scholarly journals Spitzer Space Telescope observations of bilobate comet 8P/Tuttle

2019 ◽  
Vol 632 ◽  
pp. A104
Author(s):  
O. Groussin ◽  
P. L. Lamy ◽  
M. S. P. Kelley ◽  
I. Toth ◽  
L. Jorda ◽  
...  
Keyword(s):  
Physical Properties ◽  
Confidence Level ◽  
Thermal Inertia ◽  
Infrared Camera ◽  
Equilibrium Temperature ◽  
Space Telescope ◽  
Nucleus Shape ◽  
Independent Observations ◽  
Dust Grain ◽  
Pole Orientation

Context. Comet 8P/Tuttle is a nearly isotropic comet whose physical properties are poorly known and might be different from those of ecliptic comets owing to their different origin. Two independent observations have shown that 8P/Tuttle has a bilobate nucleus. Aims. Our goal is to determine the physical properties of the nucleus (size, shape, thermal inertia, and albedo) and coma (water and dust) of 8P/Tuttle. Methods. We observed the inner coma of 8P/Tuttle with the infrared spectrograph and the infrared camera of the Spitzer Space Telescope. We obtained one spectrum (5–40 μm) on 2 November 2007 and a set of 19 images at 24 μm on 22–23 June 2008 sampling the rotational period of the nucleus. The data were interpreted using thermal models for the nucleus and the dust coma, and we considered two possible shape models of the nucleus derived from Hubble Space Telescope visible and Arecibo radar observations. Results. We favor a model for the nucleus shape that is composed of two contact spheres with respective radii of 2.7 ± 0.1 km and 1.1 ± 0.1 km and a pole orientation with RA = 285 ± 12° and Dec = +20 ± 5°. The thermal inertia of the nucleus lies in the range 0–100 J K−1 m−2 s−1∕2 and the R-band geometric albedo is 0.042 ± 0.008. The water production rate amounts to 1.1 ± 0.2 × 1028 molecules s−1 at 1.6 AU from the Sun pre-perihelion, which corresponds to an active fraction of ≈9%. At the same distance, the ɛfρ quantity amounts to 310 ± 34 cm, and it reaches 325 ± 36 cm at 2.2 AU post-perihelion. The dust grain temperature is estimated to be 258 ± 10 K, which is 37 K higher than the thermal equilibrium temperature at 1.6 AU. This indicates that the dust grains that contribute to the thermal infrared flux have a typical size of ≈10 μm. The dust spectrum exhibits broad emission around 10 μm (1.5σ confidence level) and 18 μm (5σ confidence level) that we attribute to amorphous pyroxene.

scholarly journals Search for giant planets around seven white dwarfs in the Hyades cluster with the Hubble Space Telescope

2020 ◽  
Vol 500 (3) ◽  
pp. 3920-3925
Author(s):  
Wolfgang Brandner ◽  
Hans Zinnecker ◽  
Taisiya Kopytova
Keyword(s):  
White Dwarfs ◽  
Near Infrared ◽  
Hubble Space Telescope ◽  
Infrared Camera ◽  
Detection Limits ◽  
Giant Planets ◽  
High Angular Resolution ◽  
Mass Detection ◽  
Space Telescope ◽  
Hyades Cluster

ABSTRACT Only a small number of exoplanets have been identified in stellar cluster environments. We initiated a high angular resolution direct imaging search using the Hubble Space Telescope (HST) and its Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument for self-luminous giant planets in orbit around seven white dwarfs in the 625 Myr old nearby (≈45 pc) Hyades cluster. The observations were obtained with Near-Infrared Camera 1 (NIC1) in the F110W and F160W filters, and encompass two HST roll angles to facilitate angular differential imaging. The difference images were searched for companion candidates, and radially averaged contrast curves were computed. Though we achieve the lowest mass detection limits yet for angular separations ≥0.5 arcsec, no planetary mass companion to any of the seven white dwarfs, whose initial main-sequence masses were >2.8 M⊙, was found. Comparison with evolutionary models yields detection limits of ≈5–7 Jupiter masses (MJup) according to one model, and between 9 and ≈12 MJup according to another model, at physical separations corresponding to initial semimajor axis of ≥5–8 au (i.e. before the mass-loss events associated with the red and asymptotic giant branch phase of the host star). The study provides further evidence that initially dense cluster environments, which included O- and B-type stars, might not be highly conducive to the formation of massive circumstellar discs, and their transformation into giant planets (with m ≥ 6 MJup and a ≥6 au). This is in agreement with radial velocity surveys for exoplanets around G- and K-type giants, which did not find any planets around stars more massive than ≈3 M⊙.

scholarly journals A thermophysical and dynamical study of the Hildas (1162) Larissa and (1911) Schubart

