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The Hubble Space Telescope Cluster Supernova Survey. VI. The Volumetric Type Ia Supernova Rate
Gladders, M. D.; Panagia, N.; Huang, X. +41 more
We present a measurement of the volumetric Type Ia supernova (SN Ia) rate out to z ~= 1.6 from the Hubble Space Telescope Cluster Supernova Survey. In observations spanning 189 orbits with the Advanced Camera for Surveys we discovered 29 SNe, of which approximately 20 are SNe Ia. Twelve of these SNe Ia are located in the foregrounds and background…
Deep Chandra observation of the galaxy cluster WARPJ1415.1+3612 at z =1 . An evolved cool-core cluster at high redshift
Tozzi, P.; Rosati, P.; Nonino, M. +2 more
Aims: Using the deepest (370 ks) Chandra observation of a high-redshift galaxy cluster, we perform a detailed characterization of the intra-cluster medium (ICM) of WARPJ1415.1+3612 at z = 1.03, particularly its core region. We also explore the connection between the ICM core properties and the radio/optical properties of the brightest cluster…
Extended soft X-ray emission in 3CR radio galaxies at z < 0.3: high excitation and broad line galaxies
Macchetto, F. D.; Capetti, A.; Grandi, P. +11 more
We analyze Chandra observations of diffuse soft X-ray emission associated with a complete sample of 3CR radio galaxies at z < 0.3. We focus on the properties of the spectroscopic sub-classes of high excitation galaxies (HEGs) and broad line objects (BLOs). Among the 33 HEGs we detect extended (or possibly extended) emission in about 40% of the …
On the Force-free Nature of Photospheric Sunspot Magnetic Fields as Observed from Hinode (SOT/SP)
Tiwari, Sanjiv Kumar
A magnetic field is force-free if there is no interaction between it and the plasma in the surrounding atmosphere, i.e., electric currents are aligned with the magnetic field, giving rise to zero Lorentz force. The computation of various magnetic parameters, such as magnetic energy (using the virial theorem), gradient of twist of sunspot magnetic …
On the Origin of the Supergiant H I Shell and Putative Companion in NGC 6822
Cannon, John M.; Dolphin, Andrew E.; Skillman, Evan D. +6 more
We present new Hubble Space Telescope Advanced Camera for Surveys imaging of six positions spanning 5.8 kpc of the H I major axis of the Local Group dIrr NGC 6822, including both the putative companion galaxy and the large H I hole. The resulting deep color-magnitude diagrams show that NGC 6822 has formed >50% of its stars in the last ~5 Gyr. T…
Morphological and mechanical characterization of gullies in a periglacial environment: The case of the Russell crater dune (Mars)
Lucas, Antoine; Schmidt, Frédéric; Costard, François +4 more
Gullies on terrestrial sand dunes are rare, and their presence on Mars, as well as their mechanical properties, and the quantity of fluid required for their formations currently remain poorly understood. This study focuses on gully morphologies on the Russell megadune (54.5°S; 12.7°E) using High Resolution Imaging Science Experiment (HiRISE) image…
Polar bulges and polar nuclear discs: the case of NGC 4698
Morelli, L.; Beifiori, A.; Dalla Bontà, E. +5 more
The early-type spiral NGC 4698 is known to host a nuclear disc of gas and stars which is rotating perpendicularly with respect to the galaxy main disc. In addition, the bulge and main disc are characterized by a remarkable geometrical decoupling. Indeed, they appear elongated orthogonally to each other. In this work, the complex structure of the g…
Rotational motion of Phobos
Rosenblatt, P.; Le Maistre, S.; Rambaux, N. +1 more
Context. Phobos is in synchronous spin-orbit resonance around Mars, like our Moon around the Earth. As a consequence, the rotational period of Phobos is equal in average to its orbital period. The variations of its rotational motion are described by oscillations, called physical librations, which yield information of its interior structure. The la…
Water emission from the chemically rich outflow L1157
Liseau, R.; Codella, C.; van Dishoeck, E. F. +7 more
Context. In the framework of the Herschel-WISH key program, several ortho-H2O and para-H2O emission lines, in the frequency range from 500 to 1700 GHz, were observed with the HIFI instrument in two bow-shock regions (B2 and R) of the L1157 cloud, which hosts what is considered to be the prototypical chemically-rich outflow. <…
Asymptotic Giant Branch variables in the Galaxy and the Local Group
Whitelock, Patricia A.
AGB variables, particularly the large amplitude Mira type, are a vital step on the distance scale ladder. They will prove particularly important in the era of space telescopes and extremely large ground-based telescopes with adaptive optics, which will be optimized for infrared observing. Our current understanding of the distances to these stars i…