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We present a study of the solar wind over different periods of the solar cycle, specifically focussing on the minimum between solar cycles 24 and 25, and the active, ascending phase of solar cycle 25. With the use of interplanetary…

Solar and Stellar Astrophysics · Physics 2025-06-18 A. Waszewski , J. S. Morgan , R. Ekers , M. Johnston-Hollitt , M. C. M. Cheung , N. D. R. Bhat , R. Chhetri , S. C. Fu

Measurements from the Solar Irradiance Monitor (SIM) onboard the SORCE mission indicate that solar spectral irradiance at Visible and IR wavelengths varies in counter phase with the solar activity cycle. The sign of these variations is not…

Solar and Stellar Astrophysics · Physics 2015-06-19 Serena Criscuoli , Han Uitenbroek

Solar pores are strongly magnetized regions lacking a photospheric penumbra and characterized by predominantly vertical magnetic fields. We present a multi-line study of flashes in a solar pore using high-resolution observations from the…

Solar and Stellar Astrophysics · Physics 2026-02-11 Sandeep Dubey , Christian Beck , Rahul Yadav , Tobias Felipe , Shibu K Mathew

Doppler imaging spectroscopy is the most reliable way to directly measure wind speeds of planetary atmospheres of the Solar system. However, most knowledge about atmospheric dynamics has been obtained with cloud-tracking technique, which…

Earth and Planetary Astrophysics · Physics 2019-06-14 Patrick Gaulme , Francois-Xavier Schmider , Ivan Goncalves

The distribution and evolution of the magnetic field at the solar poles through a solar cycle is an important parameter in understanding the solar dynamo. The accurate observations of the polar magnetic flux is very challenging from the…

Solar and Stellar Astrophysics · Physics 2024-07-26 Sanjay Gosain , Han Uitenbroek

The longitudinal distribution of solar active regions shows non-homogeneous spatial behaviour, which is often referred to as Active Longitude (AL). Evidence for a significant statistical relationships between the AL and the longitudinal…

Solar and Stellar Astrophysics · Physics 2018-08-22 N. Gyenge , R. Erdélyi

Coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for our understanding of the origin and acceleration of the solar wind. Observations from space missions…

The solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and the Earth's upper atmosphere (commonly referred to as space weather). These changes have a direct impact on the…

Solar and Stellar Astrophysics · Physics 2013-04-12 Andrés Muñoz-Jaramillo , María Dasi-Espuig , Laura A. Balmaceda , Edward E. DeLuca

With the assumption of radial motion and uniform longitudinal distribution of coronal mass ejections (CMEs), we propose a method to eliminate projection effects from the apparent observed CME latitude distribution. This method has been…

Astrophysics · Physics 2015-05-13 Song Wenbin , Feng Xueshang , Hu Yanqi

Both coronal holes and active regions are source regions of the solar wind. The distribution of these coronal structures across both space and time is well known, but it is unclear how much each source contributes to the solar wind. In this…

Solar and Stellar Astrophysics · Physics 2021-08-11 D. Stansby , L. M. Green , L. van Driel-Gesztelyi , T. S. Horbury

Solar active regions (ARs) are crucial for understanding the long-term evolution of solar activities and predicting eruptive phenomena, including solar flares and coronal mass ejections. However, the cycle-dependent properties in the…

Solar and Stellar Astrophysics · Physics 2025-04-25 Yuxia Liu , Tingting Xu , Miao Wan , Linhua Deng , Xinhua Zhao , Shiyang Qi , Nanbin Xiang , Weihong Zhou

The chromospheric H-alpha spectral line is a strong line in the spectrum of the Sun and other stars. In the stellar regime, this spectral line is already used as a powerful tracer of stellar activity. For the Sun, other tracers (i.e, CaII…

Solar and Stellar Astrophysics · Physics 2022-05-18 A. Diercke , C. Kuckein , P. W. Cauley , K. Poppenhäger , J. D. Alvarado-Gómez , E. Dineva , C. Denker

Over the course of its motion through the Galaxy, our solar system has encountered many interstellar environments of varying characteristics. Interstellar medium (ISM) density variations spanning seven orders of magnitude are commonly seen…

Solar and Stellar Astrophysics · Physics 2015-06-16 Katherine Wyman , Seth Redfield

The polarization of the Mg II h and k lines holds significant diagnostic potential for measuring chromospheric magnetic fields, which are crucial for understanding the physical processes governing the energy transport and dissipation in the…

Solar and Stellar Astrophysics · Physics 2026-01-01 Hao Li , Tanausú del Pino Alemán , Javier Trujillo Bueno

Major solar flares are prone to occur in active region atmospheres associated with large, complex, dynamically-evolving sunspots. This points to the importance of monitoring the evolution of starspots, not only in visible but also in ultra…

Solar and Stellar Astrophysics · Physics 2020-10-14 Shin Toriumi , Vladimir S. Airapetian , Hugh S. Hudson , Carolus J. Schrijver , Mark C. M. Cheung , Marc L. DeRosa

Future solar missions and ground-based telescopes aim to understand the magnetism of the solar chromosphere. We performed a supporting study in Quintero Noda et al. (2016) focused on the infrared Ca II 8542 A line and we concluded that is…

Solar and Stellar Astrophysics · Physics 2016-12-07 C. Quintero Noda , T. Shimizu , Y. Katsukawa , J. de la Cruz Rodriguez , M. Carlsson , T. Anan , T. Oba , K. Ichimoto , Y. Suematsu

Distribution of the positive and negative photospheric fields is studied on the base of synoptic maps of the photospheric magnetic field produced by the National Solar Observatory Kitt Peak (NSO Kitt Peak) for 1976-2016. In the analysis…

Solar and Stellar Astrophysics · Physics 2019-02-20 E. S. Vernova , M. I. Tyasto , D. G. Baranov , O. A. Danilova

This study depends on KIC 9641031 eclipsing binary system with a chromospherically active component. There are three type variations, such as geometrical variations due to eclipses, sinusoidal variations due to the rotational modulations…

Solar and Stellar Astrophysics · Physics 2016-05-04 Ezgi Yoldaş , Hasan Ali Dal

We present a statistical study of chromospheric evaporation in solar flares using simultaneous observations by the RHESSI X-ray telescope and the IRIS UV spectrograph. The results are compared with radiation hydrodynamic flare models from…

Solar and Stellar Astrophysics · Physics 2019-01-23 Viacheslav M Sadykov , Alexander G Kosovichev , Ivan N Sharykin , Graham S Kerr