- ID:
- ivo://CDS.VizieR/J/AJ/129/1818
- Title:
- Photometry of S5 0716+714
- Short Name:
- J/AJ/129/1818
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical monitoring of S5 0716+714 was performed with a 60/90 Schmidt telescope in 2003 November and December and 2004 January for studying the variability of the object on short timescales. Because of the high brightness of the source, we could carry out quasi-simultaneous measurements in three bands with a temporal resolution of about 20min by using one single telescope.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/529/A25
- Title:
- Photometry of star clusters in 5 nearby gal.
- Short Name:
- J/A+A/529/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies have started to cast doubt on the assumption that most stars are formed in clusters. Observational studies of field stars and star cluster systems in nearby galaxies can lead to better constraints on the fraction of stars forming in clusters. Ultimately this may lead to a better understanding of star formation in galaxies, and galaxy evolution in general. We aim to constrain the amount of star formation happening in long-lived clusters for four galaxies through the homogeneous, simultaneous study of field stars and star clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/467/1003
- Title:
- Photometry of star clusters in NGC 1380
- Short Name:
- J/A+A/467/1003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 1380 is a lenticular galaxy located near the center of the Fornax Cluster, northeast of NGC 1399. The globular cluster system of this galaxy was previously studied only from the ground. Recent studies of similar early-type galaxies, specially lenticular ones, reveal the existence of star clusters that apparently break up the traditional open/globular cluster dichotomy. With higher quality photometry from HST/WFPC2 we study the star clusters in NGC 1380, measuring their magnitudes, colours, sizes and projected distances from the center of the galaxy. We used deep archival HST/WFPC2 in the B and V bands. We built colour magnitude diagrams from which we selected a sample of cluster candidates. We also analysed their colour distribution and measured their sizes. Based on their location in the luminosity-size diagram we estimated probabilities of them being typical globular clusters as those found in the Galaxy. A total of about 570 cluster candidates were found down to V=26.5. We measured sizes for approximately 200 of them. The observed colour distribution has three apparent peaks. Likewise for the size distribution. We identified the smaller population as being mainly typical globular clusters, while the more extended objects have small probabilities of being such objects. Different correlations between absolute magnitudes, sizes, colours and location were inferred for these cluster sub-populations. Most extended clusters (Reff>4pc) share similar properties to the diffuse star clusters reported to inhabit luminous early-type galaxies in the Virgo galaxy cluster such as being of low surface brightness and fainter than MV~-8. We also report on a small group of (R_eff_~10pc), -8<MV<-6, red clusters located near the centre of NGC 1380, which may be interpreted as faint fuzzies.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A144
- Title:
- Photometry of stars in the LeoA HST WFC3 field
- Short Name:
- J/A+A/614/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- LeoA is an isolated gas-rich dwarf irregular galaxy of low stellar mass and metallicity residing at the outskirts of the Local Group. Ages of the stellar populations in LeoA range from ~10Myr to ~10Gyr. A large stellar halo (up to the deprojected distance of ~1.7kpc was discovered based on Subaru wide-field photometry of red giant branch stars. We analysed HST WFC3 archive observation data in the field that is partly located beyond the previously known limits of the LeoA galaxy. We performed photometry of star-like objects in the F475W and F814W passbands and studied the spatial distribution of the Leo A stars below the horizontal branch. We report a discovery of stellar halo populations (subgiants and faint red giants) in the Leo A galaxy extending up to ~2.3kpc deprojected distance from the galaxy centre. Analysis of the colour-magnitude diagram suggests old (>5Gyr) stellar populations of very low metallicity (Z~0.0001).
- ID:
- ivo://CDS.VizieR/J/ApJ/704/898
- Title:
- Photometry of the Hercules dwarf galaxy
- Short Name:
- J/ApJ/704/898
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present imaging of the recently discovered Hercules Milky Way satellite and its surrounding regions to study its structure, star formation history and to thoroughly search for signs of disruption. We robustly determine the distance, luminosity, size, and morphology of Hercules utilizing a bootstrap approach to characterize our uncertainties. We derive a distance to Hercules via a comparison to empirical and theoretical isochrones, finding a best match with the isochrone of M92, which yields a distance of 133+/-6kpc. As previous studies have found, Hercules is very elongated, with {epsilon}=0.67+/-0.03 and a half-light radius of r_h_~230pc. Using the color-magnitude-fitting package StarFISH, we determine that Hercules is old (>12Gyr) and metal-poor ([Fe/H]~-2.0), with a spread in metallicity, in agreement with previous spectroscopic work. This result is robust with respect to slight variations in the distance to Hercules and mismatches between the observed Hercules color-magnitude diagram and theoretical isochrones. We infer a total absolute magnitude of M_V_=-6.2+/-0.4. Our innovative search for external Hercules structure both in the plane of the sky and along the line of sight yields some evidence that Hercules is embedded in a larger stream of stars. A clear stellar extension is seen to the northwest with several additional candidate stellar overdensities along the position angle of Hercules out to ~35' (~1.3kpc).
