Search Publications
On the usefulness of existing solar wind models for pulsar timing corrections
Dettmar, R. -J.; Kramer, M.; Zucca, P. +15 more
Dispersive delays due to the solar wind introduce excess noise in high-precision pulsar timing experiments, and must be removed in order to achieve the accuracy needed to detect, e.g., low-frequency gravitational waves. In current pulsar timing experiments, this delay is usually removed by approximating the electron density distribution in the sol…
Mass loss via solar wind and coronal mass ejections during solar cycles 23 and 24
Wang, Yuming; Liu, Rui; Srivastava, Nandita +3 more
Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind and episodic stellar coronal mass ejections (CMEs). We investigate the mass loss rate via solar wind and CMEs as a function of solar magnetic variability represented in terms of sunspot number and solar X-ray background luminosity. We estimate the contribu…
Hemispheric asymmetry in meridional flow and the sunspot cycle
Antia, H. M.; Nandy, Dibyendu; Lekshmi, B.
Magnetohydrodynamic dynamo modelling shows that the large-scale solar meridional plasma flow plays an important role in governing the dynamics of the sunspot cycle. Observations indicate that meridional flow velocities at each solar latitude and depth vary over time and are asymmetric across the equator. Here, using helioseismic observations we ex…
Discovery statistics and 1/a distribution of long-period comets detected during 1801-2017
Dybczyński, Piotr A.; Królikowska, Małgorzata
For the last two decades, we have been observing a huge increase in discoveries of long-period comets (LPCs), especially those with large perihelion distances. We collected data for a full sample of LPCs discovered during 1801-2017, including their osculating orbits, discovery moments (to study the discovery distances) and original semimajor axes …
Asteroseismic constraints on active latitudes of solar-type stars: HD 173701 has active bands at higher latitudes than the Sun
Chaplin, William J.; Davies, Guy R.; Miglio, Andrea +6 more
We present a new method for determining the location of active bands of latitude on solar-type stars, which uses stellar-cycle-induced frequency shifts of detectable solar-like oscillations. When near-surface activity is distributed in a non-homogeneous manner, oscillation modes of different angular degree and azimuthal order will have their frequ…
Multifractal detrended moving average analysis of Kepler stars with surface differential rotation traces
De Medeiros, J. R.; de Freitas, D. B.; Das Chagas, M. L. +2 more
A multifractal formalism is employed to analyse high-precision time-series data of Kepler stars with surface differential rotation (DR) traces. The multifractal detrended moving average (MFDMA) algorithm has been explored to characterize the multiscale behaviour of the observed time series from a sample of 662 stars selected with parameters close …
On the saturation of acoustic mode frequencies at high solar activity
Rabello Soares, M. Cristina
Acoustic mode frequencies obtained by applying spherical harmonic decomposition to HMI, MDI, and GONG observations were analysed throughout the solar cycle. Evidence of a deviation from a linear relation with solar radio flux was found indicating a saturation effect at high solar activity. The Gompertz model, which is one of the most frequently us…