scholarly journals Recent High Spectral and Spatial Resolution Spectroscopy of Laser-Produced Plasmas and Electron-Ion Beam Plasmas

1977 ◽  
Vol 43 ◽  
pp. 18-18
Author(s):  
G.A. Doschek ◽  
U. Feldman ◽  
D.J. Johnson ◽  
D.J. Nagel
Keyword(s):  
Spatial Resolution ◽  
Spectral Resolution ◽  
Ion Beam ◽  
Normal Incidence ◽  
Grazing Incidence ◽  
Spectral Lines ◽  
Atomic Transition ◽  
Transition Time ◽  
High Spectral Resolution ◽  
Expansion Velocity

Spectra of plasmas produced by a CO2 laser have recently been obtained using a normal incidence slitless spectrograph and a high spectral resolution (0.028 mÅ) grazing incidence spectrograph. The slitless spectrograph forms images of the plasmas in spectral lines and is similar to the instrument flown by NRL on Skylab. The total wavelength coverage is from about 100 Å to about 600 Å. The shapes of the images depend markedly on the type of atomic transition. Time-averaged electron densities in the expanding plumes are calculated, and the expansion velocity is estimated from the profiles of lines recorded by the grazing incidence spectrograph. In addition, spectra of electron-ion beam plasmas between ∼200 Å and 2000 Å were obtained using a stigmatic normal incidence slit spectrograph. The distribution of plasma emisston between the anode and cathode, and the mass motions in the plasmas are discussed.

scholarly journals Hyperspectral and Multispectral Remote Sensing Image Fusion Based on Endmember Spatial Information

2020 ◽  
Vol 12 (6) ◽  
pp. 1009
Author(s):  
Xiaoxiao Feng ◽  
Luxiao He ◽  
Qimin Cheng ◽  
Xiaoyi Long ◽  
Yuxin Yuan
Keyword(s):  
Image Fusion ◽  
Spatial Resolution ◽  
Spectral Resolution ◽  
Spatial Information ◽  
Spectral Unmixing ◽  
High Spectral Resolution ◽  
Remote Sensing Image Fusion ◽  
Fusion Methods ◽  
Invariant Regions ◽  
The Difference

Hyperspectral (HS) images usually have high spectral resolution and low spatial resolution (LSR). However, multispectral (MS) images have high spatial resolution (HSR) and low spectral resolution. HS–MS image fusion technology can combine both advantages, which is beneficial for accurate feature classification. Nevertheless, heterogeneous sensors always have temporal differences between LSR-HS and HSR-MS images in the real cases, which means that the classical fusion methods cannot get effective results. For this problem, we present a fusion method via spectral unmixing and image mask. Considering the difference between the two images, we firstly extracted the endmembers and their corresponding positions from the invariant regions of LSR-HS images. Then we can get the endmembers of HSR-MS images based on the theory that HSR-MS images and LSR-HS images are the spectral and spatial degradation from HSR-HS images, respectively. The fusion image is obtained by two result matrices. Series experimental results on simulated and real datasets substantiated the effectiveness of our method both quantitatively and visually.

scholarly journals The Structure and Kinematics of the Ionized Gas In Centaurus A

1987 ◽  
Vol 127 ◽  
pp. 417-418
Author(s):  
J. Bland ◽  
K. Taylor ◽  
P. D. Atherton
Keyword(s):  
Spatial Resolution ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Line Of Sight ◽  
Rotating Disc ◽  
Ionized Gas ◽  
Dust Lane ◽  
Data Cubes ◽  
Fabry Perot ◽  
Centaurus A

The TAURUS Imaging Fabry-Perot System (Taylor & Atherton 1980) has been used with the IPCS at the AAT to observe the ionized gas within NGC 5128 (Cen A) at [NII]λ6548 and Hα. Seven independent (x, y,λ) data cubes were obtained along the dust lane at high spectral resolution (30 km/s FWHM) and at a spatial resolution limited by the seeing (~1″). From these data, maps of the kinematics and intensities of the ionized gas were derived over a 420″ by 300″ region. The maps are the most complete to date for this object comprising 17500 and 5300 fitted spectra in Ha and [NII]λ6548 respectively. The dust lane system is found to be well understood in terms of a differentially rotating disc of gas and dust which is warped both along and perpendicular to the line-of-sight.

scholarly journals AMBER/VLTI Snapshot Survey on Circumstellar Environments

2014 ◽  
Vol 9 (S307) ◽  
pp. 297-300 ◽  
Author(s):  
Th. Rivinius ◽  
W.J. de Wit ◽  
Z. Demers ◽  
A. Quirrenbach ◽  
Keyword(s):  
Spatial Resolution ◽  
Spectral Resolution ◽  
Spatial Scales ◽  
Line Emission ◽  
High Spectral Resolution ◽  
Unique Combination ◽  
Hot Stars ◽  
Circumstellar Environments ◽  
Colour Terms ◽  
Neutral Colour

