EDP Sciences
Free access
Volume 484, Number 2, June III 2008
Page(s) 429 - 434
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20078875
Published online 11 March 2008

A&A 484, 429-434 (2008)
DOI: 10.1051/0004-6361:20078875

Improved orbital solution and masses for the very low-mass multiple system LHS 1070

A. Seifahrt1, 2, T. Röll2, R. Neuhäuser2, A. Reiners1, F. Kerber3, H. U. Käufl3, R. Siebenmorgen3, and A. Smette4

1  Universität Göttingen, Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
    e-mail: seifahrt@astro.physik.uni-goettingen.de
2  Universität Jena, Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergässchen 2, 07745 Jena, Germany
3  ESO, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
4  ESO, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19, Chile

Received 19 October 2007 / Accepted 16 February 2008

We present a refined orbital solution for the components A, B, and C of the nearby late-M type multiple system LHS 1070. By combining astrometric datapoints from NACO/VLT, CIAO/SUBARU, and PUEO/CFHT, as well as a radial velocity measurement from the newly commissioned near infrared high-resolution spectrograph CRIRES/VLT, we achieve a very precise orbital solution for the B and C components and a first realistic constraint on the much longer orbit of the A-BC system. Both orbits appear to be co-planar. Masses for the B and C components calculated from the new orbital solution ( $M_{\rm B+C} = 0.157 \pm 0.009~{M_{\odot}}$) are in excellent agreement with theoretical models, but do not match empirical mass-luminosity tracks. The preliminary orbit of the A-BC system reveals no mass excess for the A component, giving no indication for a previously proposed fourth (D) component in LHS 1070.

Key words: astrometry -- stars: binaries -- close, stars: low-mass, brown dwarfs

© ESO 2008