Thermal properties of large main-belt asteroids observed by Herschel PACS
V. Alí-Lagoa, T. G. Müller, C. Kiss, R. Szakáts, G. Marton, A. Farkas-Takács, P. Bartczak, M. Butkiewicz-Bąk, G. Dudziński, A. Marciniak, E. Podlewska-Gaca, R. … 展开作者
V. Alí-Lagoa, T. G. Müller, C. Kiss, R. Szakáts, G. Marton, A. Farkas-Takács, P. Bartczak, M. Butkiewicz-Bąk, G. Dudziński, A. Marciniak, E. Podlewska-Gaca, R. Duffard, P. Santos-Sanz, J. L. Ortiz
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Accepted for publication in Astronomy & Astrophysics (preprint version)
Non-resolved thermal infrared observations enable studies of thermal and physical properties of asteroid surfaces provided the shape and rotational properties of the target are well determined via thermo-physical models. We used calibration-programme Herschel PACS data (70, 100, 160 $μ$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.
We present all Herschel PACS photometer observations of Mars, Saturn, Uranus, Neptune, Callisto, Ganymede, and Titan. All measurements were carefully inspected for quality problems, were reduced in a (semi-)standard way, and were calibrated. The derived flux densities are tied to the standard PACS photometer response calibration, which is based on repeated measurements of five fiducial stars. The overall absolute flux uncertainty is dominated by the estimated 5% model uncertainty of the stellar models in the PACS wavelength range between 60 and 210 micron. A comparison with the corresponding p…
In this letter we explore the environment of Pluto and Charon in the far infrared with the main aim to identify the signs of any possible dust ring, should it exist in the system. Our study is based on observations performed at 70 um with the PACS instrument onboard the Herschel Space Observatory at 9 epochs between March 14 and 19, 2012. The far-infrared images of the Pluto-Charon system are compared to those of the point spread function (PSF) reference quasar 3C454.3. The deviation between the observed Pluto-Charon and reference PSFs are less then 1 sigma indicating that clear evidence for a…
Time series observations of the dwarf planet Haumea and the Plutinos 2003VS2 and 2003AZ84 with Herschel/PACS are presented in this work. Thermal emission of these trans-Neptunian objects were acquired as part of the TNOs are Cool Herschel Space Observatory key programme. We search for the thermal light curves at 100 and 160um of Haumea and 2003AZ84, and at 70 and 160um for 2003VS2 by means of photometric analysis of the PACS data. The goal of this work is to use these thermal light curves to obtain physical and thermophysical properties of these icy Solar System bodies. Haumea's thermal light …
"TNOs are Cool": A Survey of the Transneptunian Region IV. Size/albedo characterization of 15 scattered disk and detached objects observed with Herschel Space Observatory-PACS
The D/H ratio in the atmospheres of Uranus and Neptune from Herschel PACS observations
本文分析了Herschel-PACS对天王星和海王星大气中转动R（0）和R（1）HD线的测量结果，以获得两颗行星更精确的D/H比。D/H比的推导还包括红外空间天文台（ISO）上的短波光谱仪先前对R（2）线的测量。讨论了三个转动跃迁的谱线信息，并将其应用于辐射转移计算。所有三条线的最佳同时拟合只需要与天王星的斯皮策温度廓线有一个微小的偏离，与海王星的旅行者温度廓线的偏离限制在2K以内（都在对流层顶附近）。天王星和海王星的D/H比值非常相似，分别为（4.4 $\pm$ 0.4）$\times10^{-5}$和（4.1 $\pm$ 0.4）$\times10^{-5}$。虽然氘富集在两个大气相比，原太阳值得到证实，它被发现是较低的相比，以前的分析。使用Podolak et al.（1995），Helled et al.（2011）和Nettelmann et al.（2013）的内部模型，并假设在行星历史中大气和内部发生完全混合，我们推导出天王星原行星冰的D/H介于（5.75--7.0）$\times10^{-5}$之间，海王星介于（5.1--7.7）$\times10^{-5}$之间。相反，采用彗星的D/H为（15-30）$\times10^{-5}$之间的原行星冰，我们限制两颗行星的内部模型有一个冰的质量分数为14- 32%，即这两颗行星是岩石为主。
Aims. We aim to determine far-infrared fluxes at 70, 100, and 160$μ$m of the five major Uranus satellites Titania, Oberon, Umbriel, Ariel and Miranda, based on observations with the photometer PACS-P aboard the Herschel Space Observatory. Methods. The bright image of Uranus is subtracted using a scaled Uranus point spread function (PSF) reference established from all maps of each wavelength in an iterative process removing the superimposed moons. Photometry of the satellites is performed by PSF photometry. Thermophysical models of the icy moons are fitted to the photometry of each measurement …
