On the structure of Small Magellanic Cloud star clusters. (arXiv:2101.03157v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Piatti_A/0/1/0/all/0/1">Andrés E. Piatti</a>
It has been recently shown from observational data sets the variation of
structural parameters and internal dynamical evolution of star clusters in the
Milky Way and in the Large Magellanic Cloud (LMC), caused by the different
gravitational field strengths that they experience. We report here some hints
for such a differential tidal effects in structural parameters of star clusters
in the Small Magellanic Cloud (SMC), which is nearly 10 times less massive than
the LMC. A key contribution to this study is the consideration of the SMC as a
triaxial spheroid, from which we estimate the deprojected distances to the SMC
center of the statistically significant sample of star clusters analyzed. By
adopting a 3D geometry of the SMC, we avoid the spurious effects caused by
considering that a star cluster observed along the line-of-sight is close to
the galaxy center. When inspecting the relationships between the star cluster
sizes (represented by the 90% light radii), their eccentricities, masses and
ages with the deprojected distances, we find: (i) the star cluster sizes are
not visibly affected by tidal effects, because relatively small and large
objects are spread through the SMC body. (ii) Star clusters with large
eccentricities (> 0.4) are preferentially found located at deprojected
distances smaller than $sim$ 7-8 kpc, although many star clusters with smaller
eccentricities are also found occupying a similar volume. (iii) Star clusters
more massive than log(M /Mo) $sim$ 4.0 are among the oldest star clusters,
generally placed in the outermost SMC region and with a relative small level of
flattening. These findings contrast with the more elongated, generally younger,
less massive and innermost star clusters.
It has been recently shown from observational data sets the variation of
structural parameters and internal dynamical evolution of star clusters in the
Milky Way and in the Large Magellanic Cloud (LMC), caused by the different
gravitational field strengths that they experience. We report here some hints
for such a differential tidal effects in structural parameters of star clusters
in the Small Magellanic Cloud (SMC), which is nearly 10 times less massive than
the LMC. A key contribution to this study is the consideration of the SMC as a
triaxial spheroid, from which we estimate the deprojected distances to the SMC
center of the statistically significant sample of star clusters analyzed. By
adopting a 3D geometry of the SMC, we avoid the spurious effects caused by
considering that a star cluster observed along the line-of-sight is close to
the galaxy center. When inspecting the relationships between the star cluster
sizes (represented by the 90% light radii), their eccentricities, masses and
ages with the deprojected distances, we find: (i) the star cluster sizes are
not visibly affected by tidal effects, because relatively small and large
objects are spread through the SMC body. (ii) Star clusters with large
eccentricities (> 0.4) are preferentially found located at deprojected
distances smaller than $sim$ 7-8 kpc, although many star clusters with smaller
eccentricities are also found occupying a similar volume. (iii) Star clusters
more massive than log(M /Mo) $sim$ 4.0 are among the oldest star clusters,
generally placed in the outermost SMC region and with a relative small level of
flattening. These findings contrast with the more elongated, generally younger,
less massive and innermost star clusters.
http://arxiv.org/icons/sfx.gif
