scholarly journals Radial velocities of neutral hydrogen in the anticenter region of the Galaxy

1970 ◽  
Vol 38 ◽  
pp. 164-168 ◽  
Author(s):  
L. Velden
Keyword(s):  
Emission Line ◽  
Statistical Method ◽  
Neutral Hydrogen ◽  
Radial Velocities ◽  
Line Profiles ◽  
Interstellar Gas ◽  
Observational Material ◽  
Circular Rotation ◽  
The Galaxy

An observational material of 21-cm H I emission-line profiles is investigated by a statistical method to derive the kinematical properties of the interstellar gas in the region of the galactic anticenter. A description of the method used as well as the results obtained, concerning deviations from a circular rotation, are given.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

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 Theoretical 21-cm line profiles: Comparison with observations

1970 ◽  
Vol 38 ◽  
pp. 391-396 ◽  
Author(s):  
C. Yuan
Keyword(s):  
Galactic Plane ◽  
Density Wave ◽  
Neutral Hydrogen ◽  
Wave Theory ◽  
Line Profiles ◽  
Spiral Pattern ◽  
The Galaxy ◽  
Density Wave Theory ◽  
Good Agreement

In order to make a direct comparison with observations of the 21-cm line of neutral hydrogen, theoretical profiles based on the ideas of the density-wave theory are constructed for a modified Schmidt model of the Galaxy and its theoretical spiral pattern. The comparison has covered galactic longitudes lII = 30° −330° with 10° intervals in the galactic plane. Good agreement is found in most of the above directions.

scholarly journals Unusual Emission Line Profiles of M1-1

1989 ◽  
Vol 131 ◽  
pp. 188-188
Author(s):  
Katsunori Shibata ◽  
Shin'ichi Tamura
Keyword(s):  
Emission Line ◽  
Radial Velocities ◽  
Line Profiles ◽  
High Excitation ◽  
One Dimensional ◽  
Slit Position ◽  
Gaussian Method ◽  
Pixel Array

In order to seek out intrinsically compact PN, we have observed high-excitation and angularly small PN, M1-1, with the intensified Reticon system (one-dimensional 1024 pixel-array) at the Coude focus of the 188 cm telescope. We have obtained highly resolved emission line profiles of [NII]λ6583, Hα, [OIII]λ5007, and HeIIλ4686 at several slit position angles. These lines were analyzed with the aid of Multiple Gaussian Method. From the analysis of their radial velocities and decomposed profiles, we can summarize our observational results as follows, (a) HeII were fitted by three Gaussians, those are main blue and red-components and an extremely red-shifted sub-component. Hα and [OIII] were decomposed into blue and red components. [NII] were fitted by single Gaussian.

Neutral Hydrogen in the Galactic Halo

1986 ◽  
Vol 6 (3) ◽  
pp. 358-385 ◽  
Author(s):  
R. X. McGee ◽  
Lynette M. Newton
Keyword(s):  
Optical Absorption ◽  
Satellite Data ◽  
High Intensity ◽  
Galactic Halo ◽  
Neutral Hydrogen ◽  
Radial Velocities ◽  
Line Profiles ◽  
Low Intensity ◽  
International Ultraviolet Explorer ◽  
Made In

AbstractObservations of 21 cm HI emission-line profiles have been made in 34 directions from l= 172° through 0° to l=97° at high galactic latitudes and in 59 directions towards the LMC (b~ –33°) with the aim of detecting low-intensity halo features which may be compared with other element features of similar radial velocities detected by ultraviolet or optical absorption lines. Data are presented as spectra and tables of the parameters: radial velocities, line temperatures, halfwidths and column densities. Spectra of both low-intensity (halo) and high-intensity components are given for 48 positions in three tracks across the LMC.Features near radial velocities –48 and +58 km s -1 are found in all the directions examined, whereas significant numbers of features grouped around average radial velocities + 112, +160 and +373 km s-1 (Isr) are found only in the directions of the LMC.Using the HI column densities as references, we have estimated depletions in the abundances of calcium and sodium in the halo, spiral arms and the LMC disk. In one direction towards the LMC depletions in the halo features of carbon, nitrogen, oxygen, magnesium, aluminium, silicon and iron (from International Ultraviolet Explorer (IUE) satellite data) have also been estimated.

