TNOs are cool: a survey of the trans-Neptunian region: XIV. Size/albedo characterization of the Haumea family observed with Herschel and Spitzer

Vilenius, E. and Stansberry, J. and Muller, T. and Mueller, M. and Kiss, C. and Santos-Sanz, P. and Mommert, M. and Pal, A. and Lellouch, E. and Ortiz, J. L. and Peixinho, N. and Thirouin, A. and Lykawka, P. S. and Horner, J. and Duffard, R. and Fornasier, S. and Delsanti, A. (2018) TNOs are cool: a survey of the trans-Neptunian region: XIV. Size/albedo characterization of the Haumea family observed with Herschel and Spitzer. Astronomy and Astrophysics, 618 (Article A136). ISSN 0004-6361

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Abstract

Context. A group of trans-Neptunian objects (TNOs) are dynamically related to the dwarf planet 136108 Haumea. Ten of them show strong indications of water ice on their surfaces, are assumed to have resulted from a collision, and are accepted as the only known TNO collisional family. Nineteen other dynamically similar objects lack water ice absorptions and are hypothesized to be dynamical interlopers.

Aims: We have made observations to determine sizes and geometric albedos of six of the accepted Haumea family members and one dynamical interloper. Ten other dynamical interlopers have been measured by previous works. We compare the individual and statistical properties of the family members and interlopers, examining the size and albedo distributions of both groups. We also examine implications for the total mass of the family and their ejection velocities.

Methods: We use far-infrared space-based telescopes to observe the target TNOs near their thermal peak and combine these data with optical magnitudes to derive sizes and albedos using radiometric techniques. Using measured and inferred sizes together with ejection velocities, we determine the power-law slope of ejection velocity as a function of effective diameter.

Results: The detected Haumea family members have a diversity of geometric albedos 0.3-0.8, which are higher than geometric albedos of dynamically similar objects without water ice. The median geometric albedo for accepted family members is p<SUB>V</SUB> = 0.48<SUB>-0.18</SUB><SUP>+0.28</SUP>, compared to 0.08<SUB>-0.05</SUB><SUP>+0.07</SUP> for the dynamical interlopers. In the size range D = 175-300 km, the slope of the cumulative size distribution is q = 3.2<SUB>-0.4</SUB><SUP>+0.7</SUP> for accepted family members, steeper than the q = 2.0 ± 0.6 slope for the dynamical interlopers with D &lt; 500 km. The total mass of Haumea's moons and family members is 2.4% of Haumea's mass. The ejection velocities required to emplace them on their current orbits show a dependence on diameter, with a power-law slope of 0.21-0.50. Herschel is an ESA space observatory with science instruments provided by a European-led Principal Investigator consortia and with important participation from NASA.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to Published version in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 10 Sep 2019 06:16
Last Modified: 12 Sep 2019 04:46
Uncontrolled Keywords: Kuiper belt: infrared; planetary systems; observational; photometric; astrophysics; planetary astrophysics
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020108 Planetary Science (excl. Extraterrestrial Geology)
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020102 Astronomical and Space Instrumentation
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1051/0004-6361/201732564
URI: http://eprints.usq.edu.au/id/eprint/36517

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