AbstractOHANA is an interferometric snapshot survey of the gaseous circumstellar environments of hot stars, carried out by the VLTI group at the Paranal observatory. It aims to characterize the mass-loss dynamics (winds/disks) at unexplored spatial scales for many stars. The survey employs the unique combination of AMBER's high spectral resolution with the unmatched spatial resolution provided by the VLTI. Because of the spatially unresolved central OBA-type star, with roughly neutral colour terms, their gaseous environments are among the easiest objects to be observed with AMBER, yet the extent and kinematics of the line emission regions are of high astrophysical interest.

scholarly journals Lunar Image Fusion using Wavelet Transform

2013 ◽  
pp. 211-215
Author(s):  
Dr.Vani. K ◽  
Anto. A. Micheal
Keyword(s):  
High Resolution ◽  
Image Fusion ◽  
Spatial Resolution ◽  
Spectral Resolution ◽  
Lunar Surface ◽  
High Spatial Resolution ◽  
Multispectral Image ◽  
High Spectral Resolution ◽  
Low Resolution ◽  
Mineral Mapping

This paper is an attempt to combine high resolution panchromatic lunar image with low resolution multispectral lunar image to produce a composite image using wavelet approach. There are many sensors that provide us image data about the lunar surface. The spatial resolution and spectral resolution is unique for each sensor, thereby resulting in limitation in extraction of information about the lunar surface. The high resolution panchromatic lunar image has high spatial resolution but low spectral resolution; the low resolution multispectral image has low spatial resolution but high spectral resolution. Extracting features such as craters, crater morphology, rilles and regolith surfaces with a low spatial resolution in multispectral image may not yield satisfactory results. A sensor which has high spatial resolution can provide better information when fused with the high spectral resolution. These fused image results pertain to enhanced crater mapping and mineral mapping in lunar surface. Since fusion using wavelet preserve spectral content needed for mineral mapping, image fusion has been done using wavelet approach.

scholarly journals Direct characterization of young giant exoplanets at high spectral resolution by coupling SPHERE and CRIRES+

2021 ◽  
Vol 646 ◽  
pp. A150
Author(s):  
G. P. P. L. Otten ◽  
A. Vigan ◽  
E. Muslimov ◽  
M. N’Diaye ◽  
E. Choquet ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Extrasolar Planets ◽  
Signal To Noise Ratio ◽  
Detection Limits ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
The Impact

Studies of atmospheres of directly imaged extrasolar planets with high-resolution spectrographs have shown that their characterization is predominantly limited by noise on the stellar halo at the location of the studied exoplanet. An instrumental combination of high-contrast imaging and high spectral resolution that suppresses this noise and resolves the spectral lines can therefore yield higher quality spectra. We study the performance of the proposed HiRISE fiber coupling between the direct imager SPHERE and the spectrograph CRIRES+ at the Very Large Telescope for spectral characterization of directly imaged planets. Using end-to-end simulations of HiRISE we determine the signal-to-noise ratio (S/N) of the detection of molecular species for known extrasolar planets in H and K bands, and compare them to CRIRES+. We investigate the ultimate detection limits of HiRISE as a function of stellar magnitude, and we quantify the impact of different coronagraphs and of the system transmission. We find that HiRISE largely outperforms CRIRES+ for companions around bright hosts like β Pictoris or 51 Eridani. For an H = 3.5 host, we observe a gain of a factor of up to 16 in observing time with HiRISE to reach the same S/N on a companion at 200 mas. More generally, HiRISE provides better performance than CRIRES+ in 2 h integration times between 50 and 350 mas for hosts with H < 8.5 and between 50 and 700 mas for H < 7. For fainter hosts like PDS 70 and HIP 65426, no significant improvements are observed. We find that using no coronagraph yields the best S/N when characterizing known exoplanets due to higher transmission and fiber-based starlight suppression. We demonstrate that the overall transmission of the system is in fact the main driver of performance. Finally, we show that HiRISE outperforms the best detection limits of SPHERE for bright stars, opening major possibilities for the characterization of future planetary companions detected by other techniques.

scholarly journals Wide Swath and High Resolution Airborne HyperSpectral Imaging System and Flight Validation

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1667 ◽  
Author(s):  
Dong Zhang ◽  
Liyin Yuan ◽  
Shengwei Wang ◽  
Hongxuan Yu ◽  
Changxing Zhang ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Spectral Resolution ◽  
High Efficiency ◽  
High Spatial Resolution ◽  
Imaging System ◽  
High Sensitivity ◽  
Field Of View ◽  
High Spectral Resolution ◽  
Wide Swath

Wide Swath and High Resolution Airborne Pushbroom Hyperspectral Imager (WiSHiRaPHI) is the new-generation airborne hyperspectral imager instrument of China, aimed at acquiring accurate spectral curve of target on the ground with both high spatial resolution and high spectral resolution. The spectral sampling interval of WiSHiRaPHI is 2.4 nm and the spectral resolution is 3.5 nm (FWHM), integrating 256 channels coving from 400 nm to 1000 nm. The instrument has a 40-degree field of view (FOV), 0.125 mrad instantaneous field of view (IFOV) and can work in high spectral resolution mode, high spatial resolution mode and high sensitivity mode for different applications, which can adapt to the Velocity to Height Ratio (VHR) lower than 0.04. The integration has been finished, and several airborne flight validation experiments have been conducted. The results showed the system’s excellent performance and high efficiency.

