The outer halo globular cluster NGC 6229 has a peculiar horizontal-branch (HB) morphology, with clear indications of a bimodal HB and a "" gap ÏÏ on the blue HB. In this paper, we present extensive synthetic HB simulations to determine whether peculiar distributions in the underlying physical parameters are needed to explain the observed HB morphology. We Ðnd that a unimodal mass distribution along the HB can satisfactorily account for the observed HB bimodality, provided the mass dispersion is substantially larger than usually inferred for the Galactic globular clusters. In this case, NGC 6229 should have a well-populated, extended blue tail. A truly bimodal distribution in HB masses can also satisfactorily account for the observed HB morphology, although in this case the existence of an extended blue tail is not necessarily implied. The other two well-known bimodal-HB clusters, NGC 1851 and NGC 2808, are brieÑy analyzed. While the HB morphology of NGC 1851 can also be reproduced with a unimodal mass distribution assuming a large mass dispersion, the same is not true of NGC 2808, for which a bimodal, and possibly multimodal, mass distribution seems deÐnitely required.The problem of gaps on the blue HB is also discussed. Applying the standard Hawarden and Newell s2 test, we Ðnd that the NGC 6229 gap is signiÐcant at the 99.7% level. However, in a set of 1000 simulations, blue-HB gaps comparable to the observed one are present in D6%È9% of all cases. We employ a new and simple formalism, based on the binomial distribution, to explain the origin of this discrepancy, and conclude that HawardenÏs method, in general, substantially overestimates the statistical signiÐcance of gaps. Paper I). showed that the horizontal-branch (HB) morphology of this cluster is characterized by two peculiar properties : (1) A distinctly bimodal distribution in B[V colors, consistent with the relatively small number of RR Lyrae variables, compared to the blue HB and red HB populations ; and (2) at least one "" gap ÏÏ on the blue HB, as previously noted by Fullton, & Trammell Carney, (1991). Bimodal-HB clusters are relatively rare, as are clusters with gaps on the blue HB. NGC 6229 is one of only four known casesÈthe others being NGC 2808, NGC 6388, and NGC 6441Èwhere these two anomalies are simultaneously present. As argued by many authors, an understanding of the nature of the detected peculiarities in "" bimodal ÏÏ and "" gap ÏÏ clusters would be of paramount importance for understanding the nature of the second parameter phenomenon (see, e. for producing HB bimodality in the speciÐc cases of NGC 6229, NGC 1851, and NGC 2808 ? (3) Are gaps on the blue HB a natural consequence of stellar evolution, as claimed by some authors ? (4) What is the statistical signiÐcance of gaps ?In this paper, we present extensive synthetic HB simulations for NGC 6229. We begin in the next section by laying out a proposed nomenclature for both deÐning and di †er-entiating "" bimodal ÏÏ and "" gap ÏÏ clusters. In we describe°3, the theoretical proc...

Context. The ESO public survey VISTA variables in the Vía Láctea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for about five years. Aims. We describe the progress of the survey observations in the first observing season, the observing strategy, and quality of the data obtained. Methods. The observations are carried out on the 4-m VISTA telescope in the ZY JHK s filters. In addition to the multi-band imaging the variability monitoring campaign in the K s filter has started. Data reduction is carried out using the pipeline at the Cambridge Astronomical Survey Unit. The photometric and astrometric calibration is performed via the numerous 2MASS sources observed in each pointing. Results. The first data release contains the aperture photometry and astrometric catalogues for 348 individual pointings in the ZY JHK s filters taken in the 2010 observing season. The typical image quality is ∼0. 9−1. 0. The stringent photometric and image quality requirements of the survey are satisfied in 100% of the JHK s images in the disk area and 90% of the JHK s images in the bulge area. The completeness in the Z and Y images is 84% in the disk, and 40% in the bulge. The first season catalogues contain 1.28 × 10 8 stellar sources in the bulge and 1.68 × 10 8 in the disk area detected in at least one of the photometric bands. The combined, multi-band catalogues contain more than 1.63 × 10 8 stellar sources. About 10% of these are double detections because of overlapping adjacent pointings. These overlapping multiple detections are used to characterise the quality of the data. The images in the JHK s bands extend typically ∼4 mag deeper than 2MASS. The magnitude limit and photometric quality depend strongly on crowding in the inner Galactic regions. The astrometry for K s = 15−18 mag has rms ∼ 35−175 mas. Conclusions. The VVV Survey data products offer a unique dataset to map the stellar populations in the Galactic bulge and the adjacent plane and provide an exciting new tool for the study of the structure, content, and star-formation history of our Galaxy, as well as for investigations of the newly discovered star clusters, star-forming regions in the disk, high proper motion stars, asteroids, planetary nebulae, and other interesting objects.

