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Category/Subcategory: Natural Sciences/Astronomy

Evolutionary states of red-giants stars: how to obtained them from “short” time series data from K2 and Tess

Author: Saskia Hekker
From its surface proper.es it can be difficult to determine whether a red-giant star is in its Helium-core-burning phase or only burning Hydrogen in a shell around an inert Helium core. Stars in either of these stage can have simi ... more

Views: 465

ON POSSIBLE EXPLANATIONS OF PULSATIONS IN MAIA STARS

Author: Jadwiga Daszynska-Daszkiewicz
The long-time photometric surveys in a few young open clusters allowed to identify the light variability in stars located between the well defined  Scuti variables and Slowly Pulsating B-type stars (Mowlavi et al, 2013, 2015). ... more

Views: 433

Filaments data since 1919: A basis for statistics

Author: Jean Aboudarham
From 1919 to 2002, Paris-Meudon Observatory published synoptic maps of the Solar activity. Together with maps, tables were provided, containing some information concerning at least filaments. The board of Paris Observatory funded ... more

Views: 478

Analysis of a subdwarf B pulsator observed during Campaign 2 of K2

Author: Laura Ketzer
We present an analysis of the pulsating subdwarf B (sdB) star EPIC 203948264, observed during Campaign 2 of the extended Kepler mission. A time series analysis of the short cadence data set has revealed a rich g-mode pulsation spe ... more

Views: 373

Measurements of helioseismic travel times

Author: Markus Roth
In time-distance helioseismology wave travel times are measured from the cross-correlation between Doppler velocities recorded at any two locations on the solar surface. All local helioseismology inferences rely critically on the ... more

Views: 460

Non-LTE inversion of spectropolarimetric and spectroscopic observations of a small active-region filament observed at the VTT

Author: Pavol Schwartz
An active-region filament in the active region NOAA 12159 (at solar disk coordinates [x,y] = [225,-440] arcsec) was observed with the Vacuum Tower Telescope at Tenerife on 11 September 2014. Full-Stokes spectropolarimetric observa ... more

Views: 662

Forecasting the arrival of Coronal Mass Ejections: The Drag-Based Model

Author: Bojan Vrsnak
We present a new space weather online forecast-tool for predicting the arrival of Interplanetary Coronal Mass Ejections (ICMEs). The forecast-tool is based on the “Drag-Based Model” (DBM), developed in the frame of the Europea ... more

Views: 809

Measurements of the Absorption and Scattering Cross Sections for the Interactions of Solar Acoustic Waves with Sunspots

Author: Hui Zhao
The solar acoustic waves are modified by the interaction with sunspots. The interaction can be treated as a scattering problem: an incident wave propagating toward a sunspot is scattered by the sunspot into different modes. Th ... more

Views: 367

The additional-mode garden of RRab stars

Author: László Molnár
Space-based photometric missions revealed a surprising abundance of millimagnitude-level additional modes in RR Lyrae stars. The modes that appear in the modulated fundamental-mode (RRab) stars can be ordered into four major categ ... more

Views: 449

Overcoming Systematic Effects in Ring-Diagram Fitting

Author: Richard Bogart
Although the principles involved in understanding ring-diagram mode frequencies are well understood, the procedures for determining those frequencies in the power spectra of flattened geometries are plagued by several systematic e ... more

Views: 417