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

We present the discovery of a previously unknown member of the immediate solar neighbourhood, DENIS-P J104814.7-395606.1 thereafter DENIS 1048-39), identified while mining the DENIS database for nerv nearby stars. A HIRES echelle 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 its spectral type and colour (I - J = 3.07), and is therefore very nearby. If it is single its distance is only 4.1 +/- 0.6 pc, ranking it as between our 12th and 40th closest neighbour. It is also the closest star or brown dwarf with a spectral type later than M7V. Its proper motion was deter mined through comparison of Sky atlas Schmidt plates, scanned by the MAMA microdensitometer, with the DENIS images. At 1.52 " yr(-1) it primarily attests: the closeness of DENIS 1048-39 and hence its dwarf status. These characteristics make it an obvious target for further detailed studies.