Observation of neutral hydrogen in the globular cluster NGC 2808

1991 ◽  
Vol 374 ◽  
pp. L45 ◽  
Author(s):  
D. J. Faulkner ◽  
Tania R. Scott ◽  
P. R. Wood ◽  
Alan E. Wright
Keyword(s):  
Globular Cluster ◽  
Neutral Hydrogen

A deep search for 21 CM neutral hydrogen emission in the tightly bound globular cluster NGC 6388

1989 ◽  
Vol 97 ◽  
pp. 1708 ◽  
Author(s):  
David K. Lynch ◽  
Phillip F. Bowers ◽  
John B. Whiteoak
Keyword(s):  
Globular Cluster ◽  
Neutral Hydrogen ◽  
Hydrogen Emission

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

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.

Variation of the amount of hydrogen along the galactic ridge

1967 ◽  
Vol 31 ◽  
pp. 171-172
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Surface Brightness ◽  
Milky Way ◽  
Neutral Hydrogen ◽  
Line Of Sight ◽  
Optical Surface ◽  
Hydrogen Density ◽  
Continuous Radiation ◽  
Galactic Longitude

The integralNHof neutral-hydrogen density along the line of sight is determined from the Kootwijk and Sydney surveys. The run ofNHwith galactic longitude agrees well with that of thermal continuous radiation and that of the optical surface brightness of the Milky Way.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Observations of neutral hydrogen in open clusters

1967 ◽  
Vol 31 ◽  
pp. 41-43
Author(s):  
Th. Schmidt-Kaler ◽  
R. Schwartz
Keyword(s):  
Neutral Hydrogen ◽  
Open Clusters

Neutral hydrogen is found in every young cluster observed, usually extending beyond the optical diameter, and in some cases showing expanding motions.

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.

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