scholarly journals Interstellar sodium and Galactic structure. A high-resolution survey

1985 ◽  
Vol 106 ◽  
pp. 325-328
Author(s):  
E. Maurice ◽  
A. Ardeberg ◽  
H. Lindgren
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Absorption Lines ◽  
High Spectral Resolution ◽  
Line Of Sight ◽  
Substantial Part ◽  
Galactic Rotation ◽  
Interstellar Gas ◽  
Interstellar Clouds ◽  
The Galaxy

Observation of absorption lines produced by interstellar gas is a straight-forward way to determine column densities and velocities along the line of sight of interstellar clouds. In practice, peculiar motions often mask galactic rotation and/or cause line blending. We have made a study of absorption lines of interstellar sodium covering a substantial part of the Galaxy at extremely high spectral resolution.

scholarly journals Probing the atmosphere of HD189733b with the Na i and K i lines

2020 ◽  
Vol 498 (1) ◽  
pp. 1023-1033
Author(s):  
E Keles ◽  
D Kitzmann ◽  
M Mallonn ◽  
X Alexoudi ◽  
L Fossati ◽  
...  
Keyword(s):  
High Resolution ◽  
High Altitude ◽  
Spectral Resolution ◽  
Absorption Lines ◽  
High Spectral Resolution ◽  
Transmission Spectra ◽  
Line Profiles ◽  
Line Broadening ◽  
Atmospheric Processes ◽  
Hot Jupiters

ABSTRACT High spectral resolution transmission spectroscopy is a powerful tool to characterize exoplanet atmospheres. Especially for hot Jupiters, this technique is highly relevant, due to their high-altitude absorption, e.g. from resonant sodium (Na i) and potassium (K i) lines. We resolve the atmospheric K i absorption on HD189733b with the aim to compare the resolved K i line and previously obtained high-resolution Na i-D line observations with synthetic transmission spectra. The line profiles suggest atmospheric processes leading to a line broadening of the order of ∼10 km/s for the Na i-D lines and only a few km/s for the K i line. The investigation hints that either the atmosphere of HD189733b lacks a significant amount of K i or the alkali lines probe different atmospheric regions with different temperature, which could explain the differences we see in the resolved absorption lines.

scholarly journals High-spectral resolution M-band observations of CO Rot-Vib absorption lines towards the Galactic center

2019 ◽  
Vol 626 ◽  
pp. A44 ◽  
Author(s):  
J. Moultaka ◽  
A. Eckart ◽  
K. Tikare ◽  
A. Bajat
Keyword(s):  
Spectral Resolution ◽  
Galactic Center ◽  
Complex Structure ◽  
Absorption Lines ◽  
High Spectral Resolution ◽  
Line Of Sight ◽  
Infrared Wavelength ◽  
Standard Data ◽  
Very Large Telescope ◽  
Central Parsec

Context. In the near- to mid-infrared wavelength domain, bright continuum sources in the central parsec of the Galactic center (GC) are subject to foreground absorption. These sources therefore represent ideal probes of the intervening material that is responsible for the absorption along the line of sight. Aims. Our aim is to shed light on the location and physics of the absorbing clouds. We try to find out which of the gaseous absorbing materials is intimately associated with the GC and which one is associated with clouds at a much larger distance. Methods. We used the capabilities of CRIRES spectrograph located at ESO Very Large Telescope in Chile to obtain absorption spectra of individual lines at a high spectral resolution of R = 50 000, that is, 5 km s−1. We observed the 12CO R(0), P(1), P(2), P(3), P(4), P(5), P(6), P(7) and P(9) transition lines, applied standard data reduction, and compared the results with literature data. Results. We present the results of CRIRES observations of 13 infrared sources located in the central parsec of the Galaxy. The data provide direct evidence for a complex structure of the interstellar medium along the line of sight and in the close environment of the central sources. In particular we find four cold foreground clouds at radial velocities vLSR of the order of −145, −85, −60, and −40 ± 15 km s−1 that show absorption in the lower transition lines from R(0) to P(2) and in all the observed spectra. We also find in all sources an absorption in velocity range of 50–60 km s−1, possibly associated with the so-called 50 km s−1 cloud and suggesting an extension of this cloud in front of the GC. Finally, we detect individual absorption lines that are probably associated with material much closer to the center and with the sources themselves, suggesting the presence of cold gas in the local region.

