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

1973 ◽  
Vol 26 (6) ◽  
pp. 829 ◽  
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.

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

1973 ◽  
Vol 26 (6) ◽  
pp. 861 ◽  
Author(s):  
HM Tovmassian ◽  
SE Nersessian
Keyword(s):  
Hydrogen Content ◽  
Total Mass ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Stellar Clusters

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.

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

1973 ◽  
Vol 26 (6) ◽  
pp. 853 ◽  
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.

scholarly journals High-resolution observations of the galactic centre at 1420 Mc/s in the continuum and in the neutral hydrogen line

1964 ◽  
Vol 20 ◽  
pp. 191-195
Author(s):  
N. F. Ryzhkov ◽  
T. M. Egorova ◽  
I. V. Gossachinsky ◽  
N. V. Bystrova
Keyword(s):  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Hydrogen Line ◽  
Sagittarius A ◽  
The Mean ◽  
The Right ◽  
Right Ascension ◽  
Large Pulkovo Radio Telescope ◽  
The Continuum

The large Pulkovo radio telescope has a beamwidth of 7 min of arc in R.A. at a frequency of 1420 Mc/s. The continuum emission from the source Sagittarius A was measured with a bandwidth of 5 Mc/s. The mean drift curve is shown in Figure 1. It can be separated into components according to Drake (1959) as indicated in the figure. The galactic ridge is also shown. The right ascension, the antenna temperature, the observed angular diameter, and the flux density of each component are given in Table 1. The errors given in the table can be somewhat higher in the case of components 2 and 3 because of the difficulties of separating them. The calibration of the antenna and receiver was made using the flux densities of the sources IAU 19N4A, 05N2A, 05S0A, and 18S1A according to Westerhout (1958) with the corrections given by Altenhoff et al. (1960). The atmospheric extinction at λ = 21 cm was taken from these works as well.

scholarly journals Neutral hydrogen in galactic clusters

1959 ◽  
Vol 9 ◽  
pp. 366-369
Author(s):  
F. D. Drake
Keyword(s):  
Spatial Distribution ◽  
Radio Telescope ◽  
Neutral Hydrogen ◽  
Harvard College ◽  
Cluster Emission ◽  
Galactic Clusters ◽  
Maximum Cluster ◽  
Harvard College Observatory ◽  
Right Ascension ◽  
Cluster Frequency

Observations of the neutral hydrogen content of the galactic clusters h and χ Persei, the Pleiades, the cluster in Coma Berenices, Praesepe, and M 67 have been made with the Harvard College Observatory 60-foot radio telescope. The receiver used was the original receiver made by the Ewen Knight Corporation for the Harvard 24-foot radio telescope. The observations were of three kinds: (1) right-ascension drift curves at 50 kc/s bandwidth, with the receiver fixed-tuned to the frequency of maximum cluster emission, if known, or to the frequency given by the cluster optical radial velocity; (2) conventional frequency profiles at the position of maximum cluster radiation; (3) “residual” frequency profiles, where there is significant general galactic radiation at the cluster frequency and position. These data provide the spatial distribution of any H i in the cluster vicinity that is in excess of the general galactic H i, and a frequency profile for this excess hydrogen. Any excess H i found is considered associated with the cluster if it agrees in velocity and position with the optical cluster.

scholarly journals 21 cm Hydrogen-line Survey of the Large Magellanic Cloud. I. Stellar, Nebular, and Neutral Hydrogen Radial Velocities

1964 ◽  
Vol 17 (4) ◽  
pp. 515 ◽  
Author(s):  
RX McGee
Keyword(s):  
Neutral Hydrogen ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Hydrogen Gas ◽  
Radial Velocities ◽  
Recent Survey ◽  
Hydrogen Line ◽  
Line Survey

A recent survey of the neutral hydrogen in the Large Magellanic Cloud with a 14'�5 beam and the 48�channel H�line receiver has afforded an opportunity to compare the radial velocities of a number of optical objects with the radial velocities of the hydrogen gas in their directions.

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

1973 ◽  
Vol 26 (6) ◽  
pp. 837 ◽  
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.

scholarly journals Neutral Hydrogen Gas in Star Forming Galaxies at z=0.24

2007 ◽  
Vol 3 (S244) ◽  
pp. 366-367 ◽  
Author(s):  
Philip Lah ◽  
Jayaram N. Chengalur ◽  
Frank H. Briggs ◽  
Matthew Colless ◽  
Roberto De Propris ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Atomic Hydrogen ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Gas Content ◽  
Star Forming ◽  
Emission Signal ◽  
Neutral Gas

AbstractWe use observations from the Giant Metrewave Radio Telescope (GMRT) to measure the atomic hydrogen gas content of star-forming galaxies at z = 0.24 (i.e. a look-backtime of ~3 Gyr). To measure the HI 21 cm emission signal we stack the signal from 121 galaxies with known optical positions and redshifts. We find an average HI mass for the galaxies of (2.26 ± 0.90) × 109 M⊙. We translate this HI measurement into a cosmic density of neutral gas at z=0.24 of Ωgas = (0.91 ± 0.42) × 10−3. This value is consistent with that estimated from damped Lyα systems around this redshift.

scholarly journals Neutral Hydrogen Gas in the Taurus?Orion Region Observed with a Multichannel 21 cm Line Receiver

1959 ◽  
Vol 12 (2) ◽  
pp. 127 ◽  
Author(s):  
RX McGee ◽  
JD Murray
Keyword(s):  
Line Profile ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Hydrogen Line ◽  
Short Time

A multichannel 21 cm hydrogen line receiver has been developed which is capable of producing a complete line profile in the very short time of 2 min.

scholarly journals A Sky Survey of Neutral Hydrogen at l 21 cm. II. The Detailed Distribution of Low Velocity Gas

1963 ◽  
Vol 16 (1) ◽  
pp. 136 ◽  
Author(s):  
RX McGee ◽  
JD Murray ◽  
Janice A Milton
Keyword(s):  
Radial Velocity ◽  
Line Profile ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Hydrogen Line ◽  
Low Velocity ◽  
Sky Survey

The distributions of intensity and radial velocity of neutral hydrogen gas of low radial velocity are presented in the form of detailed diagrams of T max., the temperature at the peak of a hydrogen line profile, and of the radial velocity value at the Tmax .

scholarly journals A Low Resolution Hydrogen-line Survey of the Magellanic System. I. Observations and Digital Reduction Procedures

1963 ◽  
Vol 16 (4) ◽  
pp. 552 ◽  
Author(s):  
JV Hindman ◽  
RX McGee ◽  
AWL Carter ◽  
ECJ Holmes ◽  
M Beard
Keyword(s):  
Radio Telescope ◽  
Radio Astronomy ◽  
Neutral Hydrogen ◽  
Recording System ◽  
Digital Recording ◽  
Astronomy Observatory ◽  
Hydrogen Line ◽  
Radio Astronomy Observatory ◽  
Line Survey ◽  
Magellanic System

A survey of neutral hydrogen in the Clouds of Magellan has been made using a digital recording system in conjunction with a multichannel receiver and a 21 ft aerial. The system has been developed for use with the 210 ft radio telescope of the Australian National Radio Astronomy Observatory at Parkes, N.S.W.

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