Search Publications
The haloes and environments of nearby galaxies (HERON) - I. Imaging, sample characteristics, and envelope diameters
Sales, Laura; Kormendy, John; Rich, R. Michael +16 more
We use a dedicated 0.7-m telescope to image the haloes of 119 galaxies in the Local Volume to µr ∼ 28-30 mag arcsec-2. The sample is primarily from the Two Micron All Sky Survey Large Galaxy Atlas (Jarrett et al. 2003) and extended to include nearby dwarf galaxies and more distant giant ellipticals, and spans fully the …
Extended stellar systems in the solar neighborhood. III. Like ships in the night: the Coma Berenices neighbor moving group
Meingast, Stefan; Alves, João; Fürnkranz, Verena
We report the discovery of a kinematically cold group of stars, located in the immediate neighborhood of the well-known star cluster Coma Berenices (Mel 111). The new group identified in tangential velocity space as measured by Gaia contains at least 177 coeval members distributed in two subgroups, and appears as a flattened structure parallel to …
The VISCACHA survey - I. Overview and first results
Piatti, Andrés E.; Barbuy, Beatriz; Bica, Eduardo +15 more
The VISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA) Survey is an ongoing project based on deep photometric observations of Magellanic Cloud star clusters, collected using the SOuthern Astrophysical Research (SOAR) telescope together with the SOAR Adaptive Module Imager. Since 2015 more than 200 h of telescope time were …
Evidence for an emerging disc wind and collimated outflow during an X-ray flare in the narrow-line Seyfert 1 galaxy Mrk 335
Kriss, G. A.; Fabian, A. C.; Pinto, C. +13 more
A triggered 140{ ks}XMM-Newton observation of the narrow-line Seyfert 1 (NLS1) Mrk 335 in 2015 December caught the active galaxy at its lowest X-ray flux since 2007. The NLS1 is relatively quiescent for the first {∼ }120{ ks} of the observation before it flares in brightness by a factor of about five in the last 20{ ks}. Although only part of the …
Stellar activity analysis of Barnard's Star: very slow rotation and evidence for long-term activity cycle
Rebolo, R.; Amado, P. J.; Caballero, J. A. +58 more
The search for Earth-like planets around late-type stars using ultrastable spectrographs requires a very precise characterization of the stellar activity and the magnetic cycle of the star, since these phenomena induce radial velocity (RV) signals that can be misinterpreted as planetary signals. Among the nearby stars, we have selected Barnard's S…
Stellar Proper Motions in the Orion Nebula Cluster
Lu, Jessica R.; Anderson, Jay; Morris, Mark R. +5 more
The Orion Nebula Cluster (ONC) is the nearest site of ongoing massive star formation, which allows us to study the kinematics and dynamics of the region in detail and constrain star formation theories. Using HST ACS/WFPC2/WFC3IR and Keck II NIRC2 data, we have measured the proper motions of 701 stars within an ∼6‧ × 6‧ field of view around the cen…
Automated crater detection algorithms from a machine learning perspective in the convolutional neural network era
DeLatte, D. M.; Crites, S. T.; Guttenberg, N. +1 more
Convolutional Neural Networks (CNN) offer promising opportunities to automatically glean scientifically relevant information directly from annotated images, without needing to handcraft features for detection. Crater counting started with hand counting hundreds, thousands, or even millions of craters in order to determine the age of geological uni…
Can the Superposition of Evaporative Flows Explain Broad Fe XXI Profiles during Solar Flares?
Polito, Vanessa; Testa, Paola; De Pontieu, Bart
The observation of the high-temperature (≳10 MK) Fe XXI 1354.1 Å line with the Interface Region Imaging Spectrograph has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resol…
Nighttime Magnetic Perturbation Events Observed in Arctic Canada: 2. Multiple-Instrument Observations
Russell, C. T.; Kistler, L. M.; Fazakerley, A. +14 more
The rapid changes of magnetic fields associated with nighttime magnetic perturbations with amplitudes |ΔB| of hundreds of nanoteslas and 5- to 10-min periods can induce bursts of geomagnetically induced currents that can harm technological systems. This paper presents three cases of intervals of intense and complex nighttime magnetic perturbations…
Recent seismicity in Valles Marineris, Mars: Insights from young faults, landslides, boulder falls and possible mud volcanoes
Platz, Thomas; Senthil Kumar, P.; Krishna, N. +3 more
Current seismicity of Mars is poorly known. Geodynamic models and analysis of surface faults indicate that Mars could be seismically active globally, particularly within the Tharsis region. However, published geologic constraints on such activity are sparse. In this study, we use geomorphologic observations and crater size-frequency age determinat…