The envelope of the red galaxies distribution in a z = 0.75 cluster field

We report the observation of a group of 16 red (V -I > 2) galaxies, in the magnitude range 22 ≤ V ≤ 25.5, within a projected distance of 30″ (~0.2h-1 Mpc for h = H0/75km s-1 Mpc-1) of the ultra-steep spectrum radio source 1443-198 at z = 0.753. The colours of the galaxies range from the cut-off at V - I = 2.0 to V - I = 3.3. Eight galaxies are redder than V - I = 2.3 and three are redder than V - I = 3.0. Some objects with I ≈ 23 are undetected at the magnitude limit of V=25.5. This confirms previous results on the presence of a very red envelope in some distant clusters and suggests that a fraction of cluster ellipticals are already old at z ≈ 0.75. The radio galaxy has colours and a 4000 Å break amplitude typical of evolving E/S0 galaxies, and shows signs of interaction with other objects in its immediate vicinity

The relative photometric lightcurve of UM673 A&B

From 1987 to 1993, we have carried out at ESO a photometric monitoring of the gravitationally lensed quasar UM673. The main result is that the two lensed images of UM673 did not show any significant relative variation during more than five years

The supergiant Bep star CD - 42 11721 deg and its surrounding nebula

peer reviewedNew spectroscopic and direct imagery observations of the supergiant Bep star CD - 42 11721 deg and its surrounding nebula are reported. The spectrum of the star essentially consists of Balmer and Fe II emission lines, He I emission lines are also observed, confirming the presence of spectral variations on long timescales. The clumpy arc-shaped structure of the nebula as well as the presence of motions relative to the central star highly suggest that it has been influenced by a variable mass-loss. The nebula shows both the reflection and emission characteristics. Its spectrum displays the red forbidden N II and S II lines while no oxygen forbidden lines can be detected. Its tempting to interpret this situation by a N/O overabundance which may indicate the presence of processed material in the nebula and thus confirm the evolved nature of the star

The nature of the nebula associated with the luminous blue variable star WRA 751

Narrow-band filter imagery as well as medium to high resolution spectroscopy of the nebula surrounding the luminous blue variable (LBV) star WRA 751 are presented. The nebula appears as a slowly expanding H II region of low excitation characterized by a significant N/O overabundance which may be due to the presence in the nebula of nuclear processed material ejected by the star. With the recent discovery of a nebula around HR Car, all but one known galactic LBVs are now shown to be associated with a nebula. These nebula have rather similar physical characteristics, one of the most important being that all of them apparently contain processed material

HR Carinae - A luminous blue variable surrounded by an arc-shaped nebula

New high and medium dispersion spectroscopic observations of the luminous blue variable (LBV) star HR Car are presented, showing that this star has a multiple shell expanding atmosphere and undergoes spectral variations apparently correlated with the light variations similarly to the other LBVs. Most striking are the very broad emission wings (FWZI of about 3000 km/s) of the Balmer lines, reminiscent from the broad lines observed in the spectra of Of and WR stars. A kinematic distance of 5.4 kpc and a bolometric magnitude of -9.4 put HR Car among the most luminous stars of the Galaxy. The narrow band filter imagery also reveals an arc-shaped jet like nebula associated with HR Car. Spectroscopic observations of this nebula reveal an emission nature with very low excitation. Like the star itself, the nebula is characterized by a significant N/O overabundance, probably due to the presence of nuclear processed material ejected by the star

A dusty nebula around the luminous blue variable candidate HD 168625

On the basis of narrow-band visible and near-infrared imagery as well as high-resolution spectroscopy, we report the discovery of a new LBV-type nebula around the B supergiant HD 168625. We find that it essentially consists of a dusty expanding shell from which seems to emerge a bipolar emission nebula, the whole embedded in a reflection nebulosity. The inner shell is stratified: the continuum emission arises beyond the ionized gas, and is possibly due to scattering of stellar light by large dust grains or to non-equilibrium dust emission. The unexpected presence of unidentified infrared emission bands (UIRs) in the spectrum of this object is also discussed. We finally report the non-detection of a comparable nebula around the nearby LBV HD 168607

Further observations of the light echoes from SN 1987 A

Further direct observations of the light echoes from SN 1987 A were obtained on November 12 1988 with the 3.6-m telescope and EFOSC at ESO. In agreement with predictions made from earlier observations, the radii of the two light rings are measured to be 43.3 and 72.5 arcsec. However, a noticeable diaplacement of the center of the outer ring by 2.6 arcsec to the NE from the SN position is also reported. Application of the model of planar-like sheets of material located between the SN and the observer leads to improved results

A search for gravitational lensing among highly luminous quasars - Observational strategy and survey

The observational techniques employed to search for gravitational lensing effects in highly luminous quasars (HLQs) are given, along with results of the observations. The program, begun in 1986, considers the visible and dark matter distributions at different scales in the universe to determine which extragalactic objects are gravitationally lensed. The Hubble parameter and galaxy masses are determined from the observations, and observations of microlensing effects provide data on HLQ size and structures. The redshifts are found to be between 1 and 3.6, with apparent visual magnitudes 16-18.5 and absolute visual magnitudes between -29 and -30.6. About one quarter of the images exhibit either multiple components, elongated structures, jetlike features, or faint nearby galaxies. The double quasar UM 673 and its 'overlying' lens galaxy is given as a prime example of an HLQ that is gravitationally lensed. It is theorized many more HLQs are gravitationally lensed, and specific future observations are recommended