WISE J061213.85-303612.5: a new T-dwarf binary candidate

摘要: T and Y-dwarfs are among the coolest least luminous objects detected, they can help to understand properties of giant planets. Their multiplicity shed light on formation process. We observed a sample six dwarfs one L9 dwarf with Laser Guide Star (LGS) NAOS-CONICA, adaptive optics (AO) facility, near infrared camera at ESO Very Large Telescope. From seven objects, we have identified subarcsecond binary system, WISE J0612-3036, composed two similar components spectral types T6. measure separation $\rho$ = 350$\pm$5 mas position angle $PA 235\pm1^{\circ}$. Using mean absolute magnitudes T6 in 2MASS $JHK_s$ bands, estimate distance $d$=31$\pm$6 pc derive projected 11$\pm$2 au. Another target, J2255-3118, shows very faint object 1.3 arcsec $K_{\rm s}$ image. The is marginally detected $H$, color $H-K_{\rm s}$$>$ 0.1\,mag. $HST/WFC3$ public archival data reveals that companion candidate an extended source.Together derived color, this suggests source most probably background galaxy. five other sources apparently single, 3-$\sigma$ sensitivity limits between $H$=19-21 for companions separations $\geq$ 0.5 arcsec. 0612-3036 new T-dwarf dwarfs. As case late binaries, it mass ratio close 1, although its separation, $\sim$11 au, larger than average ($\sim$ 5 au). Additional observations needed confirm system bound.