4 and L5 are at right angles to the earths position along its orbit). It would enable a MUCH more precise definition of the orbit of lots of things.
PaulieMac
5 / 5 (4) May 13, 2011
@that guy: Please remember that this piece of rock given the name Haumea is within the Kuiper Belt; hardly a place to "drop a telescope" now or in the forseeable future. Hope this answers your question.


His question actually very clearly specified the lagrange points 4 & 5 as the telescope placement locations; not the Kuiper Belt. L4 & L5 are handily illustrated here:
http://www.physic...ints.gif

I don't see any technical reason not to drop telescopes that far out. Practicality and cost would be the sticking point; it'd be an expensive program, particularly in terms of maintenance & upgrades over the lifetime of the telescopes.

d_robison
5 / 5 (1) May 13, 2011
Sort of an interesting thought, not exactly on topic to the article. Haumea was found by comparing its movement to background stars, but it moves very slowly.

Wouldn't it be easier to find all these objects if we dropped a telescope over in lagrange points 4 and 5 - and compare those pictures, rather than trying to detect a snail's pace in motion?

The perspective would set anything in system off from the background stars, and it would be easy to range them geometrically...or are these objects just too far for that to be easily done?


This is a good idea, and could be easily done, but probably the 3 biggest reasons they have not done this are: 1) Cost 2) Bureaucracy and 3) No one (to my knowledge) has sent in a proposal for this. Great idea though, I would definitely be on board for it. L4 and L5 together would be a great place to map all large KBO's.
barakn
5 / 5 (1) May 13, 2011
Performing interferometry with multiple instruments (as implied by SemiNerd) requires combining the data from them with very precise timing, not to mention that it makes it much easier if the distance between the instruments remains fixed during observation. Radio telescope networks can get away with using computers to combine recorded data after the fact as long as the data was recorded with accurate time information, but this is only possible because of the large size of radio waves. Infrared/optical instruments generally have to be linked together with fiber optics. The chance of this working with satellites floating 160 million km apart is minuscule. The two satellites would be useful for tracking KBO positions using parallax though, per that_guy's suggestion.
d_robison
5 / 5 (1) May 13, 2011
Performing interferometry with multiple instruments (as implied by SemiNerd) requires combining the data from them with very precise timing, not to mention that it makes it much easier if the distance between the instruments remains fixed during observation...The chance of this working with satellites floating 160 million km apart is minuscule. The two satellites would be useful for tracking KBO positions using parallax though, per that_guy's suggestion.


L4 and L5 would be in a fixed location with respect to the Earth and the Sun, giving you a common baseline. Keeping the two instruments at their respective LaGrangian points would be a fairly simple task as they already do so with other satellites (not with L4 and L5 but at L1 and L2). Timing wouldn't be too hard given current technologies either, the biggest problem in my mind would be cost and convincing the government that it is useful (unless you are able to convince a private corp. to do it).
that_guy
not rated yet May 13, 2011
Thank you Paul, d, and barak.

Yes, my idea is lagrange points along earth's orbit, using the difference in angle to determine the distance to the object(using triginometry), from the different offset at each angle.

typically a distant object will show very little motion from one day to the next, because they move slowly, but it might be easier to find them because the difference in angle relative to even more distant background stars, as measured by two telescopes very far apart.

However, the combined view is a very interesting idea as well. We do know the orbital mechanics of our system very well, and probably have the ability to make adjustments for the discrepancies of the orbital positions themselves (adjusting for our speed in galaxy as it relates to the orbit), made easier because these satellites would not move much in relation to each other.
woofwoofwoofoioioi
not rated yet May 15, 2011
I don't believe Haumea is shaped like a flattened rugby ball. If you ask me, the illustration clearly depicts a Sherrin.
d_robison
5 / 5 (1) May 16, 2011
Thank you Paul, d, and barak.
...typically a distant object will show very little motion from one day to the next, because they move slowly, but it might be easier to find them because the difference in angle relative to even more distant background stars, as measured by two telescopes very far apart...


This is certainly easily done, even though the movement of the object is minimal when viewing it, using parallax(Astronomy term for the trig method used) one can easily track the distance of a KBO, in fact this method can be used to find the distance between Earth stars. Perhaps when it becomes a little cheaper to launch the instruments into space and to keep them running we may start seeing scenarios like the L4/L5 baseline.
Javinator
5 / 5 (1) May 16, 2011
If a telescope were dropped in either L4 or L5, could the same parallax method be used between that telescope and a telescope on Earth? (With more error obviously).

The would mean less funding would be required (ie. easier to get) and could be used as a proof of concept to build a case for a second telescope at the remaining L4/L5 positions for less error.
d_robison
5 / 5 (1) May 24, 2011
If a telescope were dropped in either L4 or L5, could the same parallax method be used between that telescope and a telescope on Earth? (With more error obviously).

The would mean less funding would be required (ie. easier to get) and could be used as a proof of concept to build a case for a second telescope at the remaining L4/L5 positions for less error.


This could work, although depending on what part of the spectrum of light you are looking at (IR, radio, visible, etc.) you may run into some problems from the atmosphere. Also, you would be limited in the time you can look at KBO's since the Earth rotates. Good idea, but you would get more reliable data and more viewing time from L4 & L5.

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