We present results from a Chandra survey of 11 nearby, face-on spiral galaxies. 24 observations totaling 900 ks of new and archival Chandra data reveal more than 1000 X-ray point sources associated with the galaxies, diffuse emission, and hundreds of serendipitous sources. We discuss source populations and luminosity functions and show that the

Chemical analyses of late-type stars are usually carried out following the classical recipe: LTE line formation and homogeneous, plane-parallel, flux-constant, and LTE model atmospheres. We review different results in the literature that have suggested significant inconsistencies in the spectroscopic analyses, pointing out the difficulties in

We present the stellar and substellar mass function (MF) of the open cluster IC 2391, plus its radial dependence, and use this to put constraints on the formation mechanism of brown dwarfs (BDs). Our multi-band optical and infrared photometric survey with spectroscopic follow-up covers 11 deg2, making it the largest survey of this cluster to date

We present evidence for a strong correlation between the concentration of bulges and the mass of their central supermassive black hole (Mbh)-more concentrated bulges have more massive black holes. Using Cre(1/3) from Trujillo, Graham, & Caon as a measure of bulge concentration, we find that log(Mbh/Msolar)=6.81(+/- 0.95)Cre(1/3)+5.03+/-0.41. This

The varying global distribution of stars, or specifically, their concentration Cr_e, within elliptical galaxies and spiral galaxy bulges is intimately related to the mass of their central supermassive black holes (Mbh), such that log (Mbh/Msun) = 6.81(±0.95)Cr_e + 5.03±0.41. This correlation has a Spearman correlation coefficient rs=0.91, and a

Despite over 35 years of constant satellite-based measurements of cloud, reliable evidence of a long-hypothesized link between changes in solar activity and Earth’s cloud cover remains elusive. This work examines evidence of a cosmic ray cloud link from a range of sources, including satellite-based cloud measurements and long-term ground-based