Search Publications
RX J1301.9+2747: A Highly Variable Seyfert Galaxy with Extremely Soft X-Ray Emission
Shu, Xinwen; Wang, Tinggui; Sun, Luming
In this paper we present a temporal and spectral analysis of X-ray data from XMM-Newton and Chandra observations of the ultrasoft and variable Seyfert galaxy RX J1301.9+2747. In both observations the source clearly displays two distinct states in the X-ray band: a long quiescent state and a short flare (or eruptive) state which differs in count ra…
An X-Ray and Multiwavelength Survey of Highly Radio-loud Quasars at z > 4: Jet-linked Emission in the Brightest Radio Beacons of the Early Universe
Brandt, W. N.; Schneider, Donald P.; Garmire, Gordon P. +3 more
We present a systematic study of the X-ray and multiwavelength properties of a sample of 17 highly radio-loud quasars (HRLQs) at z > 4 with sensitive X-ray coverage from new Chandra and archival Chandra, XMM-Newton, and Swift observations. Eight of the new and archival observations are reported in this work for the first time. New Chandra obser…
Mars ionospheric response to solar wind variability
Fränz, M.; Lester, M.; Edberg, N. J. T. +6 more
planets with induced magnetospheres, the coupling between the ionosphere, the weak draped magnetosphere, and the solar wind is very direct in comparison to Earth. The weak induced magnetosphere itself is created by the prevailing Solar wind conditions and therefore in its shape and strength dynamically depending on it. In early 2010, Mars was loca…
Dynamics of the foreshock compressional boundary and its connection to foreshock cavities
Zhang, H.; Omidi, N.; Sibeck, D. +4 more
We use several global hybrid (kinetic ions, fluid electrons) simulation runs for steady and time-varying interplanetary magnetic field (IMF) conditions to examine the dynamics of the foreshock compressional boundary (FCB) and its connection to foreshock cavities. The results demonstrate that for steady IMF conditions, the FCB forms and evolves ove…
Towards a complete stellar mass function of the Hyades. I. Pan-STARRS1 optical observations of the low-mass stellar content
Price, P. A.; Henning, T.; Chen, W. P. +15 more
Aims: The Hyades cluster is an ideal target to study the dynamical evolution of a star cluster over the entire mass range due to its intermediate age and proximity to the Sun.
Methods: We wanted to extend the Hyades mass function towards lower masses down to 0.1 M⊙ and to use the full three-dimensional spatial information to c…
Near-Sun Flux-Rope Structure of CMEs
St. Cyr, O. C.; Gopalswamy, N.; Xie, H.
We have used the Krall flux-rope model (Krall and St. Cyr, Astrophys. J.2006, 657, 1740) (KFR) to fit 23 magnetic cloud (MC)-CMEs and 30 non-cloud ejecta (EJ)-CMEs in the Living With a Star (LWS) Coordinated Data Analysis Workshop (CDAW) 2011 list. The KFR-fit results shows that the CMEs associated with MCs (EJs) have been deflected closer to (awa…
HERschel Observations of Edge-on Spirals (HEROES). I. Far-infrared morphology and dust mass determination
Blommaert, J. A. D. L.; Bianchi, S.; Fritz, J. +11 more
Context. Edge-on spiral galaxies with prominent dust lanes provide us with an excellent opportunity to study the distribution and properties of the dust within them. The HEROES project was set up to observe a sample of seven large edge-on galaxies across various wavelengths for this investigation.
Aims: Within this first paper, we present the…
Late Spectral Evolution of the Ejecta and Reverse Shock in SN 1987A
Fransson, Claes; Kirshner, Robert P.; Leibundgut, Bruno +10 more
We present observations with the Very Large Telescope and Hubble Space Telescope (HST) of the broad emission lines from the inner ejecta and reverse shock of SN 1987A from 1999 February until 2012 January (days 4381-9100 after explosion). We detect broad lines from Hα, Hβ, Mg I], Na I, [O I], [Ca II], and a feature at ~9220 Å. We identify the latt…
A new semiempirical model of the peak electron density of the Martian ionosphere
Withers, Paul; Mendillo, Michael; Morgan, David +2 more
of the ionosphere of Mars have now reached a sufficient number to begin discussions on how best to create an empirically based model of its global morphology. Here we use nearly 113,000 values of maximum electron density (Nmax) obtained from 2005 to 2012 by the Mars Advanced Radar for Subsurface and Ionospheric Sounding on board the Mar…
ALMA Continuum Observations of a 30 Myr Old Gaseous Debris Disk around HD 21997
Apai, D.; Pascucci, I.; Ábrahám, P. +10 more
Circumstellar disks around stars older than 10 Myr are expected to be gas-poor. There are, however, two examples of old (30-40 Myr) debris-like disks containing a detectable amount of cold CO gas. Here we present Atacama Large Millimeter/Submillimeter Array (ALMA) and Herschel Space Observatory observations of one of these disks, around HD 21997, …