"TNOs are cool": A survey of the trans-Neptunian region II. The thermal lightcurve of (136108) Haumea

E. Lellouch, C. Kiss, P. Santos-Sanz, T. G. Müller, S. Fornasier, O. Groussin, P. Lacerda, J. L. Ortiz, A. Thirouin, A. Delsanti, R. Duffard, A. W. Harris, F. Henry, T. Lim, R. Moreno, M. Mommert, M. Mueller, S. Protopapa, J. Stansberry, D. TrillingE. Vilenius, A. Barucci, J. Crovisier, A. Doressoundiram, E. Dotto, P. J. Gutiérrez, O. Hainaut, P. Hartogh, D. Hestroffer, J. Horner, L. Jorda, M. Kidger, L. Lara, M. Rengel, B. Swinyard, N. Thomas

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Abstract

Thermal emission from Kuiper belt object (136108) Haumea was measured with Herschel-PACS at 100 μm and 160 μm for almost a full rotation period. Observations clearly indicate a 100 μm thermal lightcurve with an amplitude of a factor of ∼2, which is positively correlated with the optical lightcurve. This confirms that both are primarily due to shape effects. A 160 μm lightcurve is marginally detected. Radiometric fits of the mean Herschel-and Spitzer-fluxes indicate an equivalent diameter D ∼ 1300 km and a geometric albedo pv ∼ 0.70-0.75. These values agree with inferences from the optical lightcurve, supporting the hydrostatic equilibrium hypothesis. The large amplitude of the 100 μm lightcurve suggests that the object has a high projected a/b axis ratio (∼1.3) and a low thermal inertia as well as possible variable infrared beaming. This may point to fine regolith on the surface, with a lunar-type photometric behavior. The quality of the thermal data is not sufficient to clearly detect the effects of a surface dark spot.

Original languageEnglish
Article numberL147
JournalAstronomy and Astrophysics
Volume518
Issue number3
DOIs
Publication statusPublished - Jul 16 2010

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Keywords

  • Kuiper belt objects: individual: (136108) Haumea
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Lellouch, E., Kiss, C., Santos-Sanz, P., Müller, T. G., Fornasier, S., Groussin, O., Lacerda, P., Ortiz, J. L., Thirouin, A., Delsanti, A., Duffard, R., Harris, A. W., Henry, F., Lim, T., Moreno, R., Mommert, M., Mueller, M., Protopapa, S., Stansberry, J., ... Thomas, N. (2010). "TNOs are cool": A survey of the trans-Neptunian region II. The thermal lightcurve of (136108) Haumea. Astronomy and Astrophysics, 518(3), [L147]. https://doi.org/10.1051/0004-6361/201014648