Extremely Large Telescope

Abstract:

We report the discovery of a bright (f (250 μm)>400 mJy), multiply lensed submillimeter galaxy HERMES J105751.1+573027 in Herschel/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880 μm Submillimeter Array observations resolve at least four images with a large separation of ∼9″. A high-resolution adaptive optics Kp image with Keck/NIRC2 clearly shows strong lensing arcs. Follow-up spectroscopy gives a redshift of z = 2.9575, and the lensing model gives a total magnification of μ ∼ 11 ± 1. The large image separation allows us to study the multi-wavelength spectral energy distribution (SED) of the lensed source unobscured by the central lensing mass. The far-IR/millimeter-wave SED is well described by a modified blackbody fit with an unusually warm dust temperature, 88 ± 3 K. We derive a lensing-corrected total IR luminosity of (1.43 ± 0.09) × 1013 L⊙, implying a star formation rate of ∼2500 M⊙ yr-1. However, models primarily developed from brighter galaxies selected at longer wavelengths are a poor fit to the full optical-to-millimeter SED. A number of other strongly lensed systems have already been discovered in early Herschel data, and many more are expected as additional data are collected. © 2011. The American Astronomical Society. All rights reserved.

Abstract:

We present the discovery of a wide (67AU) substellar companion to the nearby (21pc) young solar-metallicity M1 dwarf CD-35 2722, a member of the ≈100Myr AB Doradus association. Two epochs of astrometry from the NICI Planet-Finding Campaign confirm that CD-35 2722B is physically associated with the primary star. Near-IR spectra indicate a spectral type of L4 ± 1 with a moderately low surface gravity, making it one of the coolest young companions found to date. The absorption lines and near-IR continuum shape of CD-35 2722B agree especially well the dusty field L4.5 dwarf 2MASS J22244381-0158521, while the near-IR colors and absolute magnitudes match those of the 5Myr old L4 planetary-mass companion, 1RXS J160929.1-210524 b. Overall, CD-35 2722B appears to be an intermediate-age benchmark for L dwarfs, with a less peaked H-band continuum than the youngest objects and near-IR absorption lines comparable to field objects. We fit Ames-Dusty model atmospheres to the near-IR spectra and find T eff= 1700-1900K and log(g)= 4.5 ± 0.5. The spectra also show that the radial velocities of components A and B agree to within ±10kms-1, further confirming their physical association. Using the age and bolometric luminosity of CD-35 2722B, we derive a mass of 31 ± 8 M Jup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be overluminous for their near-IR spectral type compared with field objects, in contrast to the underluminosity of young late-L and early-T dwarfs. © 2011. The American Astronomical Society. All rights reserved.