New neighbours: II. An M9 dwarf at d similar to 4 pc, DENIS-P J104814.7-395606.1

We present the discovery of a previously unknown member of the immediate so lar neighbourhood, DENIS-P J104814.7-395606.1 thereafter DENIS 1048-39), id entified while mining the DENIS database for nerv nearby stars. A HIRES ech elle spectrum obtained with the 10-m Keck telescope shows that it is an MS dwarf. DENIS 1048-39 has a very bright apparent magnitude (I = 12.67) for i ts spectral type and colour (I - J = 3.07), and is therefore very nearby. I f it is single its distance is only 4.1 +/- 0.6 pc, ranking it as between o ur 12th and 40th closest neighbour. It is also the closest star or brown dw arf with a spectral type later than M7V. Its proper motion was deter mined through comparison of Sky atlas Schmidt plates, scanned by the MAMA microde nsitometer, with the DENIS images. At 1.52 " yr(-1) it primarily attests: t he closeness of DENIS 1048-39 and hence its dwarf status. These characteris tics make it an obvious target for further detailed studies.