- ID:
- ivo://CDS.VizieR/J/ApJ/562/368
- Title:
- UV photometry in NGC 2808
- Short Name:
- J/ApJ/562/368
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine new observations of NGC 2808, taken with the far-UV and near-UV cameras on the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). Images were obtained in the far-UV crystal quartz (FUV/F25QTZ; pivot wavelength 1600{AA}), near-UV 2700{AA} continuum (NUV/F25CN270), and clear CCD (CCD/50CCD; pivot wavelength 5850{AA}) modes, employing a cross-shaped dither pattern.
Number of results to display per page
Search Results
7572. UV photometry of M15
- ID:
- ivo://CDS.VizieR/J/ApJ/670/379
- Title:
- UV photometry of M15
- Short Name:
- J/ApJ/670/379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep FUV and NUV images of the inner region of the dense globular cluster M15 with the HST ACS. The FUV-NUV color-magnitude diagram shows a well-defined track of horizontal branch stars, as well as a trail of blue stragglers and white dwarfs. The main-sequence turnoff is clearly visible at FUV~22.5mag and FUV-NUV~3mag, and the main-sequence stars form a prominent track that extends at least 2mag below the main-sequence turnoff. As such, this is the deepest FUV-NUV color-magnitude diagram of a globular cluster presented so far. Cataclysmic variable and blue straggler candidates are the most centrally concentrated stellar populations, which might either be an effect of mass segregation or reflect the preferred birthplace in the dense cluster core of such dynamically formed objects. We find 41 FUV sources that exhibit significant variability. We classify the variables based on an analysis of their UV colors and variability properties. We find four previously known RR Lyrae and 13 further RR Lyrae candidates, one known Cepheid and six further candidates, six cataclysmic variable candidates, one known and one probable SX Phoenicis star, and the well-known low-mass X-ray binary AC 211. Our analysis represents the first detection of SX Phoenicis pulsations in the FUV. We find that Cepheids, RR Lyrae stars, and SX Phoenicis exhibit massive variability amplitudes in this wave band (several magnitudes).
- ID:
- ivo://CDS.VizieR/J/A+A/287/769
- Title:
- UV photometry of NGC 6397
- Short Name:
- J/A+A/287/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The core of the nearby and very concentrated globular cluster NGC 6397 has been imaged through the f/96-F140W, f/48-F140W, f/96-F210M and f/48-F220W ultraviolet filters of the Faint Object Camera on board the Hubble Space Telescope down to an ultraviolet limiting magnitude of ~19. The most interesting objects in the field of view are six very bright centrally concentrated, blue stragglers observed for the first time in the UV. Using these and other data from ground-based observations, we have been able to deduce from a comparison with Kurucz's atmosphere models, temperatures of ~10000K and masses of ~1.6M_{sun}_ for the four brightest ones, which is remarkably close to twice the turn-off mass of NGC 6397. This finding supports the idea that two-star mechanisms (collisions, mergers) are at the origin of the blue stragglers in the core of NGC 6397. Since the central density is very high, collisions between main sequence stars are frequent, therefore providing the best formation mechanism. We have computed the number of such collisions in the core of NGC 6397 and found it to be of the same order as the number of bright blue stragglers observed there. Thanks to the HST resolution, we have also been able to resolve one object, previously classified as a yellow straggler, into a blend of a blue straggler and three redder stars.
- ID:
- ivo://CDS.VizieR/J/AJ/143/121
- Title:
- UV properties of Galactic globulars with GALEX.
- Short Name:
- J/AJ/143/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Galaxy Evolution Explorer (GALEX) data for 44 Galactic globular clusters (GCs) obtained during three GALEX observing cycles between 2004 and 2008. This is the largest homogeneous data set on the UV photometric properties of Galactic GCs ever collected. The sample selection and photometric analysis are discussed, and color-magnitude diagrams (CMDs) are presented. The blue and intermediate-blue horizontal branch is the dominant feature of the UV CMDs of old Galactic GCs. Our sample is large enough to display the remarkable variety of horizontal branch shapes found in old stellar populations. Other stellar types that are obviously detected are blue stragglers and post-core-He burning stars. The main features of UV CMDs of Galactic GCs are briefly discussed. We establish the locus of post-core-He burning stars in the UV CMD and present a catalog of candidate asymptotic giant branch (AGB), AGB-manque, post early-AGB, and post-AGB stars within our cluster sample.
- ID:
- ivo://CDS.VizieR/J/A+AS/109/341
- Title:
- UV properties of normal galaxies. II.
