It's the season of articles about dwarf planet Haumea and its system. Three of them recently released would confirm no less than:
* the ellipsoid shape of Haumea (article 1)
* the red spot of Haumea and a spectrum for the moons akin to the primary (article 2)
* weird tidal phenomena and strongly non-keplerian orbits in the system, with a sizable Hi'aka of about 300km (article 3)
All three articles tend to corroborate the collisional scenario for the formation of the moons.
This system is really interesting!
1. Study of the Surface of 2003 EL61: the largest carbon-depleted object in the trans-neptunian belt
http://arxiv.org/PS_cache/arxiv/pdf/080 ... 1080v1.pdf
Excerpts:
"The errors of the measured band depths for each spectrum are larger than the deviation from the mean, so we can conclude that there are no variations of the depths of the water absorption bands larger than %. We conclude that the surface of 2003 EL61 is homogeneous in a large scale. This reinforces the hypothesis that its shape is like a very elongated ellipsoid."
They admit though that their S/N is quite poor (not enough to detect the reddish spot) but would discard widespread cryovolcanism on the basis that they constrain ammonia on the surface to less than 8%, with a surface almost exclusively made of water ice.
2. NICMOS Photometry of the Unusual Dwarf Planet Haumea and its Satellites
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 0860v1.pdf
Excerpts:
"We detected Haumea’s light-curve in our observations, and found that our observations are consistent in both phase and magnitude with those of Lacerda (2008). The observed (F110WF160W) exhibits a variation of 0.03 mag from the mean which is a > 3 deviation compared to the uncertainties in our measurements. The deviation occurs at a light-curve phase 0.78, consistent with the phase centre of the red spot (Lacerda et al. 2008)."
"A more plausible explanation is that the red spot detected by Lacerda et al. (2008) is caused by an increase in the abundance of irradiated organic materials (tholins, etc.) on the surface."
3. Orbits and Masses of the Satellites of the Dwarf Planet Haumea
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 4213v1.pdf
"The excited eccentricities and mutual inclination point to an intriguing tidal history of significant semi-major axis evolution through satellite mean-motion resonances. The orbital solution indicates that Namaka and Haumea
are currently undergoing mutual events and that the mutual event season will last for the next several years."
Best fits for masses are 4.0e21kg for Haumea, 1.8e19kg for Hi'aka and about 2e18kg for Namaka (this latter poorly constrained with a large uncertainty). For Haumea, this means a density of 2.5 if the equivalent diameter is 1450km. For Hi'iaka this translates into a diameter of about 325km for a density of 1, 260km for a density of 2, confirming the large size of this moon.
Finally, Brown's team concludes by "The future holds great promise for learning more about the Haumea system, as the orbital solution indicates that Namaka and Haumea are undergoing mutual events for the next several years. This will provide excellent observational constraints on the size, shape, spin pole, density, and internal structure of Haumea and direct measurements of satellite radii, densities, and albedos. There are also interesting avenues for future theoretical inves tigations, especially into the unique nature of tidal evolution in the Haumean system."
* the ellipsoid shape of Haumea (article 1)
* the red spot of Haumea and a spectrum for the moons akin to the primary (article 2)
* weird tidal phenomena and strongly non-keplerian orbits in the system, with a sizable Hi'aka of about 300km (article 3)
All three articles tend to corroborate the collisional scenario for the formation of the moons.
This system is really interesting!
1. Study of the Surface of 2003 EL61: the largest carbon-depleted object in the trans-neptunian belt
http://arxiv.org/PS_cache/arxiv/pdf/080 ... 1080v1.pdf
Excerpts:
"The errors of the measured band depths for each spectrum are larger than the deviation from the mean, so we can conclude that there are no variations of the depths of the water absorption bands larger than %. We conclude that the surface of 2003 EL61 is homogeneous in a large scale. This reinforces the hypothesis that its shape is like a very elongated ellipsoid."
They admit though that their S/N is quite poor (not enough to detect the reddish spot) but would discard widespread cryovolcanism on the basis that they constrain ammonia on the surface to less than 8%, with a surface almost exclusively made of water ice.
2. NICMOS Photometry of the Unusual Dwarf Planet Haumea and its Satellites
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 0860v1.pdf
Excerpts:
"We detected Haumea’s light-curve in our observations, and found that our observations are consistent in both phase and magnitude with those of Lacerda (2008). The observed (F110WF160W) exhibits a variation of 0.03 mag from the mean which is a > 3 deviation compared to the uncertainties in our measurements. The deviation occurs at a light-curve phase 0.78, consistent with the phase centre of the red spot (Lacerda et al. 2008)."
"A more plausible explanation is that the red spot detected by Lacerda et al. (2008) is caused by an increase in the abundance of irradiated organic materials (tholins, etc.) on the surface."
3. Orbits and Masses of the Satellites of the Dwarf Planet Haumea
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 4213v1.pdf
"The excited eccentricities and mutual inclination point to an intriguing tidal history of significant semi-major axis evolution through satellite mean-motion resonances. The orbital solution indicates that Namaka and Haumea
are currently undergoing mutual events and that the mutual event season will last for the next several years."
Best fits for masses are 4.0e21kg for Haumea, 1.8e19kg for Hi'aka and about 2e18kg for Namaka (this latter poorly constrained with a large uncertainty). For Haumea, this means a density of 2.5 if the equivalent diameter is 1450km. For Hi'iaka this translates into a diameter of about 325km for a density of 1, 260km for a density of 2, confirming the large size of this moon.
Finally, Brown's team concludes by "The future holds great promise for learning more about the Haumea system, as the orbital solution indicates that Namaka and Haumea are undergoing mutual events for the next several years. This will provide excellent observational constraints on the size, shape, spin pole, density, and internal structure of Haumea and direct measurements of satellite radii, densities, and albedos. There are also interesting avenues for future theoretical inves tigations, especially into the unique nature of tidal evolution in the Haumean system."
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