Search Publications
Dark Matter Scaling Relations and the Assembly Epoch of Coma Early-Type Galaxies
Saglia, R. P.; Thomas, D.; Thomas, J. +5 more
Axisymmetric, orbit-based dynamical models are used to derive dark matter scaling relations for Coma early-type galaxies. From faint to bright galaxies, halo core radii and asymptotic circular velocities increase. Compared to spirals of the same brightness, the majority of Coma early-type galaxies—those with old stellar populations—have similar ha…
Magnetic flux emergence into the solar photosphere and chromosphere
Moreno-Insertis, F.; Tortosa-Andreu, A.
Aims: We model the emergence of magnetized plasma across granular convection cells and the low atmosphere, including layers up to the mid-chromosphere.
Methods: Three-dimensional numerical experiments are carried out in which the equations of MHD and radiative transfer are solved self-consistently. We use the MURaM code, which assumes local th…
Evidence of Magnetic Helicity in Emerging Flux and Associated Flare
Aulanier, G.; Schmieder, B.; Malherbe, J. M. +1 more
The aim of this paper is to look at the magnetic helicity structure of an emerging active region and show that both emergence and flaring signatures are consistent with a same sign for magnetic helicity. We present a multiwavelength analysis of an M1.6 flare occurring in the NOAA active region 10365 on 27 May 2003, in which a large new bipole emer…
Dynamical Constraints on the Masses of the Nuclear Star Cluster and Black Hole in the Late-Type Spiral Galaxy NGC 3621
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E. +2 more
NGC 3621 is a late-type (Sd) spiral galaxy with an active nucleus, previously detected through mid-infrared [Ne V] line emission. Archival Hubble Space Telescope (HST) images reveal that the galaxy contains a bright and compact nuclear star cluster. We present a new high-resolution optical spectrum of this nuclear cluster, obtained with the Echell…
WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components
Lee, C. -U.; Lähteenmäki, A.; Umana, G. +66 more
Context: BL Lacertae is the prototype of the blazar subclass named after it. Yet, it has occasionally shown a peculiar behaviour that has questioned a simple interpretation of its broad-band emission in terms of synchrotron plus synchrotron self-Compton (SSC) radiation.
Aims: In the 2007-2008 observing season we carried out a new multiwaveleng…
Gravitational potential and X-ray luminosities of early-type galaxies observed with XMM-Newton and Chandra
Matsushita, K.; Nagino, R.
Aims: We study the dark matter content in early-type galaxies and investigate whether X-ray luminosities of early-type galaxies are determined by the surrounding gravitational potential.
Methods: We derived gravitational mass profiles of 22 early-type galaxies observed with XMM-Newton and Chandra.
Results: Sixteen galaxies show constant or…
Latitude dependence of Martian pedestal craters: Evidence for a sublimation-driven formation mechanism
Head, James W.; Kadish, Seth J.; Barlow, Nadine G.
We report on the results of a survey to document and characterize pedestal craters on Mars equatorward of ∼60°N and 65°S latitude. The identification of 2696 pedestal craters reveals a strong latitude dependence, with the vast majority found poleward of 33°N and 40°S. This latitudinal extent is correlated with many climate indicators consistent wi…
A binary merger model for the formation of the Supernova 1987A triple-ring nebula
Podsiadlowski, Ph.; Morris, T.
We examine a binary merger model for the formation of the mysterious triple-ring nebula surrounding Supernova 1987A, which still has not been convincingly explained in detailed hydrodynamical calculations. During the merger of 15 and 5Msolar binary systems, mass is ejected primarily at mid-latitudes for a sufficiently evolved primary, a…
An intermediate black hole spin in the NLS1 galaxy SWIFT J2127.4+5654: chaotic accretion or spin energy extraction?
de Rosa, A.; Vaughan, S.; Fabian, A. C. +5 more
We have observed the hard X-ray selected Narrow-Line Seyfert 1 galaxy SWIFT J2127.4+5654 with Suzaku. We report the detection of a broad relativistic iron emission line from the inner accretion disc. Partial covering by either neutral or partially ionized gas cannot reproduce the spectral shape and, even if its presence is assumed, it does not sig…
A solar storm observed from the Sun to Venus using the STEREO, Venus Express, and MESSENGER spacecraft
Coates, A. J.; Winningham, J. D.; Frahm, R. A. +23 more
The suite of SECCHI optical imaging instruments on the STEREO-A spacecraft is used to track a solar storm, consisting of several coronal mass ejections (CMEs) and other coronal loops, as it propagates from the Sun into the heliosphere during May 2007. The 3-D propagation path of the largest interplanetary CME (ICME) is determined from the observat…