NGC 2580 and NGC 2588

Baume, G.; Moitinho, A.; Giorgi, E. E.; Carraro, G.; Vazquez, R. A.

doi:10.1051/0004-6361:20034427

Cited by 20 publications

(35 citation statements)

References 23 publications

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“…5 uncertainty in each coordinate. The cluster radial density profiles were computed in the usual way (see Baume et al 2004), namely calculating the surface density in concentric, equal-area rings. Since we applied this method to both the optical (V filter) and the 2MASS infrared data (K filter), this allowed us to detect the possible influence of interstellar material.…”

Section: Clusters Centers and Sizesmentioning

confidence: 99%

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The Ara OB1a association

Baume

Carraro²,

Comerón³

et al. 2011

A&A

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Context. The Ara OB1a association is a nearby complex in the fourth Galactic quadrant where a number of young/embedded star clusters are projected close to more evolved, intermediate age clusters. It is also rich in interstellar matter, and contains evidence of the interplay between massive stars and their surrounding medium, such as the rim HII region NGC 6188. Aims. We provide robust estimates of the fundamental parameters (age and distance) of the two most prominent stellar clusters, NGC 6167 and NGC 6193, that may be used as a basis for studing the star formation history of the region. Methods. The study is based on a photometric optical survey (UBVIH α ) of NGC 6167 and NGC 6193 and their nearby field, complemented with data from 2MASS-VVV, UCAC3, and IRAC-Spitzer in this region. Results. We produce a uniform photometric catalogue and estimate more robustly the fundamental parameters of NGC 6167 and NGC 6193, in addition to the IRAS 16375-4854 source. As a consequence, all of them are located at approximately the same distance from the Sun in the Sagittarius-Carina Galactic arm. However, the ages we estimate differ widely: NGC 6167 is found to be an intermediate-age cluster (20-30 Myr), NGC 6193 a very young one (1-5 Myr) with PMS, H α emitters and class II objects, and the IRAS 16375-4854 source is the youngest of the three containing several YSOs. Conclusions. These results support a picture in which Ara OB1a is a region where star formation has proceeded for several tens of Myr until the present. The difference in the ages of the different stellar groups can be interpreted as a consequence of a triggered star formation process. In the specific case of NGC 6193, we find evidence of possible non-coeval star formation.

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Section: Clusters Centers and Sizesmentioning

confidence: 99%

“…Baume et al 2004Baume et al , 2006Baume et al , 2009 Individual positions of all stars down to V = 14 were simultaneously examined in all the diagrams. At fainter magnitudes, UCAC3 does not provide reliable solutions.…”

Section: Optical Photometric Diagramsmentioning

confidence: 99%

The Ara OB1a association

Baume

Carraro²,

Comerón³

et al. 2011

A&A

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“…It is necessary to evaluate its evolutionary status through analysis of its density and other related parameters (see Aarseth 1996;de La Fuente Marcos 1997;Kroupa et al 2001) such as the slope of the mass spectrum. It is also routinely used as criteria for separating cluster-dominated from field-dominated regions in photometric diagrams (Baume et al 2004).…”

Section: Cluster Sizesmentioning

confidence: 99%

“…These results rely not only on the fundamental parameters derived for the clusters themselves, but also on careful analysis of the characteristics of the field population. From the sample described in Paper I, only NGC 2425, NGC 2635 (Moitinho et al 2006a, Paper II of this series), NGC 2588 (Baume et al 2004) and NGC 2401 (Baume et al 2006) have been the subject of publications dedicated to their detailed photometric analysis and derivation of main physical parameters. In this paper we present a detailed analysis of the fields of four open candidate cluster pairs.…”

