Search Publications
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…
The Strength of the 2175 Å Feature in the Attenuation Curves of Galaxies at 0.1 < z ≲ 3
Calzetti, D.; Battisti, A. J.; Cunha, E. da +1 more
We update the spectral modeling code MAGPHYS to include a 2175 Å absorption feature in its UV to near-IR dust attenuation prescription. This allows us to determine the strength of this feature and the shape of the dust attenuation curve in ∼5000 star-forming galaxies at $0.1\lt z\lesssim 3$ in the COSMOS field. We find that a 2175 Å absorption fea…
Astrophysical Distance Scale: The AGB J-band Method. I. Calibration and a First Application
Madore, Barry F.; Freedman, Wendy L.
A near-infrared, color-selected subset of carbon-rich asymptotic giant branch (C-AGB) stars is found to have tightly constrained luminosities in the near-infrared J band. Based on JK photometry of some 3300 C-AGB stars in the bar of the Large Magellanic Cloud (LMC) we find that these stars have a constant absolute magnitude of $\langle {M}_{J}\ran…
The Complex Space Weather Events of 2017 September
Hajra, Rajkumar; Tsurutani, Bruce T.; Lakhina, Gurbax S.
Interplanetary coronal mass ejections (ICMEs), magnetic clouds (MCs), sheaths, corotating interaction regions (CIRs), solar wind high-speed streams (HSSs), fast forward shocks (FSs), reverse waves (RWs), stream interfaces, and heliospheric current sheet crossings detected upstream of the Earth and their geoeffectiveness are studied during 2017 Sep…
Dual-wavelength ALMA Observations of Dust Rings in Protoplanetary Disks
Pascucci, Ilaria; Herczeg, Gregory J.; Wilner, David J. +13 more
We present new Atacama Large Millimeter/submillimeter Array observations for three protoplanetary disks in Taurus at 2.9 mm and comparisons with previous 1.3 mm data both at an angular resolution of ∼0"1 (15 au for the distance of Taurus). In the single-ring disk DS Tau, double-ring disk GO Tau, and multiring disk DL Tau, the same rings are detect…