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Category/Subcategory: Natural Sciences/Astronomy

Empirical Mode Decomposition studies of quasi-biennial variations in helioseismic frequencies

Author: Anne-Marie Broomhall
It is well-known that the Sun’s magnetic activity varies primarily on a time scale of 11yrs. It is also well known that the frequencies of the Sun’s natural acoustic oscillations vary in-phase with surface and atmospheric me ... more

Views: 472

16CygA&B and Kepler Legacy values : Differences between the values of frequencies by different fitters

Author: Ian Roxburgh
The differences between the oscillation frequencies and uncertainty estimates of a star derived by different fitters can be large, sufficiently large so that, were one to find a stellar model that fitted one frequency set ($\chi^ ... more

Views: 865

Asteroseismic signature of a starspot

Author: Emanuele Papini
Stellar acoustic oscillations are affected by magnetic activity, however it is unclear how a single starspot would affect the power spectrum of oscillations. Since the starspot rotates with the star, it causes a perturbation that ... more

Views: 351

Time-series spectroscopy of the eclipsing binary AB Cas with a pulsating component

Author: Kyeongsoo Hong
We present high resolution spectra of the eclipsing binary AB Cas with a δ Sct-type pulsating star, which were obtained using the Bohyunsan Optical Echelle Spectrograph in Korea. The radial velocities (RVs) for the primary and se ... more

Views: 274

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: 397

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: 314

Starspot signature on the light curve: learning about the spot distribution

Author: Ângela R. G. Santos
Starspots are cooler/darker than the stellar surface. Therefore, the total flux of a star changes when spots are visible on its surface. The presence of spots together with the stellar rotation leads to a periodic modulation on th ... more

Views: 272

The K2 RR Lyrae survey

Author: Robert Szabo
We have initiated a large survey with K2, to observe thousands of RR Lyrae stars along the ecliptic. The high photometric precision and the 80-90-day continuous coverage will allow us to investigate the light variation of these ga ... more

Views: 388

Numerical simulations of magneto-acoustic wave propagation from the upper convection zone into the chromosphere.

Author: Christian Nutto
The contribution of acoustic waves to the chromospheric heating is still an open question. To discuss this Issue, it is crucial to understand the propagation of waves from the convection zone, where the waves are excited, into the ... more

Views: 497

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: 408