Search Publications
Keck Laser Guide Star Adaptive Optics Monitoring of 2MASS J15344984-2952274AB: First Dynamical Mass Determination of a Binary T Dwarf
Dupuy, Trent J.; Ireland, Michael J.; Liu, Michael C.
We present multiepoch imaging of the T5.0+T5.5 binary 2MASS J15344984-2952274AB obtained with the Keck laser guide star adaptive optics system. Combined with archival HST imaging, our total data span ~50% of the orbital period. We use a Markov chain Monte Carlo analysis to determine a period of 15.1+ 2.3-1.6 yr and a total ma…
Spectra and anisotropy of magnetic fluctuations in the Earth's magnetosheath: Cluster observations
Alexandrova, O.; Mangeney, A.; Lacombe, C.
We investigate the spectral shape, the anisotropy of the wave vector distributions and the anisotropy of the amplitudes of the magnetic fluctuations in the Earth's magnetosheath within a broad range of frequencies [10-3, 10] Hz which corresponds to spatial scales from ~10 to 105 km. We present the first observations of a Kolm…
Characterizing the Nonthermal Emission of Cassiopeia A
Vink, J.; Helder, E. A.
We report on our analysis of the 1 Ms Chandra observation of the supernova remnant Cas A in order to localize, characterize, and quantify the nonthermal X-ray emission. More specifically, we investigated whether the X-ray synchrotron emission from the inside of the remnant is from the outward shock, but projected toward the inner ring, or from the…
Methane escape from Titan's atmosphere
Yelle, R. V.; Cui, J.; Müller-Wodarg, I. C. F.
Measurements of the mole fractions of CH4 and 40Ar by the Ion Neutral Mass Spectrometer on the Cassini orbiter are analyzed to determine the rate of vertical mixing in Titan's atmosphere and the escape flux of CH4. Analysis of the 40Ar data indicates an eddy mixing rate of 2-5 × 107 cm2
Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode
Warren, Harry P.; Doschek, George A.; Ugarte-Urra, Ignacio +2 more
Previous solar observations have shown that coronal loops near 1 MK are difficult to reconcile with simple heating models. These loops have lifetimes that are long relative to a radiative cooling time, suggesting quasi-steady heating. The electron densities in these loops, however, are too high to be consistent with thermodynamic equilibrium. Mode…
Molecular Gas in a Submillimeter Galaxy at z = 4.5: Evidence for a Major Merger at 1 Billion Years after the Big Bang
Smolčić, V.; Taniguchi, Y.; Yun, M. S. +8 more
We report the detection of CO molecular line emission in the z = 4.5 millimeter-detected galaxy COSMOS J100054+023436 (hereafter J1000+0234) using the IRAM Plateau de Bure interferometer (PdBI) and NRAO's Very Large Array (VLA). The 12CO(4-3) line as observed with PdBI has a full line width of ~1000 km s-1, an integrated line…
Heterogeneous chemistry in the atmosphere of Mars
Montmessin, Franck; Bertaux, Jean-Loup; Perrier, Séverine +6 more
Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide. These processes provide a qualitative explanation for the stability of the atmosphere of Mars, which contains 95 per cent carbon dioxide. Bala…
A SINFONI View of Galaxy Centers: Morphology and Kinematics of Five Nuclear Star Formation-Rings
Böker, Torsten; Schinnerer, Eva; Falcón-Barroso, Jesús +2 more
We present near-infrared (H- and K-band) integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. The data, obtained at the Very Large Telescope with the SINFONI spectrograph, are used to construct maps of various emission lines that reveal the individual star forming regions ("hot spots") delineating t…
IMAGES. I. Strong evolution of galaxy kinematics since z = 1
Cesarsky, C.; Östlin, G.; Yang, Y. +20 more
Nearly half the stellar mass of present-day spiral galaxies has formed since z = 1, and galaxy kinematics is an ideal tool to identify the underlying mechanisms responsible for the galaxy mass assembly since that epoch. Here, we present the first results of the ESO large program, “IMAGES”, which aims at obtaining robust measurements of the kinemat…
A Hubble and Spitzer Space Telescope Survey for Gravitationally Lensed Galaxies: Further Evidence for a Significant Population of Low-Luminosity Galaxies beyond z = 7
Richard, Johan; Smith, Graham P.; Stark, Daniel P. +4 more
We present the results of a systematic search for gravitationally lensed continuum Lyman break "dropouts" beyond a redshift 7 conducted via very deep imaging through six foreground clusters undertaken with the Hubble and Spitzer space telescopes. The survey has yielded 10 z-band and two J-band dropout candidates to photometric limits of J110<…