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Related papers: The Sun in Time: Activity and Environment

200 papers

The diagram of indices of coronal and chromospheric activity allowed us to reveal stars where solar-type activity appears and regular cycles are forming. Using new consideration of a relation between coronal activity and the rotation rate,…

Solar and Stellar Astrophysics · Physics 2015-08-06 M. M. Katsova , N. I. Bondar' , M. A. Livshits

We discuss the evolution of solar coronal element abundances over an active region lifetime. Magneto-convection drives the complexity of magnetic fields that emerge above the photosphere. This complexity is dissipated, together with that of…

Solar and Stellar Astrophysics · Physics 2025-12-16 David H. Brooks , Deborah Baker , David M. Long. Paola Testa , Harry P. Warren

By extending our self-consistent MHD simulations for the solar wind, we study the evolution of stellar winds of solar-type stars from early main sequence stage to red giant phase. Young solar-type stars are active and the mass loss rates…

Solar and Stellar Astrophysics · Physics 2015-06-12 Takeru K. Suzuki

Solar flares occur due to the sudden release of energy stored in active-region magnetic fields. To date, the pre-cursors to flaring are still not fully understood, although there is evidence that flaring is related to changes in the…

Solar and Stellar Astrophysics · Physics 2012-02-01 Sophie A. Murray , D. Shaun Bloomfield , Peter T. Gallagher

This work reviews our understanding of the magnetic fields observed in the quiet Sun. The subject has undergone a major change during the last decade (quiet revolution), and it will remain changing since the techniques of diagnostic…

Solar and Stellar Astrophysics · Physics 2011-05-03 J. Sanchez Almeida , M. Martinez Gonzalez

We investigate spatio-temporal evolution of high-degree acoustic mode frequencies of the Sun and the surface magnetic activity, over the course of multiple solar cycles, to improve our understanding of the connection between the solar…

Solar and Stellar Astrophysics · Physics 2023-12-20 Mackenzie A. Baird , Sushanta C. Tripathy , Kiran Jain

The Sun's magnetic field varies in multiple time scales. Observations show that the minimum between cycles 24 and 25 was the second consecutive minimum which was deeper and wider than several earlier minima. Since the active regions…

Solar and Stellar Astrophysics · Physics 2022-01-19 Kiran Jain , Niket Jain , Sushanta C. Tripathy , Mausumi Dikpati

Sunspots are the most spectacular manifestation of solar magnetism, yet, 99% of the solar surface remains 'quiet' at any time of the solar cycle. The quiet sun is not void of magnetic fields, though; they are organized at smaller spatial…

Solar and Stellar Astrophysics · Physics 2015-05-18 M. J. Martinez Gonzalez , R. Manso Sainz , A. Asensio Ramos , L. R. Bellot Rubio

Solar activity can be witnessed in the form of sunspots and active regions, where the magnetic field is enhanced by up to a factor 1000 as compared to that of the quiet Sun. In addition, solar activity manifests itself in terms of flares,…

Solar and Stellar Astrophysics · Physics 2025-07-25 Gottfried Mann , Frédéric Schuller

Observations of sun-like stars rotating faster than our current sun tend to exhibit increased magnetic activity as well as magnetic cycles spanning multiple years. Using global simulations in spherical shells to study the coupling of…

Solar and Stellar Astrophysics · Physics 2015-05-20 Nicholas J. Nelson , Benjamin P. Brown , Matthew K. Browning , Allan Sacha Brun , Mark S. Miesch , Juri Toomre

Recent studies have shown that the local environment of the Sun is a complex one with the presence of several supernova shock bubbles and interstellar clouds. Even within this environment, the Sun is moving with a velocity of about 15 km/s…

Astrophysics · Physics 2007-05-23 M N Vahia

The presence of magnetic field is crucial in the transport of energy through the solar atmosphere. Recent ground-based and space-borne observations of the quiet Sun have revealed that magnetic field accumulates at photospheric heights, via…

Solar and Stellar Astrophysics · Physics 2019-06-19 Juan Martínez-Sykora , Viggo H. Hansteen , Boris Gudiksen , Mats Carlsson , Bart De Pontieu , Milan Gosic

The Sun experienced a period of unprecedented activity during the 20th century, now called the Modern Maximum (MM). The decay of the MM after cycle 19 has changed the Sun, the heliosphere, and the planetary environments in many ways.…

Solar and Stellar Astrophysics · Physics 2024-03-14 K. Mursula , A. A. Pevtsov , T. Asikainen , I. Tähtinen , A. R. Yeates

X-ray and ultraviolet (XUV) emission from young stars plays a critical role in shaping the evolution of planetary atmospheres and the conditions for habitability. To assess the long-term impact of high-energy stellar radiation, it is…

Solar and Stellar Astrophysics · Physics 2025-12-16 Konstantin V. Getman , Eric D. Feigelson , Vladimir S. Airapetian , Gordon P. Garmire

Identifying the two physical mechanisms behind the production and sustenance of the quiescent solar corona and solar wind poses two of the outstanding problems in solar physics today. We present analysis of spectroscopic observations from…

Helioseismology puts strong constraints on the internal sound speed and on the rotation profile in the radiative zone. Young stars of solar type are more active and faster rotators than the Sun. So we begin to build models which include…

Solar and Stellar Astrophysics · Physics 2015-05-20 S Turck-Chieze , S Couvidat , V Duez , S Mathis , J Marques , A Palacios , L Piau

In the following short review we will outline some of the possible interaction processes of lower solar atmospheric plasma with the embedded small-scale solar magnetic fields. After introducing the topic, important types of small-scale…

Solar and Stellar Astrophysics · Physics 2022-10-07 Santiago Vargas Domínguez , Dominik Utz

The X-ray emission from the Sun reveals a very dynamic hot atmosphere, the corona, which is characterized by a complex morphology and broad range of timescales of variability and spatial structuring. The solar magnetic fields play a…

Solar and Stellar Astrophysics · Physics 2022-06-09 Paola Testa , Fabio Reale

The global magnetic field in the solar corona is known to contain free magnetic energy and magnetic helicity above that of a current-free (potential) state. But the strength of this non-potentiality and its evolution over the solar cycle…

Solar and Stellar Astrophysics · Physics 2024-05-24 Anthony R. Yeates

The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional…