相关论文: Synoptic solar radio observations as proxies for u…
Observations of intergalactic neutral hydrogen can provide a wealth of information about structure and galaxy formation, potentially tracing accretion and feedback processes on Mpc scales. Below a column density of NHI ~ 10^19 cm-2, the…
The calculation of solar absolute fluxes in the near-UV is revisited, discussing in some detail recent updates in theoretical calculations of bound-free opacity from metals. Modest changes in the abundances of elements such as Mg and the…
This work presents a detailed analysis of Cosmic Microwave Background (CMB) radiation intensity observations. The CMB is a relic of the Big Bang and its study greatly enhances our knowledge of cosmology. This work has led to new values for…
The atmospheric greenhouse effect and the hydrological cycle of Earth are key components enabling the planet to support life. Water vapor is a central element in both of these, accounting for approximately half of the present day greenhouse…
We use microwave imaging observations from the Nobeyama Radioheliograph at 17 GHz for long-term studies of solar activity. In particular, we use the polar and low-latitude brightness temperatures as proxies to the polar magnetic field and…
Inversion codes allow reconstructing a model atmosphere from observations. With the inclusion of optically thick lines that form in the solar chromosphere, such modelling is computationally very expensive because a non-LTE evaluation of the…
Magnetohydrodynamic (MHD) waves have been considered as energy sources for heating the solar chromosphere and the corona. Although MHD waves have been observed in the solar atmosphere, there are a lack of quantitative estimates on the…
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…
In recent decades our understanding of solar active regions (ARs) has improved substantially due to observations made with better angular resolution and wider spectral coverage. While prior AR observations have shown that these structures…
Corona structures and processes during the pre-impulsive stage of solar eruption are crucial to understanding the physics leading to the subsequent explosive energy release. Here we present the first microwave imaging study of a hot flux…
We present a model for atmospheric absorption of solar ultraviolet (UV) radiation. The initial motivation for this work is to predict this effect and correct it in Sounding Rocket (SR) experiments. In particular, the Full-sun Ultraviolet…
The photoelectric heating is believed to be the main heating mechanism in cool HI clouds. The heating rate can be estimated through observations of the [CII] line emission, since this is the main coolant in regions where the photoelectric…
Sunspots depict large variability during the last 100 years, a period called the Modern Maximum (MM). However, other variables are needed to study the long-term evolution, e.g., of weaker fields and different radiative emissions. Recently,…
Solar radio emissions provide several unique diagnostics to estimate different physical parameters of the solar corona, which are otherwise simply inaccessible. However, imaging the highly dynamic solar coronal emissions spanning a large…
The Solar Radiospectrograph of the University of Athens (ARTEMIS-IV) is in operation at the Thermopylae Satellite Communication Station since 1996. The observations extend from the base of the Solar Corona (650 MHz) to about 2 Solar Radii…
The aim of this work is to identify the physical processes that occur in the network and contribute to its dynamics and heating. We model the network as consisting of individual flux tubes with a non-potential field structure that are…
We compare Fourier spectra of photospheric velocity fields from very high resolution IMaX observations to those from recent 3D numerical magnetoconvection models. We carry out a proper comparison by synthesizing spectral lines from the…
Here we present a detailed analysis of solar acoustic mode frequencies and their rotational splittings for modes with degree up to 900. They were obtained by applying spherical harmonic decomposition to full-disk solar images observed by…
MHD wave propagation inside the Sun's atmosphere is closely related to the magnetic field topology. For example, magnetic fields are able to lower the cutoff frequency for acoustic waves thus allowing waves which would otherwise be trapped…
This paper presents the first results of a far-infrared search for protocluster-associated galaxy overdensities using the SPIRE instrument on-board the {\it Herschel} Space Observatory. Large ($\sim$400 arcmin$^{2}$) fields surrounding 26…