scholarly journals Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet

Science ◽  
2018 ◽  
Vol 362 (6421) ◽  
pp. 1384-1387 ◽  
Author(s):  
R. Allart ◽  
V. Bourrier ◽  
C. Lovis ◽  
D. Ehrenreich ◽  
J. J. Spake ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Mass Loss Rate ◽  
Three Dimensional ◽  
Neutral Hydrogen ◽  
Blue Shift ◽  
Spectral Signature ◽  
Night Side ◽  
Spectrally Resolved ◽  
Infrared Triplet

Stellar heating causes atmospheres of close-in exoplanets to expand and escape. These extended atmospheres are difficult to observe because their main spectral signature—neutral hydrogen at ultraviolet wavelengths—is strongly absorbed by interstellar medium. We report the detection of the near-infrared triplet of neutral helium in the transiting warm Neptune-mass exoplanet HAT-P-11b by using ground-based, high-resolution observations. The helium feature is repeatable over two independent transits, with an average absorption depth of 1.08 ± 0.05%. Interpreting absorption spectra with three-dimensional simulations of the planet’s upper atmosphere suggests that it extends beyond 5 planetary radii, with a large-scale height and a helium mass loss rate of ≲3 × 105 grams per second. A net blue-shift of the absorption might be explained by high-altitude winds flowing at 3 kilometers per second from day to night-side.

scholarly journals Observational signatures of eccentric Jupiters inside gas cavities in protoplanetary discs

2021 ◽  
Author(s):  
Clément Baruteau ◽  
Gaylor Wafflard-Fernandez ◽  
Romane Le Gal ◽  
Florian Debras ◽  
Andrés Carmona ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Scattered Light ◽  
Dust Emission ◽  
Three Dimensional ◽  
Continuum Emission ◽  
Integrated Intensity ◽  
Gas Cavity ◽  
Hydrodynamical Simulations ◽  
Small Dust

Abstract Predicting how a young planet shapes the gas and dust emission of its parent disc is key to constraining the presence of unseen planets in protoplanetary disc observations. We investigate the case of a 2 Jupiter mass planet that becomes eccentric after migrating into a low-density gas cavity in its parent disc. Two-dimensional hydrodynamical simulations are performed and post-processed by three-dimensional radiative transfer calculations. In our disc model, the planet eccentricity reaches ∼0.25, which induces strong asymmetries in the gas density inside the cavity. These asymmetries are enhanced by photodissociation and form large-scale asymmetries in 12CO J=3→2 integrated intensity maps. They are shown to be detectable for an angular resolution and a noise level similar to those achieved in ALMA observations. Furthermore, the planet eccentricity renders the gas inside the cavity eccentric, which manifests as a narrowing, stretching and twisting of iso-velocity contours in velocity maps of 12CO J=3→2. The planet eccentricity does not, however, give rise to detectable signatures in 13CO and C18O J=3→2 inside the cavity because of low column densities. Outside the cavity, the gas maintains near-circular orbits, and the vertically extended optically thick CO emission displays a four-lobed pattern in integrated intensity maps for disc inclinations $\gtrsim$ 30○. The lack of large and small dust inside the cavity in our model further implies that synthetic images of the continuum emission in the sub-millimetre, and of polarized scattered light in the near-infrared, do not show significant differences when the planet is eccentric or still circular inside the cavity.

scholarly journals Shadows and asymmetries in the T Tauri disk HD 143006: evidence for a misaligned inner disk

2018 ◽  
Vol 619 ◽  
pp. A171 ◽  
Author(s):  
M. Benisty ◽  
A. Juhász ◽  
S. Facchini ◽  
P. Pinilla ◽  
J. de Boer ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Scattered Light ◽  
Three Dimensional ◽  
Angular Separation ◽  
Position Angle ◽  
Disk Model ◽  
Disk Structure ◽  
T Tauri ◽  
Western Side