scholarly journals Neutral hydrogen in the central part of the galactic system

1959 ◽  
Vol 9 ◽  
pp. 416-422 ◽  
Author(s):  
G. W. Rougoor ◽  
J. H. Oort
Keyword(s):  
Rotation Curve ◽  
Neutral Hydrogen ◽  
Line Profiles ◽  
Rotational Model ◽  
Galactic System ◽  
The Galaxy

While trying to determine the rotation curve in 1953 Kwee, Muller, and Westerhout [1] found long and faint wings in the line profiles within 20 to 25 degrees longitude from the center. The gas responsible for these wings should therefore lie within 3 kiloparsecs from the center. The velocities of the neutral hydrogen causing these wings are far greater than could be expected on the basis of a reasonable rotational model of the Galaxy. Therefore, the wings were tentatively interpreted as being caused by high turbulent velocities in the gas. In view of the new and better data obtained with the 25-meter telescope in Dwingeloo, this interpretation has now been dropped. The new conclusion is that all of the neutral hydrogen in these regions is expanding and at the same time taking part in the galactic rotation. The evidence for this conclusion will be briefly presented.

scholarly journals Kinematics and Principal Component Analysis from IFU Spectroscopy of the Post-Starburst Quasar SDSS J0210–0903

2009 ◽  
Vol 5 (S267) ◽  
pp. 138-138
Author(s):  
David Sanmartim ◽  
Thaisa Storchi-Bergmann ◽  
Michael S. Brotherton
Keyword(s):  
Principal Component Analysis ◽  
Emission Line ◽  
Principal Component ◽  
Radial Velocities ◽  
Absorption Lines ◽  
Two Dimensional ◽  
Line Profiles ◽  
Gas Velocity ◽  
Field Unit ◽  
Integral Field

We present 2-D mapping and analysis of the gaseous kinematics of the inner 7″ × 5″ of one of nearest (z = 0.0414) and brightest post-starburst quasars (PSQ) by using spectra obtained with the Integral Field Unit (IFU) of the Gemini Multi-Object Spectrograph on the Gemini North Telescope (Allington-Smith et al. 2002). Such quasars are broad-lined AGNs that also show the Balmer jumps and the high-order Balmer absorption lines from A stars typical of massive post-starburst populations of a few hundred Myrs (Brotherton et al. 2007). From measurements of the emission-line profiles, we constructed two-dimensional maps for the flux distributions, line ratios, radial velocities and gas velocity dispersions for the Hβ and [Oiii] emitting gas, similar to those of previous studies by our group (e.g., Barbosa et al. 2009).

scholarly journals A comparison of dynamical models of the Andromeda Nebula and the Galaxy

1970 ◽  
Vol 38 ◽  
pp. 61-68
Author(s):  
V. C. Rubin ◽  
W. K. Ford
Keyword(s):  
Rotation Curve ◽  
Neutral Hydrogen ◽  
Radial Velocities ◽  
H Ii Regions ◽  
Dynamical Models ◽  
Mass Model ◽  
The Galaxy ◽  
Andromeda Nebula ◽  
M 31

(1) From new radial velocities of 67 H II regions in M 31, rotational velocities and a mass model of M 31 are derived, and compared with the rotation curve and Schmidt mass model of our galaxy. (2) It is shown that in M 31 the distribution of H II regions as identified by Baade agrees with the distribution of neutral hydrogen determined from 21-cm observations. Also, the rotation curve derived from the H II velocities outside of the nucleus is similar to the rotation curve derived from 21-cm H I observations.

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