Dedicated to an articulation of the earth from broadly ecological perspectives, eco art is a vibrant subset of contemporary art that addresses the widespread public concern with rapid climate change ...and related environmental issues. In Landscape into Eco Art , Mark Cheetham systematically examines connections and divergences between contemporary eco art, land art of the 1960s and 1970s, and the historical genre of landscape painting.
Through eight thematic case studies that illuminate what eco art means in practice, reception, and history, Cheetham places the form in a longer and broader art-historical context. He considers a wide range of media—from painting, sculpture, and photography to artists’ films, video, sound work, animation, and installation—and analyzes the work of internationally prominent artists such as Olafur Eliasson, Nancy Holt, Mark Dion, and Robert Smithson. In doing so, Cheetham reveals eco art to be a dynamic extension of a long tradition of landscape depiction in the West that boldly enters into today’s debates on climate science, government policy, and our collective and individual responsibility to the planet.
An ambitious intervention into eco-criticism and the environmental humanities, this volume provides original ways to understand the issues and practices of eco art in the Anthropocene. Art historians, humanities scholars, and lay readers interested in contemporary art and the environment will find Cheetham’s work valuable and invigorating.
Metal-organic frameworks (MOFs), a new class of solid-state materials, have recently been investigated as proton conductors, but little is known about their mechanisms. Since most of the ...conductivities reported so far were measured using powder samples, there is uncertainty as to whether they exhibit intrinsic proton transport through frameworks and/or micropores, or extrinsic transport through interparticle phases. Herein, we re-visit ferrous oxalate dihydrate Fe(ox)(H 2 O) 2 (ox = oxalate anion), which is a dense MOF and recognized as a model system for MOF-based proton conductors. By single-crystal measurements using microelectrodes, we show that protons do not transport through the crystals (<10 −9 S cm −1 ), but that the conductivity observed in powder samples originates from interparticle phases. This result raises a question as to how general is this phenomenon? We have comprehensively surveyed the literature on solid-state proton conductors and found that large numbers of MOFs, including Fe(ox)(H 2 O) 2 , have a similar activation energy to those of gels and interparticle conductors in classical solid-state materials. This indicates a considerable contribution from interparticle phases towards proton conductivity in MOFs, and single crystal analysis or special methods for powder analysis are clearly necessary to confirm intrinsic conductivity.
Context. The temperate Earth-mass planet Proxima b is the closest exoplanet to Earth and represents what may be our best ever opportunity to search for life outside the Solar System. Aims. We aim at ...directly detecting Proxima b and characterizing its atmosphere by spatially resolving the planet and obtaining high-resolution reflected-light spectra. Methods. We propose to develop a coupling interface between the SPHERE high-contrast imager and the new ESPRESSO spectrograph, both installed at ESO VLT. The angular separation of 37 mas between Proxima b and its host star requires the use of visible wavelengths to spatially resolve the planet on a 8.2-m telescope. At an estimated planet-to-star contrast of ~10-7 in reflected light, Proxima b is extremely challenging to detect with SPHERE alone. However, the combination of a ~103–104 contrast enhancement from SPHERE to the high spectral resolution of ESPRESSO can reveal the planetary spectral features and disentangle them from the stellar ones. Results. We find that significant but realistic upgrades to SPHERE and ESPRESSO would enable a 5σ detection of the planet and yield a measurement of its true mass and albedo in 20–40 nights of telescope time, assuming an Earth-like atmospheric composition. Moreover, it will be possible to probe the O2 bands at 627, 686 and 760 nm, the water vapour band at 717 nm, and the methane band at 715 nm. In particular, a 3.6σ detection of O2 could be made in about 60 nights of telescope time. Those would need to be spread over three years considering optimal observability conditions for the planet. Conclusions. The very existence of Proxima b and the SPHERE-ESPRESSO synergy represent a unique opportunity to detect biosignatures on an exoplanet in the near future. It is also a crucial pathfinder experiment for the development of extremely large telescopes and their instruments, in particular the E-ELT and its high-resolution visible and near-IR spectrograph.
