In this work we present support for recent claims that advocate a downward revision of the solar oxygen abundance. Our analysis employs spatially-resolved spectro-polarimetric observations including the Fe I lines at 6302 Angstroms, and the O I infrared triplet around 7774 Angstroms, in the quiet Sun. We used the Fe I lines to reconstruct the three

A suitable diagnostic tool for investigating the magnetism of the solar chromosphere is the observation and theoretical modeling of the Hanle and Zeeman effects in solar spicules. In our presentation we highlighted the great scientific interest of this new diagnostic window by showing how the magnetic field vector can be inferred from

Extremely low mass white dwarfs are very rare objects likely formed in compact binary systems. We present MMT optical spectroscopy of 42 low-mass white dwarf candidates serendipitously discovered in a survey for hypervelocity B-type stars. One of these objects, SDSS J0917+46, has Teff=11,288+/-72 K and logg=5.48+/-0.03 with an estimated mass of 0

The amount of information available in spectropolarimetric data is estimated. To this end, the intrinsic dimensionality of the data is inferred with the aid of a recently derived estimator based on nearest neighbor considerations and obtained applying the principle of maximum likelihood. We show in detail that the estimator correctly captures the

Context: The geometry and physical conditions in solar coronal loops are complicated and still not understood well. Recent high-resolution observations obtained with TRACE indicate the existence of sub-resolution transverse structuring not accessible to direct observation. This ingredient has not yet been taken into account in the previous

The Ca II infrared (IR) triplet lines are a promising candidate for studying chromospheric magnetism and dynamics. To study how good of a diagnostic the lines are for chromospheric magnetism in the quiet Sun we have constructed a MHD simulation in the high plasma-β regime, analyzed quiet Sun spectropolarimetric data of the lines and used a non