- ID:
- ivo://CDS.VizieR/J/A+A/412/721
- Title:
- CCD {Delta}a-photometry of 5 open clusters
- Short Name:
- J/A+A/412/721
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated 1008 objects in the area of five intermediate age open clusters (NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756) via the narrow band {Delta}a-system. The detection limit for photometric peculiarity is very low (always less than 0.009mag) due to the high number of individual frames used (193 in total). We have detected six peculiar objects in NGC 6705 and NGC 6756 from which one in the latter is almost certainly an unreddened late type foreground star. The remaining five stars are probably cluster members and bona fide chemically peculiar objects (two are {lambda} Bootis type candidates). Furthermore, we have investigated NGC 3114, a cluster for which already photoelectric {Delta}a-measurements exist. A comparison of the CCD and photoelectric values shows very good agreement. Again, the high capability of our CCD {Delta}a-photometric system to sort out true peculiar objects together with additional measurements from broad or intermediate band photometry is demonstrated.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/385/867
- Title:
- CCD {Delta}a-photometry of 5 open clusters
- Short Name:
- J/A+A/385/867
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In total, more than 550 objects within the fields of five open clusters (NGC 2439, NGC 3960, NGC 6134, NGC 6192 and NGC 6451) were investigated in order to find classical chemically peculiar stars. One bona-fide CP candidate was detected in each of the open clusters NGC 3960, NGC 6192 and NGC 6451. All three objects seem to be members of the corresponding cluster taking the results from our photometry as well as from the literature. For NGC 6192 and NGC 6451 we found widely different interstellar reddening values and therefore distances and ages in the literature. From an analysis of published Johnson UBVRI photometry, we were able to rule out a rather old age for NGC 6451. This is also supported by the finding of one peculiar object in this cluster with spectral type of about A2. Five variable objects within the field of NGC 6134 were detected. The variability exceeds 10 times (or typically 0.03 mag) the standard deviation of the weighted individual measurements. But since our observations were obtained mostly during one hour (typical integration times of five minutes per filter) on several nights within 45 days, no light curves could yet be derived. For this cluster some Am candidates were reported for which we were not able to detect a significant positive {Delta} a-value. For a description of the {Delta}a photometric system, see e.g. <GCPD/75>
- ID:
- ivo://CDS.VizieR/J/A+A/454/171
- Title:
- CCD {Delta}a-photometry of 8 open clusters
- Short Name:
- J/A+A/454/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detection of magnetic chemically peculiar (CP2) stars in open clusters of the Milky Way can be used to study the influence of different galactic environments on the (non-)presence of peculiarities, which has to be taken into account in stellar evolution models. Furthermore it is still unknown if the CP2 phenomenon evolves, i.e. does the strength of the peculiarity feature at 5200{AA} increase or decrease with age. Methods. We have observed eight young to intermediate age open clusters in the {Delta}a photometric system.
- ID:
- ivo://CDS.VizieR/J/A+A/414/23
- Title:
- CCD H{alpha} and R photometry of 334 galaxies
- Short Name:
- J/A+A/414/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types from S0/a to Im and with recession velocities of between 0 and 3000km/s. The basic data for each galaxy are narrow band H{alpha}+[NII] and R-band imaging, from which we derive star formation rates, H{alpha}+[NII] equivalent widths and surface brightnesses, and R-band total magnitudes. A strong correlation is found between total star formation rate and Hubble type, with the strongest star formation in isolated galaxies occurring in Sc and Sbc types. More surprisingly, no significant trend is found between H{alpha}+[NII] equivalent width and galaxy R-band luminosity. More detailed analyses of the data set presented here will be described in subsequent papers.
- ID:
- ivo://CDS.VizieR/J/AJ/156/134
- Title:
- CCD measurements of multiple stars at ASV & NAOR
- Short Name:
- J/AJ/156/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of classical CCD observations for 371 double or multiple stars (450 pairs) obtained at both, Serbian Astronomical Station on the mountain of Vidojevica (ASV) and Bulgarian National Astronomical Observatory at Rozhen (NAOR) are presented. At ASV the observations were performed with the 0.6 m telescope in the first half of 2016 during 11 nights, and with the newly mounted 1.4 m telescope in the second half of 2016 during 16 nights. At NAOR, the observations were performed with the 2 m telescope during four nights. In this paper, we present 477 measurements (position angle and angular separation) for these 450 pairs. Among them there are 41 pairs with published orbital or linear elements and residuals are given for them. Some pairs have measurements for several epochs. Our observed pairs have angular separations in the interval from 1.60" to 190.30", with a mean angular separation of 14.87" and a median value of 4.34". Two new pairs and linear elements for four pairs which are calculated for the first time are also presented.
