Search Publications
Atmospheric structure and helium abundance on Saturn from Cassini/UVIS and CIRS observations
Guerlet, S.; Koskinen, T. T.
We combine measurements from stellar occultations observed by the Cassini Ultraviolet Imaging Spectrograph (UVIS) and limb scans observed by the Composite Infrared Spectrometer (CIRS) to create empirical atmospheric structure models for Saturn corresponding to the locations probed by the occultations. The results cover multiple locations at low to…
Searching for propeller-phase ULXs in the XMM-Newton Serendipitous Source Catalogue
Earnshaw, H. P.; Roberts, T. P.; Sathyaprakash, R.
We search for transient sources in a sample of ultraluminous X-ray sources (ULXs) from the 3XMM-DR4 release of the XMM-Newton Serendipitous Source Catalogue in order to find candidate neutron star ULXs alternating between an accreting state and the propeller regime, in which the luminosity drops dramatically. By examining their fluxes and flux upp…
Observational signatures of a warped disk associated with cold-flow accretion
Pettini, Max; Kacprzak, Glenn G.; York, Donald G. +9 more
We present MUSE observations of the field of the quasar Q0152$-$020 whose spectrum shows a Lyman limit system (LLS) at redshift $z_{\rm abs} = 0.38$, with a metallicity Z $\gtrsim 0.06$ Z$_\odot$. The low ionization metal lines associated with the LLS present two narrow distinct absorption components with a velocity separation of 26 km ${\rm s}^{-…
INTEGRAL/SPI γ-ray line spectroscopy. Response and background characteristics
Diehl, Roland; Greiner, Jochen; Siegert, Thomas +7 more
Context. The space based γ-ray observatory INTEGRAL of the European Space Agency (ESA) includes the spectrometer instrument "SPI". This is a coded mask telescope featuring a 19-element Germanium detector array for high-resolution γ-ray spectroscopy, encapsulated in a scintillation detector assembly that provides a veto for background from charged …
Orbit and Dynamical Mass of the Late-T Dwarf GL 758 B
Cochran, William D.; Endl, Michael; Wittenmyer, Robert A. +11 more
Gl 758 B is a late-T dwarf orbiting a metal-rich Sun-like star at a projected separation of ρ ≈ 1.″6 (25 au). We present four epochs of astrometry of this system with NIRC2 at Keck Observatory spanning 2010 to 2017 together with 630 radial velocities (RVs) of the host star acquired over the past two decades from McDonald Observatory, Keck Observat…
The COS CGM Compendium. I. Survey Design and Initial Results
Lehner, Nicolas; Howk, J. Christopher; O'Meara, John M. +3 more
We present a neutral hydrogen-selected absorption-line survey of gas with H I column densities 15< {log}{N}{{H}{{I}}}< 19 at z≲ 1 using the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our main aim is to determine the metallicity distribution of these absorbers. Our sample consists of 224 absorbers selected on the ba…
Hierarchical Fragmentation in the Perseus Molecular Cloud: From the Cloud Scale to Protostellar Objects
Bourke, Tyler L.; Myers, Philip C.; Gutermuth, Robert A. +8 more
We present a study of hierarchical structure in the Perseus molecular cloud, from the scale of the entire cloud (≳ 10 pc) to smaller clumps (∼1 pc), cores (∼0.05-0.1 pc), envelopes (∼300-3000 au), and protostellar objects (∼15 au). We use new observations from the Submillimeter Array (SMA) large project “Mass Assembly of Stellar Systems and their …
X-Ray and Gamma-Ray Observations of the Fermi Bubbles and NPS/Loop I Structures
Nakashima, Shinya; Inoue, Yoshiyuki; Kataoka, Jun +3 more
The Fermi bubbles were possibly created by large injections of energy into the Galactic Center (GC), either by an active galactic nucleus (AGN) or by nuclear starburst more than ~10 Myr ago. However, the origin of the diffuse gamma-ray emission associated with Loop I, a radio continuum loop spanning across 100° on the sky, is still being debated. …
Hypervelocity stars in the Gaia era. Runaway B stars beyond the velocity limit of classical ejection mechanisms
Heber, U.; Irrgang, A.; Kreuzer, S.
Context. Young massive stars in the halo are assumed to be runaway stars from the Galactic disk. Possible ejection scenarios are binary supernova ejections (BSE) or dynamical ejections from star clusters (DE). Hypervelocity stars (HVSs) are extreme runaway stars that are potentially unbound from the Galaxy. Powerful acceleration mechanisms such as…
Plasma source and loss at comet 67P during the Rosetta mission
Altwegg, K.; Carr, C.; Henri, P. +10 more
Context. The Rosetta spacecraft provided us with a unique opportunity to study comet 67P/Churyumov-Gerasimenko (67P) from a close perspective and over a 2-yr time period. Comet 67P is a weakly active comet. It was therefore unexpected to find an active and dynamic ionosphere where the cometary ions were largely dominant over the solar wind ions, e…