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|New catalogue of blue stragglers in open clusters|
We present a catalogue of blue-straggler candidates in galactic openclusters. It is based on the inspection of the colour-magnitude diagramsof the clusters, and it updates and supersedesthe first version(Ahumada & Lapasset 1995). A new bibliographical search was made foreach cluster, and the resulting information is organised into twotables. Some methodological aspects have been revised, in particularthose concerning the delimitation of the area in the diagrams where thestragglers are selected.A total of 1887 blue-straggler candidates have been found in 427 openclusters of all ages, doubling the original number. The catalogued starsare classified into two categories mainly according to membershipinformation.The whole catalogue (Tables 8, 9, notes, and references) is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (184.108.40.206) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/463/789
|Photometry of seven overlooked open clusters in the first and fourth Galactic quadrants|
CCD BVI photometry is presented for seven previously unstudied starclusters projected towards the inner side of the Galaxy: Trumpler 23,Lynga 3, Collinder 307, Ruprecht 134, ESO552SC16, AL 5 and Kronberger 3.Colour-magnitude diagrams of the cluster regions allow us to concludethat Lynga 3 and ESO552SC16 are not clusters, but groups of bright starsprobably located in the Carina-Sagittarius spiral arm. AL 5 andKronberger 3 are so embedded in a dense stellar field that we cannotconfirm their nature. Trumpler 23 and Ruprecht 134 are twointermediate-age open clusters located well inside the solar ring whichdeserve further attention.Finally, Collinder 307 is an obscured younger cluster (250Myr) locatedin the Carina-Sagittarius spiral arm. Our results emphasize thedifficulty to search for open clusters in the inner regions of theGalaxy due to the richness of the field and the patchy nature of theinterstellar absorption, but at the same time significantly contributeto a better understanding of this complicated regions of the Milky Way.
|Open clusters in the Third Galactic Quadrant. II. The intermediate age open clusters NGC 2425 and NGC 2635|
We analyse CCD broad band (UBV(RI)_C) photometric data obtained in thefields of the poorly studied open clusters NGC 2425and NGC 2635. Both clusters are found to be ofintermediate age thus increasing the population of open clusters knownto be of the age of, or older than, the Hyades. More explicitly, we findthat NGC 2425 is a 2.2 Gyr old cluster, probably ofsolar metallicity, located at 3.5 kpc from the Sun. NGC2635 is a Hyades age (600 Myr) cluster located at a distanceof 4.0 kpc from the Sun. Its Colour Magnitude Diagram reveals that it isextremely metal poor for its age and position, thus making it a veryinteresting object in the context of Galactic Disk chemical evolutionmodels.
|NGC 6404 and 6583: two neglected intermediate-age open clusters located in the Galactic Centre direction|
We report on VI charge-coupled device photometry of two fields centredin the region of the open clusters NGC 6404 and 6583 down to V= 22.0. Sofar these clusters have never been studied, and we provide for the firsttime estimates of their fundamental parameters, namely, radial extent,age, distance and reddening. We find that the radius of NGC 6404 is 2.0arcmin, as previously proposed, while the radius of NGC 6583 is 1.0arcmin, significantly lower than previous estimates. Both clusters turnout to be of intermediate age (0.5-1.0 Gyr old), and located inside thesolar ring, at a Galactocentric distance of about 6.5 kpc. These resultsmake these objects very interesting targets for spectroscopic follow-upto measure their metallicity. In fact, they might allow us to enlarge bymore than 1 kpc the baseline of the radial abundance gradient in theGalactic disc towards the Galactic Centre direction. This baseline iscurrently rather narrow especially for clusters of this age.
|Metal abundances of RR Lyrae stars in or near seven globular clusters|
An analysis of low-resolution spectra for RR Lyrae stars in or nearseven globular clusters has been performed in order to determine themetal abundance index (Delta S) for these variables. Correlationsbetween Delta S values and spectral type show a degree of scatter. Fe/Habundance ratios of -0.62 + or - 0.08 for 47 Tucanae and -0.71 + or -0.14 for M71 have been obtained.
|A photometric study of the bright cloud B in Sagittarius. VI - 1592 new variable stars and 30 diffuse objects|
Abstract image available at:http://adsabs.harvard.edu/abs/1988A&AS...76..205T
|Uniform survey of clusters in the southern Milky Way.|
Abstract image available at:http://adsabs.harvard.edu/abs/1975AJ.....80...11V
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