Zobrazeno 1 - 10
of 22
pro vyhledávání: '"Jetsu, Lauri"'
Autor:
Jetsu, Lauri
The mainstream dynamo models predict that the sunspot cycle is stochastic. The official Solar Cycle Prediction Panel forecasts only the ongoing sunspot cycle because any forecast beyond one cycle is considered impossible. We analyse the sunspot data
Externí odkaz:
http://arxiv.org/abs/2311.08317
Autor:
Jetsu, Lauri
Unambiguous detection of signals superimposed on unknown trends is difficult for unevenly spaced data. Here, we formulate the Discrete Chi-square Method (DCM) that can determine the best model for many signals superimposed on arbitrary polynomial tre
Externí odkaz:
http://arxiv.org/abs/2002.03890
Autor:
Lehtinen, Jyri J., Käpylä, Maarit J., Hackman, Thomas, Kochukhov, Oleg, Willamo, Teemu, Marsden, Stephen C., Jeffers, Sandra V., Henry, Gregory W., Jetsu, Lauri
Publikováno v:
A&A 660, A141 (2022)
Previous studies have related surface temperature maps, obtained with the Doppler imaging (DI) technique, of LQ Hya with long-term photometry. We compare surface magnetic field maps, obtained with the Zeeman Doppler imaging (ZDI) technique, with cont
Externí odkaz:
http://arxiv.org/abs/1909.11028
Autor:
Porceddu, Sebastian, Jetsu, Lauri, Markkanen, Tapio, Lyytinen, Joonas, Kajatkari, Perttu, Lehtinen, Jyri, Toivari-Viitala, Jaana
An ancient Egyptian Calendar of Lucky and Unlucky Days, the Cairo Calendar (CC), assigns luck with the period of 2.850 days. Previous astronomical, astrophysical and statistical analyses of CC support the idea that this was the period of the eclipsin
Externí odkaz:
http://arxiv.org/abs/1810.06412
Autor:
Jetsu, Lauri, Porceddu, Sebastian
Publikováno v:
PLOS ONE, 10(12), e0144140, 2015
The Ancient Egyptians wrote Calendars of Lucky and Unlucky Days that assigned astronomically influenced prognoses for each day of the year. The best preserved of these calendars is the Cairo Calendar (hereafter CC) dated to 1244--1163 B.C. We have pr
Externí odkaz:
http://arxiv.org/abs/1601.06990
Publikováno v:
A&A 588, A38 (2016)
We study a sample of 21 young and active solar-type stars with spectral types ranging from late F to mid K and characterize the behaviour of their activity. We apply the continuous period search (CPS) time series analysis method on 16 to 27 years of
Externí odkaz:
http://arxiv.org/abs/1509.06606
Autor:
Lindborg, Marjaana, Mantere, Maarit J., Olspert, Nigul, Pelt, Jaan, Hackman, Thomas, Henry, Gregory W., Jetsu, Lauri, Strassmeier, Klaus G.
According to earlier Doppler images of the magnetically active primary giant component of the RS CVn binary II Peg, the surface of the star was dominated by one single active longitude that was clearly drifting in the rotational frame of the binary s
Externí odkaz:
http://arxiv.org/abs/1304.4144
Autor:
Hackman, Thomas, Pelt, Jaan, Mantere, Maarit J., Jetsu, Lauri, Korhonen, Heidi, Granzer, Thomas, Kajatkari, Perttu, Lehtinen, Jyri, Strassmeier, Klaus G.
FK Comae is a rapidly rotating magnetically active star, the light curve of which is modulated by cool spots on its surface. It was the first star where the "flip-flop" phenomenon was discovered. Since then, flip-flops in the spot activity have been
Externí odkaz:
http://arxiv.org/abs/1211.0914
Autor:
Porceddu Sebastian, Jetsu Lauri, Markkanen Tapio, Lyytinen Joonas, Kajatkari Perttu, Lehtinen Jyri, Toivari-Viitala Jaana
Publikováno v:
Open Astronomy, Vol 27, Iss 1, Pp 232-263 (2018)
An ancient Egyptian Calendar of Lucky and Unlucky Days, the Cairo Calendar (CC), assigns luck with the period of 2.850 days. Previous astronomical, astrophysical and statistical analyses of CC support the idea that this was the period of the eclipsin
Externí odkaz:
https://doaj.org/article/1d8da604f7794220b1844390acd6c374
Autor:
Jetsu, Lauri
The most significant periodicities in the terrestrial impact crater record are due to the human-signal: the bias of assigning integer values for the crater ages. This bias seems to have eluded the proponents and opponents of real periodicity in the o
Externí odkaz:
http://arxiv.org/abs/astro-ph/9701104