- ID:
- ivo://CDS.VizieR/J/A+A/315/40
- Title:
- Photometry of the Tuc dwarf galaxy
- Short Name:
- J/A+A/315/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present V and I CCD photometry for ~360 stars in the recently discovered dwarf galaxy Tucana. The large field investigated and the accurate photometric calibration make our data complementary to the deeper HST photometry. From the I magnitude of the tip of the red giant branch we estimate a distance modulus (m-M)_0_=24.69+/-0.16, corresponding to 870+/-60Kpc, confirming that Tucana is an isolated dwarf spheroidal located almost at the border of the Local Group. From the color of the red giant branch tip and by direct comparison with the giant branches of galactic globular clusters we estimate a metallicity [Fe/H]=-1.8+/-0.2, with no clear indication for a metallicity spread. The color-magnitude diagram indicates that Tucana has had a single star formation burst at the epoch of the Galactic globular cluster star formation. There is no evidence for an intermediate or young stellar population. We derive the V luminosity profile, the surface density profile of resolved stars, and the structural parameters of Tucana, from which we confirm that Tucana participates to the general metallicity-surface brightness-absolute magnitude relations defined by the Galaxy and M31 dwarf spheroidal and dwarf elliptical companions.
- ID:
- ivo://CDS.VizieR/J/A+AS/141/409
- Title:
- Photometry of UCM galaxies
- Short Name:
- J/A+AS/141/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Johnson B CCD photometry for the whole sample of galaxies of the Universidad Complutense de Madrid (UCM) Survey Lists I and II (Cat. <J/ApJS/95/387> and <J/ApJS/105/343>). They constitute a well-defined and complete sample of galaxies in the Local Universe with active star formation. The data refer to 191 S0 to Irr galaxies at an averaged redshift of 0.027, and complement the already published Gunn r, J and K photometries. (B-r) colours are also computed.
- ID:
- ivo://CDS.VizieR/J/A+A/365/370
- Title:
- Photometry of UCM galaxies. II.
- Short Name:
- J/A+A/365/370
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Johnson B surface photometry for the UCM Survey galaxies. One-dimensional bulge-disk decomposition is attempted, discussing on fitting functions and computational procedures. The results from this decomposition, jointly with concentration indices and an asymmetry coefficient, are employed to study the morphological properties of these galaxies. We also compare our results with the previous morphological classification established using Gunn r imaging data and with other samples of galaxies. No major statistical differences in morphology are found between red and blue data, although some characteristics such as size and luminosity concentration vary. We find a correlation between luminosity and size. Several parameters are used to segregate the objects according to their morphological type.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/19
- Title:
- Photometry of variable star candidates in M31
- Short Name:
- J/ApJ/743/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry in B, V (down to V~26mag) is presented for two 23'x23' fields of the Andromeda galaxy (M31) that were observed with the blue channel camera of the Large Binocular Telescope during the Science Demonstration Time. Each field covers an area of about 5.1x5.1kpc^2^ at the distance of M31 ({mu}_M31_~24.4mag), sampling, respectively, a northeast region close to the M31 giant stream (field S2) and an eastern portion of the halo in the direction of the galaxy minor axis (field H1). The stream field spans a region that includes Andromeda's disk and giant stream, and this is reflected in the complexity of the color-magnitude diagram of the field. One corner of the halo field also includes a portion of the giant stream. Even though these demonstration time data were obtained under non-optimal observing conditions, the B photometry, which was acquired in time-series mode, allowed us to identify 274 variable stars (among which 96 are bona fide and 31 are candidate RR Lyrae stars, 71 are Cepheids, and 16 are binary systems) by applying the image subtraction technique to the selected portions of the observed fields. Differential flux light curves were obtained for the vast majority of these variables. Our sample mainly includes pulsating stars that populate the instability strip from the Classical Cepheids down to the RR Lyrae stars, thus tracing the different stellar generations in these regions of M31 down to the horizontal branch of the oldest (t~10Gyr) component.
- ID:
- ivo://CDS.VizieR/J/A+A/357/437
- Title:
- Photometry of young star groupings in spirals
- Short Name:
- J/A+A/357/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiband photometric observations of three spiral galaxies selected in a sample suited for the study of young stellar groupings and their relationship with the parent galaxy and the galactic environment. Star forming regions have been identified using an objective technique based on a multivariate statistical analysis. Maps of young star groupings are given for each galaxy. The luminosity functions of the young star group populations show a remarkable similarity with a slope in the range -1.52 to -1.33. The size distributions peak around the classical 100pc value of the Local Group associations for two out of the three galaxies. NGC 1058 shows smaller associations (peak at ~50pc). The total number of young groups per unit B absolute luminosity of the galaxy is significantly greater in UGC 12732. The activity of star formation is in all three galaxies clearly stronger in the central regions.
