Abstract
The transneptunian region has proven to be a valuable probe to test models of the formation and evolution of the solar system. To further advance our current knowledge of these early stages requires an increased knowledge of the physical properties of Transneptunian Objects (TNOs). Colors and albedos have been the best way so far to classify and study the surface properties of a large number TNOs. However, they only provide a limited fraction of the compositional information, required for understanding the physical and chemical processes to which these objects have been exposed since their formation. This can be better achieved by near-infrared (NIR) spectroscopy, since water ice, hydrocarbons and nitrile compounds display diagnostic absorption bands in this wavelength range. Visible and NIR spectra taken from ground-based facilities have been observed for ∼80 objects so far, covering the full range of spectral types: from neutral to extremely red with respect to the Sun, featureless to volatile-bearing and volatile-dominated (Barkume et al. 2008; Guilbert et al. 2009; Barucci et al. 2011; Brown 2012). The largest TNOs are bright and thus allow for detailed and reliable spectroscopy: they exhibit complex surface compositions, including water ice, methane, ammonia and nitrogen. Smaller objects are more difficult to observe even from the largest telescopes in the world. In order to further constrain the inventory of volatiles and organics in the solar system, and understand the physical and chemical evolution of these bodies, high-quality NIR spectra of a larger sample of TNOs need to be observed. JWST/NIRSpec is expected to provide a substantial improvement in this regard, by increasing both the quality of observed spectra and the number of observed objects. In this paper, we review the current knowledge of TNO properties and provide diagnostics for using NIRSpec to constrain TNO surface compositions.
Highlights
The outer solar system is occupied by a vast population of icy objects orbiting beyond Neptune, generally referred to as Transneptunian Objects (TNOs)
This paper focuses on TNO observations with Near-Infrared Spectrograph (NIRSpec) (e.g., Bagnasco et al, 2007), but additional information on all instruments can be found at the James Webb Space Telescope (JWST) User Documentation page
Our results were tested against the official JWST Exposure Time Calculator (ETC) and were found to agree with the ETC results to typically better than ±10%
Summary
The outer solar system is occupied by a vast population of icy objects orbiting beyond Neptune, generally referred to as Transneptunian Objects (TNOs). They hold valuable information on the chemical and physical conditions that prevailed in the early solar system, in this critical region of the protoplanetary disk where various ice lines were located (for example, the H2O ice line may have been located from 2 to 5 au, and the CO snowline from 8 to 12 au during the evolution of the JWST/NIRSpec Observations of TNOs. Sun’s protoplanetary disk, (Dodson-Robinson et al, 2009). - The Classical Belt, known as the Kuiper Belt, made of two dynamical components—the Cold Classical Objects and Hot Classical Objects (Nesvorny, 2015b) Overall, they form a donut-shaped structure roughly located between the 3:2 and 2:1 mean-motion resonances with Neptune. The orbits of scattered disk objects are unstable on the timescale of the age of the solar system
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