Hydrogen Content of Young Stellar Clusters. V. Clusters NGC6604, 6611, and 6823

Measurements of the total amount of hydrogen gas associated with the O-type clusters NGC 6604, 6611, and 6823 are reported. Only a small part of the large visible nebula in which NGC 6604 appears to be embedded is associated with the cluster. The small ionized nebula associated with NGC6604 has a mass of ~600Mo and is part of a larger neutral cloud. The mass of the ionized nebula associated with NGC 6611 is ~ 5000 M 0, while a neutral hydrogen shell with a total mass of ~ 105 M 0 probably surrounds the ionized nebula. The cluster NGC 6823 is embedded in a bright nebula of mass ~ 1800 Mo. A neutral hydrogen shell of mass ~ 2000 M 0 surrounds the ionized nebula, so that the total mass of hydrogen associated with NGC 6823 is ~ 4000 Mo.

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Hydrogen Content of Young Stellar Clusters. I. Methods of Observation and Reduction

Australian Journal of Physics ◽

10.1071/ph730829 ◽

1973 ◽

Vol 26 (6) ◽

pp. 829 ◽

Cited By ~ 6

Author(s):

HM Tovmassian

Keyword(s):

Radio Telescope ◽

Hydrogen Content ◽

Data Reduction ◽

Neutral Hydrogen ◽

Hydrogen Gas ◽

Continuum Emission ◽

Stellar Clusters ◽

Hydrogen Line ◽

Galactic Clusters

Observations of 16 open galactic clusters in their continuum emission and at the neutral hydrogen line have been made with the Parkes 64 m radio telescope in an attempt to determine the total amount of hydrogen gas associated with them. In this, the first of a series of five papers, the observing procedure and the method of data reduction are described.

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Hydrogen Content of Young Stellar Clusters. IV.Clusters NGC6231, 6383, 6514, and 6531

Australian Journal of Physics ◽

10.1071/ph730853 ◽

1973 ◽

Vol 26 (6) ◽

pp. 853 ◽

Cited By ~ 1

Author(s):

HM Tovmassian ◽

SE Nersessian ◽

ET Shahbazian

Keyword(s):

Hydrogen Content ◽

Total Mass ◽

Line Emission ◽

Neutral Hydrogen ◽

Type Star ◽

Stellar Clusters ◽

Hydrogen Line ◽

Hydrogen Atoms ◽

The Continuum

The total amount of hydrogen associated with the young stellar clusters NGC6231, 6383, 6514, and 6531 has been obtained from observations in the continuum at 1410 MHz and in the hydrogen-line emission. NGC6231 contains in its southern part a cloud of neutral hydrogen atoms of density 6 cm- 3 and total mass l00M0 and in its northern part a small ionized cloud of the same density and a mass of ~ 50 M 0. NGC 6383 is embedded in a large neutral hydrogen complex, of which a small part of mass ~450M0 is ionized. The Trifid nebula is ionized by a single 07-type star at nearly twice the accepted distance of NGC6514 and the existence of NGC6514 as a physical cluster appears to be doubtful. The mass of the ionization-bounded Trifid nebula is nearly 5000M0 ? Neither neutral nor ionized hydrogen was found in association with NGC6531.

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Hydrogen Content of Young Stellar Clusters. II. Clusters NGC2175, 2264, 2353, and 2362

Australian Journal of Physics ◽

10.1071/ph730837 ◽

1973 ◽

Vol 26 (6) ◽

pp. 837 ◽

Cited By ~ 1

Author(s):

HM Tovmassian ◽

ET Shahbazian

Keyword(s):

Electron Density ◽

Hydrogen Content ◽

Neutral Hydrogen ◽

Gaseous Hydrogen ◽

Stellar Clusters

Measurements of the total amount of gaseous hydrogen associated with the O-type stellar clusters NGC 2175, 2264, 2353, and 2362 are reported. For the nebula in which NGC2175 is embedded, a mean electron density of 20cm- 3 and a mass of ionized hydrogen of 1400Mo were obtained. For the nebula in which NGC2264 is embedded, a mean electron density of 10 cm - 3 and a mass of ionized hydrogen of 60Mo (with a possible, though unlikely, additional 40Mo of neutral hydrogen) were obtained. No hydrogen in association with NGC 2353 or 2362 was detected.

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Hydrogen Content of Young Stellar Clusters. III. Clusters NGC3293, 6167, 6193, 6200, and 6204

Australian Journal of Physics ◽

10.1071/ph730843 ◽

1973 ◽

Vol 26 (6) ◽

pp. 843 ◽

Cited By ~ 1

Author(s):

HM Tovmassian ◽

ET Shahbazian ◽

SE Nersessian

Keyword(s):

Hydrogen Content ◽

Neutral Hydrogen ◽

Type Star ◽

Stellar Clusters

The total amount of hydrogen associated with the O-type clusters NGC 3293, 6193, and 6204 and the suspected clusters NGC6167 and 6200 has been measured. Neither neutral nor ionized hydrogen was found to be associated with NGC 3293 and the visible nebula in this region is most likely associated with a single 07-type star, which does not appear to belong to the cluster, while an irregular expanding shell of neutral hydrogen probably surrounds the ionized nebula. The mass of hydrogen associated with NGC6193 does not exceed 500MQ? Neither neutral nor ionized hydrogen was detected at the position ofNGC 6204. The features detected by hydrogenline observations at the positions of suspected clusters NGC6167 and 6200 provide evidence that both visual groupings may be real clusters. The amount of neutral hydrogen probably connected with NGC6167 is ~ 1000 M Q ?

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Motions of neutral hydrogen at high latitudes

Symposium - International Astronomical Union ◽

10.1017/s0074180900101068 ◽

1967 ◽

Vol 31 ◽

pp. 265-278 ◽

Cited By ~ 1

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.

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