OA@INAF - Istituto Nazionale di Astrofisica
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PDRs4All. II. JWST's NIR and MIR imaging view of the Orion Nebula
Full text linkContext. The James Webb Space Telescope (JWST) has captured the most detailed and sharpest infrared (IR) images ever taken of the inner region of the Orion Nebula, the nearest massive star formation region, and a prototypical highly irradiated dense photo-dissociation region (PDR). Aims: We investigate the fundamental interaction of far-ultraviolet (FUV) photons with molecular clouds. The transitions across the ionization front (IF), dissociation front (DF), and the molecular cloud are studied at high-angular resolution. These transitions are relevant to understanding the effects of radiative feedback from massive stars and the dominant physical and chemical processes that lead to the IR emission that JWST will detect in many Galactic and extragalactic environments. Methods: We utilized NIRCam and MIRI to obtain sub-arcsecond images over ~150″ and 42″ in key gas phase lines (e.g., Pa α, Br α, [FeII] 1.64 µm, H2 1−0 S(1) 2.12 µm, 0-0 S(9) 4.69 µm), aromatic and aliphatic infrared bands (aromatic infrared bands at 3.3-3.4 µm, 7.7, and 11.3 µm), dust emission, and scattered light. Their emission are powerful tracers of the IF and DF, FUV radiation field and density distribution. Using NIRSpec observations the fractional contributions of lines, AIBs, and continuum emission to our NIRCam images were estimated. A very good agreement is found for the distribution and intensity of lines and AIBs between the NIRCam and NIRSpec observations. Results: Due to the proximity of the Orion Nebula and the unprecedented angular resolution of JWST, these data reveal that the molecular cloud borders are hyper structured at small angular scales of ~0.1-1″ (~0.0002-0.002 pc or ~40-400 au at 414 pc). A diverse set of features are observed such as ridges, waves, globules and photoevaporated protoplanetary disks. At the PDR atomic to molecular transition, several bright features are detected that are associated with the highly irradiated surroundings of the dense molecular condensations and embedded young star. Toward the Orion Bar PDR, a highly sculpted interface is detected with sharp edges and density increases near the IF and DF. This was predicted by previous modeling studies, but the fronts were unresolved in most tracers. The spatial distribution of the AIBs reveals that the PDR edge is steep and is followed by an extensive warm atomic layer up to the DF with multiple ridges. A complex, structured, and folded H0/H2 DF surface was traced by the H2 lines. This dataset was used to revisit the commonly adopted 2D PDR structure of the Orion Bar as our observations show that a 3D "terraced" geometry is required to explain the JWST observations. JWST provides us with a complete view of the PDR, all the way from the PDR edge to the substructured dense region, and this allowed us to determine, in detail, where the emission of the atomic and molecular lines, aromatic bands, and dust originate. Conclusions: This study offers an unprecedented dataset to benchmark and transform PDR physico-chemical and dynamical models for the JWST era. A fundamental step forward in our understanding of the interaction of FUV photons with molecular clouds and the role of FUV irradiation along the star formation sequence is provided...
