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Related papers: The magnetic future of the Sun

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We report on the results of the Sun in Time multi-wavelength program (X-rays to the UV) of solar analogs with ages covering ~0.1-7 Gyr. The chief science goals are to study the solar magnetic dynamo and to determine the radiative and…

Astrophysics · Physics 2009-11-10 I. Ribas , E. F. Guinan , M. Guedel , M. Audard

We use X-ray observations of the nearby binaries 61 Cyg A/B (K5V and K7V) and Alpha Cen A/B (G2V and K1V) to study the long-term evolution of magnetic activity in weakly to moderately active G + K dwarfs over nearly a decade. Specifically…

Solar and Stellar Astrophysics · Physics 2015-06-05 J. Robrade , J. H. M. M. Schmitt , F. Favata

The last solar minimum has been unusually quiet compared to the previous minima (since space-based radiometric measurements are available). The Sun's magnetic flux was substantially lower during this minimum. Some studies also show that the…

Solar and Stellar Astrophysics · Physics 2015-09-02 F. Shakeri , L. Teriaca , S. K. Solanki

Multi-wavelength studies of solar analogs (G0-5 V stars) with ages from ~50 Myr to 9 Gyr have been carried out as part of the "Sun in Time" program for nearly 20 yrs. From these studies it is inferred that the young (ZAMS) Sun was rotating…

Solar and Stellar Astrophysics · Physics 2015-05-13 Edward F. Guinan , Scott G. Engle

The extreme-ultraviolet (EUV; 100 -- 911 \AA) spectra of F, G, K, and M stars provide diagnostics of the stellar chromosphere through the corona, with line and continuum formation temperatures spanning roughly 10$^{4}$ - 10$^{7}$ K. The EUV…

In the present paper, we model the wind of solar analogues at different ages to investigate the evolution of the solar wind. Recently, it has been suggested that winds of solar type stars might undergo a change in properties at old ages,…

Solar and Stellar Astrophysics · Physics 2018-05-02 D. Ó Fionnagáin , A. A. Vidotto

We investigate the X-ray and UV emission detected by RHESSI and TRACE in the context of a solar flare on the 16th November 2002 with the goal of better understanding the evolution of the flare. We analysed the characteristics of the X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-11 Hamish A. S. Reid , Nicole Vilmer , Guillaume Aulanier , Etienne Pariat

Variations of the solar UV irradiance are an important driver of chemical and physical processes in the Earth's upper atmosphere and may also influence global climate. Here we reconstruct solar UV irradiance in the range 115-400 nm over the…

Solar and Stellar Astrophysics · Physics 2009-11-23 N. A. Krivova , S. K. Solanki , T. Wenzler , B. Podlipnik

To address the role of energetic processes in the solar nebula, we provide a detailed characterization of magnetic flaring in stellar analogs of the pre-main sequence Sun based on 23 hours observations of 43 analogs of the young Sun in the…

Astrophysics · Physics 2009-11-07 Eric D. Feigelson , Gordon P. Garmire , Steven H. Pravdo

Solar observations with the Atacama Large Millimeter/submillimeter Array (ALMA) provide us with direct measurements of the brightness temperature in the solar chromosphere. We study the temperature distributions obtained with ALMA Band 6…

Solar and Stellar Astrophysics · Physics 2019-02-13 Shahin Jafarzadeh , Sven Wedemeyer , Mikolaj Szydlarski , Bart De Pontieu , Reza Rezaei , Mats Carlsson

The Sun has a steady 11-year cycle in magnetic activity most well-known by the rising and falling in the occurrence of dark sunspots on the solar disk in visible bandpasses. The 11-year cycle is also manifest in the variations of emission…

Solar and Stellar Astrophysics · Physics 2016-09-19 Ricky Egeland , Willie Soon , Sallie Baliunas , Jeffrey C. Hall , Alexei A. Pevtsov , Gregory W. Henry

The far ultraviolet (FUV) continuum flux is recognized as a very sensitive diag- nostic of the temperature structure of the Sun's lower chromosphere. Until now analysis of the available stellar FUV data has shown that solar-type stars must…

Solar and Stellar Astrophysics · Physics 2015-05-30 Jeffrey L. Linsky , Rachel Bushinsky , Tom Ayres , Juan Fontenla , Kevin France

Finding solar-analog stars with fundamental properties as close as possible to the Sun and studying the characteristics of their surface magnetic activity is a very promising way to understand the solar variability and its associated dynamo…

The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…

Solar and Stellar Astrophysics · Physics 2015-09-15 Amir Caspi , Thomas N. Woods , Harry P. Warren

We take a broad look at the problem of identifying the magnetic solar causes of space weather. With the lackluster performance of extrapolations based upon magnetic field measurements in the photosphere, we identify a region in the near UV…

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph (IRIS). The observations were made of a solar active region on 2015 December 18 as part of the…

Solar and Stellar Astrophysics · Physics 2017-08-30 T. S. Bastian , G. Chintzoglou , B. De Pontieu , M. Shimojo , D. Schmit , J. Leenaarts , M. Loukitcheva

We present and analyze FUSE observations of six solar analogs. These are single, main-sequence G0-5 strs selected as proxies for the Sun at several stages of its main-sequence lifetime. The emission features in the FUSE 920-1180 A…

Astrophysics · Physics 2009-11-07 Edward F. Guinan , Ignasi Ribas , Graham M. Harper

It is well known that the magnetic activity of solar type stars decreases with age, but it is widely debated in the literature whether there is a smooth decline or if there is an early sharp drop until 1-2 Gyr followed by a relatively…

We present ultraviolet (UV) spectroscopy of the 17 Myr, G0V star, HIP 67522. The UV spectrum is characterized by strong chromospheric and transition region emission lines. There was moderate spectral variability during the observations…

(abridged) We investigate the long-term evolution of X-ray coronae of solar analogs based on high-resolution X-ray spectroscopy and photometry with XMM-Newton. Six nearby main-sequence G stars with ages between ~0.1 Gyr and \~1.6 Gyr and…

Astrophysics · Physics 2009-11-10 A. Telleschi , M. Guedel , K. Briggs , M. Audard , J. -U. Ness , S. L. Skinner
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