Serpentinization in the Thermal Evolution of Icy Kuiper Belt Objects in the Early Solar System

Here we present an improved algorithm to model the serpentinization process in planetesimals in the early solar system. Although it is hypothesized that serpentinization-like reactions played an important role in the thermal evolution of planetesimals, few and restricted models are available in this topic. These processes may be important, as the materials involved were abundant in these objects. Our model is based on the model by Góbi & Kereszturi and contains improvements in the consideration of heat capacities and lithospheric pressure and in the calculation of the amount of interfacial water. Comparison of our results with previous calculations shows that there are significant differences in, e.g., the serpentinization time-the time necessary to consume most of the reactants at specific initial conditions-or the amount of heat produced by this process. In a simple application we show that in icy bodies, under some realistic conditions, below the melting point of water ice, serpentinization reaction using interfacial water may be able to proceed and eventually push the local temperature above the melting point to start a "runaway" serpentinization. According to our calculations in objects with radii R ≳ 200 km, serpentinization might have quickly reformed nearly the whole interior of these bodies in the early solar system

"TNOs are Cool": A survey of the trans-Neptunian region XV. Physical characteristics of 23 resonant trans-Neptunian and scattered disk objects

The goal of this work is to determine the physical characteristics of resonant, detached and scattered disk objects in the transneptunian region, observed mainly in the framework of the "TNOs are Cool!" Herschel Open Time Key Program. Based on thermal emission measurements with the Herschel/PACS and Spitzer/MIPS instruments we determine size, albedo, and surface thermal properties for 23 objects using radiometric modelling techniques. This is the first analysis in which the physical properties of objects in the outer resonances are determined for a notable sample. In addition to the results for individual objects, we have compared these characteristics with the bulk properties of other populations of the transneptunian region. The newly analyzed objects show a large variety of beaming factors, indicating a diversity of thermal properties, and in general, they follow the albedo-colour clustering identified earlier for Kuiper belt objects and Centaurs, further strengthening the evidence for a compositional discontinuity in the young Solar System

Thermal properties of large main-belt asteroids observed by Herschel PACS

Non-resolved thermal infrared observations enable studies of thermal and physical properties of asteroid surfaces provided the shape and physical models. We used calibration-programme Herschel PACS data (70, 100, 160 $\\mu$m) and state-of-the-art shape models derived from adaptive-optics observations and/or optical light curves to constrain for the first time the thermal inertia of twelve large main-belt asteroids. We also modelled previously well-characterised targets such as (1) Ceres or (4) Vesta as they constitute important benchmarks. Using the scale as a free parameter, most targets required a re-scaling $\\sim$5\\% consistent with what would be expected given the absolute calibration error bars. This constitutes a good cross-validation of the scaled shape models, although some targets required larger re-scaling to reproduce the IR data. We obtained low thermal inertias typical of large main belt asteroids studied before, which continues to give support to the notion that these surfaces are covered by fine-grained insulating regolith. Although the wavelengths at which PACS observed are longwards of the emission peak for main-belt asteroids, they proved to be extremely valuable to constrain size and thermal inertia and not too sensitive to surface roughness. Finally, we also propose a graphical approach to help examine how different values of the exponent used for scaling the thermal inertia as a function of heliocentric distance (i.e. temperature) affect our interpretation of the results

Small Bodies: Near and Far Database for thermal infrared observations of small bodies in the Solar System

In this paper, we present the Small Bodies: Near and Far Infrared Database, an easy-to-use tool intended to facilitate the modelling of thermal emission of small bodies of the Solar System. Our database collects measurements of thermal emissions for small Solar System targets that are otherwise available in scattered sources and provides a complete description of the data, including all information necessary to perform direct scientific analyses and without the need to access additional external resources. This public database contains representative data of asteroid observations of large surveys (e.g. AKARI, IRAS, and WISE) as well as a collection of small body observations of infrared space telescopes (e.g. the Herschel Space Observatory) and provides a web interface to access this data. We also provide an example for the direct application of the database and show how it can be used to estimate the thermal inertia of specific populations, e.g. asteroids within a given size range. We show how different scalings of thermal inertia with heliocentric distance (i.e. temperature) may affect our interpretation of the data and discuss why the widely-used radiative conductivity exponent (α = -3/4) might not be adequate in general, as suggested in previous studies. The database is available at http://https://ird.konkoly.h

