Search Publications
Proper Motions in Terzan 5: Membership of the Multi-iron Subpopulations and First Constraint on the Orbit
Dalessandro, E.; Massari, D.; Rich, R. M. +6 more
By exploiting two sets of high-resolution images obtained with the Hubble Space Telescope Advanced Camera for Surveys/Wide Field Channel over a baseline of ∼10 years, we have measured relative proper motions (PMs) of ∼70,000 stars in the stellar system Terzan 5. The results confirm the membership of the three subpopulations with different iron abu…
A Two-ribbon White-light Flare Associated with a Failed Solar Eruption Observed by ONSET, SDO, and IRIS
Cheng, X.; Ding, M. D.; Chen, P. F. +4 more
Two-ribbon brightenings are one of the most remarkable characteristics of an eruptive solar flare and are often used to predict the occurrence of coronal mass ejections (CMEs). Nevertheless, it was recently called into question whether all two-ribbon flares are eruptive. In this paper, we investigate a two-ribbon-like white-light (WL) flare that i…
Formation and Eruption of a Small Flux Rope in the Chromosphere Observed by NST, IRIS, and SDO
Wang, Haimin; Yurchyshyn, Vasyl; Kumar, Pankaj +1 more
Using high-resolution images from the 1.6 m New Solar Telescope at Big Bear Solar Observatory, we report the direct evidence of chromospheric reconnection at the polarity inversion line between two small opposite polarity sunspots. Small jetlike structures (with velocities of ∼20-55 km s-1) were observed at the reconnection site before …
Binary Frequencies in a Sample of Globular Clusters. II. Sample Analysis and Comparison to Models
Bregman, Joel N.; Ji, Jun
Binary stars are predicted to have an important role in the evolution of globular clusters, so we obtained binary fractions for 35 globular clusters that were imaged in the F606W and F814W with the Advanced Camera for Surveys on the Hubble Space Telescope. When compared to the values of prior efforts, we find significant discrepancies, despite eac…
Constraining the Redshift Evolution of the Cosmic Microwave Background Blackbody Temperature with PLANCK Data.
Martins, C. J. A. P.; Kocevski, D.; Atrio-Barandela, F. +4 more
We constrain the deviation of adiabatic evolution of the universe using the data on the cosmic microwave background (CMB) temperature anisotropies measured by the Planck satellite and a sample of 481 X-ray selected clusters with spectroscopically measured redshifts. To avoid antenna beam effects, we bring all of the maps to the same resolution. We…
The Herschel Exploitation of Local Galaxy Andromeda (HELGA). VI. The Distribution and Properties of Molecular Cloud Associations in M31
Fritz, J.; Cooray, A.; Lebouteiller, V. +18 more
In this paper we present a catalog of giant molecular clouds (GMCs) in the Andromeda (M31) galaxy extracted from the Herschel Exploitation of Local Galaxy Andromeda (HELGA) data set. GMCs are identified from the Herschel maps using a hierarchical source extraction algorithm. We present the results of this new catalog and characterize the spatial d…
Estimating the Height of CMEs Associated with a Major SEP Event at the Onset of the Metric Type II Radio Burst during Solar Cycles 23 and 24
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +2 more
We studied the coronal mass ejection (CME) height at the onset of 59 metric type II radio bursts associated with major solar energetic particle (SEP) events, excluding ground level enhancements (GLEs), during solar cycles 23 and 24. We calculated CME heights using a simple flare-onset method used by Gopalswamy et al. to estimate CME heights at the…
Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field
Verscharen, Daniel; Hollweg, Joseph V.; Bourouaine, Sofiane +1 more
Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Bot…
Variable Reddening and Broad Absorption Lines in the Narrow-line Seyfert 1 Galaxy WPVS 007: An Origin in the Torus
Komossa, S.; Terndrup, Donald M.; Leighly, Karen M. +2 more
We report the discovery of an occultation event in the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007 in 2015 February and March. In concert with longer timescale variability, these observations place strong constraints on the nature and location of the absorbing material. Swift monitoring has revealed a secular decrease since ∼2010 accompan…
Correcting for Interplanetary Scattering in Velocity Dispersion analysis of Solar Energetic Particles
Laitinen, T.; Valtonen, E.; Dalla, S. +1 more
To understand the origin of Solar Energetic Particles (SEPs), we must study their injection time relative to other solar eruption manifestations. Traditionally the injection time is determined using the Velocity Dispersion Analysis (VDA) where a linear fit of the observed event onset times at 1 AU to the inverse velocities of SEPs is used to deriv…