Identification of active star formation regions in the galactic plane

1982 ◽  
Vol 259 ◽  
pp. 664
Author(s):  
A. G. Ananth ◽  
B. V. Nagaraja
Keyword(s):  
Star Formation ◽  
Galactic Plane ◽  
Active Star ◽  
Active Star Formation ◽  
Star Formation Regions

scholarly journals Star Formation Thresholds in Low Surface Brightness Dwarf Galaxies

1999 ◽  
Vol 171 ◽  
pp. 274-281
Author(s):  
Liese van Zee
Keyword(s):  
Star Formation ◽  
Comparative Study ◽  
Column Density ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Critical Threshold ◽  
Active Star ◽  
Comparison Sample ◽  
Active Star Formation ◽  
Low Surface Brightness

AbstractThe results of a comparative study of star formation thresholds in gas-rich, low surface brightness, dwarf galaxies are presented. Approximately half the galaxies in the study were “high MH/LB” galaxies, which appear to have inefficient star formation properties. The comparison sample comprised of otherwise “normal” dwarf galaxies, with moderate current star formation rates. In all systems, sites of active star formation were associated with local peaks in the HI column density. For both types of galaxies, the azimuthally averaged gas column density is low. Similar to other LSB systems, the global gas densities are well below the critical threshold for star formation throughout the system. Thus, star formation is inhibited globally, but occurs locally in these gas-rich dwarf galaxies.

scholarly journals Lithium Abundance and Spacial Distribution of T Tauri Stars

1992 ◽  
Vol 150 ◽  
pp. 395-397
Author(s):  
Jane Gregorio-Hetem ◽  
Jacques R.D. Lépine
Keyword(s):  
Star Formation ◽  
Equivalent Width ◽  
Molecular Cloud ◽  
Resonance Line ◽  
T Tauri Stars ◽  
Lithium Abundance ◽  
Active Star ◽  
T Tauri ◽  
Star Formation Regions ◽  
Line Equivalent Width

We determined temperatures and Lithium 6707 A resonance line equivalent width of a sample of 62 T Tauri stars. Lithium abundances were then estimated by using a grid of curves of growth. The lithium abundance is shown to decrease with the distance of the stars to the nearest dense core of a molecular cloud. This effect is interpreted as being due to the ages of the stars, the youngest ones being closer to still active star formation regions.

scholarly journals Ammonia towards dust clumps in the giant molecular cloud associated with RCW 106

2012 ◽  
Vol 8 (S292) ◽  
pp. 50-50
Author(s):  
Vicki Lowe ◽  
Maria R. Cunningham ◽  
James S. Urquhart ◽  
Shinji Horiuchi
Keyword(s):  
Star Formation ◽  
Radio Telescope ◽  
Molecular Cloud ◽  
Galactic Plane ◽  
High Mass ◽  
Mass Star ◽  
Giant Molecular Clouds ◽  
Molecular Line ◽  
Star Forming ◽  
Star Formation Regions

AbstractHigh-mass stars are known to be born within giant molecular clouds (GMCs); However, the exact processes involved in forming a high-mass star are still not well understood. It is clear that high-mass stars do not form in isolation, and that the processes surrounding high-mass star formation may affect the environment of the entire molecular cloud. We are studying the GMC associated with RCW 106 (G333), which is one of the most active massive-star formation regions in the Galactic plane. This GMC, located at l = 333° b = − 0.5°, has been mapped in over 20 molecular line transitions with the Mopra radio telescope (83-110 GHz), in Australia, and with the Swedish-ESO Submillimeter Telescope (SEST) in the 1.2 mm cool dust continuum. The region is also within the Spitzer GLIMPSE infrared survey (3.6, 4.5, 5.8, and 8.0 μm) area. We have decomposed the dust continuum using a clump-finding algorithm (CLUMPFIND), and are using the multiple molecular line traditions from the Mopra radio telescope to classify the type and stage of star formation taking place therein. Having accurate physical temperatures of the star forming clumps is essential to constrain other parameters to within useful limits. To achieve this, we have obtained pointed NH3 observations from the Tidbinbilla 70-m radio telescope, in Australia, towards these clumps.

scholarly journals Physical and chemical properties of the AFGL 333 cloud

2006 ◽  
Vol 2 (S237) ◽  
pp. 471-471
Author(s):  
Takeshi Sakai ◽  
Tomoharu Oka ◽  
Satoshi Yamamoto
Keyword(s):  
Star Formation ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Active Star ◽  
Active Star Formation ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractWe have found massive clumps without any sign of active star formation in the AFGL 333 cloud. We present a study of the physical and chemical properties of the AFGL 333 cloud.

Regions of active star formation in O associations. I

Astrophysics ◽  
1991 ◽  
Vol 33 (1) ◽  
pp. 319-324
Author(s):  
A. V. Oskanyan
Keyword(s):  
Star Formation ◽  
Active Star ◽  
Active Star Formation

Regions of active star formation in O associations. II

Astrophysics ◽  
1991 ◽  
Vol 33 (2) ◽  
pp. 447-453
Author(s):  
A. V. Oskanyan
Keyword(s):  
Star Formation ◽  
Active Star ◽  
Active Star Formation

scholarly journals Sub-Millimeter Spectral Line Observations in Very Dense Regions

1987 ◽  
Vol 115 ◽  
pp. 173-173
Author(s):  
Neal J. Evans ◽  
Lee G. Mundy ◽  
John H. Davis ◽  
Paul Vanden Bout
Keyword(s):  
Star Formation ◽  
Spectral Line ◽  
Millimeter Wave ◽  
Volume Density ◽  
High Density ◽  
Active Star ◽  
Millimeter Wavelengths ◽  
Active Star Formation ◽  
Very High

In a search for very high density (n ≳ 107 cm−3) regions, the Millimeter Wave Observatory 5-m telescope was used to observe several submillimeter lines. The regions studied were Orion A, M17, S140, and NGC2024. The lines were CS(J=7-6), H2CO(JK-1K1=515→414), and HCN(J=4-3). These data are combined with data at millimeter wavelengths to derive the volume density and the results are compared to those deduced from millimeter lines alone (Snell et al. 1984). In NGC2024, higher densities (≳ 107 cm−3) are clearly indicated by the sub-mm lines than were derived by Snell et al. In M17, derived densities are also higher, but uncertainties overlap the Snell et al. solutions. The range of densities derived from CS and HCN are consistent. The sub-millimeter lines of these species appear to be good probes of the highest densities present in regions of active star formation.

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