We present a test for the degree of symmetry in the distribution of the Hα brightness along the arms of a sample of spiral galaxies. The test consists of deriving the cross-correlation function of the Hα brightness as a function of curvilinear distance along pairs of opposed arms, after unfolding the arms geometrically. Our results reveal a

We present a first determination of distances and extinctions for individual stars in the first release of the APOKASC catalogue, built from the joint efforts of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the Kepler Asteroseismic Science Consortium (KASC). Our method takes into account the spectroscopic constraints

Context: Inversion techniques are the most powerful methods to obtain information about the thermodynamical and magnetic properties of solar and stellar atmospheres. In the recent years, we have witnessed the development of highly sophisticated inversion codes that are now widely applied to spectro-polarimetric observations. The majority of these

We present spectroscopy of the Hα emision line in the X-ray transient V4 04 Cyg. Along with the spectroscopy, simultaneus photometry was used in order t o renormalize the spectra to agree with the photometry, giving us spectrophotom etric data. We have found evidence to show the presence of flares in both the l ine and continuum on a time-scale

Since the discovery of the first brown dwarfs (Tiede 1; Rebolo et al. 1995, Gliese 229B; Nakajima et al. 1995) the complement of identified brown dwarfs has grown to over 700. Yet our understanding of these cool objects is still somewhat lacking. Current models struggle to reproduce the observed variation in photometric and spectroscopic properties

We have used the Chandra X-ray Observatory to observe the following six black hole X-ray transients in quiescence: GRO J0422+32 (orbital period Porb=5.1 hr), A0620--00 (Porb=7.8 hr), GS2000+25 (Porb=8.3 hr), 4U1543--47 (Porb=27.0 hr), GRO J1655--40 (Porb=62.9 hr), GS2023+338 (Porb=155 hr). Previous to these Chandra observations there was only a