We have derived a new H_{β} absorption index definition, which is fully optimized as an age indicator for old and intermediate-aged stellar populations. Rather than using stellar spectra, we employed theoretical SEDs at moderately high resolution for simple stellar populations of different ages and metallicities. The new index, which is virtually

We introduce the new Galactic Plane Hα survey IPHAS, present our PNe selection method, and discuss two examples of very distant new PNe.

We report on the unprecedented red supergiant (RSG) population of a massive young cluster, located at the base of the Scutum-Crux Galactic arm. We identify candidate cluster RSGs based on 2MASS photometry and medium-resolution spectroscopy. With follow-up high-resolution spectroscopy, we use CO band-head equivalent width and high-precision radial

We present first results from our search for brown dwarf and giant planet companions around G and K type stars in the Upper Sco OB association. Our survey is designed to detect companions as faint as I=20 about 2 arcsec from the star. This sensitivity corresponds to 10MJ at 300 AU according to current evolutionary models. The host stars were

Luminous Compact Blue Galaxies (LCBGs) are high surface brightness starburst galaxies bluer than a typical SBc and with typical luminosities L*, which are undergoing a major burst of star formation. LCBGs are the closest counterparts of the numerous population of starburst galaxies observed at high redshift, including Lyman-break galaxies at z 2

We present the results of a deep wide-field near-infrared survey of 12deg2 of the Pleiades conducted as part of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Galactic Cluster Survey (GCS). We have extracted over 340 high-probability proper motion (PM) members down to 0.03M{sun} using a combination of UKIDSS