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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: 484

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: 456

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: 425

Solar Physics Research Integrated Network Group (SPRING) : A Next Generation Ground-based Synoptic Network

Author: Sanjay gosain
SPRING is an evolving concept for next generation solar synoptic observations network. It is envisaged that the new network will cater to the needs of (i) Helioseismology community, by providing improved resolution Doppler observa ... more

Views: 579

Reconnection between emerging and pre-existing magnetic fields observed with IRIS: a case study for EST observations

Author: Salvo Guglielmino
We report multi-wavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the unipolar plage of a ... more

Views: 28

Short- and mid-term activity-related variations in the solar acoustic frequencies

Author: Ângela R. G. Santos
The activity-related variations in the solar acoustic frequencies have been known for 30 years. However, the importance of the different contributions is still not well established. With this in mind, we developed an empirical mod ... more

Views: 484

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: 516

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: 429

Solarnet Transnational Access and Service Programme 2013 - 2017

Author: Solarnet - High Resolution Solar Physics Network
As a part of the SOLARNET project, the Transnational Access and Service Programme supports the access of the European solar physics community to some of the best European telescopes. To enhance the efficiency of data usage, exte ... more

Views: 438

Signatures of magnetic activity in the p mode frequencies of solar-type stars observed by Kepler

Author: René Kiefer
Several hundred stars were observed in the short cadence mode of the Kepler satellite during the nominal mission phase. This generated a large pool of data which can provide insight into the characteristics of stellar activity cyc ... more

Views: 779