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Thermodynamic evolution of a sigmoidal active region with associated flares
Mulay, Sargam M.; Tripathi, Durgesh; Mason, Helen
Active regions often show S-shaped structures in the corona called sigmoids. These are highly sheared and twisted loops formed along the polarity inversion line. They are considered to be one of the best pre-eruption signatures for CMEs. Here, we investigate the thermodynamic evolution of an on-disc sigmoid observed during 2015 December 24-28. For…
Quasi-periodic ripples in the heliosphere from 1 to 40 AU
Birch, M. J.; Hargreaves, J. K.
This study extends the investigation of the ripples in the solar wind and the interplanetary magnetic field at L1 reported by Birch and Hargreaves (2020) to cover heliospheric distances from 1 to 40 AU, using data from the Voyager 2, Ulysses, Juno, Cassini, Themis and Apollo-12 spacecraft. The ripples were extracted from the source data using a ba…
Testing and Validating Two Morphological Flare Predictors by Logistic Regression Machine Learning
Erdélyi, R.; Korsós, M. B.; Morgan, H. +1 more
Whilst the most dynamic solar active regions (ARs) are known to flare frequently, predicting the occurrence of individual flares and their magnitude, is very much a developing field with strong potentials for machine learning applications. The present work is based on a method which is developed to define numerical measures of the mixed states of …
Molecular Gas in a Gravitationally Lensed Galaxy Group at z = 2.9
Richard, Johan; Brammer, Gabriel; Whitaker, Katherine E. +5 more
Most molecular gas studies of z > 2.5 galaxies are of intrinsically bright objects, despite the galaxy population being primarily normal galaxies with less extreme star formation rates. Observations of normal galaxies at high redshift provide a more representative view of galaxy evolution and star formation, but such observations are challengin…
European VLBI Network Observations of the Proposed Dual AGN SDSS J101022.95+141300.9
Paragi, Zsolt; Frey, Sándor; Gabányi, Krisztina Éva +3 more
During galaxy merger events, the supermassive black holes in the center of the galaxies may form a pair of active galactic nuclei (AGN) with kiloparsec-scale or even parsec-scale separation. Recently, optical observations revealed a promising dual-AGN candidate at the center of the galaxy SDSS J101022.95+141300.9 (hereafter J1010+1413). The presen…
Strongly lensed candidates from the HSC transient survey
Suyu, Sherry H.; Jaelani, Anton T.; Nagao, Tohru +5 more
We present a lensed quasar search based on the variability of lens systems in the Hyper Suprime-Cam (HSC) transient survey. Starting from 101 353 variable objects with i-band photometry in the HSC transient survey, we used a variability-based lens search method measuring the spatial extent in difference images to select potential lensed quasar can…
Wide companions to M and L subdwarfs with Gaia and the Virtual Observatory
Cortés-Contreras, M.; Solano, E.; Lodieu, N. +3 more
Aims: The aim of the project is to identify wide common proper motion companions to a sample of spectroscopically confirmed M and L metal-poor dwarfs (also known as subdwarfs) to investigate the impact of metallicity on the binary fraction of low-mass metal-poor binaries and to improve the determination of their metallicity from the higher-ma…
Nonequilibrium Ionization Plasma during a Large Solar Limb Flare Observed by Hinode/EIS
Imada, S.
This study on plasma heating considers the time-dependent ionization process during a large solar flare on 2017 September 10, observed by Hinode/EUV Imaging Spectrometer (EIS). The observed Fe XXIV/Fe XXIII ratios increase downstream of the reconnection outflow, and they are consistent with the time-dependent ionization effect at a constant electr…
Astrophysical parameters and dynamical evolution of open clusters: NGC 2587, Collinder 268 and Melotte 72, and Pismis 7
Çakmak, Hikmet; Karataş, Yüksel; Bonatto, Charles +1 more
We determined astrophysical and dynamical parameters of the open clusters (OCs) NGC 2587, Collinder 268 (Col 268), Melotte 72 (Mel 72), and Pismis 7 from Gaia DR2 photometric/astrometric data and a new technique, fitCMD. fitCMD provides (Z, Age(Gyr)) as (0.025, 0.45) for NGC 2587, (0.0025, 0.5) for Col 268, (0.011, 1.25) for Mel 72, and (0.008, 1.…
Analytic Estimates of the Achievable Precision on the Physical Properties of Transiting Planets Using Purely Empirical Measurements
Stevens, Daniel J.; Gaudi, B. Scott; Johnson, Jennifer A. +4 more
We present analytic estimates of the fractional uncertainties on the mass, radius, surface gravity, and density of a transiting planet, using only empirical or semi-empirical measurements. We first express these parameters in terms of transit photometry and radial velocity (RV) observables, as well as the stellar radius R⋆, if required.…