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Category/Subcategory: Natural Sciences/Astronomy

Physical formulation of the eigenfrequency condition of mixed modes of stellar oscillations

Author: Masao Takata
The frequency condition for the mixed modes of nonradial stellar oscillations is generally examined by a simple physical model based on a running-wave picture. The coupling coefficient between the gravity-wave oscillation in the ... more

Views: 275

High cadence observations and analysis of spicular-type events using CRISP onboard SST

Author: Juie Shetye
A statistical study of spectral images, taken from the CRISP instrument at the Swedish 1-m Solar Telescope in H-alpha 656.28 nm of fast spicules, present Doppler velocities in the range of -41km/s to +41 km/s. Remarkably, many ... more

Views: 368

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: 396

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: 405

Celebrating Mopra: looking to the future

Author: Michael Burton
Workshop poster for "Celebrating Mopra: looking to the future", held at the University of New South Wales in Sydney on Dec 9-11, 2015. Also including a workshop on the JCMT and the East Asia Observatory.

Views: 554

Effects of the HeII ionization zones on oscillation frequencies Applications to Kepler and CoRoT stars

Author: mutlu yildiz
Solar-like oscillation frequencies of 93 target stars of Kepler and CoRoT are analyzed. In the present study, we present results for two of them. Recently, two new reference frequencies nu_min1 and nu_min2 are found in the spacin ... more

Views: 439

Validating Spherical Born Kernels for Meridional Flows

Author: Vincent Böning
We present the current status of an undergoing validation of a recently developed model for computing spherical Born approximation sensitivity functions for flows. In a first step, power spectra and reference cross-correlations fr ... more

Views: 472

Some general results on relative magnetic helicity and field line helicity

Author: Jean-Jacques Aly
We present some general considerations on two quantities that are of common use in solar physics: the relative magnetic helicity H and the field line helicity h of a magnetic field B contained in some domain D. 1. We show how t ... more

Views: 88

The Early Local Universe – Inside and Outside the Stars

Author: Birgitta Nordstrom
Extremely metal-poor (EMP) halo stars with [Fe/H] below ~ -3 are considered to be fossil records of conditions in the early halo. In the naïve picture in which iron is a proxy for overall metallicity and indirectly for time, EMP ... more

Views: 481

Revisiting the Instability Strip for rapidly oscillating Ap stars

Author: Maragrida Cunha
Chemically peculiar stars are stage to a wide variety of physical phenomena. Progress in the understanding of these objects, through the study of their oscillations, can help us characterize these physical phenomena and better und ... more

Views: 351