Several coronal bright points identified in a quiet region of the Sun from SOHO/EIT Fe XII images are found to have a time evolution from birth to decay which is extremely well correlated with the rise and fall of magnetic flux as determined from photospheric magnetograms made with the SOHO/MDI instrument. Radiative losses of the bright points are found to be much less than conductive losses bu...

Bright EUV sunspot plumes have been observed in five out of nine sunspot regions with the Coronal Diagnostic Spectrometer – CDS on SOHO. In the other four regions the brightest line emissions may appear inside the sunspot but are mainly concentrated in small regions outside the sunspot areas. These results are in contrast to those obtained during the Solar Maximum Mission, but are compatible wi...

Recent advances have made it possible to obtain two-dimensional line-of-sight magnetic field maps of the solar corona from spectropolarimetric observations of the Fe XIII 1075 nm forbidden coronal emission line. Together with the linear polarization measurements that map the azimuthal direction of the coronal magnetic field projected in the plane of the sky containing Sun center, these coronal ...

A sudden depletion or intensity “dimming” of the X-ray corona sometimes accompanies a solar eruptive flare or coronal mass ejection (CME). We have identified a dimming that occurred just prior to a “halo” CME, observed on 1997 April 7 using the Soft X-ray Telescope (SXT) on Yohkoh. Halo CMEs are prime candidates for “space weather” effects. The dimming occurred in compact regions near a flare o...

Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the properties of larger brightenings gives unreliable estimates of the power-law exponent α characterising their distribution. Here we take the approach of statistically modelling light curves representative of the quiet Sun...

An observational relationship has been well established among magnetic reconnection, high-energy flare emissions and the rising motion of erupting flux ropes. In this paper, we verify that the rate of magnetic reconnection in the low corona is temporally correlated with the evolution of flare nonthermal emissions in hard X-rays and microwaves, all reaching their peak values during the rising ph...

We present a comprehensive model of the global properties of Alfvén waves in the solar atmosphere and the fast solar wind. Linear non-WKB wave transport equations are solved from the photosphere to a distance past the orbit of the Earth, and for wave periods ranging from 3 s to 3 days. We derive a radially varying power spectrum of kinetic and magnetic energy fluctuations for waves propagating ...

The widths of spectral lines in the ultraviolet (UV) and extreme ultraviolet (EUV) spectral regions that are formed in the solar transition region and corona are usually greater than the optically thin widths due to thermal Doppler broadening calculated under the assumption of ionization equilibrium. Although opacity can explain the widths of some lines, there are a host of optically thin lines...

Recent observations of coronal-loop waves by TRACE and within the corona as a whole by CoMP clearly indicate that the dominant oscillation period is 5 minutes, thus implicating the solar p modes as a possible source. We investigate the generation of tube waves within the solar convection zone by the buffeting of p modes. The tube waves—in the form of longitudinal sausage waves and transverse ki...

The X-ray and extreme-ultraviolet (EUV) emissions from the low-mass stars significantly affect evolution of planetary atmosphere. However, it is, observationally difficult to constrain stellar high-energy emission because strong interstellar extinction EUV photons. In this study, we simulate XUV (X-ray+EUV) Sun-like by extending solar coronal heating model that self-consistently solves, with su...