scholarly journals The Emission Spectrum of the Hot Jupiter WASP-79b from HST/WFC3

2021 ◽  
Vol 163 (1) ◽  
pp. 7
Author(s):  
Trevor O. Foote ◽  
Nikole K. Lewis ◽  
Brian M. Kilpatrick ◽  
Jayesh M. Goyal ◽  
Giovanni Bruno ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Energy Transport ◽  
Thermal Emission ◽  
Hubble Space Telescope ◽  
Vertical Mixing ◽  
Wide Field ◽  
Forward Models ◽  
Wide Range ◽  
Solar Metallicity ◽  
Recirculation Factor

Abstract Here we present a thermal emission spectrum of WASP-79b, obtained via Hubble Space Telescope Wide Field Camera 3 G141 observations as part of the PanCET program. As we did not observe the ingress or egress of WASP-79b’s secondary eclipse, we consider two scenarios: a fixed mid-eclipse time based on the expected occurrence time, and a mid-eclipse time as a free parameter. In both scenarios, we can measure thermal emission from WASP-79b from 1.1 to 1.7 μm at 2.4σ confidence consistent with a 1900 K brightness temperature for the planet. We combine our observations with Spitzer dayside photometry (3.6 and 4.5 μm) and compare these observations to a grid of atmospheric forward models that span a range of metallicities, carbon-to-oxygen ratios, and recirculation factors. Given the strength of the planetary emission and the precision of our measurements, we found a wide range of forward models to be consistent with our data. The best-match equilibrium model suggests that WASP-79b’s dayside has a solar metallicity and carbon-to-oxygen ratio, alongside a recirculation factor of 0.75. Models including significant H− opacity provide the best match to WASP-79b’s emission spectrum near 1.58 μm. However, models featuring high-temperature cloud species—formed via vigorous vertical mixing and low sedimentation efficiencies—with little day-to-night energy transport also match WASP-79b’s emission spectrum. Given the broad range of equilibrium chemistry, disequilibrium chemistry, and cloudy atmospheric models consistent with our observations of WASP-79b’s dayside emission, further observations will be necessary to constrain WASP-79b’s dayside atmospheric properties.

Characterising Two Ultra-Hot Jupiters with the Hubble Space Telescope

2020 ◽  
Author(s):  
Billy Edwards ◽  
Quentin Changeat ◽  
William Pluriel ◽  
Niall Whiteford ◽  
Kai Hou Yip ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Hubble Space Telescope ◽  
Cloud Model ◽  
Thermal Structure ◽  
Emission Spectra ◽  
Pressure Profile ◽  
Wide Field ◽  
Space Telescope ◽  
Thermal Inversion ◽  
Hot Jupiters

<p>The Hubble Space Telescope’s Wide Field Camera 3 (WFC3) has been widely used for transmission and emission spectroscopy of exoplanet atmospheres, identifying the main molecular constituents, detecting the presence of clouds and probing their thermal structure. Hubble observations of the emission spectra of a number of ultra-hot Jupiters have led to somewhat surprising results. Initially, these very hot planets were predicted to have inverted temperature pressure profiles due to strong optical absorption by TiO/VO in the upper atmospheres. However, observations of their emission spectra have been inconclusive on their thermal structure and composition. While some datasets show rich spectral features, others can be fit with simple blackbody models.</p> <p>We will present the analysis of Hubble WFC3 transmission and emission spectra for two ultra-hot Jupiters: WASP-76 b and KELT-7 b. In each case, the data was reduced and fitted using the open-source codes Iraclis and Taurex3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of TiO and VO or non-grey clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyse this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, removing the need for a non-grey cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of titanium oxide (TiO) and an atmospheric thermal inversion. Meanwhile, our study of KELT-7 b uncovers a rich transmission spectrum which suggests the presence of water and H-. In contrast, the extracted emission spectrum does not contain strong absorption features and, although it is not consistent with a simple blackbody, it can be explained by a varying temperature-pressure profile, collision induced absorption (CIA) and H-. </p> <p>These finding bring new insights into the nature of this intriguing class of planets but more data is required to fully understand them and thus we will also present the anticipated results of further characterisation.</p>

Extreme exoplanets as a tool to understand trends in exoplanets atmospheres.

