相关论文: Estimating activity cycles with probabilistic meth…

We attempt to provide a quantitative theoretical explanation for the observations that Ca II H/K emission and X-ray emission from solar-like stars increase with decreasing Rossby number (i.e., with faster rotation). Assuming that these…

The chromospheric emission estimated in the core of different lines, such as Ca II H & K, Na D1 and D2, and Halpha, is not always correlated between lines, as the Ca II H & K and Halpha emission time series are anti-correlated for a few…

We analyse the relation between the activity cycle length and the Rossby number and collected a sample of 44 main sequence stars with well-known activity cycle periods and rotation periods. We find a linear behaviour in the…

We present a method of chromospheric flux simulation for 13 late-type main-sequence stars. These Sun-like stars have well-determined cyclic flux variations similar to 11 yr solar activity cycle. Our flux prediction is based on chromospheric…

We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. We analyse light-curves spanning up to 9 years of 125 nearby…

The growing field of large-scale time domain astronomy requires methods for probabilistic data analysis that are computationally tractable, even with large datasets. Gaussian Processes are a popular class of models used for this purpose…

An update is given on the current status of solar and stellar dynamos. At present, it is still unclear why stellar cycle frequencies increase with rotation frequency in such a way that their ratio increases with stellar activity. The…

The problem of prediction of a given time series is examined on the basis of recent nonlinear dynamics theories. Particular attention is devoted to forecast the amplitude and phase of one of the most common solar indicator activity, the…

Aims. Other stars are known to have magnetic cycles similar to that of the Sun. The relationship between these activity variations and the observed radial-velocity is still not satisfactorily understood. In this first paper our aim is to…

Spectroscopic equilibrium allows us to obtain precise stellar parameters in Sun-like stars. It relies on the assumption of the iron excitation and ionization equilibrium. However, several works suggest that magnetic activity may affect…

The cyclicity of 33 solar-type stars that are similar to 11-year and to the quasi-biennial variations of solar radiation have studied. Our calculation were based on new simultaneous observations of the flux variations of the photospheric…

Zeeman Doppler imaging has successfully mapped the large-scale magnetic fields of stars over a large range of spectral types, rotation periods and ages. When observed over multiple epochs, some stars show polarity reversals in their global…

This paper studies high-dimensional curve time series with common stochastic trends. A dual functional factor model structure is adopted with a high-dimensional factor model for the observed curve time series and a low-dimensional factor…

Star clusters are studied widely both as benchmarks for stellar evolution models and in their own right. Cluster age and mass distributions within galaxies are probes of star formation histories, and of cluster formation and disruption…

We present a method, based on the kinematic analysis of the Galactic disk stars, to clarify whether the internal motions of the stellar system in spiral arms follow those expected in the density wave theory. The method relies on the…

This paper proposes the idea that the observed dependence of stellar activity cycles on rotation rate can be a manifestation of a stronger dependence on the effective temperature. Observational evidence is recalled and theoretical arguments…

We study the short-periodic component of stellar activity with a cycle periods Pcyc up to 1000 days using the Kepler mission photometry of fast-rotating (rotational periods from 1 to 4 days) stars with spectra of M4V to F3V. Applying the…

Human behavior drives a range of complex social, urban, and economic systems, yet understanding its structure and dynamics at the individual level remains an open question. From credit card transactions to communications data, human…

Since the early 1970s, stellar population modelling has been one of the basic tools for understanding the physics of unresolved systems from observation of their integrated light. Models allow us to relate the integrated spectra (or…

Stellar activity remains a limiting factor in measuring precise planet parameters from radial velocity spectroscopy, not least in the search for Earth mass planets orbiting in the habitable zones of Sun-like stars. One approach to mitigate…