Search Publications
Physical structure of the envelopes of intermediate-mass protostars
Maret, S.; Ceccarelli, C.; Johnstone, D. +11 more
Context. Intermediate mass protostars provide a bridge between low- and high-mass protostars. Furthermore, they are an important component of the UV interstellar radiation field. Despite their relevance, little is known about their formation process.
Aims: We present a systematic study of the physical structure of five intermediate mass, cand…
On the Solar Chromosphere Observed at the LIMB with Hinode
Judge, Philip G.; Carlsson, Mats
Broadband images in the Ca II H line, from the Broadband Filter Imager (BFI) instrument on the Hinode spacecraft, show emission from spicules emerging from and visible right down to the observed limb. Surprisingly, little absorption of spicule light is seen along their lengths. We present formal solutions to the transfer equation for given (ad hoc…
Spectroscopy of z∼ 5 Lyman break galaxies in the ESO Remote Galaxy Survey
Milvang-Jensen, Bo; Bremer, M. N.; Lehnert, M. D. +2 more
We present the global results of a large spectroscopic survey carried out in order to identify z∼ 5 Lyman break galaxies (LBGs) across 10 widely separated ∼45 arcmin2 fields to a depth of IAB= 26.3. The redshifts of seventy 4.6 < z < 5.6 LBGs were identified through their Lyα emission and/or a strong continuum break, wi…
Prediction of uncertainties in atmospheric properties measured by radio occultation experiments
Withers, Paul
Refraction due to gradients in ionospheric electron density, Ne, and neutral number density, nn, can shift the frequency of radio signals propagating through a planetary atmosphere. Radio occultation experiments measure time series of these frequency shifts, from which Ne and nn can be determined. Major …
The physical scale of the far-infrared emission in the most luminous submillimetre galaxies - II. Evidence for merger-driven star formation
Wilner, David J.; Yun, Min S.; Fazio, Giovanni G. +10 more
We present high-resolution 345-GHz interferometric observations of two extremely luminous (Lir >~ 1013 Lsolar), submillimetre-selected galaxies (SMGs) in the Cosmic Evolution Survey (COSMOS) field with the Submillimeter Array (SMA). Both targets were previously detected as unresolved point sources by the SMA in …
Direct Evidence for Gravitational Instability and Moonlet Formation in Saturn's Rings
Cooper, N. J.; Murray, C. D.; Evans, M. W. +3 more
New images from the Cassini spacecraft reveal optically thick clumps, capable of casting shadows, and associated structures in regions of Saturn's F ring that have recently experienced close passage by the adjacent moon Prometheus. Using these images and modeling, we show that Prometheus' perturbations create regions of enhanced density and low re…
The photochemical model of Titan’s atmosphere and ionosphere: A version without hydrodynamic escape
Krasnopolsky, Vladimir A.
There are observational and theoretical evidences both in favor of and against hydrodynamic escape (HDE) on Titan, and the problem remains unsolved. A test presented here for a static thermosphere does not support HDE on Titan and Triton but favors HDE on Pluto. Cooling of the atmosphere by the HCN rotational lines is limited by rotational relaxat…
A 3 km atmospheric boundary layer on Titan indicated by dune spacing and Huygens data
Lorenz, Ralph D.; Radebaugh, Jani; Tokano, Tetsuya +2 more
Some 20% of Titan's surface is covered in large linear dunes that resemble in morphology, size and spacing (1-3 km) those seen on Earth. Although gravity, atmospheric density and sand composition are very different on these two worlds, this coincident size scale suggests that the controlling parameter limiting the growth of giant dunes, namely the…
Discovery of K-Shell Emission Lines of Neutral Atoms in the Galactic Center Region
Koyama, Katsuji; Nobukawa, Masayoshi; Tsuru, Takeshi Go +2 more
The K-shell emission line of neutral iron from the Galactic center (GC) region is one of the keys concerning the structure and activity of the GC. The origin is still an open question, but possibly due either to X-ray radiation or to electron bombarding to neutral atoms. To address this issue, we analyzed the Suzaku X-ray spectrum from the GC regi…
Electron density and temperature measurements in the cold plasma environment of Titan: Implications for atmospheric escape
Dougherty, M. K.; Wahlund, J. -E.; Edberg, N. J. T. +4 more
We present electron temperature and density measurements of Titan's cold ionospheric plasma from the Langmuir probe instrument on Cassini from 52 flybys. An expression of the density as a function of temperature is presented for altitudes below two Titan radii. The density falls off exponentially with increased temperature as log(ne) = …