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The signature of primordial black holes in the dark matter halos of galaxies
Hawkins, M. R. S.
Aims: The aim of this paper is to investigate the claim that stars in the lensing galaxy of a gravitationally lensed quasar system can always account for the observed microlensing of the individual quasar images.
Methods: A small sample of gravitationally lensed quasar systems was chosen where the quasar images appear to lie on the fring…
Blasts from the Past: Supernova Shock Breakouts among X-Ray Transients in the XMM-Newton Archive
Alp, Dennis; Larsson, Josefin
The first electromagnetic signal from a supernova (SN) is released when the shock crosses the progenitor surface. This shock breakout (SBO) emission provides constraints on progenitor and explosion properties. Observationally, SBOs appear as minute- to hour-long extragalactic X-ray transients. They are challenging to detect and only one SBO has be…
The First Light Curve Modeling and Orbital Period Change Investigation of Nine Contact Binaries around the Short-period Cutoff
Li, Kai; Xia, Qi-Qi; Gao, Xing +5 more
In this paper, we present the first light curve synthesis and orbital period change analysis of nine contact binaries around the short-period limit. It is found that all these systems are W-subtype contact binaries. One of them is a medium contact system while the others are shallow contact ones. Four of them manifest obvious O'Connell effect expl…
Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of Gaia
Vanderburg, Andrew; Dupuy, Trent J.; Kraus, Adam L. +4 more
The orbits of binary stars and planets, particularly eccentricities and inclinations, encode the angular momentum within these systems. Within stellar multiple systems, the magnitude and (mis)alignment of angular momentum vectors among stars, disks, and planets probes the complex dynamical processes guiding their formation and evolution. The accur…
The Pristine Dwarf-Galaxy survey - II. In-depth observational study of the faint Milky Way satellite Sagittarius II
Navarro, Julio F.; Martin, Nicolas; Ibata, Rodrigo A. +11 more
We present an extensive study of the Sagittarius II (Sgr II) stellar system using MegaCam g and I photometry, narrow-band, metallicity-sensitive calcium H&K doublet photometry and Keck II/DEIMOS multiobject spectroscopy. We derive and refine the Sgr II structural and stellar properties inferred at the time of its discovery. The colour-magnitud…
Abundances in the Milky Way across Five Nucleosynthetic Channels from 4 Million LAMOST Stars
Lewis, Geraint F.; Buder, Sven; Bland-Hawthorn, Joss +10 more
Large stellar surveys are revealing the chemodynamical structure of the Galaxy across a vast spatial extent. However, the many millions of low-resolution spectra observed to date are yet to be fully exploited. We employ The Cannon, a data-driven approach for estimating chemical abundances, to obtain detailed abundances from low-resolution (R = 180…
Constraints on the circumburst environments of short gamma-ray bursts
Kouveliotou, Chryssa; O'Connor, Brendan; Beniamini, Paz
Observational follow up of well localized short gamma-ray bursts (SGRBs) has left $20\!-\!30{{\ \rm per\ cent}}$ of the population without a coincident host galaxy association to deep optical and NIR limits (≳26 mag). These SGRBs have been classified as observationally hostless due to their lack of strong host associations. It has been argued that…
Studying the ISM at ∼10 pc scale in NGC 7793 with MUSE. I. Data description and properties of the ionised gas
Della Bruna, Lorenza; Östlin, Göran; Smith, Linda J. +10 more
Context. Studies of nearby galaxies reveal that around 50% of the total Hα luminosity in late-type spirals originates from diffuse ionised gas (DIG), which is a warm, diffuse component of the interstellar medium that can be associated with various mechanisms, the most important ones being "leaking" HII regions, evolved field stars, and shocks.
Quiet, Discrete Auroral Arcs—Observations
Marghitu, O.; Karlsson, T.; Andersson, L. +5 more
Quiet, discrete auroral arcs are an important and fundamental consequence of solar wind-magnetosphere interaction. We summarize the current standing of observations of such auroral arcs. We review the basic characteristics of the arcs, including occurrence in time and space, lifetimes, width and length, as well as brightness, and the energy of the…
Coronal Magnetic Field Topology from Total Solar Eclipse Observations
Druckmüller, Miloslav; Boe, Benjamin; Habbal, Shadia
Measuring the global magnetic field of the solar corona remains exceptionally challenging. The fine-scale density structures observed in white-light images taken during total solar eclipses are currently the best proxies for inferring the magnetic field direction in the corona from the solar limb out to several solar radii (R⊙). We pres…