Astrophys. J., 786, 32 (2014/May-1)
Magellan adaptive optics first-light observations of the exoplanet β Pic b. I. Direct imaging in the far-red optical with MagAO+VisAO and in the near-IR with NICI.
MALES J.R., CLOSE L.M., MORZINSKI K.M., WAHHAJ Z., LIU M.C., SKEMER A.J., KOPON D., FOLLETTE K.B., PUGLISI A., ESPOSITO S., RICCARDI A., PINNA E., XOMPERO M., BRIGUGLIO R., BILLER B.A., NIELSEN E.L., HINZ P.M., RODIGAS T.J., HAYWARD T.L., CHUN M., FTACLAS C., TOOMEY D.W. and WU Y.-L.
Abstract (from CDS):
We present the first ground-based CCD (λ < 1 µm) image of an extrasolar planet. Using the Magellan Adaptive Optics system's VisAO camera, we detected the extrasolar giant planet β Pictoris b in Y-short (YS, 0.985 µm), at a separation of 0.470±0.''010 and a contrast of (1.63±0.49)x10–5. This detection has a signal-to-noise ratio of 4.1 with an empirically estimated upper limit on false alarm probability of 1.0%. We also present new photometry from the Gemini Near-Infrared Coronagraphic Imager instrument on the Gemini South telescope, in CH4S,1%(1.58 µm), KS(2.18 µm), and Kcont(2.27 µm). A thorough analysis of our photometry combined with previous measurements yields an estimated near-IR spectral type of L2.5±1.5, consistent with previous estimates. We estimate log (Lbol/L☉) = -3.86±0.04, which is consistent with prior estimates for β Pic b and with field early-L brown dwarfs (BDs). This yields a hot-start mass estimate of 11.9±0.7 MJup for an age of 21±4 Myr, with an upper limit below the deuterium burning mass. Our Lbol-based hot-start estimate for temperature is Teff= 1643±32 K (not including model-dependent uncertainty). Due to the large corresponding model-derived radius of R = 1.43±0.02 RJup, this Teff is ∼250 K cooler than would be expected for a field L2.5 BD. Other young, low-gravity (large-radius), ultracool dwarfs and directly imaged EGPs also have lower effective temperatures than are implied by their spectral types. However, such objects tend to be anomalously red in the near-IR compared to field BDs. In contrast, β Pic b has near-IR colors more typical of an early-L dwarf despite its lower inferred temperature.
brown dwarfs - instrumentation: adaptive optics - planetary systems - planets and satellites: detection - planets and satellites: individual: Pictoris b - stars: individual: a Pictoris
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