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X-Ray Properties of Protostars in the Orion Nebula
Robberto, M.; Grosso, N.; Micela, G. +8 more
The origin and evolution of the X-ray emission in very young stellar objects (YSOs) are not yet well understood because it is very hard to observe YSOs in the protostellar phase. Using COUP data, we study the X-ray properties of stars in the ONC in different evolutionary classes: luminosities, hydrogen column densities NH, effective pla…
Transverse Oscillations of Flowing Prominence Threads Observed with Hinode
Oliver, R.; Ballester, J. L.; Terradas, J. +1 more
Recent observations with the Hinode Solar Optical Telescope display an active region prominence whose fine threads oscillate in the vertical direction as they move along a path parallel to the photosphere. A seismological analysis of this event is carried out by taking advantage of the small radius of these structures compared to the total length …
X-ray emission from dense plasma in classical T Tauri stars: hydrodynamic modeling of the accretion shock
Orlando, S.; Peres, G.; Reale, F. +3 more
Context: High spectral resolution X-ray observations of classical T Tauri stars (CTTSs) demonstrate the presence of plasma at temperature T∼ 2-3× 106 K and density n_e∼ 1011-1013 cm-3, which are unobserved in non-accreting stars. Stationary models suggest that this emission is due to shock-heated accreti…
The Nascent Red Sequence at z ~ 2
Demarco, R.; Pentericci, L.; Rosati, P. +12 more
We present new constraints on the evolution of the early-type galaxy color-magnitude relation (CMR) based on deep near-infrared imaging of a galaxy protocluster at z = 2.16 obtained using NICMOS on board the Hubble Space Telescope. This field contains a spectroscopically confirmed space overdensity of Lyα- and Hα-emitting galaxies that surrounds t…
Mass and gas profiles in A1689: joint X-ray and lensing analysis
Lemze, Doron; Rephaeli, Yoel; Barkana, Rennan +1 more
We carry out a comprehensive joint analysis of high-quality HST/ACS and Chandra measurements of A1689, from which we derive mass, temperature, X-ray emission and abundance profiles. The X-ray emission is smooth and symmetric, and the lensing mass is centrally concentrated indicating a relaxed cluster. Assuming hydrostatic equilibrium we deduce a 3…
Realistic Numerical Simulations of Solar Convection and Oscillations in Magnetic Regions
Kosovichev, A. G.; Mansour, N. N.; Jacoutot, L. +1 more
We have used 3D, compressible, nonlinear radiative magnetohydrodynamics simulation to study the influence of magnetic fields of various strengths on convective cells and on the excitation mechanisms of acoustic oscillations by calculating the spectral properties of the convective motions and oscillations. The results reveal substantial changes of …
Main-Sequence Fitting Distance to the σ Ori Cluster
Walter, F. M.; Wolk, S. J.; Sherry, W. H. +1 more
The σ Ori cluster is an unbound aggregate of a few hundred young, low-mass stars centered on the multiple system σ Ori. This cluster is of great interest because it is at an age when roughly half of the stars have lost their protoplanetary disks, and the cluster has a very large population of brown dwarfs. One of the largest sources of uncertainty…
The hydrogen-deficient knot of the `born-again' planetary nebula Abell 58 (V605 Aql)
Barlow, M. J.; Liu, X. -W.; De Marco, O. +3 more
We have analysed deep optical spectra of the `born-again' planetary nebula Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent a nova-like eruption in 1919. Our analysis shows that the extinction towards the central knot is much higher than previously thought, with c(Hβ) = 2.0. The outer nebula is less reddened, with c(…
VLT-VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies. I. The sample and first results
Colina, L.; Monreal-Ibero, A.; Arribas, S. +3 more
Context: (Ultra)Luminous Infrared Galaxies [(U)LIRGs] are much more numerous at cosmological distances than locally, and are likely the precursors of elliptical galaxies. Studies of the physical structure and kinematics of representative samples of these galaxies at low redshift are needed in order to understand the interrelated physical processes…
Enceladus: An estimate of heat flux and lithospheric thickness from flexurally supported topography
Neukum, Gerhard; Thomas, Peter C.; Hussmann, Hauke +4 more
We have identified flexural uplift along a rift zone of the Harran Sulci, Enceladus, using Cassini images and stereo-derived topography. On the assumption that the upraised topography is related to a flexed elastic plate, shape modeling yields an effective lithospheric thickness of 0.3 km and, combined with the strength envelope, a mechanical lith…