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The far reaches of the β Pictoris debris disk
Janson, Markus; Brandeker, Alexis; Olofsson, Göran +1 more
The nearby young star β Pictoris hosts a rich and complex planetary system, with at least two giant planets and a nearly edge-on debris disk that contains several dynamical subpopulations of planetesimals. While the inner ranges of the debris disk have been studied extensively, less information is known about the outer, fainter parts of the disk. …
A hyperluminous obscured quasar at a redshift of z ≈ 4.3
Burgarella, Denis; Oliver, Seb; Małek, Katarzyna +9 more
In this work we report the discovery of the hyperluminous galaxy HELP_J100156.75 + 022344.7 at a photometric redshift of $z$ ≈ 4.3. The galaxy was discovered in the Cosmological Evolution Survey (COSMOS) field, one of the fields studied by the Herschel Extragalactic Legacy Project (HELP). We present the spectral energy distribution (SED) of the ga…
The chemical composition of the accretion disc and donor star in ultra-compact X-ray binaries: A comprehensive X-ray analysis
Vasilopoulos, Georgios; Webb, Natalie; Koliopanos, Filippos +1 more
We have analysed the X-ray spectra of all known Ultra-Compact X-ray Binaries (UCXBs), with the purpose of constraining the chemical composition of their accretion disc and donor star. Our investigation was focused on the presence (or absence) of the Fe Kα emission line, which was used as the probe of chemical composition of the disc, based on prev…
High-resolution spectroscopy of the hot Am star HR 3383
Nielsen, K. E.; Leckrone, D. S.; Wahlgren, G. M.
We present the spectrum analysis of the hot Am star HR 3383 (A1 Vm). Hubble Space Telescope STIS and Nordic Optical Telescope SOFIN data are modelled with synthetic spectra, and abundances are investigated for 78 elements. Most light elements up through oxygen show deficiencies, compared to solar abundances, followed by the general trend of increa…
Solar Origin of Bare Ion Anomalies in the Solar Wind and Interplanetary Coronal Mass Ejections
Reeves, Katharine K.; Raymond, John C.; Stevens, Michael L. +3 more
Previous studies of the solar wind and interplanetary coronal mass ejections (ICMEs) have shown periods throughout solar cycle 23 when heliospheric measurements of ion composition appear anomalous. In these cases, C6+ and other bare ion densities, i.e., fully stripped ions, are unusually low, leading it to be classified as the Outlier s…
ARMADA. I. Triple Companions Detected in B-type Binaries α Del and ν Gem
Gies, Douglas R.; Klement, Robert; Monnier, John D. +19 more
Ground-based optical long-baseline interferometry has the power to measure the orbits of close binary systems at ∼10 µas precision. This precision makes it possible to detect "wobbles" in the binary motion due to the gravitational pull from additional short-period companions. We started the ARrangement for Micro-Arcsecond Differential Astrom…
Probing within the Bondi radius of the ultramassive black hole in NGC 1600
Walker, S. A.; Runge, J.
We present deep (250 ks) Chandra observations of the nearby galaxy group NGC 1600, which has at its centre an ultramassive black hole (17 ± 1.5 billion M⊙). The exceptionally large mass of the black hole coupled with its low redshift makes it one of only a handful of black holes for which spatially resolved temperature and density profi…
Modeling the Observed Distortion of Multiple (Ghost) CME Fronts in STEREO Heliospheric Imagers
Wang, Yuming; Shen, Chenglong; Lockwood, Mike +10 more
In this work we have, for the first time, applied the interpretation of multiple "ghost-fronts" to two synthetic coronal mass ejections (CMEs) propagating within a structured solar wind using the Heliospheric Upwind eXtrapolation time (HUXt) solar wind model. The two CMEs occurred on 2012 June 13-14 showing multiple fronts in images from Solar Ter…
The Kiloparsec-scale Fe Ka Emission in the Compton-thin Seyfert 2 Galaxy NGC 4388 Resolved by Chandra
Fabbiano, Giuseppina; Shu, Xinwen; Wang, Junfeng +4 more
We present imaging and spectral analysis of the combined ∼48 ks Chandra observations of Seyfert 2 galaxy NGC 4388. Compared with previous studies, three prominent extended X-ray structures around the nucleus on a kiloparsec-scale are well imaged, allowing an in-depth spatially resolved study. Both the extended hard continuum (4-6 keV) and the Fe K…
Numerical Modeling of Latitudinal Gradients for Galactic Cosmic-Ray Protons during Solar Minima: Comparing with Ulysses Observations
Qin, Gang; Shen, Zhenning; Zuo, Pingbing +2 more
The latitudinal gradients of galactic cosmic-ray (GCR) protons measured by Ulysses during two successive minima provide a unique opportunity to study the modulation effects in polar regions of the heliosphere. In this work, a GCR modulation model based on numerically solving the Parker transport equation is used to study the latitudinal distributi…