Search Publications
Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars
Brandt, W. N.; Luo, B.; Fan, X. +8 more
We present XMM-Newton imaging spectroscopy of 10 weak emission-line quasars (WLQs) at 0.928≤slant z≤slant 3.767, six of which are radio-quiet, and four that are radio-intermediate. The new X-ray data enabled us to measure the power-law photon index, at rest-frame energies >2 keV, in each source with relatively high accuracy. These measurements …
Testing the white dwarf mass-radius relation and comparing optical and far-UV spectroscopic results with Gaia DR2, HST, and FUSE
Barstow, M. A.; Holberg, J. B.; Casewell, S. L. +3 more
Observational tests of the white dwarf mass-radius relationship have always been limited by the uncertainty in the available distance measurements. Most studies have focused on Balmer line spectroscopy because these spectra can be obtained from ground-based observatories, while the Lyman lines are only accessible to space-based UV telescopes. We p…
SMHASH: anatomy of the Orphan Stream using RR Lyrae stars
Law, David R.; Kollmeier, Juna A.; van der Marel, Roeland P. +29 more
Stellar tidal streams provide an opportunity to study the motion and structure of the disrupting galaxy as well as the gravitational potential of its host. Streams around the Milky Way are especially promising as phase space positions of individual stars will be measured by ongoing or upcoming surveys. Nevertheless, it remains a challenge to accur…
The effect of inflation on the morphology-derived rheological parameters of lava flows and its implications for interpreting remote sensing data - A case study on the 2014/2015 eruption at Holuhraun, Iceland
Kolzenburg, S.; Jaenicke, J.; Münzer, U. +1 more
Morphology-derived lava flow rheology is a frequently used tool in volcanology and planetary science to determine rheological parameters and deduce the composition of lavas on terrestrial planets and their moons. These calculations are usually based on physical equations incorporating 1) lava flow driving forces: gravity, slope and flow-rate and 2…
Jovian electrons in the inner heliosphere. Proposing a new source spectrum based on 30 years of measurements
Potgieter, M. S.; Heber, B.; Vogt, A. +2 more
Context. Since the Pioneer 10 flyby of Jupiter it has become well known that electrons of Jovian origin dominate the lower MeV range of charged energetic particles in the inner heliosphere.
Aims: Because the Jovian source can be treated as point-like in numerical models, many attempts to investigate charged particle transport in the inner hel…
SHOTGLAS. I. The ultimate spectroscopic census of extreme horizontal branch stars in ω Centauri
Calamida, Annalisa; Latour, Marilyn; Randall, Suzanna K. +2 more
The presence of extreme horizontal branch (EHB) and blue hook stars in some Galactic globular clusters (GGCs) constitutes one of the remaining mysteries of stellar evolution. While several evolutionary scenarios have been proposed to explain the characteristics of this peculiar population of evolved stars, their observational verification has been…
The connection between the peaks in velocity dispersion and star-forming clumps of turbulent galaxies
Fisher, D. B.; Glazebrook, K.; Obreschkow, D. +5 more
We present Keck/OSIRIS adaptive optics observations with 150-400 pc spatial sampling of 7 turbulent, clumpy disc galaxies from the DYNAMO sample ($0.07<z<0.2$). DYNAMO galaxies have previously been shown to be well matched in properties to main sequence galaxies at $z\sim1.5$. Integral field spectroscopy observations using adaptive optics ar…
Asymmetry in Solar Torsional Oscillation and the Sunspot Cycle
Antia, H. M.; Nandy, Dibyendu; Lekshmi, B.
Solar torsional oscillations are migrating bands of slower- and faster-than-average rotation, which are strongly related to the Sun’s magnetic cycle. We perform a long-term study (16 yr) of hemispherical asymmetry in solar torsional oscillation velocity using helioseismic data for the first time. We study the north-south asymmetry in the velocity …
Resolving Star Formation on Subkiloparsec Scales in the High-redshift Galaxy SDP.11 Using Gravitational Lensing
Verma, A.; Lamarche, C.; Stacey, G. J. +7 more
We investigate the properties of the interstellar medium, star formation, and the current-day stellar population in the strongly lensed star-forming galaxy H-ATLAS J091043.1-000321 (SDP.11), at z = 1.7830, using new Herschel and Atacama Large Millimeter/submillimeter Array (ALMA) observations of far-infrared fine-structure lines of carbon, oxygen,…
The Discovery of a New Massive Molecular Gas Component Associated with the Submillimeter Galaxy SMM J02399-0136
Ivison, R. J.; Smail, Ian; Frayer, David T. +3 more
We present CO(1-0), CO(3-2), and CO(7-6) observations using the Green Bank Telescope (GBT) and the Atacama Large Millimeter Array (ALMA) of the z = 2.8 submillimeter galaxy SMM J02399-0136. This was the first submillimeter-selected galaxy discovered and remains an archetype of the class, comprising a merger of several massive and active components…