- ID:
- ivo://CDS.VizieR/J/A+AS/71/297
- Title:
- CCD UBV photometry of stars in Sex A
- Short Name:
- J/A+AS/71/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD UBV photometry of 2279 stars in Sextans A is presented. Differences with the photometric scales of Sandage and Carlson (1985AJ.....90.1019S) and Hoessel et al. (1983ApJ...274..577H) are discussed; recalibration of the Sandage and Carlson data for Cepheids in Sextans A results in a smaller value for the distance modulus, {mu}=25.6. A similar value for the distance modulus is obtained from the colour-colour diagram. Colour-colour and colour-magnitude diagrams for the whole galaxy and for different parts are presented indicating a general star formation activity all over Sextans A. The contribution of stars brighter than M_pg_=-3 to the total blue light of the galaxy amounts to 25%, a much higher value than what is found for other dwarf irregular galaxies in the Local Group. The integrated birthrate per unit mass of massive stars for the galaxy is found to be much higher than in the Magellanic Clouds, suggesting that the rate in Sextans A was probably smaller in the past. Different slopes for high mass and low mass IMF parts are needed to account for its low surface brightness. The formation of massive stars seems to be favoured for systems of decreasing mass or, given the relation between total mass and metal content, for galaxies of decreasing metallicity.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/127/1014
- Title:
- CCD UBVRIHa photometry in NGC 3603
- Short Name:
- J/AJ/127/1014
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRI and H{alpha} photometry of the extremely compact, starburst cluster NGC 3603. Ground-based images, Hubble Space Telescope (HST) archival data, as well as Chandra X-ray data have been used for this study. We present, for the first time, optical color-magnitude diagrams (CMDs) for the stars in the cluster core down to V=22mag. A well-defined main sequence (MS) as well as low-mass pre-main-sequence (PMS) stars can clearly be seen in the CMDs. This result confirms the finding by Eisenhauer et al. (1998ApJ...498..278E) that low-mass stars are forming in the starburst cluster. We also derive an age (1+/-1Myr) and distance of the cluster (V_0_-M_V_=14.2+/-0.2mag, i.e., d=6.9+/-0.6kpc).
- ID:
- ivo://CDS.VizieR/J/other/BASI/32.295
- Title:
- CCD UBVRI photometry of 3 open clusters
- Short Name:
- J/other/BASI/32.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometric observations of three open clusters Berkeley 15 (= OCl 414), Czernik 18 (= OCl 426) and NGC 2401 (= OCl 588), obtained for the first time in UBVRI filters down to V=20mag, are presented here. They are located at distances of 1259, 955 and 3467 parsecs with their respective ages estimated as ~5x10^9^years, ~0.8 to 1x10^9^years and ~1x10^9^years. While OCl 414 and OCl 426 are in the direction of the Auriga - Perseus constellations, OCl 588 is placed in the direction of Ophiuchus constellation in our Galaxy. The clusters studied here are of intermediate and old age category.
- ID:
- ivo://CDS.VizieR/J/MNRAS/327/23
- Title:
- CCD UBVRI photometry of 7 open star clusters
- Short Name:
- J/MNRAS/327/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive cluster parameters and mass functions from new UBVRI CCD photometric observations of ~3500 stars reaching down to V~20mag for the distant southern open star clusters NGC 3105, NGC 3603, Melotte 105, Hogg 15, NGC 4815, Pismis 20 and NGC 6253. For NGC 3105 and Hogg 15, CCD data are presented for the first time. The observations were carried out in 1992 between February 28 and March 8, June 5 and 9, and July 9 and 12 in the Cousins U, B, V, R and I photometric bands using CCD detector at the 1.0-m Elizabeth Telescope at the South African Astronomical Observatory (SAAO), Sutherland.
- ID:
- ivo://CDS.VizieR/J/A+A/388/149
- Title:
- CCD Vilnius photometry of M56
- Short Name:
- J/A+A/388/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations of field stars in an area north-east of the globular cluster M 56 were obtained in six bands of the Vilnius photometric system. The data sets cover a field of 9'x9.5'. An outline of the data pathway from observations to reduction via IRAF is outlined in this text. Photometry of 366 stars brighter than 18th V magnitude has been obtained and the analysis of the observational errors is discussed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/497/1791
- Title:
- CCD Washington photometry of Antlia cluster
- Short Name:
- J/MNRAS/497/1791
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extension of our previous research on the early-type galaxy population of the Antlia cluster (d~35Mpc), achieving a total coverage of ~2.6deg^2^ and performing surface photometry for ~300 galaxies, 130 of which are new uncatalogued ones. Such new galaxies mainly fall in the low surface brightness (LSB) regime, but there are also some lenticulars (S0) which support the existence of unique functions that connect bright and dwarf galaxies in the scaling relations. We analyse the projected spatial distribution of galaxies up to a distance of ~800kpc from NGC 3268, the adopted centre, as well as the radial velocity distribution and the correlation between galaxy colour and effective radius with the projected spatial distribution. We also obtain the luminosity function of the early-type galaxies and the distribution of stellar masses using the T1-band magnitudes and adopted mass-luminosity ratios. Additionally, we correlate the central galaxy distribution with an X-ray emission map from the literature. Based on the analysis of the radial velocities and galaxy colour distributions, we find that galaxies redder than the colour-magnitude relation (CMR) have a velocity distribution strongly concentrated towards the values of the dominant galaxies and are homogeneously distributed throughout the cluster. Those bluer than the CMR, in turn, have a much more extended radial velocity distribution and are concentrated towards the centre of the cluster. We also identify 12 candidates to ultra diffuse galaxies (UDG), that seem to be split into two families, and speculate about their origins in the context of the cluster structure.
