Correlation of HI shells and CO clumps in the outer Milky Way

An automatic identification of HI shells in the 2nd and 3rd Galactic Quadrants

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307001275 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 91-95

Author(s):

Soňa Ehlerová

Keyword(s):

Size Distribution ◽

Power Law ◽

Radial Distribution ◽

Milky Way ◽

Hii Regions ◽

Automatic Identification ◽

Automatic Method ◽

Hi Shells ◽

Scale Length

AbstractWe briefly discuss different methods used to identify HI shells in TB datacubes. Then we give results for our automatic method applied to LDS and LAB HI surveys of the Milky Way (2nd and 3rd quadrants). We fit the radial distribution of HI shells (the exponential profile with the scale length of 3 kpc) and the size distribution (the power law with the index of 2.1). We compare the distribution of identified HI shells with HII regions and study the differences between identifications in the 2nd and 3rd quadrants.

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GS242-03+37: a lucky survivor in the galactic gravitational field

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832918 ◽

2018 ◽

Vol 619 ◽

pp. A101 ◽

Cited By ~ 2

Author(s):

S. Ehlerová ◽

J. Palouš

Keyword(s):

Star Formation ◽

Milky Way ◽

Star Clusters ◽

Young Star ◽

Stellar Winds ◽

Supernova Explosions ◽

High Velocity Clouds ◽

Shell Approximation ◽

Hi Shells ◽

Young Star Clusters

Context. HI shells and supershells, found in discs of many galaxies including our own, are formed by the activity of young and massive stars (supernova explosions and stellar winds), but the formation of these structures may be linked to other energetic events, such as interactions of high-velocity clouds with the galactic disc. The larger structures in particular significantly influence their surroundings; their walls are often places where molecular clouds reside and where star formation happens. Aims. We explore the HI supershell GS242-03+37, a large structure in the outer Milky Way. Its size and position make it a good case for studying the effects of large shells on their surrounding. Methods. We perform numerical simulations of the structure with the simplified hydrodynamical code RING, which uses the thin-shell approximation. The best fit is found by a comparison with the HI data and then we compare our model with the distribution of star clusters near this supershell. Results. The best model of GS242-03+37 requires, contrary to previous estimates, a relatively low amount of energy, and it has an old age of ∼100 Myr. We also find that the distribution of young star clusters (with ages <120 Myr) is correlated with walls of the supershell, while the distribution of older clusters is not. Clusters that have the highest probability of being born in the wall of the supershell show an age sequence along the wall. Conclusions. GS242-03+37 is a relatively old structure, shaped by the differential rotation, and its wall is a birthplace of several star clusters. The star formation started at a time when the supershell was not already supersonically expanding; it was a result of the density increase due to the galactic shear and oscillations perpendicular to the disc of the Milky Way.

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Continuum observations of the Milky Way

Symposium - International Astronomical Union ◽

10.1017/s0074180900101019 ◽

1967 ◽

Vol 31 ◽

pp. 235 ◽

Cited By ~ 1

Author(s):

F. J. Kerr

Keyword(s):

Milky Way

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Variation of the amount of hydrogen along the galactic ridge

Symposium - International Astronomical Union ◽

10.1017/s0074180900100889 ◽

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.

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