2021 ◽  
Author(s):  
Bob Jacobs ◽  
Jean-Michel Désert ◽  
Saugata Barat ◽  
Michael Line ◽  
Lorenzo Pino
Keyword(s):  
Data Analysis ◽  
Hubble Space Telescope ◽  
Extreme Conditions ◽  
Wide Field ◽  
Atmospheric Physics ◽  
Atmospheric Processes ◽  
Analysis Techniques ◽  
Hot Jupiters ◽  
Wide Range ◽  
Composition Structure

<div>The interpretation of general trends in exoplanet atmospheres is challenging because they exhibit a wide range of diverse properties in terms of composition, structure, and overall atmospheric physics. In this context exoplanet’s in extreme regimes can help to understand global planetary properties.</div> <div><strong> </strong></div> <div>In this project, we focus on a few exoplanets that are outliers in their atmospheric properties and discuss what we can learn about the overall population of hot-jupiters from these peculiar objects.  We present studies of exo-atmospheric processes in extreme regimes of temperature, of entropy, of radiative and advective timescales, and of formation stages. This project combines these various physical properties in a unique and innovative manner to understand the most crucial properties of hot-Jupiters.</div> <div><strong> </strong></div> <p>Practically, we leverage the unique capabilities of Hubble Space Telescope Wide Field Camera 3 together with novel data analysis techniques to understand the nature of a set of exoplanets that reside under these extreme conditions. Ultimately, this project enable us to improve our understanding of exo-atmospheric processes and planet formation that ultimately shape the atmospheres of hot Jupiters that are observed today. </p>

scholarly journals Testing the evolution of correlations between supermassive black holes and their host galaxies using eight strongly lensed quasars

2020 ◽  
Vol 501 (1) ◽  
pp. 269-280
Author(s):  
Xuheng Ding ◽  
Tommaso Treu ◽  
Simon Birrer ◽  
Adriano Agnello ◽  
Dominique Sluse ◽  
...  
Keyword(s):  
Black Holes ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Wide Field ◽  
Host Galaxies ◽  
Field Surveys ◽  
Instrumental Resolution ◽  
The Moment

ABSTRACT One of the main challenges in using high-redshift active galactic nuclei (AGNs) to study the correlations between the mass of a supermassive black hole ($\mathcal {M}_{\rm BH}$) and the properties of its active host galaxy is instrumental resolution. Strong lensing magnification effectively increases instrumental resolution and thus helps to address this challenge. In this work, we study eight strongly lensed AGNs with deep Hubble Space Telescope imaging, using the lens modelling code lenstronomy to reconstruct the image of the source. Using the reconstructed brightness of the host galaxy, we infer the host galaxy stellar mass based on stellar population models. $\mathcal {M}_{\rm BH}$ are estimated from broad emission lines using standard methods. Our results are in good agreement with recent work based on non-lensed AGNs, demonstrating the potential of using strongly lensed AGNs to extend the study of the correlations to higher redshifts. At the moment, the sample size of lensed AGNs is small and thus they provide mostly a consistency check on systematic errors related to resolution for non-lensed AGNs. However, the number of known lensed AGNs is expected to increase dramatically in the next few years, through dedicated searches in ground- and space-based wide-field surveys, and they may become a key diagnostic of black holes and galaxy co-evolution.

scholarly journals UV and X-ray observations of the neutron star LMXB EXO 0748–676 in its quiescent state