Abstract.A systematic search of the 2MASS point source catalog, covering 47% of the sky, was carried out aiming to reveal any hidden globular clusters in our Galaxy. Eight new star clusters were discovered by a search algorithm based on finding peaks in the apparent stellar surface density, and a visual inspection of their vicinities yielded additional two. They all are concentrated toward the Galactic plane and are hidden behind up to A V = 20 mag which accounts for their late discovery. The majority of new clusters are associated with H regions or unidentified IRAS sources suggesting that they are young, probably similar to Arches or open clusters. Only one candidate has morphology similar to a globular cluster and the verification of its nature will require deeper observations with higher angular resolution than the 2MASS data.

Abstract. We present optical spectroscopy of H ii regions in the Local Group galaxy IC 10 and UBV R photometry of foreground stars in three fields towards this galaxy. From these data, we find that the foreground reddening due to the Milky Way is E(B − V ) = 0.77 ± 0.07 mag. We find that IC 10 contains considerable internal dust, which qualitatively explains the variety of reddening values found by studies of its different stellar populations. Based upon our foreground reddening, IC 10 has intrinsic photometric properties like those of a blue compact dwarf galaxy, and not those of a dwarf irregular. This result is consistent with much evidence that IC 10 is in the throes of a starburst that began at least 10 Myr ago. We also report the discovery of a new WR star in the H ii region HL111c.Key words. galaxies: individual: IC 10 -galaxies: local group -galaxies: fundamental parameters -galaxies: starburst -galaxies: dwarf IntroductionIC 10 has long been recognized as a peculiar object (Hubble 1936), and is now considered the Local Group's representative of a starburst galaxy (van den Bergh 2000). As we will show, IC 10 may very well be the nearest example of a blue compact dwarf galaxy (BCD). Certainly, its surface brightness is similar to that seen in BCDs once we account for the foreground reddening. Among Local Group dwarf galaxies, IC 10 has the highest surface density of WR stars and the highest current rate of star formation (Mateo 1998). The presence of so many WR stars and the high Hα luminosity emphasize that IC 10 is undergoing a strong burst of star formation that began at Send offprint requests to: M. G. Richer, e-mail: richer@astrosen.unam.mx least 10 Myr ago. Observations of 21-cm emission from H i reveal that IC 10 consists of an inner disk embedded in an extended, complex, counter-rotating envelope (Shostak & Skillman 1989), and leads Wilcots & Miller (1998) to conclude that IC 10 is still in its formative stage. These H i observations emphasize the youth of the current star formation episode, for there is a notable lack of interstellar medium structures that are attributable to supernovae (Wilcots & Miller 1998). Several studies of the stellar populations in IC 10 have revealed the existence of young, intermediate-age, and old stellar populations (Massey & Armandroff 1995;Sakai et al. 1999;Borissova et al. 2000). However, with the exception of the very recent star formation, very little is known of the history of star formation in IC 10, and nothing is known of the star formation history outside of the star-forming region.Article published by EDP Sciences and available at http://www.aanda.org or http://dx