We have carried out an analysis of the high resolution optical spectra of post-AGB candidates SAO 85766 (IRAS 18062+2410), SAO 34504 (IRAS 22272+5435), HD 187885 (IRAS 19500-1709), HD 331319 (IRAS 19475+3119), HD 168625 (IRAS 18184-1623) and IRAS 10215-5916. All these objects have far-infrared colors similar to planetary nebulae and proto-

An exceptional variability phase occurred in the peculiar F-type hypergiant ρ Cas (Ia+) when the V brightness dimmed by about a full magnitude between June and September 2000. The star recovered from this deep minimum by April 2001. It is the third outburst of ρ Cas on record in the last century. We detect the formation of TiO bands in high

A detailed analysis of how environment affects the star formation history of early-type galaxies (ETGs) is undertaken via high signal-to-noise ratio stacked spectra obtained from a sample of 20 977 ETGs (morphologically selected) from the Sloan Digital Sky Survey-based SPIDER survey. Two major parameters are considered for the study: the central

NGC4321 is a two-armed grand design spiral galaxy in the Virgo Cluster. HI emission line data with 15 arcsecond resolution from the VLA map the velocity field of the hydrogen gas in the disk of NGC4321. In a grand design spiral galaxy, the presence of a spiral density wave causes deviations from circular rotation in the gas. The observed velocity

We present 5-40 μm spectroscopy of 41 planetary nebulae (PNe) in the Magellanic Clouds, observed with the Infrared Spectrograph on board the Spitzer Space Telescope. The spectra show the presence of a combination of nebular emission lines and solid state features from dust, superimposed on the thermal IR continuum. By analyzing the 25 LMC and 16

We present results on low-resolution mid-infrared spectroscopy of a sample of 70 infrared-luminous galaxies and quasars obtained with the Infrared Spectrograph (IRS) onboard Spitzer. We selected the sample from the European Large Area Infrared Survey (Oliver et al. 2000, Rowan-Robinson et al. 2004), which was carried out with the Infrared Space