Context. While planet formation is thought to occur early in the history of a protoplanetary disk, the presence of planets embedded in disks, or of other processes driving disk evolution, might be traced from their imprints on the disk structure. Aims. We study the morphology of the disk around the T Tauri star HD 143006, located in the ~5–11 Myr-old Upper Sco region, and we look for signatures of the mechanisms driving its evolution. Methods. We observed HD 143006 in polarized scattered light with VLT/SPHERE at near-infrared (J-band, 1.2 μm) wavelengths, reaching an angular resolution of ~0.037′′ (~6 au). We obtained two datasets, one with a 145 mas diameter coronagraph, and the other without, enabling us to probe the disk structure down to an angular separation of ~0.06′′ (~10 au). Results. In our observations, the disk of HD 143006 is clearly resolved up to ~0.5′′ and shows a clear large-scale asymmetry with the eastern side brighter than the western side. We detect a number of additional features, including two gaps and a ring. The ring shows an overbrightness at a position angle (PA) of ~140°, extending over a range in position angle of ~60°, and two narrow dark regions. The two narrow dark lanes and the overall large-scale asymmetry are indicative of shadowing effects, likely due to a misaligned inner disk. We demonstrate the remarkable resemblance between the scattered light image of HD 143006 and a model prediction of a warped disk due to an inclined binary companion. The warped disk model, based on the hydrodynamic simulations combined with three-dimensional radiative transfer calculations, reproduces all major morphological features. However, it does not account for the observed overbrightness at PA ~ 140°. Conclusions. Shadows have been detected in several protoplanetary disks, suggesting that misalignment in disks is not uncommon. However, the origin of the misalignment is not clear. As-yet-undetected stellar or massive planetary companions could be responsible for them, and naturally account for the presence of depleted inner cavities.

Peculiar Gas Dynamics in the Starburst Galaxy NGC 253

1995 ◽  
Vol 12 (1) ◽  
pp. 20-25 ◽  
Author(s):  
Bärbel Koribalski ◽  
John B. Whiteoak ◽  
Sally Houghton
Keyword(s):  
Gas Dynamics ◽  
Large Scale ◽  
Near Infrared ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Starburst Galaxy ◽  
Relative Proximity ◽  
First Results ◽  
Suitable Object ◽  
Absorption Measurements

AbstractHere we present our first results of a study of the neutral hydrogen gas (HI) in the southern spiral galaxy NGC 253 with the Australia Telescope Compact Array. The relative proximity of NGC 253 makes it a very suitable object for detailed studies of large-scale, as well as nuclear, gas dynamics. Several peculiar features have been found. The HI distribution is asymmetric in the outer regions, probably as a result of the strong warping of the spiral arms. A bar associated with the disc, clearly visible in the optical and near-infrared, also reveals its signature in the neutral hydrogen gas. HI absorption measurements reveal unusual motions of the gas in the nuclear region which seem to indicate a fast-rotating ring of cold gas as well as outflow of gas. Similar features have been found in other starburst galaxies, such as M 82, NGC 1808 and NGC 4945, and are interpreted in terms of bar-induced gas dynamics and star formation.

scholarly journals The distance to M31 in the era of precision cosmology

2012 ◽  
Vol 8 (S289) ◽  
pp. 235-235
Author(s):  
David Valls-Gabaud
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Hubble Space Telescope ◽  
Three Dimensional ◽  
Eclipsing Binaries ◽  
Wide Field ◽  
Acoustic Oscillations ◽  
Data Set ◽  
Red Giant ◽  
Precision Cosmology

AbstractWith the advent of precision cosmology, where distances out to redshifts z < 0.6 can be measured to 2% precision on the basis of baryon acoustic oscillations, it appears essential to establish an accurate calibration of the primary and secondary indicators of the cosmological distance ladder. Here we review recent attempts at anchoring M31 very accurately using three independent methods, and discuss in detail the systematics that affect each. Two double-lined eclipsing binaries yield a distance to M31 which is precise to 4%. New Bayesian methods have been applied to determine the tip of the red-giant branch, even in sparsely populated colour–magnitude diagrams, and provide unique insights in the context of a precise three-dimensional distribution of the satellites in the M31 system. Over 2500 Cepheids have been identified in large-scale multi-colour surveys of M31, the largest homogeneous data set thus far obtained for any galaxy. A subset of 68 with periods longer than 10 days have been observed with the Wide-Field Camera 3 on board the Hubble Space Telescope, yielding the tightest-ever near-infrared period–luminosity relation, with a mean distance error of 1%. Combined with other measurements, the distance to M31 is now measured with a precision of 3%. Forthcoming improvements, and their implications, are also discussed.

scholarly journals Infrared Background Starlight: Observations and Galaxy Models

1990 ◽  
Vol 139 ◽  
pp. 35-47
Author(s):  
G. G. Fazio ◽  
T. M. Dame ◽  
S. Kent
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Galactic Disk ◽  
Dust Emission ◽  
Three Dimensional ◽  
Infrared Region ◽  
Global Scale ◽  
Three Dimensional Model ◽  
Infrared Telescope ◽  
The Galaxy

The near-infrared region of the spectrum is a particularly advantageous window for observing the distribution of old, evolved stars in the galactic disk and bulge. These stars are important because they provide an excellent tracer of the overall stellar mass distribution. At shorter wavelengths extinction is a serious problem, and at longer wavelengths the flux is dominated by dust emission. A summary of the large-scale diffuse near-infrared observations of the Galaxy is presented, as is a summary of the results obtained from these data on the structure of the galactic disk and bulge. The importance of combining CO and near-infrared maps of similar resolution to determine a three-dimensional model of galactic extinction is demonstrated. The Spacelab-2 Infrared Telescope (IRT) data are used in conjunction with a proposed galactic model to make preliminary measurements of the global scale parameters of the Galaxy.