- ID:
- ivo://CDS.VizieR/J/A+A/385/793
- Title:
- Cepheids in Magellanic Clouds. II.
- Short Name:
- J/A+A/385/793
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of CCD observations of ten new suspected second overtone mode Cepheids in the SMC does not confirm the nature of such stars; most of them appear to be first overtone mode Cepheids. A careful analysis of the OGLE best second overtone mode candidates and of the second overtone component of double mode Cepheids in SMC and LMC has been performed in order to clarify the possible effects of a resonance between pulsation modes. There are some indications that such a resonance is indeed operating in these pulsators. A brief discussion of the effects of blending on the light curve shape is also reported, and the usefulness of the Fourier parameters as mode discriminators is discussed. The observations were performed with the direct CCD camera at the Dutch 0.91m telescope of La Silla (ESO) during three runs in November 1997 (6 nights), July 1998 (12 nights) and October 1998 (15 nights). The CCD detector was the ESO chip No. 33, which is a TEK CCD with 512x512 pixels, pixel size of 27{mu}m and spatial resolution of 0.44", providing a small field of view of 3.77'x3.77'. 8 fields were selected in order to observe the ten second overtone candidates.
- ID:
- ivo://CDS.VizieR/II/253A
- Title:
- Chandra Deep Field South: multi-colour data
- Short Name:
- II/253A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 3 contains the object catalogue of the COMBO-17 CDFS field. The observations were carried out with the Wide Field Imager (WFI) at the MPG/ESO 2.2-m telescope on La Silla, Chile, between October 1999 and January 2001 in four independent observing runs. The field measures 31.5'x30', is centered on RA=03:32:25, DE=-27:48:50 and contains the Chandra Deep Field South. The table contains 63501 objects found on the deep R-band image cdfs_r.fit by SExtractor with S/N>3. The 5-{sigma} magnitude limit for point sources is Rmag=26.0. Morphological information from the SExtractor measurement is included. Multiple observations in different observing runs of six different filters allow the identification of variable objects. The table contains positions, flags and flux measurements in UBVRI and 12 optical medium-band filters. In addition, we include multi-colour classification, photometric redshifts, luminosity distances and a number of absolute restframe magnitudes in different filters (Johnson, Sloan, Bessell). cdfs_u.fit, cdfs_b.fit, cdfs_v.fit, cdfs_r.fit and cdfs_i.fit are coadded sumframes in UBVRI of the CDFS field. These sumframes are stacked from flat-fielded and cosmic-corrected individual images by applying only full pixel shifts. Therefore, the coordinate frames differ slightly between the images. The coordinates in Table 3 refer to image cdfs_r.fit. The images in BVRI are obtained from observations carried out in observing run D (Oct 1999, see also Note (11) in the byte-by-byte description of table3.dat) while the U-band image is obtained from observing run G (Jan 2001). The exposure times are 14400s (U), 5000s (B), 8400s (V), 15000s (R) and 7550s (I). The intensity levels are given in units of photons hitting the detector (already corrected for the gain of the CCD). The data included here supersede the table2.dat of the COMBO-17 published in 2001 (J/A+A/377/442)
- ID:
- ivo://CDS.VizieR/J/A+A/377/442
- Title:
- Chandra Deep Field South: R-band photometry
- Short Name:
- J/A+A/377/442
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table2 is based on an object list that was created by applying SExtractor software to an R-band image coadded from 36 frames with 15070s total exposure time taken in October 1999 using the Wide Field Imager at the MPG/ESO 2.2-m telescope on La Silla, Chile. The field measures 31.5'x30', is centered on 03:32:25-27:48:50 and contains the Chandra Deep Field South. The average PSF is on the order of 0.75". The catalog contains 63501 objects found by SExtractor with S/N>3. It has not been cleaned for spurious detection of false objects arising from scattered light or diffraction spikes of extremely bright stars. Using this object list aperture magnitudes 'Bmag', 'Vmag' and 'Rmag' were measured on B-, V- and R-band images taken in October 1999. These are listed with its errors. Additionally an aperture magnitude 'R2mag' with its error is included that is taken from R-band imaging from February 2000 with an exposure time of 8440s taken in 21 frames, yielding a total exposure time in the R-band of 23510s=6.5h. The 10-sigma magnitude limits for point sources are Bmag=24.9, Vmag=24.6, Rmag=25.1 and R2mag=24.8. The aperture magnitudes were calculated by counting the flux in an aperture with a Gaussian weighting function of 1.3" width. The flux is scaled to the total flux expected for stars.
- ID:
- ivo://CDS.VizieR/J/PAZh/41/27
- Title:
- Classical Cepheids BVIc observations
- Short Name:
- J/PAZh/41/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2013-2014, we obtained 14959 CCD frames in the BVIc photometric system for 170 classical Cepheids from the General Catalogue of Variable Stars. We performed our observations with the 76-cm telescope of the South African Astronomical Observatory (SAAO, South Africa) using the SBIG ST-10XME CCD camera. The tables of observations, the plots of light curves, and the current light elements are presented.
