The Size and Shape of the Oblong Dwarf Planet Haumea

Lockwood, Alexandra; Brown, Michael E.; Stansberry, J.

doi:10.1007/s11038-014-9430-1

Cited by 32 publications

(54 citation statements)

References 33 publications

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“…L. Ortiz et al, in preparation), and (2) 2003 VS 2 also presents an asymmetric lightcurve with a 0.04 mag difference Sheppard 2007;Thirouin et al 2010). The observed asymmetric lightcurves can be perfectly explained thanks to the lightcurve modeling of objects with spot or hemispheric albedo variations reported by Lacerda et al (2008;Lellouch et al 2010;Snodgrass et al 2010;Carry et al 2012;Lockwood et al 2014). Besides these cases, there is an even more wellknown case: Pluto.…”

Section: Period-detection Methodsmentioning

confidence: 76%

Rotational Properties of the Haumea Family Members and Candidates: Short-Term Variability

Thirouin¹,

Sheppard²,

Noll³

et al. 2016

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Haumea is one of the most interesting and intriguing trans-Neptunian objects (TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly pure water ice on the surface. It has at least two satellites and a dynamically related family of more than 10 TNOs with very similar proper orbital parameters and similar surface properties. The Haumean family is the only one currently known in the trans-Neptunian belt. Various models have been proposed, but the formation of the family remains poorly understood. In this work, we have investigated the rotational properties of the family members and unconfirmed family candidates with short-term variability studies, and report the most complete review to date. We present results based on five years of observations and report the short-term variability of five family members and seven candidates. The mean rotational periods, from Maxwellian fits to the frequency distributions, are 6.27 ± 1.19 hr for the confirmed family members, 6.44 ± 1.16 hr for the candidates, and 7.65 ± 0.54 hr for other TNOs (without relation to the family). According to our study, there is a possibility that Haumea family members rotate faster than other TNOs; however, the sample of family members is still too limited for a secure conclusion. We also highlight the fast rotation of 2002 GH 32 . This object has a 0.36 ± 0.02 mag amplitude lightcurve and a rotational period of about 3.98 hr. Assuming 2002 GH 32 is a triaxial object in hydrostatic equilibrium, we derive a lower limit to the density of 2.56 g cm −3 . This density is similar to Haumea's and much more dense than other small TNO densities.

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Section: Period-detection Methodsmentioning

confidence: 76%

Rotational Properties of the Haumea Family Members and Candidates: Short-Term Variability

Thirouin¹,

Sheppard²,

Noll³

et al. 2016

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“…Haumea is larger than other dwarf planets such as Ceres (radius 473 km), or satellites such as Dione (radius 561 km) or Ariel (radius 579 km), all of which are nominally round. Despite this, Haumea exhibits a reflectance light curve with a very large peak-to-trough amplitude, ∆m ≈ 0.28 in 2005(Rabinowitz et al 2006), ∆m = 0.29 in 2007 (Lacerda et al 2008), and ∆m = 0.32 in 2009 (Lockwood et al 2014). Since Haumea's surface is spectrally uniform, such an extreme change in brightness can only be attributed to a difference in the area presented to the observer.…”

Section: Introductionmentioning

confidence: 99%

Haumea’s Shape, Composition, and Internal Structure

Dunham

Desch

Probst

2019

ApJ

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We have calculated the figure of equilibrium of a rapidly rotating, differentiated body to determine the shape, structure, and composition of the dwarf planet Haumea. Previous studies of Haumea's light curve have suggested Haumea is a uniform triaxial ellipsoid consistent with a Jacobi ellipsoid with axes ≈ 960 × 774 × 513 km, and bulk density ≈ 2600 kg m −3 . In contrast, observations of a recent stellar occultation by Haumea indicate its axes are ≈ 1161 × 852 × 523 km and its bulk density ≈ 1885 kg m −3 ; these results suggest that Haumea cannot be a fluid in hydrostatic equilibrium and must be partially supported by interparticle forces. We have written a code to reconcile these contradictory results and to determine if Haumea is in fact a fluid in hydrostatic equilibrium. The code calculates the equilibrium shape, density, and ice crust thickness of a differentiated Haumea after imposing (semi-) axes lengths a and b. We find Haumea is consistent with a differentiated triaxial ellipsoid fluid in hydrostatic equilibrium with axes of best fit a = 1050 km, b = 840 km, and c = 537 km. This solution for Haumea has ρ avg = 2018 kg m −3 , ρ core = 2680 kg m −3 , and core axes a c = 883 km, b c = 723 km, and c c = 470 km, which equates to an ice mantle comprising ∼ 17% of Haumea's volume and ranging from 67 to 167 km in thickness. The thick ice crust we infer allows for Haumea's collisional family to represent only a small fraction of Haumea's pre-collisional ice crust. For a wide range of parameters, the core density we calculate for Haumea suggests that today the core is composed of hydrated silicates and likely underwent serpentinization in the past.

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“…Haumea has a 3-axial shape with sizes estimated as about 1900 × 1 × 1000 km, a mass of 4.006 × 10 21 kg and a short spin period of 3.92 h (Rabinowitz et al 2006;Lacerda, Jewitt & Peixinho E-mail: acb@ua.es 2008; Thirouin et al 2010;Santos et al 2012;Lockwood, Brown & Stansberry 2014). From that available data and the assumption that Haumea has a fluid equilibrium shape, it has been argued (Rabinowitz et al 2008) that its density should be in the 2.6-3.3 g cm −3 range, much higher than Pluto's.…”

Section: Introductionmentioning

confidence: 99%

On the genesis of the Haumea system

Bagatín

Benavídez

Ortiz

et al. 2016

Mon. Not. R. Astron. Soc.

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The scenarios proposed in the literature for the genesis of the system formed by the dwarf planet 136108 Haumea, its two satellites and a group of some 10 bodies (the family) with semimajor axes, eccentricities and inclinations close to Haumea's values, are analysed against collisional, physical, dynamical and statistical arguments in order to assess their likelihood. All scenarios based on collisional events are reviewed under physical arguments and the corresponding formation probabilities in a collisional environment are evaluated according to the collisional evolution model ALICANDEP. An alternative mechanism is proposed based on the potential possibility of (quasi-) independent origin of the family with respect to Haumea and its satellites. As a general conclusion the formation of the Haumea system is a low-probability event in the currently assumed frame for the evolution of the outer Solar system. However, it is possible that current knowledge is missing some key element in the whole story that may contribute to increase the odds for the formation of such a system.

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The Size and Shape of the Oblong Dwarf Planet Haumea

Cited by 32 publications

References 33 publications

Rotational Properties of the Haumea Family Members and Candidates: Short-Term Variability

Rotational Properties of the Haumea Family Members and Candidates: Short-Term Variability

Haumea’s Shape, Composition, and Internal Structure

On the genesis of the Haumea system

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