Numerical simulations of the dynamical friction suffered by a star cluster near the Galactic center have been performed with a parallelized tree code .
Gerhard ( 2001 ) has suggested that dynamical friction , which causes a cluster to lose orbital energy and spiral in towards the galactic center , may explain the presence of a cluster of very young stars in the central parsec , where star formation might be prohibitively difficult owing to strong tidal forces .
The clusters modeled in our simulations have an initial total mass of 10 ^ { 5 } – 10 ^ { 6 } { M _ { \odot } } and initial galactocentric radii of 2.5–30 pc .
We have identified a few simulations in which dynamical friction indeed brings a cluster to the central parsec , although this is only possible if the cluster is either very massive ( \sim 10 ^ { 6 } { M _ { \odot } } ) , or is formed near the central parsec ( \lesssim 5 pc ) .
In both cases , the cluster should have an initially very dense core ( > 10 ^ { 6 } { M _ { \odot } } pc ^ { - } 3 ) .
The initial core collapse and segregation of massive stars into the cluster core , which typically happens on a much shorter time scale than that characterizing the dynamical inspiral of the cluster toward the Galactic center , can provide the requisite high density .
Furthermore , because it is the cluster core which is most likely to survive the cluster disintegration during its journey inwards , this can help account for the observed distribution of presumably massive He I stars in the central parsec .