Search Publications
Missions
Journals
Publication Years
Effects of Solar Activity on Taylor Scale and Correlation Scale in Solar Wind Magnetic Fluctuations
Zhou, G.; Wan, W.; He, H. -Q.
The correlation scale and the Taylor scale are evaluated for interplanetary magnetic field fluctuations from two-point, single time correlation function using the Advanced Composition Explorer (ACE), Wind, and Cluster spacecraft data during the time period from 2001 to 2017, which covers over an entire solar cycle. The correlation scale and the Ta…
Measuring Star Formation Histories, Distances, and Metallicities with Pixel Color-Magnitude Diagrams. II. Applications to Nearby Elliptical Galaxies
van Dokkum, Pieter; Conroy, Charlie; Cook, B. A.
We present spatially resolved measurements of star formation histories (SFHs), metallicities, and distances in three nearby elliptical galaxies and the bulge of M31 derived using the pixel color-magnitude diagram (pCMD) technique. We compute pCMDs from archival Hubble Space Telescope photometry of M87, M49, NGC 3377, and M31, and we fit the data u…
Predicting the Time of Arrival of Coronal Mass Ejections at Earth From Heliospheric Imaging Observations
Vourlidas, Angelos; Stenborg, Guillermo; Dal Lago, Alisson +3 more
The time of arrival (ToA) of coronal mass ejections (CMEs) at Earth is a key parameter due to the space weather phenomena associated with the CME arrival, such as intense geomagnetic storms. Despite the incremental use of new instrumentation and the development of novel methodologies, ToA estimated errors remain above 10 h on average. Here, we inv…
Solar east-west flow correlations that persist for months at low latitudes are dominated by active region inflows
Gizon, Laurent; Birch, Aaron C.; Duvall, Thomas L. +2 more
Context. Giant-cell convection is believed to be an important component of solar dynamics. For example, it is expected to play a crucial role in maintaining the Sun's differential rotation.
Aims: We reexamine early reports of giant convective cells detected using a correlation analysis of Dopplergrams. We extend this analysis using 19 years o…
On the Origin of Metal-poor Stars in the Solar Neighborhood
Bilir, Selçuk; Şahin, Timur
We determined the ages, kinematic parameters, and Galactic orbital parameters of six metal-poor (-2.4 < [Fe/H] < -1.0 dex), F-type, high-proper-motion (HPM) stars to investigate their HPM nature and origin. For the kinematical procedure, the astrometric data from the Gaia DR2 were used. High-resolution ELODIE spectra of the six dwarfs were a…
Oxygen Atom Escape from the Martian Atmosphere during Proton Auroral Events
Shematovich, V. I.; Kalinicheva, E. S.
We present the model calculation results of the atomic oxygen loss rate from the Martian atmosphere induced by precipitation of high-energy protons and hydrogen atoms (H/H+) from the solar wind plasma. Penetration of energetic protons and hydrogen atoms from the solar wind plasma to the upper atmosphere of Mars at altitudes of 100-250 k…
Chromospheric Magnetic Field: A Comparison of He I 10830 Å Observations with Nonlinear Force-free Field Extrapolation
Shimizu, Toshifumi; Asensio Ramos, Andrés; Inoue, Satoshi +1 more
The nonlinear force-free field (NLFFF) modeling has been extensively used to infer the three-dimensional magnetic field in the solar corona. One of the assumptions in the NLFFF extrapolation is that the plasma beta is low, but this condition is considered to be incorrect in the photosphere. We examine direct measurements of the chromospheric magne…
New observations of DW Cnc: where is the 38 min signal?
Ramírez, S. H.; Echevarría, J.; Segura Montero, O.
We present extensive radial velocity observations of the intermediate polar DW Cnc during its 2018-2019 low state. We show that the 86 min signal associated with the orbital period is strong in our radial velocity analysis, power spectrum search, and in our Doppler tomography. However, we find that the velocity modulation associated with the 70 mi…
On the Nature of the T Tauri Triple System
Chapillon, E.; Schaefer, G. H.; Guilloteau, S. +4 more
We present a multiwavelength analysis to reveal the nature of the enigmatic T Tauri triple star system. New optical and infrared measurements are coupled with archival X-ray, UV, and millimeter data sets to show the morphologies of disk material and outflow kinematics. A dark lane of obscuring material is seen in silhouette in several emission lin…
Discovery of a retrogradely rotating neutron star in the X-ray pulsar GX 301-2
Doroshenko, Victor; Tsygankov, Sergey S.; Poutanen, Juri +3 more
We report on the analysis of the spin evolution of a slow X-ray pulsar GX 301-2 along the orbit using long-term monitoring by Fermi/Gamma-ray Burst Monitor. Based on the observationally confirmed accretion scenario and an analytical model for the accretion of angular momentum, we demonstrate that in this system, the neutron star spins retrogradely…