Search Publications
X-rays observations of a super-Chandrasekhar object reveal an ONe and a CO white dwarf merger product embedded in a putative SN Iax remnant
Todt, Helge; Langer, Norbert; Oskinova, Lidia M. +2 more
The merger of two white dwarfs (WDs) is a natural outcome of the evolution of many binary stars. Recently, a WD merger product, IRAS 00500+6713, was identified. IRAS 00500+6713 consists of a central star embedded in a circular nebula. The analysis of the optical spectrum of the central star revealed that it is hot, hydrogen, and helium free, and i…
Purveyors of fine halos. II. Chemodynamical association of halo stars with Milky Way globular clusters
Grebel, Eva K.; Hanke, Michael; Bastian, Ulrich +2 more
A long-lasting open question in the field of Galactic archeology refers to the size of the contribution from former globular cluster (GC) stars to the formation of the stellar halo of the Milky Way. We contribute to answering this important question by establishing observational links between the present-day halo field star population and GCs. To …
Lithium and beryllium in the Gaia-Enceladus galaxy
Molaro, P.; Cescutti, G.; Fu, X.
Data from Gaia DR2 and The Apache Point Observatory Galactic Evolution Experiment surveys revealed a relatively new component in the inner Galactic halo, which is likely the dynamical remnant of a disrupted dwarf galaxy named Gaia-Enceladus that collided with the Milky Way about 10 Gyr ago. This merging event offers an extraordinary opportunity to…
Irregular Dust Features around Intermediate-mass Young Stars with GPI: Signs of Youth or Misaligned Disks?
Monnier, John D.; Kraus, Stefan; Hinkley, Sasha +14 more
We are undertaking a large survey of over 30 disks using the Gemini Planet Imager (GPI) to see whether the observed dust structures match spectral energy distribution predictions and have any correlation with stellar properties. GPI can observe near-infrared light scattered from dust in circumstellar environments using high-resolution Polarimetric…
Physical Processes of Meso-Scale, Dynamic Auroral Forms
Sergeev, V. A.; Nishimura, Y.; Forsyth, C. +2 more
Meso-scale auroral forms, such as poleward boundary intensifications, streamers, omega bands, beads and giant undulations, are manifestations of dynamic processes in the magnetosphere driven, to a large part, by plasma instabilities in the magnetotail. New observations from ground- and space-based instrumentation and theoretical treatments are giv…
The gravity field and interior structure of Dione
Tortora, Paolo; Zannoni, Marco; Hemingway, Douglas +1 more
During its mission in the Saturn system, Cassini performed five close flybys of Dione. During three of them, radio tracking data were collected during the closest approach, allowing estimation of the full degree-2 gravity field by precise spacecraft orbit determination.
The gravity field of Dione is dominated by J2 and C22SMASHing the low surface brightness SMC
Bell, Eric F.; Monachesi, Antonela; Choi, Yumi +22 more
The periphery of the Small Magellanic Cloud (SMC) can unlock important information regarding galaxy formation and evolution in interacting systems. Here, we present a detailed study of the extended stellar structure of the SMC using deep colour-magnitude diagrams, obtained as part of the Survey of the MAgellanic Stellar History (SMASH). Special ca…
Onset of Turbulent Fast Magnetic Reconnection Observed in the Solar Atmosphere
Chitta, L. P.; Lazarian, A.
Fast magnetic reconnection powers explosive events throughout the universe, from gamma-ray bursts to solar flares. Despite its importance, the onset of astrophysical fast reconnection is the subject of intense debate and remains an open question in plasma physics. Here we report high-cadence observations of two reconnection-driven solar microflare…
The solar wind from a stellar perspective. How do low-resolution data impact the determination of wind properties?
Güdel, M.; Airapetian, V. S.; Jin, M. +5 more
Context. Due to the effects that they can have on the atmospheres of exoplanets, stellar winds have recently received significant attention in the literature. Alfvén-wave-driven 3D magnetohydrodynamic models, which are increasingly used to predict stellar wind properties, contain unconstrained parameters and rely on low-resolution stellar magnetog…
Globular Cluster Systems and Galaxy Formation
Beasley, Michael A.
Globular clusters (GCs) are compact, gravitationally bound systems of up to ∼¼1 million stars. The GCs in the Milky Way contain some of the oldest stars known, and provide important clues to the early formation and continuing evolution of our Galaxy. More generally, GCs are associated with galaxies of all types and masses, from low-mass dwarf gala…