scholarly journals A survey of neutral hydrogen at high galactic latitudes

1959 ◽  
Vol 9 ◽  
pp. 390-397 ◽  
Author(s):  
W. C. Erickson ◽  
H. L. Helfer ◽  
H. E. Tatel
Keyword(s):  
Galactic Plane ◽  
Neutral Hydrogen ◽  
The Other ◽  
Galactic Latitude ◽  
Line Profiles ◽  
Carnegie Institution ◽  
Frequency Bandwidth ◽  
Carnegie Institution Of Washington ◽  
Video Frequency

Approximately 1000 observations of neutral hydrogen have been obtained with the 54-channel H-line receiver and the Würzburg antenna of the Carnegie Institution of Washington. H-line profiles have been observed at 10-degree intervals along the ±20-, ±30-, and ± 40-degree parallels of galactic latitude; at 20-degree intervals along the ± 50- and ±60-degree parallels; at 40-degree intervals along the ±70- and ±80-degree parallels and at the poles. Approximately two dozen observations have been taken at points near the galactic plane in order to correlate these observations with the Leiden survey [1]. The beamwidth of the Würzburg antenna was about 2 degrees. The observations were taken in two series, one series during the summer of 1957, and the other series during 1958 January. The video frequency bandwidth of the receiver is 12 kc/s. The profiles consist of averages of from two to six scans with integration times from 4.8 to 7.5 minutes.

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 Radio observations of some details in the H I local spiral arm

1970 ◽  
Vol 38 ◽  
pp. 169-172
Author(s):  
N. V. Bystrova ◽  
J. V. Gossachinsky ◽  
T. M. Egorova ◽  
V. M. Rozanov ◽  
N. F. Ryzhkov
Keyword(s):  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Central Star ◽  
The Other ◽  
Radio Observations ◽  
Positive Side ◽  
Western Border ◽  
H Ii Region ◽  
Spiral Arm

The observations were made with the large Pulkovo radiotelescope (beamwidth 7′, bandwidth 20 and 10 kHz). Figure 1 contains our drift curves across the cluster NGC 2264. The details on them may be identified with Raimond's (1966) clouds, but the proofs for the reality of the connection between the cluster and the clouds are not very reliable. The cloud ‘b’ is believed to be connected with NGC 2264 because of their close neighborhood. But on the other side of the galactic plane in this region we have found a bright and narrow (∼1°) detail, whose middle falls exactly on the western border of the H II region around the star λ Orionis (Figure 2). Figure 3 contains the computed drift curves at different velocities for Δf = 20 kHz according to the model of the neutral hydrogen expanding envelope proposed by Wade (1957) around the H II region λ Ori. Figure 4 represents our observations. Although some details, in particular the narrow detail at the velocity −1.4 km s−1, are very similar to the calculated ones, our observations differ from Wade's model in that they do not have any velocity symmetry relative to zero; in fact the details are situated only at the positive side. This fact may eliminate one half of the proposed envelope. There is no symmetry relative to the central star and no coincidence of the velocity of the narrowest detail with the velocities of the central star and nebula.

scholarly journals Fine structure in the Magellanic Stream

1978 ◽  
Vol 79 ◽  
pp. 131-132
Author(s):  
A. G. D. Philip ◽  
A. G. Davis
Keyword(s):  
Fine Structure ◽  
West Virginia ◽  
Radio Telescope ◽  
Neutral Hydrogen ◽  
Astronomical Observatory ◽  
Carnegie Institution ◽  
Carnegie Institution Of Washington ◽  
Magellanic Stream

Dr Erkes and I, of Dudley Observatory, and Dr Ken Turner, of the Carnegie Institution of Washington, used the 300 foot radio telescope at the National Radio Astronomical Observatory, Greenbank, West Virginia in March of 1977 to measure neutral hydrogen at 21 cm in three 2° strips across positions indicated by Mathewson, Cleary, and Murray (1974, Astrophys. J., 190, 291) as being part of the Magellanic Stream. in region “A” (centred at α = 22h44m, δ = +24 0.5) no hydrogen was found above the background (3 × 1019 H atoms cm−2). in a revised map Mathewson and Schwarz (1976, Mon. Not. R. astr. Soc., 176, 47P) show that this region is not occupied by the stream. in regions “B” and “C” (centred at α = 23h10m, δ = +11° and α = 0h00m, δ = −17°) hydrogen was detected at the velocities found by Mathewson and Schwarz. Maps of the structure found in these regions are shown in Figure 1.

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.

Southern Hemisphere Seti Survey: Five Years of Project Meta II

1997 ◽  
Vol 161 ◽  
pp. 611-621
Author(s):  
Guillermo A. Lemarchand ◽  
Fernando R. Colomb ◽  
E. Eduardo Hurrell ◽  
Juan Carlos Olalde
Keyword(s):  
Southern Hemisphere ◽  
Scattering Theory ◽  
Galactic Plane ◽  
Narrow Band ◽  
Neutral Hydrogen ◽  
Sky Survey ◽  
Inertial Frames ◽  
Interstellar Scattering ◽  
Extraterrestrial Origin ◽  
Spectral Channels

AbstractProject META II, a full sky survey for artificial narrow-band signals, has been conducted from one of the two 30-m radiotelescopes of the Instituto Argentino de Radioastronomía (IAR). The search was performed near the 1420 Mhz line of neutral hydrogen, using a 8.4 million channels Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earths rotation, which provides a characteristic changing signature for narrow-band signals of extraterrestrial origin. Among the 2 × 1013spectral channels analyzed, 29 extra-statistical narrow-band events were found, exceeding the average threshold of 1.7 × 10−23Wm−2. The strongest signals that survive culling for terrestrial interference lie in or near the galactic plane. A description of the project META II observing scheme and results is made as well as the possible interpretation of the results using the Cordes-Lazio-Sagan model based in interstellar scattering theory.

Sign in / Sign up

Export Citation Format

Share Document