scholarly journals Binary asteroid (31) Euphrosyne: ice-rich and nearly spherical

2020 ◽  
Vol 641 ◽  
pp. A80
Author(s):  
B. Yang ◽  
J. Hanuš ◽  
B. Carry ◽  
P. Vernazza ◽  
M. Brož ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Family Formation ◽  
Large Fraction ◽  
Imaging Study ◽  
Spherical Shape ◽  
Hydrostatic Equilibrium ◽  
Main Belt ◽  
Binary Asteroid ◽  
Water Ice ◽  
The Impact

Aims. Asteroid (31) Euphrosyne is one of the biggest objects in the asteroid main belt and it is also the largest member of its namesake family. The Euphrosyne family occupies a highly inclined region in the outer main belt and contains a remarkably large number of members, which is interpreted as an outcome of a disruptive cratering event. Methods. The goals of this adaptive-optics imaging study are threefold: to characterize the shape of Euphrosyne, to constrain its density, and to search for the large craters that may be associated with the family formation event. Results. We obtained disk-resolved images of Euphrosyne using SPHERE/ZIMPOL at the ESO 8.2 m VLT as part of our large program (ID: 199.C-0074, PI: Vernazza). We reconstructed its 3D shape via the ADAM shape modeling algorithm based on the SPHERE images and the available light curves of this asteroid. We analyzed the dynamics of the satellite with the Genoid meta-heuristic algorithm. Finally, we studied the shape of Euphrosyne using hydrostatic equilibrium models. Conclusions. Our SPHERE observations show that Euphrosyne has a nearly spherical shape with the sphericity index of 0.9888 and its surface lacks large impact craters. Euphrosyne’s diameter is 268 ± 6 km, making it one of the top ten largest main belt asteroids. We detected a satellite of Euphrosyne – S/2019 (31) 1 – that is about 4 km across, on a circular orbit. The mass determined from the orbit of the satellite together with the volume computed from the shape model imply a density of 1665 ± 242 kg m−3, suggesting that Euphrosyne probably contains a large fraction of water ice in its interior. We find that the spherical shape of Euphrosyne is a result of the reaccumulation process following the impact, as in the case of (10) Hygiea. However, our shape analysis reveals that, contrary to Hygiea, the axis ratios of Euphrosyne significantly differ from those suggested by fluid hydrostatic equilibrium following reaccumulation.

scholarly journals Stability of temperatures from TIMED/SABER v1.07 (2002–2009) and Aura/MLS v2.2 (2004–2009) compared with OH(6-2) temperatures observed at Davis Station, Antarctica

2010 ◽  
Vol 10 (9) ◽  
pp. 21547-21565 ◽  
Author(s):  
W. J. R. French ◽  
F. J. Mulligan
Keyword(s):  
Cold Bias ◽  
Spatial And Temporal Scales ◽  
Ground Station ◽  
Volume Emission ◽  
The Difference ◽  
Miss Distance ◽  
Hydroxyl Layer ◽  
The Impact ◽  
Long Term Studies

Abstract. Temperature profiles from two satellite instruments – TIMED/SABER and Aura/MLS – have been used to calculate hydroxyl-layer equivalent temperatures for comparison with values measured from OH(6-2) emission lines observed by a ground-based spectrometer located at Davis Station, Antarctica (68° S, 78° E). The profile selection criteria – <500 km from the ground station and solar zenith angles >97° – yielded a total of 2359 SABER profiles over 8 years (2002–2009) and 7407 MLS profiles over 5.5 years (2004–2009). The availability of simultaneous OH volume emission rate (VER) profiles from the SABER (OH-B channel) enabled an assessment of the impact of several different weighting functions in the calculation of OH-equivalent temperatures. The maximum difference between all derived hydroxyl layer equivalent temperatures was less than 3 K. Restricting the miss-distance and miss-time criteria showed little effect on the bias, suggesting that the OH layer is relatively uniform over the spatial and temporal scales considered. However, a significant trend was found in the bias between SABER and Davis OH of ~0.7 K/year over the 8-year period with SABER becoming warmer compared with the Davis OH temperatures. In contrast, Aura MLS exhibited a cold bias of 9.9 ± 0.4 K compared with Davis OH, but importantly, the bias remained constant over the 2004–2009 year period examined. The difference in bias behaviour of the two satellites has significant implications for multi-annual and long-term studies using their data.

