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Suprathermal Outflowing H+ Ions in the Lobe Driven by an Interplanetary Shock: 1. An Observation Event
Mouikis, C. G.; Wang, Chih-Ping; Wang, Xueyi +2 more
To better understand how sharp changes in the solar wind and interplanetary magnetic field conditions affect the ionosphere outflows at high latitudes, we analyze an event observed on 17 July 2002 showing suprathermal (tens to hundreds of eV) outflowing H+ ions in the lobe driven by the impact of an interplanetary (IP) shock. A spacecra…
X-ray flux and spectral variability of the blazar OJ 287 with Suzaku
Gupta, Alok C.; Wiita, Paul J.; Xu, Haiguang +4 more
We present analyses of Suzaku XIS light curves and spectra of the BL Lac object OJ 287 with observations positioned primarily around proposed recurrent optical outbursts. The first two observations were performed in 2007 April 10-13 (epoch 1) and 2007 November 7-9 (epoch 2) that, respectively, correspond to a low and a high optical state and which…
Supervised star, galaxy, and QSO classification with sharpened dimensionality reduction
Trager, S. C.; Lourens, M. A. A.; Kim, Y. +2 more
Aims. We explored the use of broadband colors to classify stars, galaxies, and quasi-stellar objects (QSOs). Specifically, we applied sharpened dimensionality reduction (SDR)-aided classification to this problem, with the aim of enhancing cluster separation in the projections of high-dimensional data clusters to allow for better classification per…
HD 28185 revisited: an outer planet, instead of a brown dwarf, on a Saturn-like orbit
Vanderburg, Andrew; Wittenmyer, Robert A.; Huang, Chelsea X. +3 more
As exoplanet surveys reach ever-higher sensitivities and durations, planets analogous to the Solar system giant planets are increasingly within reach. HD 28185 is a Sun-like star known to host a
Radial properties of dust in galaxies: Comparison between observations and isolated galaxy simulations
De Looze, I.; Baes, M.; Palla, M. +8 more
We study the importance of several processes that influence the evolution of dust and its grain size distribution on spatially resolved scales in nearby galaxies. Here, we compiled several multi-wavelength observations for the nearby galaxies NGC 628 (M74), NGC 5457 (M101), NGC 598 (M33), and NGC 300. We applied spatially resolved spectral energy …
Evidence of dark contents in the centre of NGC 6517
Xie, Yi; Zhang, Liyun; Lian, Yujie +3 more
Millisecond pulsars can serve as effective probes to investigate the presence of intermediate-mass black holes (IMBHs) within Galactic globular clusters (GCs). Based on the standard structure models for GCs, we conduct simulations to analyse the distributions of pulsar accelerations within the central region of NGC 6517. By comparing the measured …
Constraints on Acoustic Wave Energy Fluxes and Radiative Losses in the Solar Chromosphere from Non-LTE Inversions
Milić, I.; da Silva Santos, J. M.; de la Cruz Rodríguez, J. +3 more
Accurately assessing the balance between acoustic wave energy fluxes and radiative losses is critical for understanding how the solar chromosphere is thermally regulated. We investigate the energy balance in the chromosphere by comparing deposited acoustic flux and radiative losses under quiet and active solar conditions using non–local thermodyna…
A Self-consistent Data-driven Model for Determining Stellar Parameters from Optical and Near-infrared Spectra
Stassun, Keivan G.; Kounkel, Marina; Chandra, Vedant +3 more
Data-driven models, which apply machine learning to infer physical properties from large quantities of data, have become increasingly important for extracting stellar properties from spectra. In general, these methods have been applied to data in one wavelength regime or another. For example, APOGEE Net has been applied to near-IR spectra from the…
Time Variability of FUV Emission from Cool Stars on Multi-year Timescales
France, Kevin; Youngblood, Allison; Kamgar, Leo
The physical and chemical properties of planetary atmospheres are affected by temporal evolution of ultraviolet (UV) radiation inputs from their host stars at all time scales. While studies of X-ray/UV flare properties and long-term stellar evolution of exoplanet host stars have provided new constraints regarding stellar inputs to exoplanetary sys…
A catalogue of observed geo-effective CME/ICME characteristics
Foldes, Raffaello; Erdélyi, Robertus; Del Moro, Dario +7 more
One of the goals of Space Weather studies is to achieve a better understanding of impulsive phenomena, such as Coronal Mass Ejections (CMEs), to improve our ability to forecast their propagation characteristics and mitigate the risks to our technologically driven society. The essential part of achieving this goal is to assess the performance of fo…