Haumea's thermal emission revisited in the light of the occultation results

A recent multi -chord occultation measurement of the dwarf planet (136108) Haumea (Ortiz et al., 2017) revealed an elongated shape with the longest axis comparable to Pluto's mean diameter. The chords also indicate a ring around Haumea's equatorial plane, where its largest moon, Hi'iaka, is also located. The Haumea occultation size estimate (size of an equal-volume sphere(1) D-equ = 1595 km) is larger than previous radiometric solutions (equivalent sizes in the range between 1150 and 1350 km), which lowers the object's density to about 1.8 g/cm3, a value closer to the densities of other large TNOs. We present unpublished and also reprocessed Herschel and Spitzer mid- and far-infrared measurements. We compare 100 and 160 pm thermal lightcurve amplitudes - originating from Haumea itself - with models of the total measured system fluxes (ring, satellite, Haumea) from 24-350 pm. The combination with results derived from the occultation measurements allows us to reinterpret the object's thermal emission. Our radiometric studies show that Haumea's crystalline water ice surface must have a thermal inertia of about 5 J K-3 m-s(-1) (combined with a root mean square of the surface slopes of 0.2). We also have indications that the satellites (at least Hi'iaka) must have high geometric albedos > 0.5, otherwise the derived thermal amplitude would be inconsistent with the total measured system fluxes at 24, 70, 100, 160, 250, and 350 pm. The high albedos imply sizes of about 300 and 150 km for Hi'iaka and Namaka, respectively, indicating unexpectedly high densities > 1.0 g cm(-3) for TNOs this small, and the assumed collisional formation from Haumea's icy crust. We also estimated the thermal emission of the ring for the time period 1980-2030, showing that the contribution during the Spitzer and Herschel epochs was small, but not negligible. Due to the progressive opening of the ring plane, the ring emission will be increasing in the next decade when JWST is operational. In the MIRI 25.5 pm band it will also be possible to obtain a very high-quality thermal lightcurve to test the derived Haumea properties

An UXor among FUors: Extinction-related Brightness Variations of the Young Eruptive Star V582 Aur

V582 Aur is an FU Ori-type young eruptive star in outburst since similar to 1985. The eruption is currently in a relatively constant plateau phase, with photometric and spectroscopic variability superimposed. Here we will characterize the progenitor of the outbursting object, explore its environment, and analyze the temporal evolution of the eruption. We are particularly interested in the physical origin of the two deep photometric dips, one that occurred in 2012 and one that is ongoing since 2016. We collected archival photographic plates and carried out new optical, infrared, and millimeter-wave photometric and spectroscopic observations between 2010 and 2018, with a high sampling rate during the current minimum. Besides analyzing the color changes during fading, we compiled multiepoch spectral energy distributions and fitted them with a simple accretion disk model. Based on pre-outburst data and a millimeter continuum measurement, we suggest that the progenitor of the V582 Aur outburst is a low-mass T Tauri star with average properties. The mass of an unresolved circumstellar structure, probably a disk, is 0.04M(circle dot). The optical and near-infrared spectra demonstrate the presence of hydrogen and metallic lines, show the CO band head in absorption, and exhibit a variable Ha profile. The color variations strongly indicate that both the similar to 1 yr long brightness dip in 2012 and the current minimum since 2016 are caused by increased extinction along the line of sight. According to our accretion disk models, the reddening changed from A(V) = 4.5 to 12.5mag, while the accretion rate remained practically constant. Similarly to the models of the UXor phenomenon of intermediate- and low-mass young stars, orbiting disk structures could be responsible for the eclipses