In addition to clearly biological microbial mats, lava tubes contain many non-biological appearing mineral deposits that contain life. The discovery that such deposits contain abundant life can help guide our detection of life on other extrater-restrial bodies.

We discuss the relations between the metallicity gradients and the other characteristics of a set of dwarf elliptical galaxies in different environments. We suggest that dEs have typically metallicity gradients of -0.30 ± 0.25 dex/re, unrelated to their mass. Dwarf elliptical galaxies with embedded disks, or dS0, may have flat metallicity gradients

We present a review on the determination of the primordial helium abundance Yp, based on the study of hydrogen and helium recombination lines in extragalactic H ii regions. We also discuss the observational determinations of the increase of helium to the increase of oxygen by mass ΔY/ΔO, and compare them with predictions based on models of galactic

Investigations of interacting and merging galaxies at high redshift are vital to our understanding of their formation and evolution. To date, the identification of interactions at z ~ 3 and above has relied on rest-frame ultraviolet morphological parameters. Here, we present five serendipitous spectroscopic z ~ 3 Lyman break galaxy (LBG) pairs with

Over the past few years, ground- and space-based atmospheric measurements have revealed a large inter-decadal variability in the amount of radiation reaching the Earth's surface, also known as global dimming and brightening. However, the underlying physical causes of these changes remain unexplained. Clouds and aerosols, or their interactions

Our recent study of solar-type stars from the HARPS GTO sample provides highly accurate information with regard to Lithium abundances in stars with and without detected planets (Israelian et al. 2009). When the Li abundances of planet bearing stars are compared with the “single” stars, we find an excess of Li depletion in planet hosts with