- Short Name:
- J/A+AS/109/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the last decade several satellite and balloon borne experiments have collected a large number of ultraviolet fluxes of normal galaxies measured through apertures of various sizes and shapes. We have homogenized this data set by deriving scale corrections with respect to IUE. In a forthcoming paper, these data will be used to derive standard luminosity profiles and total magnitudes.
- ID:
- ivo://CDS.VizieR/J/A+AS/114/527
- Title:
- UV properties of normal galaxies. III.
- Short Name:
- J/A+AS/114/527
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the previous papers of this series (Longo et al. =1991A&AS...90..375L; Rifatto et al. =1995A&AS..109..341R) we collected and reduced to the same system all the available photometric data obtained in the ultraviolet (UV) range for normal (i.e. non active) galaxies. Here we use these data to derive standard UV luminosity profiles for three morphological bins (E/S0; Sa/Sb; Sc/Sd) and extrapolated total magnitudes for almost 400 galaxies. We find that: 1) the UV growth curves are well matched by the B-band revised standard luminosity profiles, once a proper shift in the effective radius is applied, and 2) the UV light in early-type galaxies is more centrally concentrated than the visible light.
- ID:
- ivo://CDS.VizieR/J/MNRAS/300/303
- Title:
- UV-selected galaxy redshift survey
- Short Name:
- J/MNRAS/300/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table contains the first results of a spectroscopic survey of galaxies constructed from a flux-limited sample of stars, galaxies and QSOs imaged at 2000{AA} with the FOCA balloon-borne imaging camera (see Milliard et al., 1992A&A...257...24M) The galaxies were selected in the rest frame ultraviolet (UV), in Selected Area 57. Accurate positions for the UV sources have been obtained by matching with optical counterparts using APM scans of the Palomar Sky Survey limited at B=20.5. The results presented here are derived from optical spectroscopy conducted with the WIYN telescope and the WHT for 142 faint sources. The redshift distribution for this UV- selected sample extends over 0<z<0.5, and a high fraction of the sources show intense nebular emission lines and UV-optical colours bluer than normal Hubble sequence galaxies. Updated results for these galaxies were published later (see Sullivan et al. 2000, Cat. <J/MNRAS/312/442>)
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/442
- Title:
- UV-selected galaxy redshift survey. II.
- Short Name:
- J/MNRAS/312/442
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present further spectroscopic observations for a sample of galaxies selected in the vacuum ultraviolet (UV) at 2000{AA} from the FOCA balloon-borne imaging camera of Milliard et al. (1992A&A...257...24M). This work represents an extension of the initial study by Treyer et al. (Cat. <J/MNRAS/300/303>). Our enlarged catalogue contains 433 sources (~3 times as many as in our earlier study) across two FOCA fields. 273 of these are galaxies, nearly all with redshifts z~0-0.4. Nebular emission-line measurements are available for 216 galaxies, allowing us to address issues of excitation, reddening and metallicity. The UV and H{alpha} luminosity functions strengthen our earlier assertions that the local volume-averaged star formation rate is higher than indicated from earlier surveys. Moreover, internally within our sample, we do not find a steep rise in the UV luminosity density with redshift over 0<z<0.4. Our data are more consistent with a modest evolutionary trend, as suggested by recent redshift survey results. Investigating the emission-line properties, we find no evidence for a significant number of AGN in our sample; most UV-selected sources to z~0.4 are intense star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A141
- Title:
- UV selected sources in the GOODS-S field
- Short Name:
- J/A+A/545/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust attenuation in galaxies is poorly known, especially at high redshift. And yet the amount of dust attenuation is a key parameter to deduce accurate star formation rates from ultraviolet (UV) rest-frame measurements. The wavelength dependence of the dust attenuation is also of fundamental importance to interpret the observed spectral energy distributions (SEDs) and to derive photometric redshifts or physical properties of galaxies. We want to study dust attenuation at UV wavelengths at high redshift, where the UV is redshifted to the observed visible light wavelength range. In particular, we search for a UV bump and related implications for dust attenuation determinations.
- ID:
- ivo://CDS.VizieR/J/AJ/139/1338
- Title:
- UV-selected stars in Tau and Upper Sco
- Short Name:
- J/AJ/139/1338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a Galaxy Evolution Explorer (GALEX) Cycle 1 guest investigator program covering 56deg^2^ near the Taurus T association and 12deg^2^ along the northern edge of the Upper Scorpius OB association. We combined photometry in the GALEX far-ultraviolet and near-ultraviolet bands with data from the Two Micron All Sky Survey to identify candidate young (<~100Myr old) stars as those with an ultraviolet excess relative to older main-sequence stars. Follow-up spectroscopy of a partial sample of these candidates suggests five new members of Taurus, with 8-20 expected from additional observations, and five new members of Upper Scorpius, with three to six expected from additional observations.
