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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…
Subarcsecond Blobs in Flare-related Coronal Jets
Zhang, Q. M.; Ni, L.
In this paper, we report multiwavelength observations of subarcsecond blobs in coronal jets. In AR 12149, a C5.5 circular-ribbon flare occurred at ∼04:55 UT on 2014 August 24, which consisted of a discrete circular ribbon and a short inner ribbon inside. Two jets (jet1 and jet2) were related to the flare. Jet1 appeared first and experienced untwis…
Expected intermediate-mass black holes in the Virgo cluster - I. Early-type galaxies
Soria, Roberto; Graham, Alister W.
We expand upon the AMUSE-Virgo survey which imaged 100 early-type Virgo cluster galaxies with the Chandra X-ray Observatory, and we place an emphasis on potential intermediate-mass black holes (IMBHs). Virgo early-type galaxies with absolute magnitudes M_B≳ -20.5 mag have B-band luminosities that scale with the square of the stellar velocity dispe…
GROWTH on S190510g: DECam Observation Planning and Follow-up of a Distant Binary Neutron Star Merger Candidate
Duev, Dmitry A.; Kong, Albert K. H.; Cook, David O. +23 more
The first two months of the third Advanced LIGO and Virgo observing run (2019 April-May) showed that distant gravitational-wave (GW) events can now be readily detected. Three candidate mergers containing neutron stars (NS) were reported in a span of 15 days, all likely located more than 100 Mpc away. However, distant events such as the three new N…
SOFIA Far-infrared Imaging Polarimetry of M82 and NGC 253: Exploring the Supergalactic Wind
Morris, Mark R.; Staguhn, Johannes; Dowell, C. Darren +23 more
We present far-infrared polarimetry observations of M82 at 53 and 154 µm and NGC 253 at 89 µm, which were taken with High-resolution Airborne Wideband Camera-plus (HAWC+) in polarimetry mode on the Stratospheric Observatory for Infrared Astronomy. The polarization of M82 at 53 µm clearly shows a magnetic field geometry perpendicu…
Long-term Variations of Venus’s 365 nm Albedo Observed by Venus Express, Akatsuki, MESSENGER, and the Hubble Space Telescope
Marcq, Emmanuel; Imamura, Takeshi; Titov, Dmitrij V. +16 more
An unknown absorber near the cloud-top level of Venus generates a broad absorption feature from the ultraviolet (UV) to visible, peaking around 360 nm, and therefore plays a critical role in the solar energy absorption. We present a quantitative study of the variability of the cloud albedo at 365 nm and its impact on Venus’s solar heating rates ba…