ON THE ORIGIN OF HIGH-ALTITUDE OPEN CLUSTERS IN THE MILKY WAY

ABSTRACT We present a dynamical study of the effect of the bar and spiral arms on the simulated orbits of open clusters in the Galaxy. Specifically, this work is devoted to the puzzling presence of high-altitude open clusters in the Galaxy. For this purpose we employ a very detailed observationally...

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Published inAstrophysical journal. Letters Vol. 817; no. 1; pp. 1 - 6
Main Authors Martinez-Medina, L. A., Pichardo, B., Moreno, E., Peimbert, A., Velazquez, H.
Format Journal Article
LanguageEnglish
Published United States The American Astronomical Society 20.01.2016
Subjects
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHAOS THEORY
CLASSIFICATION
COMPARATIVE EVALUATIONS
Computer simulation
CONCENTRATION RATIO
DIFFUSION
Galactic structure
Galaxies
galaxies: kinematics and dynamics
galaxies: spiral
galaxies: structure
MASS
Mathematical models
MILKY WAY
Milky Way Galaxy
Open clusters
open clusters and associations: general
ORBITS
Planes
STAR CLUSTERS
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Summary:ABSTRACT We present a dynamical study of the effect of the bar and spiral arms on the simulated orbits of open clusters in the Galaxy. Specifically, this work is devoted to the puzzling presence of high-altitude open clusters in the Galaxy. For this purpose we employ a very detailed observationally motivated potential model for the Milky Way and a careful set of initial conditions representing the newly born open clusters in the thin disk. We find that the spiral arms are able to raise an important percentage of open clusters (about one-sixth of the total employed in our simulations, depending on the structural parameters of the arms) above the Galactic plane to heights beyond 200 pc, producing a bulge-shaped structure toward the center of the Galaxy. Contrary to what was expected, the spiral arms produce a much greater vertical effect on the clusters than the bar, both in quantity and height; this is due to the sharper concentration of the mass on the spiral arms, when compared to the bar. When a bar and spiral arms are included, spiral arms are still capable of raising an important percentage of the simulated open clusters through chaotic diffusion (as tested from classification analysis of the resultant high-z orbits), but the bar seems to restrain them, diminishing the elevation above the plane by a factor of about two.
Bibliography:LET33439
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ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8205/817/1/L3