scholarly journals The local standard of rest from data on young objects with account for the Galactic spiral density wave

2014 ◽  
Vol 441 (1) ◽  
pp. 142-149 ◽  
Author(s):  
V. V. Bobylev ◽  
A. T. Bajkova
Keyword(s):  
Density Wave ◽  
Spiral Density Wave ◽  
Local Standard ◽  
Galactic Spiral ◽  
Local Standard Of Rest

scholarly journals Detection of Hα Emission on High Velocity 21 cm Clouds

1990 ◽  
Vol 139 ◽  
pp. 193-198
Author(s):  
Guido Münch ◽  
Eckhart Pitz
Keyword(s):  
High Velocity ◽  
Galactic Latitude ◽  
Emission Rates ◽  
High Galactic Latitude ◽  
Continuum Intensity ◽  
Lyman Continuum ◽  
Local Standard ◽  
Direct Measurements ◽  
Hα Emission ◽  
Local Standard Of Rest

The measurement of Hα emission on two high galactic latitude clouds known to emit 21 cm lines with local standard of rest (LSR) velocities of −50 and −85 km s−1 is reported. The Hα lines have been found nearly at the velocities of the 21 CM features and have emission rates of 0.2 Rayleigh. The diffuse Lyman continuum intensity required to produce HI ionization at the measured rate is in agreement with the direct measurements made with the ultraviolet (UV) spectrometer of the Voyager 2 spacecraft.

scholarly journals The Evolution of Giant Molecular Clouds

1980 ◽  
Vol 87 ◽  
pp. 137-149 ◽  
Author(s):  
Colin Norman ◽  
Joseph Silk
Keyword(s):  
Spatial Distribution ◽  
Star Formation ◽  
Molecular Clouds ◽  
Supernova Remnants ◽  
Density Wave ◽  
Collective Effects ◽  
Giant Molecular Clouds ◽  
Spiral Density Wave ◽  
External Galaxies ◽  
Co Observations

We discuss the origin, lifetime, destruction, spatial distribution and relation to star formation of giant molecular clouds. A coagulation model including the effects of spiral density wave shocks is described. We explore implications for CO observations of external galaxies. The collective effects of OB star winds and supernova remnants in disrupting clouds are considered.

scholarly journals What Happened to Stellar Drifts?

1977 ◽  
Vol 45 ◽  
pp. 275-278
Author(s):  
S.V.M. Clube
Keyword(s):  
Stellar Kinematics ◽  
Solar Motion ◽  
Local Standard ◽  
History Of ◽  
Galactic Astronomy ◽  
The Given ◽  
Local Standard Of Rest

The concepts of a local standard of rest and a standard solar motion and the nature of the data giving rise to these concepts are so much part of the given knowledge of galactic astronomy that it hardly seems possible that anything new might be learnt from continued study of this subject. But the examination of local stellar kinematics is by no means a tidy subject, and the history of its development does conceal one or two peculiarities which bear reconsideration.

A New Halo Survey

1984 ◽  
Vol 88 ◽  
pp. 139-150
Author(s):  
Bruce W. Carney ◽  
David W. Latham
Keyword(s):  
Data Analysis ◽  
Proper Motion ◽  
Preliminary Results ◽  
Halo Stars ◽  
Analysis Methods ◽  
Local Standard ◽  
Data Analysis Methods ◽  
Local Standard Of Rest

AbstractWe describe a new survey of proper motion stars now nearing completion. We briefly discuss the survey’s completeness and our data analysis methods. We present preliminary results for the motion of the Local Standard of Rest (LSR) with respect to the most extreme velocity stars and the possible presence of a metallicity gradient amongst the halo stars.

scholarly journals The kinematics of nearby stars and large-scale radial motion in the Galaxy

1985 ◽  
Vol 106 ◽  
pp. 145-148 ◽  
Author(s):  
S.V.M. Clube
Keyword(s):  
Large Scale ◽  
Radial Motion ◽  
Crucial Importance ◽  
Local Standard ◽  
The Galaxy ◽  
Nearby Stars ◽  
Local Standard Of Rest

The concept of star streams originally due to Kapteyn is revived. It is suggested that the existence of Stream II may have been overlooked, yet it is of crucial importance in specifying the true local standard of rest.

scholarly journals 2D-Galactic chemical evolution: the role of the spiral density wave

2019 ◽  
Vol 490 (1) ◽  
pp. 665-682 ◽  
Author(s):  
M Mollá ◽  
S Wekesa ◽  
O Cavichia ◽  
Á I Díaz ◽  
B K Gibson ◽  
...  
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Formation Rate ◽  
Density Wave ◽  
Spiral Wave ◽  
Elemental Abundance ◽  
Abundance Pattern ◽  
Spiral Density Wave ◽  
Azimuthal Symmetry

ABSTRACT We present a 2D chemical evolution code applied to a Milky Way type Galaxy, incorporating the role of spiral arms in shaping azimuthal abundance variations, and confront the predicted behaviour with recent observations taken with integral field units. To the usual radial distribution of mass, we add the surface density of the spiral wave and study its effect on star formation and elemental abundances. We compute five different models: one with azimuthal symmetry which depends only on radius, while the other four are subjected to the effect of a spiral density wave. At early times, the imprint of the spiral density wave is carried by both the stellar and star formation surface densities; conversely, the elemental abundance pattern is less affected. At later epochs, however, differences among the models are diluted, becoming almost indistinguishable given current observational uncertainties. At the present time, the largest differences appear in the star formation rate and/or in the outer disc (R ≥ 18 kpc). The predicted azimuthal oxygen abundance patterns for t ≤ 2 Gyr are in reasonable agreement with recent observations obtained with VLT/MUSE for NGC 6754.

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