Fundamental physics measurements with Galileo FOC satellites and the Galileo for science project. I. A 3D-CAD and a box wing for modeling the effects of nonconservative forces
Full text linkThis paper introduces the main problems related to the modeling of the effects of nongravitational perturbations on satellites of the Galileo FOC constellation. The problem is addressed from the point of view of the scientific objectives of the Galileo for Science (G4S_2.0) project. These objectives are reflected in a set of fundamental physics measurements that will exploit the orbits and atomic clocks aboard the Galileo satellites, in particular the GSAT-0201 and GSAT-0202 satellites characterized by elliptical orbits, and not by almost circular orbits such as in the case of the remaining satellites of the constellation. The main focus is on the modeling of the direct solar radiation pressure, the largest nongravitational perturbation on GNSS satellites. After an in-depth presentation of the main nongravitational perturbations of interest, and of the models currently in use in the literature for their consideration, the work focuses on the amplitudes of the different effects and, with particular attention, on their intrinsic knowledge. Finally, two different models are introduced for the structure of the Galileo satellite specially developed for the objectives of G4S_2.0. The first is a simple model of the box-wing type, developed on the basis of the information currently available on the characteristics of the satellite. The second is a 3D model of the Galileo spacecraft, somewhat sophisticated due to the richness of the details on the structure and the various elements that make up the surfaces of the satellite. The activities carried out and in progress with these models and those planned with their subsequent updated versions are described
Streamlining LOFAR operations with the new telescope manager specification system
Full text linkThe Low Frequency Array (LOFAR) is Europe's largest radio telescope, designed, built and operated by ASTRON and international LOFAR partners. It is a complex instrument which had an expensive active human workflow and became difficult to adjust. The new Telescope Manager Specification System (TMSS) solves this by the introduction of a dynamic scheduler, a data-quality assessment workflow and a specification system that allows easy versioned specification of known observing setups but also detailed adjustments of observations and processing pipelines. In this presentation we will show the new optimized operations workflow and dynamic scheduling with TMSS...
Metal line emission around z<1 galaxies
Full text linkWe characterize, for the first time, the average extended emission in
multiple lines ([OII], [OIII], and Hbeta) around a statistical sample of 560
galaxies at z~0.25-0.85. By stacking the Multi Unit Spectroscopic Explorer
(MUSE) 3D data from two large surveys, the MUSE Analysis of Gas around Galaxies
(MAGG) and the MUSE Ultra Deep Field (MUDF), we detect significant [OII]
emission out to ~40 kpc, while [OIII] and Hbeta emission is detected out to ~30
kpc. Via comparisons with the nearby average stellar continuum emission, we
find that the line emission at 20-30 kpc likely arises from the disk-halo
interface. Combining our results with that of our previous study at z~1, we
find that the average [OII] surface brightness increases independently with
redshift over z~0.4-1.3 and with stellar mass over M* ~10^{6-12} Msun, which is
likely driven by the star formation rate as well as the physical conditions of
the gas. By comparing the observed line fluxes with photoionization models, we
find that the ionization parameter declines with distance, going from log q
(cm/s) ~7.7 at <=5 kpc to ~7.3 at 20-30 kpc, which reflects a weaker radiation
field in the outer regions of galaxies. The gas-phase metallicity shows no
significant variation over 30 kpc, with a metallicity gradient of ~0.003
dex/kpc, which indicates an efficient mixing of metals on these scales.
Alternatively, there could be a significant contribution from shocks and
diffuse ionized gas to the line emission in the outer regions
Design and development of the reflecting panels for the large size telescopes at the southern site of the Cherenkov Telescope Array Observatory (CTAO)
Full text linkIn the context of the Cherenkov Telescope Array gamma-ray Observatory (CTAO), two large-size telescopes, each with a diameter of 23 m, will be installed at the southern site in Paranal, Chile. They are referred to as Large Size Telescope South, LST-S (it should be noted that 4 Large Size Telescopes, with a similar optical configuration, are already being installed at the CTAO northern side of La Palma, Canary Islands, Spain). INAF oversees the coordination of the implementation effort related to the LST-S telescopes. They will use a single mirror parabolic shape to capture images with moderate angular resolution. To achieve this shape, 198 hexagonal reflecting panels will be assembled into the telescope structure. Each panel is roughly 150 cm side-to-side in size and weighs less than 50 kg. It comprises two solid glass plates bonded to a lightweight honeycomb structure of an aluminum alloy core. The panels are spherical and distributed in three coronas with different curvature radii to achieve the desired shape. They will be exposed to the open air for several years and must withstand mechanical stresses, wind impact, and possible strong earthquake solicitations. The panels are the elements of the telescope's segmented primary mirror. The development activities for such large panels performed to optimize the mirror design and the results after the production of prototypes are summarized in this paper...
Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission
Full text linkNASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β, resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense
Opto-mechanical design of a bifocal panoramic lens for space applications
Full text linkIn this paper, we provide a detailed description of a bifocal panoramic lens (BPL), which allows recording a 360°×100° field and, simultaneously, a 20° circular field at a higher resolution. The BPL optical design has been specifically optimized for space environment operations. Furthermore, we describe the results of the tolerance and ghost analyses conducted on the camera, highlighting the challenges arising when dealing with such a wide-field objective due to entrance pupil aberrations and distortions...
The first high-redshift cavity power measurements of cool-core galaxy clusters with the International LOFAR Telescope
No full textRadio-mode feedback associated with the active galactic nuclei (AGNs) at the cores of galaxy clusters injects a large amount of energy into the intracluster medium (ICM), offsetting radiative losses through X-ray emission. This mechanism prevents the ICM from rapidly cooling down and fueling extreme starburst activity as it accretes onto the central galaxies, and it is therefore a key ingredient in the evolution of galaxy clusters. However, the influence and mode of feedback at high redshifts (z ∼ 1) remains largely unknown. Low-frequency sub-arcsecond-resolution radio observations taken with the International LOFAR Telescope have demonstrated their ability to assist X-ray observations with constraining the energy output from the AGNs (or "cavity power") in galaxy clusters, thereby enabling research at higher redshifts than before. In this pilot project, we tested this hybrid method on a high-redshift (0.6 The reduced images are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/687/A31..
Jupiter's Hotspots as observed by JIRAM-Juno: limb darkening in thermal infrared
No full textThe Jupiter InfraRed Auroral Mapper (JIRAM) instrument onboard the Juno spacecraft performed repeated observations of Jupiter's North Equatorial Belt (NEB) around the time of 12th Juno pericenter passage on 2018 April 1. The data consist of thermal infrared images and show, among other atmospheric features, two bright Hotspots on the boundary between the NEB and the Equatorial Zone. Night-time images of the same areas at different emission angles were used to constrain the trend of the limb-darkening function. Comparison with simulated observations, computed for different emission angles, total opacities, single scattering albedo ω0, and asymmetry parameter g suggests that ω0 ~ 0.90 ± 0.05 and g ~ 0.37 ± 0.15 provide best match with data. Subsequently, we computed the ω0 and g resulting from different size distributions, taking into account the complex refractive indices of ammonium hydrosulfide (NH4SH) by Howett et al. [2007] and Ferraro et al. [1980]. Only the former data set is marginally consistent with JIRAM observations. Similarly, ammonia and hydrazine barely reproduce the experimental data. Tholin, although not usually considered a realistic component for Jupiter's aerosols, provides a better match for particle radii between 0.7 and 1 μm, both as a pure material as well as a thick coating over NH4SH cores. Notably, this radius range is consistent with the mean radius of aerosols as estimated by Ragent et al. [1998] on the basis of Galileo entry probe data. Comparison with literature suggests that similar results can be achieved by a large variety of contaminants bearing C-N bounds...
Weak-lensing Analysis of the Complex Cluster Merger A746 with Subaru/Hyper Suprime-Cam
No full textThe galaxy cluster A746 (z = 0.214), featuring a double radio relic system, two isolated radio relics, a possible radio halo, disturbed V-shaped X-ray emission, and intricate galaxy distributions, is a unique and complex merging system. We present a weak-lensing analysis of A746 based on wide-field imaging data from Subaru/Hyper Suprime-Cam observations. The mass distribution is characterized by a main peak, which coincides with the center of the X-ray emission. At this main peak, we detect two extensions toward the north and west tracing the cluster galaxy and X-ray distributions. Despite the ongoing merger, our estimate of the A746 global mass M 500 = 4.4 ± 1.0 × 1014 M ⊙ is consistent with the previous results from Sunyaev-Zel'dovich and X-ray observations. We conclude that reconciling the distributions of mass, galaxies, and intracluster medium with the double radio relic system and other radio features remains challenging...