Conceptual design of the adaptive optics system for the laser communication relay demonstration ground station at Table Mountain

2013 ◽  
Author(s):  
Lewis C. Roberts ◽  
Norman A. Page ◽  
Rick S. Burruss ◽  
Tuan N. Truong ◽  
Sharon Dew ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Adaptive Optics ◽  
Laser Communication ◽  
Ground Station ◽  
Table Mountain ◽  
Adaptive Optics System

New View of the Solar Chromosphere

2019 ◽  
Vol 57 (1) ◽  
pp. 189-226 ◽  
Author(s):  
Mats Carlsson ◽  
Bart De Pontieu ◽  
Viggo H. Hansteen
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Numerical Models ◽  
Transverse Magnetic ◽  
Solar Photosphere ◽  
Solar Chromosphere ◽  
Image Reconstruction Techniques ◽  
New Instrumentation ◽  
Field Unit ◽  
The Impact

The solar chromosphere forms a crucial, yet complex and until recently poorly understood, interface between the solar photosphere and the heliosphere. ▪ Advances in high-resolution instrumentation, adaptive optics, image reconstruction techniques, and space-based observatories allow unprecedented high-resolution views of the finely structured and highly dynamic chromosphere. ▪ Dramatic progress in numerical computations allows 3D radiative magnetohydrodynamic forward models to take the place of the previous generation of 1D semiempirical atmosphere models. These new models provide deep insight into complex nonlocal thermodynamic equilibrium chromospheric diagnostics and enable physics-based interpretations of observations. ▪ This combination of modeling and observations has led to new insights into the role of shock waves, transverse magnetic waves, magnetic reconnection and flux emergence in the chromospheric energy balance, the formation of spicules, the impact of ion-neutral interactions, and the connectivity between chromosphere and transition region. ▪ During the next few years, the advent of new instrumentation (integral-field-unit spectropolarimetry) and observatories (ALMA, DKIST), coupled with novel inversion codes and expansion of existing numerical models to deal with ever more complex physical processes (including multifluid approaches), is expected to lead to major new insights into the dominant heating processes in the chromosphere and beyond.

scholarly journals SUPER

2018 ◽  
Vol 620 ◽  
pp. A82 ◽  
Author(s):  
C. Circosta ◽  
V. Mainieri ◽  
P. Padovani ◽  
G. Lanzuisi ◽  
M. Salvato ◽  
...  
Keyword(s):  
Star Formation ◽  
Adaptive Optics ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
X Ray ◽  
Narrow Component ◽  
The Impact

Theoretical models of galaxy formation suggest that the presence of an active galactic nucleus (AGN) is required to regulate the growth of its host galaxy through feedback mechanisms, produced by, for example, AGN-driven outflows. Although many observational studies have revealed that such outflows are common both at low and high redshift, a comprehensive picture is still missing. In particular, the peak epoch of galaxy assembly (1 <  z <  3) has been poorly explored so far, and current observations in this redshift range are mostly limited to targets with high chances to be in an outflowing phase. This paper introduces SUPER (a SINFONI Survey for Unveiling the Physics and Effect of Radiative feedback), an ongoing ESO’s VLT/SINFONI Large Programme. SUPER will perform the first systematic investigation of ionized outflows in a sizeable and blindly-selected sample of 39 X-ray AGN at z ∼ 2, which reaches high spatial resolutions (∼2 kpc) thanks to the adaptive optics-assisted IFS observations. The outflow morphology and star formation in the host galaxy will be mapped through the broad component of [O III]λ5007 and the narrow component of Hα emission lines. The main aim of our survey is to infer the impact of outflows on the on-going star formation and to link the outflow properties to a number of AGN and host galaxy properties. We describe here the survey characteristics and goals, as well as the selection of the target sample. Moreover, we present a full characterization of its multi-wavelength properties: we measure, via spectral energy distribution fitting of UV-to-FIR photometry, stellar masses (4 × 109 − 2 × 1011 M⊙), star formation rates (25 − 680 M⊙ yr−1) and AGN bolometric luminosities (2 × 1044 − 8 × 1047 erg s−1), along with obscuring column densities (up to 2 × 1024 cm−2) and luminosities in the hard 2 − 10 keV band (2 × 1043 − 6 × 1045 erg s−1) derived through X-ray spectral analysis. Finally, we classify our AGN as jetted or non-jetted according to their radio and FIR emission.

