Even though it was discovered more than a decade ago , LSR1610 - 0040 remains an enigma .
This object has a peculiar spectrum that exhibits some features typically found in L subdwarfs , and others common in the spectra of more massive M dwarf stars .
It is also a binary system with a known astrometric orbital solution .
Given the available data , it remains a challenge to reconcile the observed properties of the combined light of LSR1610 - 0040AB with current theoretical models of low-mass stars and brown dwarfs .
We present the results of a joint fit to both astrometric and radial velocity measurements of this unresolved , low-mass binary .
We find that the photocentric orbit has a period P = 633.0 \pm 1.7 days , somewhat longer than previous results , with eccentricity of e = 0.42 \pm 0.03 , and we estimate that the semi-major axis of the orbit of the primary is a _ { 1 } \approx 0.32 AU , consistent with previous results .
While a complete characterization of the system is limited by our small number of radial velocity measurements , we establish a likely primary mass range of 0.09 - 0.10 M _ { \odot } from photometric and color-magnitude data .
For a primary mass in this range , the secondary is constrained to be 0.06 - 0.075 M _ { \odot } , making a negligible contribution to the total I-band luminosity .
This effectively rules out the possibility of the secondary being a compact object such as an old , low-mass white dwarf .
Based on our analysis , we predict a likely angular separation at apoapsis comparable to the resolution limits of current high-resolution imaging systems .
Measuring the angular separation of the A & B components would finally enable a full , unambiguous solution for the masses of the components of this system .