- ID:
- ivo://CDS.VizieR/J/AJ/146/52
- Title:
- CCD measurements of multiple stars at NAOR and ASV
- Short Name:
- J/AJ/146/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 2m telescope of the Bulgarian National Astronomical Observatory at Rozhen, observations of 222 double or multiple stars were carried out during three nights in 2011. This is the sixth series of measurements of CCD frames of double and multiple stars obtained at Rozhen. Also in 2011, using the 0.6m telescope of the Serbian Astronomical Station on the mountain of Vidojevica, observations of 208 double or multiple stars were carried out during six nights. This is the first series of measurements of CCD frames of double and multiple stars obtained at this station. In this paper, we present the results for the position angle and angular separation for 337 pairs and residuals for 72 pairs with published orbital elements or linear solutions. These observations have angular separations in the range from 1.37'' to 172.81'', with a median angular separation of 7.66''. We also present the recalculated linear solutions for four pairs and one linear solution that has been calculated for the first time.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/425
- Title:
- CCD photometry and astrometry of double stars
- Short Name:
- J/A+AS/139/425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric and astrometric data of about 280 visual double stars of the "intermediate" class, i.e. with angular separations mainly in the range 2"<{rho}<12". The observations have been obtained in 1991-92 with a CCD camera attached to the 91cm Dutch telescope at ESO La Silla, Chile. Differential magnitudes of the double star components as well as magnitudes and colour indices of the individual components have been determined in the Cousins V and I passbands with an internal error of about 0.005mag and an external accuracy of less than 0.03mag. In addition, angular separations have been secured to an internal accuracy of 0.004" and position angles to about 0.05{deg}.
- ID:
- ivo://CDS.VizieR/J/A+A/374/132
- Title:
- CCD photometry and astrometry of double stars
- Short Name:
- J/A+A/374/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new astrometric and photometric data for 253 visual double stars of the "intermediate" class, i.e. with angular separations in the range 1 to 15 arcsec. The multi-colour observations were obtained in 1992-94 as part of the ESO Key Programme "Visual Double Stars" performed at La Silla Observatory (Chile). Differential magnitudes and colours have been secured in a systematic way while component magnitudes and colour indices have been determined in the V and I passbands of the Cousins standard system in good photometric conditions only. Internal and mean external errors are respectively smaller than 0.01mag and a few hundred of a magnitude (0.02 to 0.03mag). Relative positions are obtained as a by-product with internal errors of the order of 0.006arcsec in angular separation and 0.08{deg} in position angle. Final accuracies are thoroughly discussed: we illustrate the overall excellent quality of the data and estimate the quality degradation for angular separations barely larger than the width of the seeing disk.
- ID:
- ivo://CDS.VizieR/J/A+AS/67/327
- Title:
- CCD photometry in NGC 7492
- Short Name:
- J/A+AS/67/327
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry in B,V colors of the globular cluster NGC 7492 (B1950 = 23 05.7 -15 54) is presented.
- ID:
- ivo://CDS.VizieR/J/A+A/443/157
- Title:
- CCD photometry in 6 open clusters
- Short Name:
- J/A+A/443/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Within the sample of six young open clusters (NGC 1502, NGC 3105, Stock 16, NGC 6268, NGC 7235 and NGC 7510) we have investigated 1753 objects using the narrow band, three filter Delta a photometric system resulting in the detection of eleven bona-fide magnetic chemically peculiar (CP) stars and five Be or metal-weak stars. The results for the distant cluster NGC 3105 is most important because of the still unknown influence of the global metallicity gradient of the Milky Way. These findings confirms that CP stars are present in open clusters of very young ages (logt>=6.90) at galactocentric distances up to 11.4kpc. For all programme clusters the age, reddening and distance modulus were derived using the corresponding isochrones. Some additional variable stars within Stock 16 could be identified by comparing different photometric studies.
