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Category/Subcategory: Natural Sciences/Astronomy

Quasi-periodic pulsations in stellar flares

Author: Anne-Marie Broomhall
Quasi-periodic pulsations (QPPs) are a common feature of solar flares that are observed in many different wavelengths. Although QPPs appear not to be as abundant in white light Kepler flare light curves as they are in solar flar ... more

Views: 418

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: 319

Flux Emergence in the Quiet Sun From the Photosphere to the Corona

Author: Ioannis Kontogiannis
We report preliminary results on the evolution of a small-scale bipolar magnetic feature, from its emergence at the photosphere to its brightening at the corona. We use imaging and spectral observations from the space-born Hinode ... more

Views: 4

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: 24

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: 400

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: 506

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: 497

Isochrones of M67 with an Expanded Set of Parameters

Author: Lucas Viani
We create isochrones of M67 using the Yale Rotating Stellar Evolution Code. In addition to metallicity, parameters that are traditionally held fixed, such as the mixing length parameter and initial helium abundance, also vary. The ... more

Views: 437

Preliminary Results from a Coronal Oscillations Instrument during the 2017 Total Eclipse

Author: Pawel Rudawy
An instrument using fast-frame cameras has been used during several recent total solar eclipses to search for oscillations in the green-line coronal emission. A much more sophisticated version of the instrument was prepared, teste ... more

Views: 21

Looking for Magnetic Field in Kepler Red Giants

Author: Jérôme Ballot
Spectropolarimetric measurements allow us to detect and measure magnetic field through Zeeman effect in stellar photospheres. We observed with the spectropolarimeters Narval (at Telescope Bernard Lyot) and ESPADONS (at CFHT) a few ... more

Views: 393