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There have been numerous reports of quasiperiodicities in solar activity in the intermediate period range. However, no accepted explanation for the episodic occurrence of quasiperiodicities has emerged. This paper examines the possibility…

Solar and Stellar Astrophysics · Physics 2015-10-12 Ian Edmonds

Magnetic chemically peculiar stars of the main sequence can present rotational periods as long as many decades. Here we report the results of an observational campaign started in 2001 aimed at establishing these very long periods from the…

Solar and Stellar Astrophysics · Physics 2022-08-22 M. Giarrusso , M. Cecconi , R. Cosentino , M. Munari , A. Ghedina , F. Ambrosino , W. Boschin , F. Leone

The magnetic field of the Sun is generated by internal dynamo process with a cyclic period of 11 years or a 22 year magnetic cycle. The signatures of the Sun's magnetic cycle are observed in the different layers of its atmosphere and in its…

Solar and Stellar Astrophysics · Physics 2023-09-26 Sandra V. Jeffers , Rene Kiefer , Travis S. Metcalfe

Many gravitationally lensed quasars exhibit flux ratio "anomalies" that cannot be explained under the hypothesis that the lensing potential is smooth on scales smaller than one kpc. Micro-lensing by stars is a natural source of granularity…

Astrophysics · Physics 2007-05-23 Paul L. Schechter , Joachim Wambsganss

Measurements of maximum magnetic flux, minimum intensity, and size are presented for 12 967 sunspot umbrae detected on the NASA/NSO spectromagnetograms between 1993 and 2004 to study umbral structure and strength during the solar cycle. The…

Solar and Stellar Astrophysics · Physics 2011-04-07 T. A. Schad , M. J. Penn

A nearby star having a near-transit of a galaxy will cause a time-dependent weak lensing of the galaxy. Because the effect is small, we refer to this as weak microlensing. This could provide a useful method to weigh low-mass stars and brown…

Solar and Stellar Astrophysics · Physics 2015-05-14 Jonathan Coles , Prasenjit Saha , Hans Martin Schmid

The cold dark matter may be in a meta-stable state and decays to other particles with a very long lifetime. If the decaying products of the dark matter are weakly interacting, e.g. neutrinos, then it would have little impact on…

Astrophysics · Physics 2008-11-26 Yan Gong , Xuelei Chen

With the discovery of now more than 500 exoplanets, we present a statistical analysis of the planetary orbital periods and their relationship to the rotation periods of their parent stars. We test whether the structure of planetary orbits,…

Earth and Planetary Astrophysics · Physics 2011-09-22 Jean-Paul Zoghbi

The positron anomaly recently reported by the cosmic-ray measurements suggests that, if explained by the decay of dark matter particle, the decay source is closely linked up with the leptonic sector of the standard model. It is observed…

High Energy Physics - Phenomenology · Physics 2014-11-21 Shigeki Matsumoto , Koichi Yoshioka

The magnetic fields of solar-type stars are observed to cycle over decadal periods -11 years in the case of the Sun. The fields originate in the turbulent convective layers of stars and have a complex dependency upon stellar rotation rate.…

Solar and Stellar Astrophysics · Physics 2017-08-02 A. Strugarek , P. Beaudoin , P. Charbonneau , A. S. Brun , J. -D. do Nascimento

The Sun shows a global magnetic field cycle traditionally best visible in the photosphere as a changing sunspot cycle featuring roughly an 11 year period. In addition we know that our host star also harbours small-scale magnetic fields…

Solar and Stellar Astrophysics · Physics 2017-12-20 D. Utz , R. Muller , T. Van Doorsselaere

Context. The discovery of an extrasolar planet with an ocean has crucial importance in the search for life beyond Earth. The polarimetric detection of specularly reflected light from a smooth liquid surface is anticipated theoretically,…

Earth and Planetary Astrophysics · Physics 2021-09-15 J. Takahashi , Y. Itoh , T. Matsuo , Y. Oasa , Y. P. Bach , M. Ishiguro

This paper presents time series observations and analysis of broadband night sky airglow intensity 4 September 2018 through 30 April 2020. Data were obtained at 5 sites spanning more than 8500 km during the historically deep minimum of…

Solar and Stellar Astrophysics · Physics 2021-12-06 Albert D. Grauer , Patricia A. Grauer

We study the influence of stellar metallicity on the fraction of stars with planets (i.e., the occurrence rate of planetary systems) and the average number of planets per star (i.e., the occurrence rate of planets). The former directly…

Earth and Planetary Astrophysics · Physics 2019-03-06 Wei Zhu

I list the 16 planetary nebulae (PNe) known to contain close-binary nuclei, and show that the nebulae generally have axisymmetric structures, including elliptical, bipolar, or ring morphologies. The orbital periods range from 2.7 hr to 16…

Astrophysics · Physics 2007-05-23 Howard E. Bond

While the quiet Sun magnetic field shows only little variation with the solar cycle, long-term variations cannot be completely ruled out from first principles. We investigate the potential effect of quiet Sun magnetism on spectral solar…

Solar and Stellar Astrophysics · Physics 2020-06-05 M. Rempel

The color-magnitude diagram of the lower main sequence, as measured from a volume-limited sample of nearby stars, shows an abrupt downward jump between Mv = 12 and 13. This jump indicates that the observed mass-radius relationship steepens…

Astrophysics · Physics 2009-10-30 J. Christopher Clemens , I. Neill Reid , John E. Gizis , M. Sean O'Brien

Aims. We analyze observational data from 4 instruments to study the correlations between chromospheric emission, spanning the heights from the temperature minimum region to the middle chromosphere, and photospheric magnetic field. Methods:…

Solar and Stellar Astrophysics · Physics 2014-11-20 Maria A. Loukitcheva , Sami K. Solanki , Stephen M. White

Magnetic reconnection is a fundamental plasma process that plays a critical role not only in energy release in the solar atmosphere, but also in fusion, astrophysical, and other space plasma environments. One of the challenges in explaining…

Solar and Stellar Astrophysics · Physics 2020-10-14 L. -J. Guo , B. De Pontieu , Y. -M. Huang , H. Peter , A. Bhattacharjee

Solar quasi-biennial oscillations with period range 0.6 to 4 years, are prominent in records of solar activity. Here we show that the 1.6 year quasi-biennial oscillation in solar activity has the exceptional feature of phase inversion…

Solar and Stellar Astrophysics · Physics 2021-10-27 Ian R. Edmonds