We obtained deep H- and K-band images of DENIS-P J104814 - 395606 using SofI and the speckle camera SHARP-I at the ESO-3.5m-NTT as well as QUIRC at the Mauna Kea 2.2m telescope between December 2000 and June 2001 .
The target was recently discovered as nearby M9-dwarf among DENIS sources ( Delfosse et al .
2001 ) .
We detect parallactic motion on our images and determine the distance to be 4.6 \pm 0.3 pc , more precise than previously known .
From the available colors , the distance , and the spectral type , we conclude from theoretical models that the star has a mass of \sim 0.075 to 0.09 ~ { } M _ { \odot } and an age of \sim 1 to 2 Gyrs .
We also obtained H- and K-band spectra of this star with ISAAC at the VLT .
A faint companion candidate is detected 6 ^ { \prime \prime } NNW of the star , which is 6.4 \pm 0.5 mag fainter in H. However , according to another image taken several month later , the companion candidate is not co-moving with the M9-dwarf .
Instead , it is a non-moving background object .
Limits for undetected companion candidates are such that we can exclude any stellar companions outside of \sim 0.25 ^ { \prime \prime } ( 1 AU ) , any brown dwarf companions ( above the deuterium burning mass limit ) outside of \sim 2 ^ { \prime \prime } ( 9 AU ) , and also any companion down to \sim 40 M _ { jup } with \geq 0.15 ^ { \prime \prime } ( 0.7 AU ) separation , all calculated for an age of 2 Gyrs .
Our observations show that direct imaging of sub-stellar companions near the deuterium burning mass limit in orbit around nearby ultra-cool dwarfs is possible , even with separations that are smaller than the semi-major axis of the outermost planet in our solar system , namely a few tens of AU .