scholarly journals A coma-free super-high resolution optical spectrometer using 44 high dispersion sub-gratings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hua-Tian Tu ◽  
An-Qing Jiang ◽  
Jian-Ke Chen ◽  
Wei-Jie Lu ◽  
Kai-Yan Zang ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Wavelength Region ◽  
Ultra Violet ◽  
High Spectral Resolution ◽  
Visible Range ◽  
High Dispersion ◽  
Charge Coupled Device ◽  
Wide Range ◽  
High Resolution Spectrometer

AbstractUnlike the single grating Czerny–Turner configuration spectrometers, a super-high spectral resolution optical spectrometer with zero coma aberration is first experimentally demonstrated by using a compound integrated diffraction grating module consisting of 44 high dispersion sub-gratings and a two-dimensional backside-illuminated charge-coupled device array photodetector. The demonstrated super-high resolution spectrometer gives 0.005 nm (5 pm) spectral resolution in ultra-violet range and 0.01 nm spectral resolution in the visible range, as well as a uniform efficiency of diffraction in a broad 200 nm to 1000 nm wavelength region. Our new zero-off-axis spectrometer configuration has the unique merit that enables it to be used for a wide range of spectral sensing and measurement applications.

scholarly journals Inferring Convective Weather Characteristics with Geostationary High Spectral Resolution IR Window Measurements: A Look into the Future

2009 ◽  
Vol 26 (8) ◽  
pp. 1527-1541 ◽  
Author(s):  
Justin M. Sieglaff ◽  
Timothy J. Schmit ◽  
W. Paul Menzel ◽  
Steven A. Ackerman
Keyword(s):  
Temporal Resolution ◽  
Spectral Resolution ◽  
Atmospheric Stability ◽  
Absorption Lines ◽  
High Spectral Resolution ◽  
High Temporal Resolution ◽  
Tropospheric Temperature ◽  
Carbon Dioxide Absorption ◽  
Water Vapor Absorption ◽  
Infrared Radiances

Abstract A high spectral resolution geostationary sounder can make spectrally detailed measurements of the infrared spectrum at high temporal resolution, which provides unique information about the lower-tropospheric temperature and moisture structure. Within the infrared window region, many spectrally narrow, relatively weak water vapor absorption lines and one carbon dioxide absorption line exist. Frequent measurement of these absorption lines can provide critical information for monitoring the evolution of the lower-tropospheric thermodynamic state. This can improve short-term convective forecasts by monitoring regions of changing atmospheric stability. While providing valuable observations, the current geostationary sounders are spectrally broad and do not resolve the important spectrally narrow absorption lines needed to observe the planetary boundary layer. The usefulness of high spectral resolution measurements from polar-orbiting instruments has been shown in the literature, as has the usefulness of high temporal resolution measurements from geostationary instruments. Little attention has been given to the combination of high temporal along with high spectral resolution measurements. This paper demonstrates the potential utility of high temporal and high spectral resolution infrared radiances.

scholarly journals Observations of interstellar Lyman-α absorption

1970 ◽  
Vol 36 ◽  
pp. 281-301 ◽  
Author(s):  
Edward B. Jenkins
Keyword(s):  
Neutral Hydrogen ◽  
Local Region ◽  
Line Of Sight ◽  
Small Scale ◽  
Line Broadening ◽  
Interstellar Gas ◽  
B Stars ◽  
Hydrogen Density ◽  
The Galaxy ◽  
To Come