2020 ◽  
Vol 501 (1) ◽  
pp. 1453-1462
Author(s):  
A S Parikh ◽  
N Degenaar ◽  
J V Hernández Santisteban ◽  
R Wijnands ◽  
I Psaradaki ◽  
...  
Keyword(s):  
Neutron Star ◽  
Thermal Emission ◽  
Hubble Space Telescope ◽  
Dense Matter ◽  
Continuum Emission ◽  
Quiescent State ◽  
X Ray ◽  
Low Level ◽  
Low Mass ◽  
Different Origins

ABSTRACT The accretion behaviour in low-mass X-ray binaries (LMXBs) at low luminosities, especially at <1034 erg s−1, is not well known. This is an important regime to study to obtain a complete understanding of the accretion process in LMXBs, and to determine if systems that host neutron stars with accretion-heated crusts can be used probe the physics of dense matter (which requires their quiescent thermal emission to be uncontaminated by residual accretion). Here, we examine ultraviolet (UV) and X-ray data obtained when EXO 0748–676, a crust-cooling source, was in quiescence. Our Hubble Space Telescope spectroscopy observations do not detect the far-UV continuum emission, but do reveal one strong emission line, C iv. The line is relatively broad (≳3500 km s−1), which could indicate that it results from an outflow such as a pulsar wind. By studying several epochs of X-ray and near-UV data obtained with XMM–Newton, we find no clear indication that the emission in the two wavebands is connected. Moreover, the luminosity ratio of LX/LUV ≳ 100 is much higher than that observed from neutron star LMXBs that exhibit low-level accretion in quiescence. Taken together, this suggests that the UV and X-ray emission of EXO 0748–676 may have different origins, and that thermal emission from crust-cooling of the neutron star, rather than ongoing low-level accretion, may be dominating the observed quiescent X-ray flux evolution of this LMXB.

Examining the emission and transmission spectra of WASP-79b with retrieval 

2021 ◽  
Author(s):  
Michelle Bieger ◽  
Quentin Changeat
Keyword(s):  
Hubble Space Telescope ◽  
Emission Spectra ◽  
Temperature Structure ◽  
Wide Field ◽  
Transmission Spectra ◽  
Analysis Pipeline ◽  
Confidence Levels ◽  
Iron Hydride ◽  
Best Fit ◽  
Data Analysis Pipeline

<p>Retrieval tools provide a way of determining an exoplanet atmosphere's temperature structure and composition with an observed planetary spectrum, working backwards to determine the chemistry and temperature by iteratively comparing synthetic spectra that have been constructed via a forward model to the observed spectra and determining a best-fit result (Barstow and Heng, 2020). This talk will be presenting the emission and reanalysed transmission spectrum and retrieval analysis of WASP-79b, an inflated hot Jupiter first detected by Smalley et al. (2012). Previous transmission spectra of WASP-79b has been analysed in Sozten et al. (2020), Skaf et al. (2020), and Rathcke et al. (2021); all studies agreeing on detections of H2O with various confidence levels, with the latter finding moderate evidence of an H- bound-free opacity compared to iron hydride abundance found by the other studies. Using the publicly available \verb+Iraclis+ data analysis pipeline and the Bayesian atmospheric retrieval framework TauREx 3, we will be adding to the global picture of this planet by examining the Hubble Space Telescope emission spectra as captured by the Wide Field Camera 3 G141 grism (PI: David Sing, proposal ID: 14767). </p>

Orthopteran DCMD neuron: a reevaluation of responses to moving objects. I. Selective responses to approaching objects

1992 ◽  
Vol 68 (5) ◽  
pp. 1654-1666 ◽  
Author(s):  
F. C. Rind ◽  
P. J. Simmons
Keyword(s):  
Moving Objects ◽  
Temporal Frequency ◽  
Angular Acceleration ◽  
Spike Rate ◽  
Single Peak ◽  
Wide Field ◽  
Movement Detector ◽  
Star Wars ◽  
Wide Range ◽  
Real Objects

