Over one thousand objects have been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the outer planets formed, and is an analog for unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the outer Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are only beginning to be revealed. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of their thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine those physical properties. While Spitzer has provided the first results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its wavelength coverage will permit profound advances in the field. We propose to perform radiometric measurements of 141 objects, including 25 known multiple systems. This large sample will permit: (i) A determination of the size distribution of the large (> 200 km) objects, thought to have remained unchanged from the accretion phase. (ii) Systematic searches for correlations between size, albedo, and other physical and orbital parameters, diagnostic of formation and evolution processes. (iii) Determination of mass-density for at least 20 binary TNOs, diagnostic of nebular chemistry and interior structure. (iv) The first study of their thermophysical properties, including thermal inertia and surface emissivity. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto and beyond), our results will prov...ide a benchmark for understanding the solar system debris disk, and extra-solar ones as well.
Publication
The Albedo-Color Diversity of Transneptunian Objects . Lacerda Pedro et al. . The Astrophysical Journal Letters, Volume 793, Issue 1, article id. L2, 6 pp. (2014). . 793 . 10.1088\/2041-8205\/793\/1\/L2 . 2014ApJ...793L...2L , Optimized Herschel/PACS photometer observing and data reduction strategies for moving solar system targets . Kiss C. et al. . Experimental Astronomy, Volume 37, Issue 2, pp.161-174 . 37 . 10.1007\/s10686-013-9350-5 . 2014ExA....37..161K ,
Instrument
SPIRE_SpirePhoto_small, PACS_PacsPhoto_largeScan
Temporal Coverage
2010-01-27T14:21:01Z/2012-09-10T21:04:57Z
Version
SPG v14.2.0
Mission Description
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
European Space Agency, 2013, Tnos Are Cool: A Survey Of The Transneptunian Region, SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-cm1ph2p
