Polymerization of acrylamide in dispersion with paraffinic and aromatic liquids as oil phase

Baade, W.; Reichert, Karl‐Heinz

doi:10.1002/marc.1986.030070501

Cited by 43 publications

(21 citation statements)

References 9 publications

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“…Ozsvath (1960) developed one of the earliest by assigning MPs to stars located inside the cluster region according to the difference in stellar-density found in adjacent field regions of comparable size. Similar algorithms can be found applied with small variations in a great number of articles (Baade 1983;Mateo & Hodge 1986;Chiosi et al 1989;Mighell et al 1996;Bonatto & Bica 2007;Maia et al 2010;Pavani et al 2011;Bukowiecki et al 2011, etc.). Some authors have attempted to refine this method by utilizing regions of variable sizes instead of boxes of fixed sizes, to compare the CMDs of field stars and stars within the cluster region (Froebrich et al 2010;Piatti & Bica 2012).…”

Section: Field Star Contaminationmentioning

confidence: 89%

ASteCA: Automated Stellar Cluster Analysis

Perren

Vazquez

Piatti

2015

A&A

112

121

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We present the Automated Stellar Cluster Analysis package (ASteCA), a suit of tools designed to fully automate the standard tests applied on stellar clusters to determine their basic parameters. The set of functions included in the code make use of positional and photometric data to obtain precise and objective values for a given cluster's center coordinates, radius, luminosity function and integrated color magnitude, as well as characterizing through a statistical estimator its probability of being a true physical cluster rather than a random overdensity of field stars. ASteCA incorporates a Bayesian field star decontamination algorithm capable of assigning membership probabilities using photometric data alone. An isochrone fitting process based on the generation of synthetic clusters from theoretical isochrones and selection of the best fit through a genetic algorithm is also present, which allows ASteCA to provide accurate estimates for a cluster's metallicity, age, extinction and distance values along with its uncertainties. To validate the code we applied it on a large set of over 400 synthetic The results show that ASteCA is able to recover cluster parameters with an acceptable precision even for those clusters affected by substantial field star contamination. ASteCA is written in Python and is made available as an open source code which can be downloaded ready to be used from its official site.

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Section: Field Star Contaminationmentioning

confidence: 89%

ASteCA: Automated Stellar Cluster Analysis

Perren

Vazquez

Piatti

2015

A&A

112

121

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“…The corresponding distance d = 3.4 kpc is moderately larger than the distance derived to Cep OB1 by Garmany & Stencel (1992), but clearly consistent with the distance to NGC 7380, believed to be its nuclear cluster, derived by other authors. For example, photometric determinations give DM = 12.5 (Baade 1983;Chavarría-K. et al 1994), while Massey et al (1995) find DM = 12.9 ± 0.1 from spectroscopic parallaxes of 10 stars. Therefore this seven stars in our sample appear to be members of Cep OB1 and hence be located on the Perseus.…”

Section: The Cepheus Regionmentioning

confidence: 99%

Stellar tracers of the Cygnus Arm

Negueruela

Marco

2003

A&A

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Abstract. We present medium-resolution spectroscopy of a sample of stars in the second Galactic quadrant selected from the literature because their colours suggest that they are moderately-reddened early-type stars at very large distances. From the derived spectral types and observed colours, we calculate distances to all these objects. For a sizable fraction of our sample, we find distances well in excess of what is expected for Perseus Arm objects, even allowing for rather generous errors. In the interval l = 150• −180• , there is a large number of objects with distances in excess of 4 kpc, which are likely tracing the Outer or Cygnus Arm. In particular, we find that the association Cam OB3 is placed on this Arm. Based on our results, the extent and definition of the associations Cas OB4 and Aur OB2 need to be reevaluated.

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“…In a study of NGC 6383, Fitzgerald et al (1978) found a ratio of 21 MS to 8 PMS members in the cluster core. Baade (1983) found a weak concentration of PMS members towards cluster centre in NGC 457, NGC 7380, and IC 1805, together with the presence of extended haloes, which could otherwise just be weak members, not necessarily PMS stars. In a study of IC 348, Lada & Lada (1995) found a radial decay of both star density and subclustering, without specifying the differences between MS and PMS stars.…”

Section: Spatial Distributionmentioning

confidence: 99%

Physical parameters of pre-main sequence stars in open clusters

Delgado

Alfaro

Yun

2011

A&A

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Aims. The aims are twofold: we search and analyse pre-main sequence (PMS) stars in Galactic young open clusters (YOCs) to determine the ages, masses, and spatial distribution of PMS members in YOCs, and to check and compare the performances of different model isochrones. Methods. We compare UBVRI photometric observations to theoretical isochrones in the photometric diagrams. The comparison simultaneously provides membership assignments for both main sequence (MS) and PMS stars and estimates for the physical properties of the cluster candidate members: masses, ages, and spatial distribution inside the cluster. Results. The photometric measurement of an average (U − V) excess, supposedly indicative of accretion disks, is considered prior to membership assignment. This photometric excess is correlated with cluster age, suggesting that disks able to show up in (U − V) excess vanish at ages around 5 Myr. We find that comparing photometry to models in the colour-magnitude (CM) diagram leads to better results for the masses than performing the comparison in the theoretical HR plane. The obtained cluster mass functions show a marginal steepening with cluster age. Significant variations in the mass function slopes are found with the models used in member selection. The clusters NGC 3293 and NGC 2362 are found to have mass functions flatter than the Salpeter slope for all models considered. The relation between the calculated dispersion of PMS age and the characteristic clustering scale of the cluster shows interesting agreement with previous findings in star-forming regions in a wide range of scales. Finally, the ratio of characteristic clustering scales for PMS candidate members in different mass ranges can be interpreted as suggesting mass segregation, in the sense of a relatively wider spatial distribution for the lower mass members in older clusters. Conclusions. The relations between the different cluster parameters show that the procedure applied to assign cluster membership and to measure physical parameters for the selected members is well founded.

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Polymerization of acrylamide in dispersion with paraffinic and aromatic liquids as oil phase

Cited by 43 publications

References 9 publications

ASteCA: Automated Stellar Cluster Analysis

ASteCA: Automated Stellar Cluster Analysis

Stellar tracers of the Cygnus Arm

Physical parameters of pre-main sequence stars in open clusters

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