1. The "descending contralateral movement detector" (DCMD) neuron in the locust has been challenged with a variety of moving stimuli, including scenes from a film (Star Wars), moving disks, and images generated by computer. The neuron responds well to any rapid movement. For a dark object moving along a straight path at a uniform velocity, the DCMD gives the strongest response when the object travels directly toward the eye, and the weakest when the object travels away from the eye. Instead of expressing selectivity for movements of small rather than large objects, the DCMD responds preferentially to approaching objects. 2. The neuron shows a clear selectivity for approach over recession for a variety of sizes and velocities of movement both of real objects and in simulated movements. When a disk that subtends > or = 5 degrees at the eye approaches the eye, there are two peaks in spike rate: one immediately after the start of movement; and a second that builds up during the approach. When a disk recedes from the eye, there is a single peak in response as the movement starts. There is a good correlation between spike rate and angular acceleration of the edges of the image over the eye. 3. When an object approaches from a distance sufficient for it to subtend less than one interommatidial angle at the start of its approach, there is a single peak in response. The DCMD tracks the approach, and, if the object moves at 1 m/s or faster, the spike rate increases throughout the duration of object movement. The size of the response depends on the speed of approach. 4. It is unlikely that the DCMD encodes the time to collision accurately, because the response depends on the size as well as the velocity of an approaching object. 5. Wide-field movements suppress the response to an approaching object. The suppression varies with the temporal frequency of the background pattern. 6. Over a wide range of contrasts of object against background, the DCMD gives a stronger response to approaching than to receding objects. For low contrasts, the selectivity is greater for objects that are darker than the background than for objects that are lighter.

scholarly journals KULTUREL DYNAMIK I OPLEVELSESBYRUMMET – EN ANALYSE AF BRANDTS KLÆDEFABRIK

2010 ◽  
Vol 38 (109) ◽  
pp. 55-69
Author(s):  
Hjørdis Havsteen Brandrup
Keyword(s):  
Public Space ◽  
Urban Space ◽  
Homeless People ◽  
Public Domain ◽  
Wide Field ◽  
Textile Mill ◽  
Urban Experience ◽  
Wide Range ◽  
The City ◽  
Cultural Dynamic

CULTURAL DYNAMIC IN THE URBAN EXPERIENCE SCAPE – AN ANALYSIS OF BRANDTS KLÆDEFABRIKBrandts Klædefabrik (Brandt’s Textile Mill) is a cultural cluster in the city of Odense, Denmark. The cultural experiences available at Brandts Klædefabrik cover a wide field and are relevant for people of all levels of education and all ages, embracing as they do not only fine culture but also triviality and excitement. Brandts Klædefabrik is therefore a culturally inclusive place, although its symbolic power is dominated by a cultural and economic elitetrying to maintain an exclusively controlled social and physical order in the urban space. However, Brandts Klædefabrik is part of a city which contains a wide range of cultural groups: a Danish cultural elite, immigrants, homeless people and drug addicts. In this cultural multiplicity Brandts Klædefabrik is a cultural cluster and an urban entertainment district which does not include marginalised groups. Paradoxically, the attempt to maintainan exclusive order to satisfy an audience with buying power runs against the creative profile of the area, in which cultural and social multiplicity are important values. The area around Brandts Klædefabrik is a public space; but if it is going to be a public domain and the scene of cultural exchanges between different groups in the city, it needs to become more culturally inclusive. Brandts Klædefabrik may turn into a public domain if a cultural dynamic and multiplicity are given the chance to unfold there.

scholarly journals Massive Star Cluster Formation and Destruction in Luminous Infrared Galaxies in GOALS. II. An ACS/WFC3 Survey of Nearby LIRGs

2021 ◽  
Vol 923 (2) ◽  
pp. 278
Author(s):  
S. T. Linden ◽  
A. S. Evans ◽  
K. Larson ◽  
G. C. Privon ◽  
L. Armus ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Early Stage ◽  
Cluster Formation ◽  
Age Distribution ◽  
Star Clusters ◽  
Star Cluster ◽  
Wide Field ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies ◽  
Cluster Age