Three-dimensional grain angle measurement of softwood (Hinoki cypress) using near infrared spatially and spectrally resolved imaging (NIR-SSRI)

Holzforschung ◽  
2019 ◽  
Vol 73 (9) ◽  
pp. 817-826
Author(s):  
Te Ma ◽  
Tetsuya Inagaki ◽  
Satoru Tsuchikawa
Keyword(s):  
Near Infrared ◽  
Linear Regression Analysis ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Gaussian Process Regression ◽  
Nonlinear Least Squares ◽  
Angle Measurement ◽  
Hinoki Cypress ◽  
Spectrally Resolved ◽  
Surface Angle

Abstract As the strength of wood is greatly affected by its three-dimensional (3D) grain angles (the dive angle and the surface angle), the wood industry today requires automatic, rapid, and robust measurement techniques for measuring them simultaneously. In the present study, a near infrared spatially and spectrally resolved imaging (NIR-SSRI) system was designed in a line scan model, mainly including an NIR hyperspectral imaging camera and a halogen spotlight source (Ø 1 mm). Spatially resolved diffuse reflectance images at three target wavelengths (1002 nm, 1217 nm, and 1413 nm) were obtained from Hinoki cypress [Chamaecyparis obtusa (Siebold & Zucc.) Endl.] samples at various (0°, 3°, 6°, … 45°) dive angles and surface angles (0°, 3°, 6°, … 45°). The scattering patterns caused by the “tracheid effect” were almost elliptical. Subsequently, nonlinear least squares fitting was used to determine their eccentricities (e) and rotation angles (θ). The e values at each selected wavelength were highly correlated with the dive angle reference values; and the global identification model developed using Gaussian process regression (GPR) under five-fold cross-validation (CV) reached a determination coefficient (r2) of 0.98 with a root mean square error (RMSE) of 2.2°. On the other hand, local surface angle identification models developed using linear regression analysis achieved determination coefficients higher than 0.90 on r2 and an RMSE of CV lower than 3.8° when the dive angle was lower than 30°.

scholarly journals Interferometric and spectroscopic monitoring of emission lines: detection of CIRs in hot star winds

2003 ◽  
Vol 212 ◽  
pp. 166-167
Author(s):  
Luc Dessart ◽  
Olivier Chesneau
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Mass Loss Rate ◽  
Rotation Period ◽  
Infrared Emission ◽  
Emission Lines ◽  
Stellar Rotation ◽  
Time Space ◽  
Geometrical Constraints ◽  
The Impact

We present a theoretical study of hot star wind emissivity in the presence of hypothetical large scale wind structures. Contrary to previous investigations that have focused on the resulting P-Cygni profile variability, we investigate the impact on observable optical and near-infrared emission lines. Our working hypothesis assumes, that such extended wind over-densities are formed via a rotationaly modulated stellar mass loss rate, that gives rise to the so-called co-rotating interaction regions (CIR). Within this context, we find that the variability of emission lines traces an un-equivocal S-shape in the frequency-time space,i.e.,a spiraling pattern with positiveandnegative accelerations towards the line-of-sight over one stellar rotation period. Further, we demonstrate how lines forming at different heights can then be used to provide dynamical and geometrical constraints on the wind structures. Complementary to this spectroscopic approach, we also present theoretical expectations for forthcoming VLT-amber observations of a perturbed hot star outflow presenting such CIRs. The spectrally dispersed visibility and fringe phase output by the Differential Interferometry (DI) method show clearly-defined signatures of the presence of these CIRs. Extrapolating the adequacy of DI beyond the detection of CIRs, we speculate that this method provides very fruitful information on putative large scale structures in hot star environments.

scholarly journals Optoacoustic Calcium Imaging of Deep Brain Activity in an Intracardially Perfused Mouse Brain Model