Absorption at the Lyman-α transition from interstellar neutral hydrogen has been observed in the ultraviolet spectra of 18 nearby O and B stars. Radiation damping is the dominant cause of line broadening, which makes the derived line-of-sight column densities proportional to the square of the observed equivalent widths. An average hydrogen density on the order of 0.1 atom cm−3 has been found for most of the stars observed so far. This is in contrast to the findings from surveys of 21-cm radio emission, which suggest 0.7 atom cm−3 exists in the local region of the Galaxy. Several effects which might introduce uncertainties into the Lyman-α measurements are considered, but none seems to be able to produce enough error to explain the disagreement with the 21-cm data. The possibility that small-scale irregularities in the interstellar gas could give significantly lower values at Lyman-α is explored. However, a quantitative treatment of the factor of ten discrepancy in Orion indicates the only reasonable explanation requires the 21-cm flux to come primarily from small, dense, hot clouds which are well separated from each other. The existence of such clouds, however, poses serious theoretical difficulties.

scholarly journals The Proposed Columbus Mission: High and Low Resolution Spectroscopy in the 100–2000 Å Spectral Region

1984 ◽  
Vol 86 ◽  
pp. 72-75
Author(s):  
Jeffrey L. Linsky
Keyword(s):  
High Resolution ◽  
Spectral Range ◽  
Spectral Region ◽  
Extreme Ultraviolet ◽  
High Spectral Resolution ◽  
Low Resolution ◽  
Interstellar Gas ◽  
Scientists And Engineers ◽  
Ionization Balance ◽  
Far Ultraviolet

For the past year a Joint Working Group of NASA and ESA scientists and engineers has been defining the scientific objectives and instrument parameters for a proposed satellite to obtain far and extreme ultraviolet spectra of stars, interstellar gas, solar system objects, and galaxies. The project, now called Columbus, incorporates the scientific goals of the previously proposed NASA Far Ultraviolet Spectrograph Explorer (FUSE) and ESA Magellan missions.The prime spectral range of Columbus, 900–1200 Å, cannot be observed by IUE or Space Telescope. In this spectral range Copernicus was able to observe bright stars (mv ≤ 6) with high resolution and the Hopkins Ultraviolet Telescope (HUT) will observe faint sources at low resolution, but Columbus will be the first instrument capable of high spectral resolution observations of faint sources (mv ≈ 17). High resolution spectra in the 900–1200 Å region will permit studies of the Lyman lines of atomic H and D, the molecules H2 and HD, resonance lines of C III and O VI, and other species listed in Table 1. Columbus also is being designed to observe the 1200–2000 Å spectral region at high resolution, permitting measurements of many stages of ionization for the same atom (i.e. N I, II, III, V; C II, III, IV; and S II, III, IV, VI). The broad coverage of ionization states is essential for the analysis of interstellar and stellar plasmas where the ionization balance can be quite complex.

scholarly journals Goals for the Application of High-Resolution X-ray Spectroscopy to the Diagnosis of Stellar Coronal Plasmas

1990 ◽  
Vol 115 ◽  
pp. 94-109 ◽  
Author(s):  
Jeffrey L. Linsky
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Transient Flow ◽  
Emission Measure ◽  
Active Regions ◽  
High Sensitivity ◽  
High Spectral Resolution ◽  
Spectral Features ◽  
Signal To Noise ◽  
X Ray

AbstractI provide examples of how high-resolution x-ray spectra may be used to determine the temperature and emission measure distributions, electron densities, steady and transient flow velocities, and location of active regions in stellar coronae. For each type of measurement I estimate the minimum spectral resolution required to resolve the most useful spectral features. In general, high sensitivity is required to obtain sufficient signal-to-noise to exploit the high spectral resolution. Although difficult, each measurement should be achievable with the instrumentation proposed for AXAF.

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.

Spectroscopic and structural characterization of three silaisocyanides: exploring an elusive class of reactive molecules at high resolution

2015 ◽  
Vol 51 (56) ◽  
pp. 11305-11308 ◽  
Author(s):  
Sven Thorwirth ◽  
Ralf I. Kaiser ◽  
Kyle N. Crabtree ◽  
Michael C. McCarthy
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Structural Characterization ◽  
High Spectral Resolution ◽  
First Time

The fundamental silaisocyanides HCCNSi, HC4NSi, and NCNSi have been characterized at high spectral resolution for the first time. All three chains are good candidates for radio astronomical detection.

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