(Abridged) We use Herschel PACS observations at 70 and 160$μ$m to probe the protoplanetary disks around young stars in the CepOB2 clusters Tr37 and NGC7160 and to trace the small-scale cloud structure. We detect 95 protoplanetary disks at 70$μ$m, 41 at 160$μ$m, and obtain upper limits for over 130 objects. The detection fraction at 70$μ$m depends on the spectral type (88% for K4 or earlier, 17% for M3 or later stars) and on the disk type ($\sim$50% for full and pre-transitional disks, $\sim$35% for transitional disks, no low-excess/depleted disks detected). Non-accreting disks are consistent w…
Debris discs are the dusty aftermath of planet formation processes around main-sequence stars. Analysis of these discs is often hampered by the absence of any meaningful constraint on the location and spatial extent of the disc around its host star. Multi-wavelength, resolved imaging ameliorates the degeneracies inherent in the modelling process, making such data indispensable in the interpretation of these systems. The Herschel Space Observatory observed HD 105211 (Eta Cru, HIP 59072) with its PACS instrument in three far-infrared wavebands (70, 100 and 160 um). Here we combine these data wit…
Dust in debris disks is produced by colliding or evaporating planetesimals, remnants of the planet formation process. Warm dust disks, known by their emission at < 24 micron, are rare (4% of FGK main sequence stars) and especially interesting because they trace material in the region likely to host terrestrial planets, where the dust has a very short dynamical lifetime. Statistical analyses of the source counts of excesses as found with the mid-IR Wide Field Infrared Survey Explorer (WISE) suggest that warm-dust candidates found for the Kepler transiting-planet host-star candidates can be expl…
The thermal emission of comet C/2013 A1 (Siding Spring) was observed on March 31, 2013, at a heliocentric distance of 6.48 au using the PACS photometer camera of the Herschel Space Observatory. The comet was clearly active, showing a coma that could be traced to a distance of 10", i.e. 50000 km. Analysis of the radial intensity profiles of the coma provided dust mass and dust production rate; the derived grain size distribution characteristics indicate an overabundance of large grains in the thermal emission. We estimate that activity started about 6 months before these observations, at a heli…
An icy Kuiper-Belt around the young solar-type star HD 181327
HD 181327是一颗年轻的F5/F6 V恒星，属于美如画β移动星群（1200万年前）。它在90天文单位处有一条光学薄的星周物质带。我们的目标是详细研究粉尘的性质，并约束气尘比。我们获得了远红外观测与赫歇尔/PACS仪器，和3.2毫米的ATCA阵列的意见。带的几何形状的约束与新减少的HST/NICMOS图像，打破了磁盘的几何形状和尘埃属性之间的简并。我们使用辐射转移代码GRaTer来计算模型的大网格，并且我们通过贝叶斯分析来确定最佳再现光谱能量分布的晶粒模型。我们试图用PACS光谱检测[OI]和[CII]线，为我们的光化学代码ProDiMo提供可观的数据。HST的观测证实了尘埃被限制在一个狭窄的带中。用PACS在远红外中检测连续谱，并用PACS和ATCA两者解析盘。气体谱线的中等积分仅提供线通量的上限。我们发现，HD 181327尘埃盘由微米级颗粒的多孔无定形硅酸盐和碳质材料包围的一个重要的冰层，总尘埃质量为0.05 M \oplus（最多1毫米）。我们讨论的证据表明，颗粒是蓬松的聚集体。气体管线上的上限没有提供明确的约束：只有当PAH丰度高时，气体质量才必须低于17 M \oplus。尽管对气体盘的约束很弱，但HD 181327的年龄和尘埃盘的性质表明它已经通过了气态行星形成的阶段。尘埃揭示了一群冰冷的小行星，类似于原始的柯伊伯带，这可能是未来向形成中的类地行星输送水和挥发物的…
This paper presents a study of circumstellar debris around Sun-like stars using data from the Herschel DEBRIS Key Programme. DEBRIS is an unbiased survey comprising the nearest ~90 stars of each spectral type A-M. Analysis of the 275 F-K stars shows that excess emission from a debris disc was detected around 47 stars, giving a detection rate of 17.1+2.6-2.3 per cent, with lower rates for later spectral types. For each target a blackbody spectrum was fitted to the dust emission to determine its fractional luminosity and temperature. The derived under- lying distribution of fractional luminosity…
