The IRAS Deep Survey (IDS) of the North Ecliptic Pole region remains one of the deepest complete far-infrared-selected galaxy samples available. ISOCAM observations in the LW3 filter (12-18{mu}m) of 3.2'x3.2' fields centered on the nominal positions of 94 out of the 98 IDS sources yielding 116 ISOCAM detections. The resulting sample has allowed us to assess the source reliability, identify confusion effects, and pinpoint optical counterparts. To fully exploit the potential of this sample for investigating galaxy evolution, we carried out optical observations of candidate identifications to 100 out of the 116 ISOCAM sources. Optical imaging was acquired for 88 galaxies in 54 IDS fields: 44 galaxies were imaged in both the B- and the R-band, 33 only in the R-band, and 11 only in the B-band. These observations aimed at extending the MIR/FIR spectral energy distribution to the optical region and achieving morphological information. In addition, spectra were obtained for 65 IDS fields, 20 of which had not been observed before. Redshifts were measured for the 85 galaxies found within the positional error circles of 77 ISOCAM sources detected in those IDS fields.
We present the results of a study on galaxy interactions, tides, and other processes that produce luminous fine-scale substructures in the galaxy clusters: Coma, Perseus, Abell 2199, AWM 3, and AWM 5. All unusual structures in these clusters can be categorized into seven morphologies: interacting galaxies, multiple galaxies (noninteracting), distorted galaxies, tailed galaxies, line galaxies, dwarf galaxy groups, and galaxy aggregates. The various morphologies are described, and a catalog is presented, of 248 objects in these five clusters along with color, and positional information obtained from CCD images taken with the WIYN 3.5 m telescope in broadband B and R filters.
The cluster Abell 2104 is one of the lowest redshift clusters (z=0.153) known to have a gravitational lensing arc. We present detailed analysis of the cluster properties such as the gravitational potential using the X-ray data from ROSAT (HRI) and ASCA, as well as optical imaging and spectroscopic data from the CFHT.
Most of the sources detected in the extreme ultraviolet (EUV; 100-600{AA}) by the ROSAT/WFC and EUVE all-sky surveys have been identified with active late-type stars and hot white dwarfs that are near enough to the Earth to escape absorption by interstellar gas. However, about 15 per cent of EUV sources are as yet unidentified with any optical counterparts. We examine whether the unidentified EUV sources may consist of the same population of late-type stars and white dwarfs. We present B and R photometry of stars in the fields of seven of the unidentified EUV sources. We detect in the optical the entire main-sequence and white dwarf population out to the greatest distances where they could still avoid absorption. We use colour-magnitude diagrams to demonstrate that, in most of the fields, none of the observed stars has the colours and magnitudes of late-type dwarfs at distances less than 100pc. Similarly, none of the observed stars is a white dwarf within 500pc that is hot enough to be a EUV emitter. The unidentified EUV sources we study are not detected in X-rays, while cataclysmic variables, X-ray binaries, and active galactic nuclei generally are. We conclude that some of the EUV sources may be a new class of nearby objects, which are either very faint at optical bands or which mimic the colours and magnitudes of distant late-type stars or cool white dwarfs. One candidate for optically faint objects is isolated old neutron stars, slowly accreting interstellar matter. Such neutron stars are expected to be abundant in the Galaxy, and have not been unambiguously detected.
We present accurate photometry on the Johnson B, Kron-Cousins R photometric system for approximately 100,000 stars in a 1/3deg^2^ field centered on the dwarf spheroidal galaxy in Fornax. We identify numerous probable short-period variable stars, blue stars that appear to be the main sequence of a small population with an age of order 108yr, and two distinct types of luminous red star: an extended sequence of primarily carbon stars and a clump of mostly M giants slightly more luminous than the giant-branch tip. The spatial distribution of each of these subpopulations within the Fornax dwarf galaxy is considered.
We have imaged the recently discovered stellar overdensity located approximately one core radius from the center of the Fornax dwarf spheroidal galaxy using the Magellan Clay 6.5m telescope with the Magellan Instant Camera. Superb seeing conditions allowed us to probe the stellar populations of this overdensity and of a control field within Fornax to a limiting magnitude of R=26. The color-magnitude diagram of the overdensity field is virtually identical to that of the control field, with the exception of the presence of a population arising from a very short (less than 300Myr in duration) burst of star formation 1.4Gyr ago.
We perform detailed surface photometry, based on B- and/or R-band CCD images of 92 faint galaxies. They are a subsample of those galaxies which were studied by Hopp et al. (1994) in the direction of three nearby voids. We derive integral photometric parameters and radial surface brightness profiles and compare them to those of several faint galaxy samples, located in different environments, and of a bright field galaxy sample. According to the obtained photometric characteristics, our sample is a mixture of intrinsically bright and faint galaxies, about 60% of them belonging to the bright subsample (M_B_<-19.0). These bright ones show mean characteristics of typical Freeman's disks and are mainly located in the background of the observed voids. The faint subsample (M_B_>=-19.0) has parameters typical for the low-surface-brightness (LSB) galaxies. There are a few well isolated galaxies both among the bright and faint subsamples.
We carried out CCD photometry in the Johnson-Cousins B and R bands of 23 dwarf galaxies: SDIG, ESO 410-17, KK11, ESO 245-05, KKs3, KK27, KK38, KK40, IC 4662, KK244, KK246, KK247, KK248, KK249, KK253, KK255, KK256, KK257, KK258, KK259, UGCA 438, ESO 347-17, and UGCA 442. Both isolated galaxies and members of the Sculptor group and the NGC 1313 group were observed. The galaxy sample is characterized by a median distance of 9.3Mpc, and median absolute magnitude of -14.8mag. The central surface brightnesses are in the range from 22.2 to 24.4mag/arcsec^2^ in B.
We present the results of a photometric and spectroscopic study of seven members of the NGC 5328 group of galaxies, a chain of galaxies spanning over 200kpc (H0=70km/s/Mpc). We analyse the galaxy structure and study the emission-line properties of the group members looking for signatures of star formation and active galactic nucleus activity. We finally attempt to infer, from the modelling of line-strength indices, the stellar population ages of the early-type members.
File table3 contains a summary of selected B and R photometry data for 72 irregular dwarf galaxies within the 10 Mpc volume. It is supplemented by the indication of their field or group membership and by their rotational velocities as inferred from the literature.
