Speckle interferometric observations made with the 6 m telescope of the
Special Astrophysical Observatory of the Russian Academy of Sciences in 2000
revealed the triple nature of the nearby (πHip=51.80±1.74 mas)
low-mass young (≈200 Myr) star GJ 900. The configuration of the triple
system allowed it to be dynamically unstable. Differential photometry performed
from 2000 through 2004 yielded I- and K-band absolute magnitudes and
spectral types for the components to be IA=6.66±0.08,
IB=9.15±0.11, IC=10.08±0.26, KA=4.84±0.08,
KB=6.76±0.20, KC=7.39±0.31, SpA≈K5--K7,
SpB≈M3--M4, SpC≈M5--M6. The ``mass--luminosity''
relation is used to estimate the individual masses of the components:
MA≈0.64M⊙,
MB≈0.21M⊙,
MC≈0.13M⊙. From the observations of the
components relative motion in the period 2000--2006, we conclude that GJ 900 is
a hierarchical triple star with the possible orbital periods
PA−BC≈80 yrs and PBC≈20 yrs. An analysis of the 2MASS
images of the region around GJ 900 leads us to suggest that the system can
include other very-low-mass components.Comment: 7 pages, 5 figure