Using high-contrast imaging with the SPHERE instrument at the Very Large Telescope (VLT), we report the first images of a cold brown dwarf companion to the exoplanet host star HD 4113A. The brown ...dwarf HD 4113C is part of a complex dynamical system consisting of a giant planet, a stellar host, and a known wide M-dwarf companion. Its separation of 535 ± 3 mas and H-band contrast of 13.35 ± 0.10 mag correspond to a projected separation of 22 AU and an isochronal mass estimate of 36 ± 5 MJ based on COND models. The companion shows strong methane absorption, and through fitting an atmosphere model, we estimate a surface gravity of logg = 5 and an effective temperature of ~500–600 K. A comparison of its spectrum with observed T dwarfs indicates a late-T spectral type, with a T9 object providing the best match. By combining the observed astrometry from the imaging data with 27 years of radial velocities, we use orbital fitting to constrain its orbital and physical parameters, as well as update those of the planet HD 4113A b, discovered by previous radial velocity measurements. The data suggest a dynamical mass of 66−4+5 $66^{+5}_{-4}$ 66−4+5 MJ and moderate eccentricity of 0.44−0.07+0.08 $0.44^{+0.08}_{-0.07}$ 0.44−0.07+0.08 for the brown dwarf. This mass estimate appears to contradict the isochronal estimate and that of objects with similar temperatures, which may be caused by the newly detected object being an unresolved binary brown dwarf system or the presence of an additional object in the system. Through dynamical simulations, we show that the planet may undergo strong Lidov-Kozai cycles, raising the possibility that it formed on a quasi-circular orbit and gained its currently observed high eccentricity (e ~ 0.9) through interactions with the brown dwarf. Follow-up observations combining radial velocities, direct imaging, and Gaia astrometry will be crucial to precisely constrain the dynamical mass of the brown dwarf and allow for an in-depth comparison with evolutionary and atmosphere models.
Abstract
We present observations of the Herbig Ae star HD 169142 with the VLT/SPHERE instruments InfraRed Dual-band Imager and Spectrograph (IRDIS) (K1K2 and H2H3 bands) and the Integral Field ...Spectrograph (IFS) (Y, J and H bands). We detect several bright blobs at ∼180 mas separation from the star, and a faint arc-like structure in the IFS data. Our reference differential imaging (RDI) data analysis also finds a bright ring at the same separation. We show, using a simulation based on polarized light data, that these blobs are actually part of the ring at 180 mas. These results demonstrate that the earlier detections of blobs in the H and KS bands at these separations in Biller et al. as potential planet/substellar companions are actually tracing a bright ring with a Keplerian motion. Moreover, we detect in the images an additional bright structure at ∼93 mas separation and position angle of 355°, at a location very close to previous detections. It appears point-like in the YJ and K bands but is more extended in the H band. We also marginally detect an inner ring in the RDI data at ∼100 mas. Follow-up observations are necessary to confirm the detection and the nature of this source and structure.
HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L′ and M′ observations of the planet from the NACO instrument at the VLT from ...the NACO-ISPY survey, as well as a new Y –H spectrum and K-band photometry from SPHERE-SHINE. Using these data, we confirm the nature of the companion as a warm, dusty planet with a mid-L spectral type. From comparison of its SED with the BT-Settl atmospheric models, we derive a best-fit effective temperature of Teff = 1618 ± 7 K, surface gravity log g = 3.78−0.03+0.04 $\log g\,{=}\,3.78^{+0.04}_{-0.03}$logg = 3.78−0.03+0.04 and radius R = 1.17 ± 0.04RJ (statistical uncertainties only). Using the DUSTY and COND isochrones we estimate a mass of 8 ± 1MJ. Combining the astrometric measurements from our new datasets and from the literature, we show the first indications of orbital motion of the companion (2.6σ significance)and derive preliminary orbital constraints. We find a highly inclined orbit ( i = 1.07−10+13 $i\,{=}\,107^{+13}_{-10}$i = 107−10+13 deg) with an orbital period of 800−400+1200 $800^{+1200}_{-400}$800−400+1200 yr. We also report SPHERE sparse aperture masking observations that investigate the possibility that HIP 65426 b was scattered onto its current orbit by an additional companion at a smaller orbital separation. From this data we rule out the presence of brown dwarf companions with masses greater than 16 MJ at separations larger than 3 AU, significantly narrowing the parameter space for such a companion.
