We present Hα and [O III] (5007 Å) images of the nebula powered by the jet of the black hole candidate and microquasar Cygnus X–1, observed with the 2.5m Isaac Newton Telescope (INT). The ring-like structure is luminous in [O III] and there exists a thin outer shell with a high [O III] / Hα flux ratio. This outer shell probably originates in the collisionally excited atoms close to the front of...

We discuss the relative merits of using UV and Hα as star formation indicators from galaxy surveys. In particular, comparing UV and Hα in the CFRS gives a limit of a factor 2.5 for the UV(2800 Å) extinction from dust, using the conversion factors of Madau et al. 1998 (Salpeter IMF, 0.1−125 M⊙). Our strong correlation between B and Hα argues for a universal IMF slope. The Hα LF at z = 0.2 shows ...

We have used the technique of spectro-astrometry to study the milli-arcsecond scale structure of the emission lines in the T Tauri star RU Lupi. The wings of the Hα emission are found to be displaced from the star towards the southwest (blue wing) and northeast (red wing) with angular scales of 20-30 milli-arcsecs. This structure is consistent with a bipolar outflow from the star. From a study ...

We present the discovery of a 40 kpc Hα tail and at least 29 emission-line objects downstream of a star-forming galaxy ESO 137-001 in a rich, nearby cluster A3627. The galaxy is known to possess a dramatic 70 kpc X-ray tail. The detected Hα tail coincides positionally with the X-ray tail. The Hα emission in the galaxy is sharply truncated on the front and the sides near the nucleus, indicating ...

We report the cumulative results of an ongoing near-infrared search for redshifted Hα emission from normal galaxies at z>2. An infrared search reduces the bias due to reddening. Using narrow-band imaging with the Near Infrared Camera on the Keck I 10-m telescope, a survey area of almost 12 square arcminutes has been covered. Target regions were selected by matching the redshifts of QSO emission...

We report X-ray fluxes in the 2–10 keV band from LINERs (low-ionization nuclear emission-line regions) and low-luminosity Seyfert galaxies obtained with the ASCA satellite. Observed X-ray luminosities are in the range between 4×10 and 5×10 ergs s, which are significantly smaller than that of the “classical” low-luminosity Seyfert 1 galaxy NGC 4051. We found that X-ray luminosities in 2–10 keV o...

We present Hα spectropolarimetry of a large sample of pre-main sequence (PMS) stars of low and intermediate mass, and argue that the technique is a powerful tool in studying the circumstellar geometry around these objects. For the intermediate mass (2 – 15 M⊙) Herbig Ae/Be stars we find that 16 out of 23 show a line effect, which immediately implies that flattening is common among these objects...

We present here the results of spectroscopic studies in the Hα region of the active eclipsing binary AR Lac (G2IV+K0IV) obtained at Catania Astrophysical Observatory in 1989, 1990, 1994, 1996 and 1997. Accurate measurements of radial velocities by using the cross-correlation method have been made and a new orbital solution has been derived. The equivalent width of the Hα emission core has been ...

We present preliminary results from a programme to obtain multi-object nearinfrared spectroscopy of galaxies at redshifts 0.7 < z < 1.5. We are using the instrument CIRPASS (the Cambridge Infra-Red PAnoramic Survey Spectrograph), in multi-object mode, to survey Hα in galaxies at z ∼ 1. We aim to address the true star formation history of the universe at this epoch: potentially the peak period o...

We present near-infrared spectroscopy and narrow-band imaging at the wavelength of redshifted Hα for a sample of 30 high-redshift, far-infrared luminous galaxies. This sample is selected from surveys in the submillimeter, millimeter and radio wavebands and has complete redshift coverage with a median redshift of z ∼ 2.4. We use our data to measure the Hα properties of these systems and to gauge...