SCExAO AND GPI Y JH BAND PHOTOMETRY AND INTEGRAL FIELD SPECTROSCOPY OF THE YOUNG BROWN DWARF COMPANION TO HD 1160

We present high signal-to-noise ratio, precise Y JH photometry and Y band (0.957–1.120 μm) spectroscopy of HD 1160 B, a young substellar companion discovered from the Gemini NICI Planet Finding Campaign using the Subaru Coronagraphic Extreme Adaptive Optics instrument and the Gemini Planet Imager. HD 1160 B has typical mid-M dwarf-like infrared colors and a spectral type of M5.5 , where the blue edge of our Y band spectrum rules out earlier spectral types. Atmospheric modeling suggests HD 1160 B has an effective temperature of 3000–3100 K, a surface gravity of log g = 4–4.5, a radius of 1.55 ± 0.10 RJ, and a luminosity of log L/L⊙ = −2.76 ± 0.05. Neither the primary’s Hertzspring–Russell diagram position nor atmospheric modeling of HD 1160 B show evidence for a subsolar metallicity. Interpretation of the HD 1160 B spectroscopy depends on which stellar system components are used to estimate the age. Considering HD 1160 A, B and C jointly, we derive an age of 80–125 Myr, implying that HD 1160 B straddles the hydrogen-burning limit (70–90 MJ). If we consider HD 1160 A alone, younger ages (20–125 Myr) and a brown dwarf-like mass (35–90 MJ) are possible. Interferometric measurements of the primary, a precise Gaia parallax, and moderate-resolution spectroscopy can better constrain the system’s age and how HD 1160 B fits within the context of (sub)stellar evolution.