scholarly journals Optical Chromospheric Spectral Lines in K and M Dwarf Stars

1989 ◽  
Vol 104 (2) ◽  
pp. 75-78
Author(s):  
R.D. Robinson ◽  
L.E. Cram
Keyword(s):  
Heating Rate ◽  
Spectral Resolution ◽  
Effective Temperature ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
Dwarf Stars ◽  
M Dwarf Stars ◽  
M Dwarf

AbstractObservations are reported of the Ca II resonance lines and II α in dK and dM stars, made with high S/N ratio and high spectral resolution. Ca II emission is found in all stars observed, and those having weak Ca II exhibit marked Hα absorption. It is found that the strengths of the two kinds of chromospheric, lines are not tightly correlated, an effect which can be shown to be independent of the effective temperature of the stars. The result implies that a one-parameter description (e.g. heating rate) of the chromospheres is not viable. While lateral inhomogeneities are likely to be an important second parameter, we also suggest that the Hα line may be formed in a region considerable higher that in which the Ca II lines are formed.

Star And Planet’s Characterisation Through High Spectral Resolution

2020 ◽  
Author(s):  
Maria Chiara Maimone ◽  
Andrea Chiavassa ◽  
Jeremy Leconte ◽  
Matteo Brogi
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Molecular Species ◽  
Climate Model ◽  
Global Climate Model ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
High Resolution Spectroscopy ◽  
Stellar Disk ◽  
Precise Knowledge

&lt;p&gt;The study of exoplanets atmospheres is one of the most intriguing challenges in exoplanet field nowadays and the High Resolution Spectroscopy (HRS) has recently emerged as one of the leading methods for detecting atomic and molecular species in their atmospheres. In terms of numbers, if we define the resolution power R,&lt;span class=&quot;Apple-converted-space&quot;&gt;&amp;#160; &lt;/span&gt;where &amp;#955;&amp;#160;is the wavelength and &amp;#916;&amp;#955;&amp;#160;is the spectral resolution:&lt;/p&gt; &lt;p&gt;&lt;span class=&quot;Apple-converted-space&quot;&gt;&amp;#160; &amp;#160; &amp;#160;R= &amp;#955;/&amp;#916;&amp;#955;&lt;/span&gt;&lt;/p&gt; &lt;p&gt;then, &amp;#8220;High Resolution Spectroscopy&amp;#8221; means R &gt; 50 000.&lt;/p&gt; &lt;p&gt;Nevertheless extraordinary results have been achieved (Birkby, 2018), High Resolution Spectroscopy alone is not enough. 1D models of the host star have been coupled to HRS observations, but they do not reproduce the complexity of stellar convection mechanism (Chiavassa &amp; Brogi, 2019). On the contrary,&lt;span class=&quot;Apple-converted-space&quot;&gt;&amp;#160; &lt;/span&gt;3D Radiative Hydrodynamical simulations (3D RHS) take it into account intrinsically, allowing us to correctly reproduce asymmetric and blue-shifted spectral lines due to the granulation pattern of the stellar disk, which is a very important source of uncertainties at this resolution level (Chiavassa et al. 2017).&lt;/p&gt; &lt;p&gt;However, numerical simulations have been computed independently for star and planet so far, while the acquired spectra are an entanglement of both the signals. In particular, some molecular species (e.g, CO) form in the same region of the spectrum, thus planetary and stellar spectral lines are completely mixed and overlapped.&lt;span class=&quot;Apple-converted-space&quot;&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt; &lt;p&gt;Therefore, a next step forward is needed: computing stellar and planetary models &lt;em&gt;together.&lt;/em&gt;&lt;/p&gt; &lt;p&gt;With our work, we aim at upgrading the already-in-place 3D radiative transfer code Optim3D (Chiavassa et al. 2009) &amp;#8212;largely used for stellar purposes so far &amp;#8212; to taking into account also the exoplanetary contribution.&lt;span class=&quot;Apple-converted-space&quot;&gt;&amp;#160;&lt;/span&gt;We propose to use simultaneously 3D RHS, performed for stars, and the innovative Global Climate Model (GCM), drawn up for exoplanets, in order to generate unprecedented precise synthetic spectra.&amp;#160;As a springboard to test the code, we are carrying out the analysis of CO and H2O molecules on the well-know benchmark HD189733.&amp;#160;Indeed, to disentangle those star&amp;#8217;s and its companion&amp;#8217;s signals due to the same molecules is one of the most challenging problems.&amp;#160;In the end, we will be able to compute a complete dynamic characterisation: on one side, a precise knowledge of the stellar dynamic (i.e. convection-related surface structures) would allow to extract unequivocally the planetary signal; on the other one, a well-modelled dynamic of the planet (i.e. depth, shape, and position of spectral lines) would provide us with considerable information about the planetary atmospheric circulation.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document