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 67 ◽  
Author(s):  
Oleksiy Degtyaruk ◽  
Benedict Mc Larney ◽  
Xosé Deán-Ben ◽  
Shy Shoham ◽  
Daniel Razansky
Keyword(s):  
Mouse Brain ◽  
Large Scale ◽  
Near Infrared ◽  
Brain Activity ◽  
Three Dimensional ◽  
Mammalian Brain ◽  
Visible Range ◽  
Light Spectrum ◽  
Optoacoustic Imaging

One main limitation of established neuroimaging methods is the inability to directly visualize large-scale neural dynamics in whole mammalian brains at subsecond speeds. Optoacoustic imaging has advanced in recent years to provide unique advantages for real-time deep-tissue observations, which have been exploited for three-dimensional imaging of both cerebral hemodynamic parameters and direct calcium activity in rodents. Due to a lack of suitable calcium indicators excitable in the near-infrared window, optoacoustic imaging of neuronal activity at deep-seated areas of the mammalian brain has been impeded by the strong absorption of blood in the visible range of the light spectrum. To overcome this, we have developed and validated an intracardially perfused mouse brain preparation labelled with genetically encoded calcium indicator GCaMP6f that closely resembles in vivo conditions. By overcoming the limitations of hemoglobin-based light absorption, this new technique was used to observe stimulus-evoked calcium dynamics in the brain at penetration depths and spatio-temporal resolution scales not attainable with existing neuroimaging techniques.

Urban energetics applications and Geomatic technologies in a Smart City perspective

2015 ◽  
Vol 6 (1) ◽  
pp. 19-29 ◽  
Author(s):  
G. Bitelli ◽  
P. Conte ◽  
T. Csoknyai ◽  
E. Mandanici
Keyword(s):  
Smart City ◽  
Laser Scanning ◽  
Near Infrared ◽  
Three Dimensional ◽  
Energy Sector ◽  
Primary Objective ◽  
Airborne Lidar ◽  
City Management ◽  
Urban Context ◽  
Research Areas

The management of an urban context in a Smart City perspective requires the development of innovative projects, with new applications in multidisciplinary research areas. They can be related to many aspects of city life and urban management: fuel consumption monitoring, energy efficiency issues, environment, social organization, traffic, urban transformations, etc. Geomatics, the modern discipline of gathering, storing, processing, and delivering digital spatially referenced information, can play a fundamental role in many of these areas, providing new efficient and productive methods for a precise mapping of different phenomena by traditional cartographic representation or by new methods of data visualization and manipulation (e.g. three-dimensional modelling, data fusion, etc.). The technologies involved are based on airborne or satellite remote sensing (in visible, near infrared, thermal bands), laser scanning, digital photogrammetry, satellite positioning and, first of all, appropriate sensor integration (online or offline). The aim of this work is to present and analyse some new opportunities offered by Geomatics technologies for a Smart City management, with a specific interest towards the energy sector related to buildings. Reducing consumption and CO2 emissions is a primary objective to be pursued for a sustainable development and, in this direction, an accurate knowledge of energy consumptions and waste for heating of single houses, blocks or districts is needed. A synoptic information regarding a city or a portion of a city can be acquired through sensors on board of airplanes or satellite platforms, operating in the thermal band. A problem to be investigated at the scale A problem to be investigated at the scale of the whole urban context is the Urban Heat Island (UHI), a phenomenon known and studied in the last decades. UHI is related not only to sensible heat released by anthropic activities, but also to land use variations and evapotranspiration reduction. The availability of thermal satellite sensors is fundamental to carry out multi-temporal studies in order to evaluate the dynamic behaviour of the UHI for a city. Working with a greater detail, districts or single buildings can be analysed by specifically designed airborne surveys. The activity has been recently carried out in the EnergyCity project, developed in the framework of the Central Europe programme established by UE. As demonstrated by the project, such data can be successfully integrated in a GIS storing all relevant data about buildings and energy supply, in order to create a powerful geospatial database for a Decision Support System assisting to reduce energy losses and CO2 emissions. Today, aerial thermal mapping could be furthermore integrated by terrestrial 3D surveys realized with Mobile Mapping Systems through multisensor platforms comprising thermal camera/s, laser scanning, GPS, inertial systems, etc. In this way the product can be a true 3D thermal model with good geometric properties, enlarging the possibilities in respect to conventional qualitative 2D images with simple colour palettes. Finally, some applications in the energy sector could benefit from the availability of a true 3D City Model, where the buildings are carefully described through three-dimensional elements. The processing of airborne LiDAR datasets for automated and semi-automated extraction of 3D buildings can provide such new generation of 3D city models.

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