Fractional part of rational power arbitrary small
I think that the wolfram link cited the first result (Vijayaraghavan 1941) incorrectly where it reports that
$\{ (3/2)^n \}$ has infinitely many accumulation points in both $[0, 1/2)$ and $[1/2, 1]$.
The first result actually is
$\{ (3/2)^n \}$ has infinitely many accumulation points in $[0,1]$.
The second result cited by wolfram is by Flatto, Lagarias, Pollington (1995) which is available here: http://matwbn.icm.edu.pl/ksiazki/aa/aa70/aa7023.pdf. In the introduction of this paper by them, it reports that
Vijayaraghavan later remarked that it was striking that one could not even decide whether or not $(3/2)^n$ mod $1$ has infinitely many limit points in $[0, 1/2)$ or in $[1/2, 1)$.
This paper proved that
$$\limsup\{ (3/2)^n \} - \liminf \{(3/2)^n\} \geq \frac13. $$
A few later results are mentioned (Dubickas 2006, 2008) in Yann Bugeaud's book "Distribution Modulo One and Diophantine Approximation" (for example, p. xi, p. 67 and p. 68).
$\{ (3/2)^n \}$ has a limit point in $[0.238117 . . . , 0.761882 . . .]$ which has length $0.523764 . . .$.
$\{(3/2)^n\}$ has a limit point in $[0, 8/39] \cup [18/39, 21/39] \cup [31/39, 1]$, of total length $19/39$.
I will show that if $a = 1+\sqrt{2}$ then the limit points of $\{a^n\}$ are $0$ and $1$.
I know that this doesn't tell anything about rational $a$, but this might be of use.
Note that this method can show this for $a$ and $b$ roots of $x^2-2ux-v = 0$ where $u$ and $v$ are positive integers such that $v < 2u+1$. This case is $u=v=1$; $u=1, v=2$ also works.
If $a = \sqrt{2}+1$ and $b = 1-\sqrt{2}$ then $ab = -1$ and $a+b = 2$.
Therefore $a$ and $b$ are the roots of $x^2-2x-1 = 0$.
If $u_n = a^n+b^n$, then $u_0 = 2, u_1 = 2$.
Since $a^{n+2} =a^n(a^2) =a^n(2a+1) =2a^{n+1}+a^n$ and similarly for $b$,
$\begin{array}\\ u_{n+2} &=a^{n+2}+b^{n+2}\\ &=2a^{n+1}+a^n+2b^{n+1}+b^n\\ &=2u_{n+1}+u_n\\ \end{array} $
Therefore $u_n$ is a positive integer for all $n$.
Since $|b| < 1$, $|b^n| \to 0$.
Since $b < 0$, $b^{2n} > 0$ and $b^{2n+1} < 0$.
Therefore, since $a^n = u_n - b^n$, $\{a^{2n}\} =\{u_{2n}-b^{2n}\} =1-b^{2n} $ so $\{a^{2n}\} \to 1 $ and $\{a^{2n+1}\} =\{u_{2n+1}-b^{2n+1}\} =\{u_{2n+1}+|b^{2n+1}\} =|b^{2n+1}| $ so $\{a^{2n+1}\} \to 0 $.
Therefore the limits points of $\{a^n\}$ are $0$ and $1$.