Abstract We present the results of a Hubble Space Telescope WFC3 near-UV and Advanced Camera for Surveys Wide Field Channel optical study into the star cluster populations of a sample of 10 luminous infrared galaxies (LIRGs) in the Great Observatories All-Sky LIRG Survey. Through integrated broadband photometry we have derived ages, masses, and extinctions for a total of 1027 star clusters in galaxies with d L < 110 Mpc in order to avoid issues related to cluster bending. The measured cluster age distribution slope of dN / d τ ∝ τ − 0.5 + / − 0.12 is steeper than what has been observed in lower-luminosity star-forming galaxies. Further, differences in the slope of the observed cluster age distribution between inner- ( dN / d τ ∝ τ − 1.07 + / − 0.12 ) and outer-disk ( dN / d τ ∝ τ − 0.37 + / − 0.09 ) star clusters provide evidence of mass-dependent cluster destruction in the central regions of LIRGs driven primarily by the combined effect of strong tidal shocks and encounters with massive giant molecular clouds. Excluding the nuclear ring surrounding the Seyfert 1 nucleus in NGC 7469, the derived cluster mass function (CMF; dN / dM ∝ M α ) offers marginal evidence for a truncation in the power law at M t ∼ 2×106 M ⊙ for our three most cluster-rich sources, which are all classified as early stage mergers. Finally, we find evidence of a flattening of the CMF slope of dN / dM ∝ M − 1.42 ± 0.1 for clusters in late-stage mergers relative to early stage (α = −1.65 ± 0.02), which we attribute to an increase in the formation of massive clusters over the course of the interaction.

Wide Field Camera 3 instrument optical design for the Hubble Space Telescope

2004 ◽  
Author(s):  
Jennifer A. Turner-Valle ◽  
Joseph Sullivan ◽  
John E. Mentzell ◽  
Robert A. Woodruff
Keyword(s):  
Hubble Space Telescope ◽  
Optical Design ◽  
Wide Field ◽  
Space Telescope

scholarly journals Momentum and Energy Transport by Gravity Waves in Stochastically Driven Stratified Flows. Part I: Radiation of Gravity Waves from a Shear Layer

2007 ◽  
Vol 64 (5) ◽  
pp. 1509-1529 ◽  
Author(s):  
Nikolaos A. Bakas ◽  
Petros J. Ioannou
Keyword(s):  
Shear Flow ◽  
Shear Layer ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Energy ◽  
Energy Transport ◽  
Wave Spectrum ◽  
Internal Gravity Waves ◽  
Wave Interference ◽  
Wide Range

Abstract In this paper, the emission of internal gravity waves from a local westerly shear layer is studied. Thermal and/or vorticity forcing of the shear layer with a wide range of frequencies and scales can lead to strong emission of gravity waves in the region exterior to the shear layer. The shear flow not only passively filters and refracts the emitted wave spectrum, but also actively participates in the gravity wave emission in conjunction with the distributed forcing. This interaction leads to enhanced radiated momentum fluxes but more importantly to enhanced gravity wave energy fluxes. This enhanced emission power can be traced to the nonnormal growth of the perturbations in the shear region, that is, to the transfer of the kinetic energy of the mean shear flow to the emitted gravity waves. The emitted wave energy flux increases with shear and can become as large as 30 times greater than the corresponding flux emitted in the absence of a localized shear region. Waves that have horizontal wavelengths larger than the depth of the shear layer radiate easterly momentum away, whereas the shorter waves are trapped in the shear region and deposit their momentum at their critical levels. The observed spectrum, as well as the physical mechanisms influencing the spectrum such as wave interference and Doppler shifting effects, is discussed. While for large Richardson numbers there is equipartition of momentum among a wide range of frequencies, most of the energy is found to be carried by waves having vertical wavelengths in a narrow band around the value of twice the depth of the region. It is shown that the waves that are emitted from the shear region have vertical wavelengths of the size of the shear region.

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