Dedicated to an articulation of the earth from broadly
ecological perspectives, eco art is a vibrant subset of
contemporary art that addresses the widespread public concern with
rapid climate change ...and related environmental issues. In
Landscape into Eco Art , Mark Cheetham systematically
examines connections and divergences between contemporary eco art,
land art of the 1960s and 1970s, and the historical genre of
landscape painting.
Through eight thematic case studies that illuminate what eco art
means in practice, reception, and history, Cheetham places the form
in a longer and broader art-historical context. He considers a wide
range of media-from painting, sculpture, and photography to
artists' films, video, sound work, animation, and installation-and
analyzes the work of internationally prominent artists such as
Olafur Eliasson, Nancy Holt, Mark Dion, and Robert Smithson. In
doing so, Cheetham reveals eco art to be a dynamic extension of a
long tradition of landscape depiction in the West that boldly
enters into today's debates on climate science, government policy,
and our collective and individual responsibility to the planet.
An ambitious intervention into eco-criticism and the
environmental humanities, this volume provides original ways to
understand the issues and practices of eco art in the Anthropocene.
Art historians, humanities scholars, and lay readers interested in
contemporary art and the environment will find Cheetham's work
valuable and invigorating.
Context.
Detecting and characterizing substellar companions for which the luminosity, mass, and age can be determined independently is of utter importance to test and calibrate the evolutionary ...models due to uncertainties in their formation mechanisms. HD 19467 is a bright and nearby star hosting a cool brown dwarf companion detected with radial velocities and imaging, making it a valuable object for such studies.
Aims.
We aim to further characterize the orbital, spectral, and physical properties of the HD 19467 system.
Methods.
We present new high-contrast imaging data with the SPHERE and NaCo instruments. We also analyze archival data from the instruments HARPS, NaCo, HIRES, UVES, and ASAS. Furthermore, we use proper motion data of the star from H
IPPARCOS
and
Gaia
.
Results.
We refined the properties of the host star and derived an age of 8.0
+2.0
−1.0
Gyr based on isochrones, gyrochronology, and chemical and kinematic arguments. This age estimate is slightly younger than previous age estimates of ~9–11 Gyr based on isochrones. No orbital curvature is seen in the current imaging, radial velocity, and astrometric data. From a joint fit of the data, we refined the orbital parameters for HD 19467B, including: a period of 398
+95
−93
yr, an inclination of 129.8
+8.1
−5.1
deg, an eccentricity of 0.56 ± 0.09, a longitude of the ascending node of 134.8 ± 4.5 deg, and an argument of the periastron of 64.2
+5.5
−6.3
deg. We assess a dynamical mass of 74
+12
−9
M
J
. The fit with atmospheric models of the spectrophotometric data of the companion indicates an atmosphere without clouds or with very thin clouds, an effective temperature of 1042
+77
−71
K, and a high surface gravity of 5.34
+0.8
−0.9
dex. The comparison to model predictions of the bolometric luminosity and dynamical mass of HD 19467B, assuming our system age estimate, indicates a better agreement with the Burrows et al. (1997, ApJ, 491, 856) models; whereas, the other evolutionary models used tend to underestimate its cooling rate.
Resonant ultrasound spectroscopy has been used to analyze magnetic and ferroelectric phase transitions in two multiferroic metal-organic frameworks (MOFs) with perovskite-like structures (CH sub(3)) ...sub(2) NH sub(2)M(HCOO) sub(3) (DMAMF, M = Co, Mn). Elastic and anelastic anomalies are evident at both the magnetic ordering temperature and above the higher temperature ferroelectric transition. Broadening of peaks above the ferroelectric transition implies the diminishing presence of a dynamic process and is caused by an ordering of the central DMA ((CH sub(3)) sub(2) NH sub(2) super(+)) cation which ultimately causes a change in the hydrogen bond conformation and provides the driving mechanism for ferroelectricity. This is unlike traditional mechanisms for ferroelectricity in perovskites which typically involve ionic displacements. A comparison of these mechanisms is made by drawing on examples from the literature. Small elastic stiffening at low temperatures suggests weak magnetoelastic coupling in these materials. This behavior is consistent with other magnetic systems studied, although there is no change in Q super(-1) associated with magnetic order-disorder, and is the first evidence of magnetoelastic coupling in MOFs. This could help lead to the tailoring of MOFs with a larger coupling leading to magnetoelectric coupling via a common strain mechanism.
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