相关论文: Neon and oxygen in low activity stars: towards a c…

Recent improvements in the modeling of solar convection and line formation led to downward revisions of the solar photospheric abundances of the lighter elements, which in turn led to changes in the radiative opacity of the solar interior…

An analysis using modern atomic data of fluxes culled from the literature for O VIII and Ne IX lines observed in solar active regions by the P78 and Solar Maximum Mission satellites confirms that the coronal Ne/O abundance ratio varies by a…

A survey of Ne, O and Fe coronal abundances culled from the recent literature for about 60 late-type stars confirms that the Ne/O ratio of stellar outer atmospheres is about two times the value recently recommended by Asplund et al. The…

The standard solar model was so reliable that it could predict the existence of the massive neutrino. Helioseismology measurements were so precise that they could determine the depth of the convection zone. This agreement between theory and…

The new solar composition, when applied to compute a model of the Sun, leads to serious disagreement between the predictions of the model and the observations obtained by helioseismology. New measurements of the coronal Ne/O abundance ratio…

Properties of the Sun's interior can be determined accurately from helioseismological measurements of solar oscillations. These measurements, however, are in conflict with photospheric elemental abundances derived using 3-D hydrodynamic…

To revisit the long-standing problem of possible inconsistency concerning the oxygen composition in the current galactic gas and in the solar atmosphere (i.e., the former being appreciably lower by ~0.3 dex) apparently contradicting the…

The interior structure of the Sun can be studied with great accuracy using observations of its oscillations, similar to seismology of the Earth. Precise agreement between helioseismological measurements and predictions of theoretical solar…

Aims: To determine the neon-to-oxygen abundance in the quiet Sun, a proxy for the photospheric abundance ratio. Method: An emission measure method applied to extreme ultraviolet emission lines of Ne IV-VI and O III-V ions observed by the…

The recent downward revision of the solar photospheric abundances now leads to severe inconsistencies between the theoretical predictions for the internal structure of the Sun and the results of helioseismology. There have been claims that…

Using the results of our first paper on the Chandra HRC observation of the Orion Nebula Cluster (ONC), here we explore the relation between the coronal activity of its 1-Myr-old pre-main sequence population and stellar parameters. We find…

A thorough critical literature survey has been carried out for reliable measurements of oxygen and neon abundances of planetary nebulae (PNe) and HII regions. By contrasting the results of PNe and of HII regions, we aim to address the…

We report on non-LTE Ne abundances for a sample of B-type stellar members of the Orion Association. The abundances were derived by means of non-LTE fully metal-blanketed model atmospheres and extensive model atoms with updated atomic data.…

Element abundance ratios of magnesium to neon (Mg/Ne) and neon to oxygen (Ne/O) in the transition region of the quiet Sun have been derived by re-assessing previously published data from the Coronal Diagnostic Spectrometer on board the…

X-ray emission is an important indicator of stellar activity. In this paper, we study stellar X-ray activity using the XMM-Newton and LAMOST data for different types of stars. We provide a sample including 1259 X-ray emitting stars, of…

Recent solar abundance analyses (Asplund et al. 2004; Lodders 2003) revise downward the abundances of C, N, O, Ne, and Ar, which reduces the solar photospheric Z/X to 0.017, and Z to ~0.013. Solar models evolved with standard opacities and…

There have been recent downward revisions of the solar photospheric abundances of Oxygen and other heavy elements. These revised abundances along with OPAL opacities are not consistent with seismic constraints. In this work we show that the…

We examine the constraints imposed by helioseismic data on the solar heavy element abundances. In prior work we argued that the measured depth of the surface convection zone R_CZ and the surface helium abundance Y_surf were good metallicity…

XMM-Newton and Chandra have greatly deepened our knowledge of stellar coronae giving access to a variety of new diagnostics such that nowadays a review of stellar X-ray astronomy necessarily must focus on a few selected topics. Attempting…

Recent studies of spectral lines of the CNO elements in the Sun and unevolved disk and halo stars show that most published abundance data may be affected by systematic errors due to inadequate 1D modelling of stellar atmospheres. This…