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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 710146.0, MPI für Astronomie / Publikationen_mpia
Magellan Adaptive Optics first-light observations of the exoplanet b Pic B. I. Direct imaging in the far-red optical with MagAO+VisAO and in the Near-IR with NICI
Authors: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.; Wu, Y.-L.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:The Astrophysical Journal
Issue / Number:1
Start Page:id. 32 (22 pp)
Audience:Not Specified
Abstract / Description:We present the first ground-based CCD (lambda < 1 mum) image of an extrasolar planet. Using the Magellan Adaptive Optics system's VisAO camera, we detected the extrasolar giant planet beta Pictoris b in Y-short (YS , 0.985 mum), at a separation of 0.470 ± 0.''010 and a contrast of (1.63 ± 0.49) × 10-5. 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 CH 4S,1% (1.58 mum), KS (2.18 mum), and K cont (2.27 mum). 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 (L bol/L &sun;) = -3.86 ± 0.04, which is consistent with prior estimates for beta Pic b and with field early-L brown dwarfs (BDs). This yields a hot-start mass estimate of 11.9 ± 0.7 M Jup for an age of 21 ± 4 Myr, with an upper limit below the deuterium burning mass. Our L bol-based hot-start estimate for temperature is T eff = 1643 ± 32 K (not including model-dependent uncertainty). Due to the large corresponding model-derived radius of R = 1.43 ± 0.02 R Jup, this T eff 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, beta Pic b has near-IR colors more typical of an early-L dwarf despite its lower inferred temperature.
Free Keywords:brown dwarfs; instrumentation: adaptive optics; planetary systems; planets and satellites: detection; planets and satellites: individual: beta Pictoris b; stars: individual: beta Pictoris
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.1088/0004-637X/786/1/32
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