2021 ◽  
Author(s):  
Cristian F Chavez ◽  
T G Müller ◽  
J P Marshall ◽  
J Horner ◽  
H Drass ◽  
...  
Keyword(s):  
Thermal Inertia ◽  
Infrared Camera ◽  
Asteroid Belt ◽  
Effective Diameter ◽  
Early Solar System ◽  
Dynamical Study ◽  
Axis Ratio ◽  
Ellipsoidal Shape ◽  
Dynamical Simulations ◽  
Taxonomical Classification

Abstract The Hilda asteroids are among the least studied populations in the asteroid belt, despite their potential importance as markers of Jupiter’s migration in the early Solar system. We present new mid-infrared observations of two notable Hildas, (1162) Larissa and (1911) Schubart, obtained using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST), and use these to characterise their thermal inertia and physical properties. For (1162) Larissa, we obtain an effective diameter of 46.5$^{+2.3}_{-1.7}$ km, an albedo of 0.12 ± 0.02, and a thermal inertia of 15$^{+10}_{-8}$ Jm−2s1/2K−1. In addition, our Larissa thermal measurements are well matched with an ellipsoidal shape with an axis ratio a/b=1.2 for the most-likely spin properties. Our modelling of (1911) Schubart is not as refined, but the thermal data point towards a high-obliquity spin-pole, with a best-fit a/b=1.3 ellipsoidal shape. This spin-shape solution is yielding a diameter of 72$^{+3}_{-4}$ km, an albedo of 0.039± 0.02, and a thermal inertia below 30 Jm−2s1/2K−1 (or 10$^{+20}_{-5}$ Jm−2s1/2K−1). As with (1162) Larissa, our results suggest that (1911) Schubart is aspherical, and likely elongated in shape. Detailed dynamical simulations of the two Hildas reveal that both exhibit strong dynamical stability, behaviour that suggests that they are primordial, rather than captured objects. The differences in their albedos, along with their divergent taxonomical classification, suggests that despite their common origin, the two have experienced markedly different histories.

Spitzer and Hubble Space Telescope Constraints on the Physical Properties of the z  ~ 7 Galaxy Strongly Lensed by A2218

2004 ◽  
Vol 618 (1) ◽  
pp. L5-L8 ◽  
Author(s):  
E. Egami ◽  
J.-P. Kneib ◽  
G. H. Rieke ◽  
R. S. Ellis ◽  
J. Richard ◽  
...  
Keyword(s):  
Physical Properties ◽  
Hubble Space Telescope ◽  
Space Telescope

Evaluation for Climates Adaptive Capability of Traditional Tuzhang Dwelling

2012 ◽  
Vol 450-451 ◽  
pp. 1219-1222
Author(s):  
Tao Zhang ◽  
Jia Ping Liu ◽  
Jun Wang ◽  
Qi Wei Zhang
Keyword(s):  
Thermal Properties ◽  
Thermal Resistance ◽  
Physical Properties ◽  
Thermal Wave ◽  
Thermal Inertia ◽  
Index Data ◽  
Adaptive Capability ◽  
Reduction Coefficient ◽  
Inertia Index ◽  
Thermal Physical Properties

Present study is concentrated on evaluating the climate adaptive capability of Tuzhang dwellings. The comparisons to different thermal physical properties such as thermal resistance R0, thermal inertia index data D, reduction coefficient of thermal wave transferring V0 and thermal transferring delaying time ξ0 have been performed between Tuzhang dwelling and normal brick house. Comparing results show that Tuzhang dwelling has much better thermal properties than normal brick house. Therefore, regarding to climate adaptive capability, traditional Tuzhang dwelling is vastly superior to brick house.

scholarly journals Chemometrics as a Tool to Gain Insight into Fiber Rope Aging from Infrared Images

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Ellen Marie Nordgård-Hansen ◽  
Håkon Jarle Hassel ◽  
Rune Schlanbusch
Keyword(s):  
Image Processing ◽  
Thermal Properties ◽  
Physical Properties ◽  
Real Life ◽  
Infrared Camera ◽  
Limiting Factor ◽  
Infrared Images ◽  
The Many ◽  
Thermo Physical Properties ◽  
Insight Into

Fiber ropes are steadily gaining in popularity for offshore lifting purposes. One limiting factor is many fibers’ low tolerance for high temperatures. Measurements of rope temperature and changes in thermo-physical properties are therefore highly relevant, a task which may be performed using an infrared camera. Chemometrics is one tool among the many techniques available for image processing. The present paper details results from applying chemometrics to infrared images obtained from recent cyclic-bend-over-sheave testing. It is shown how this tool contributes to separating the various phenomena going on, like changes in thermal properties, vertical rope movement, surface degradation, and rope twist. A brief discussion on the applicability for real-life monitoring is also given.

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