scholarly journals Comparison of Multiscale Imaging Methods for Brain Research

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1377
Author(s):  
Jessica Tröger ◽  
Christian Hoischen ◽  
Birgit Perner ◽  
Shamci Monajembashi ◽  
Aurélien Barbotin ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Brain Research ◽  
Super Resolution ◽  
Synaptic Proteins ◽  
Physiological Status ◽  
Basic Set ◽  
Recent Developments ◽  
Quantitative Manner ◽  
The Impact ◽  
The Brain

A major challenge in neuroscience is how to study structural alterations in the brain. Even small changes in synaptic composition could have severe outcomes for body functions. Many neuropathological diseases are attributable to disorganization of particular synaptic proteins. Yet, to detect and comprehensively describe and evaluate such often rather subtle deviations from the normal physiological status in a detailed and quantitative manner is very challenging. Here, we have compared side-by-side several commercially available light microscopes for their suitability in visualizing synaptic components in larger parts of the brain at low resolution, at extended resolution as well as at super-resolution. Microscopic technologies included stereo, widefield, deconvolution, confocal, and super-resolution set-ups. We also analyzed the impact of adaptive optics, a motorized objective correction collar and CUDA graphics card technology on imaging quality and acquisition speed. Our observations evaluate a basic set of techniques, which allow for multi-color brain imaging from centimeter to nanometer scales. The comparative multi-modal strategy we established can be used as a guide for researchers to select the most appropriate light microscopy method in addressing specific questions in brain research, and we also give insights into recent developments such as optical aberration corrections.

scholarly journals Stability of temperatures from TIMED/SABER v1.07 (2002–2009) and Aura/MLS v2.2 (2004–2009) compared with OH(6-2) temperatures observed at Davis Station, Antarctica

2010 ◽  
Vol 10 (23) ◽  
pp. 11439-11446 ◽  
Author(s):  
W. J. R. French ◽  
F. J. Mulligan
Keyword(s):  
Cold Bias ◽  
Spatial And Temporal Scales ◽  
Ground Station ◽  
Volume Emission ◽  
The Difference ◽  
Miss Distance ◽  
Hydroxyl Layer ◽  
The Impact ◽  
Long Term Studies

Abstract. Temperature profiles from two satellite instruments – TIMED/SABER and Aura/MLS – have been used to calculate hydroxyl-layer equivalent temperatures for comparison with values measured from OH(6-2) emission lines observed by a ground-based spectrometer located at Davis Station, Antarctica (68° S, 78° E). The profile selection criteria – miss-distance <500 km from the ground station and solar zenith angles >97° – yielded a total of 2359 SABER profiles over 8 years (2002–2009) and 7407 MLS profiles over 5.5 years (2004–2009). The availability of simultaneous OH volume emission rate (VER) profiles from the SABER (OH-B channel) enabled an assessment of the impact of several different weighting functions in the calculation of OH-equivalent temperatures. The maximum difference between all derived hydroxyl layer equivalent temperatures was less than 3 K. Restricting the miss-distance and miss-time criteria showed little effect on the bias, suggesting that the OH layer is relatively uniform over the spatial and temporal scales considered. However, a significant trend was found in the bias between SABER and Davis OH of ~0.7 K/year over the 8-year period with SABER becoming warmer compared with the Davis OH temperatures. In contrast, Aura/MLS exhibited a cold bias of 9.9 ± 0.4 K compared with Davis OH, but importantly, the bias remained constant over the 2004–2009 year period examined. The difference in bias behaviour of the two satellites has significant implications for multi-annual and long-term studies using their data.

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