Section: Introductionmentioning

confidence: 99%

Open clusters in the Third Galactic Quadrant III. Alleged binary clusters

Vazquez

Moitinho

Carraro³

et al. 2010

A&A

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Aims. We aim to determine accurate distances and ages of eight open clusters in order to: (1) assess their possible binarity (2) provide probes to trace the structure of the Third Galactic Quadrant. Methods. Cluster reddenings, distances, ages and metallicities are derived from ZAMS and isochrone fits in UBVRI photometric diagrams. Field contamination is reduced by restricting analysis to stars within the cluster limits derived from star counts. Further membership control is done by requiring that stars have consistent positions in several diagrams and by using published spectral types. Results. The derived distances, ages and metallicities have shown that none of the analysed clusters compose binary/double systems. Of the four candidate pairs, only NGC 2383/NGC 2384 are close to each other, but have different metallicities and ages. Ruprecht 72 and Ruprecht 158 are not clusters but fluctuations of the field stellar density. Haffner 18 is found to be the superposition of two stellar groups at different distances: Haffner 18(1) at 4.5 kpc and Haffner 18(2) between 9.5 and 11.4 kpc from the Sun. The derived distances and ages have been used to situate the clusters in the Galactic context. In particular, young stellar groups trace spiral structure at large Galactocentric radii. At least two clusters formed during the last few 10 8 yr in an interstellar medium with less than solar abundances. Conclusions. In contrast with the LMC, double clusters are apparently rare, or even non existent, in the undisturbed environment of the Third Galactic Quadrant. This leaves open the question of whether binary clusters form more easily toward denser and more violent regions of the Milky Way such as the inner Galaxy.

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“…the 3 M ⊙ turnover in NGC 6231 (Sung et al 1998) and "dips" at certain masses that are difficult to ascribe to random sampling effects (NGC 3293, Baume et al 2003;NGC 6231, Sung et al 1998;NGC 2571, Georgi et al 2002NGC 2580, Baume et al 2004; and the Orion Nebula Cluster, see . There may even be an example of a cluster with different IMFs in different subregions (NGC 7654, Pandey et al 2001).…”

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confidence: 99%

Fifty Years of IMF Variation: The Intermediate-Mass Stars

Scalo

The Initial Mass Function 50 Years Later

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I track the history of star count estimates of the Milky Way field star and open cluster IMFs, concentrating on the neglected mass range from 1 to 15 M⊙. The prevalent belief that the IMF is universal appears to be without basis for this mass range. Two recent estimates of the field star IMF using different methods and samples give values of the average logarithmic slope Γ between -1.7 and -2.1 in the mass range 1.1 to 4 M⊙. Two older estimates between 2 and 15 M⊙, using much smaller samples, disagree severely; the field IMF in this range is essentially unknown from star counts. Variations in Γ among open cluster IMFs in this same mass range have not decreased despite numerous detailed studies, with a rather uniformly distributed spread of about 1.0 to 1.4, even for studies using homogeneous data and reduction procedures and including only clusters with a significant mass range. These cluster variations might be accommodated by the combined effects of sampling, systematic errors, stellar evolution uncertainties, dynamical evolution, and unresolved binaries. If so, then the cluster data are consistent with a universal IMF, but are also consistent with sizeable variations. The data do not allow an estimate of an average IMF or Γ because the average depends on the choice of weighting procedure and other effects. There is little basis for claims that the field star IMF is steeper or flatter than the cluster IMF in this mass range. If the spread in cluster IMFs is in excess of the effects listed above, real IMF variations must occur that do not depend much on environmental physical conditions explored so far. The complexity of the star formation process seen both in observations and in simulations of turbulent cluster formation suggests that large realization-to-realization differences might be expected. In this case an individual cluster IMF would be in part the product of evolutionary contingency in star formation, and the significant function of interest is the probability distribution of IMF parameters. In either case an average IMF can probably be better determined from the field star IMF using data from future space astrometric missions, or from combinations of indirect constraints using integrated light or chemical evolution applied to whole galaxies.

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NGC 2580 and NGC 2588

Cited by 20 publications

References 23 publications

The Ara OB1a association

The Ara OB1a association

Open clusters in the Third Galactic Quadrant III. Alleged binary clusters

Fifty Years of IMF Variation: The Intermediate-Mass Stars

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