A study of dust cloud parameters by Vilnius photometry

Smriglio, F.; Dasgupta, A. K.; Boyle, R. P.

doi:10.1515/astro-1996-0307

Cited by 5 publications

(5 citation statements)

References 3 publications

(4 reference statements)

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“…Smriglio et al (1989) have shown that the Sigma-Q classifications are in good agreement with the published MIv classifications. The GIC classifications are achieved interactively with an estimate of the photometric errors on the classification in each Q-Q diagram.…”

Section: Classification Of Starssupporting

confidence: 75%

Vilnius CCD photometry of NGC 4755 and 47 Tuc

Dodd¹,

Banks²,

Zdanavicius³

et al. 1996

Open Astronomy

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Section: Classification Of Starssupporting

confidence: 75%

Vilnius CCD photometry of NGC 4755 and 47 Tuc

Dodd¹,

Banks²,

Zdanavicius³

et al. 1996

Open Astronomy

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“…In total, we found 406 individual metallicity values for 188 open clusters in 64 publications. (Strömgren 1966), -Vilnius: a seven filter system (Smriglio et al 1990), -Washington: a four filter system introduced by Canterna (1976).…”

Section: Target Selection and Literature Assessmentmentioning

confidence: 99%

On the metallicity of open clusters

Paunzen¹,

Heiter

Netopil

et al. 2010

A&A

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Context. Metallicity is one of four free parameters typically considered when fitting isochrones to the cluster sequence. Unfortunately, this parameter is often ignored or assumed to be solar in most papers. Hence an unknown bias is introduced in the estimation of the other three cluster parameters (age, reddening and distance). Furthermore, studying the metallicity of open clusters allows us not only to derive the Galactic abundance gradient on a global scale, but also to trace the local solar environment in more detail. Tracing the solar environment within 4000 × 4000 pc 2 we identify a patchy metallicity distribution as an extension to the Local Bubble that significantly influences the estimation of the Galactic metallicity gradient, even on a global scale. In addition, further investigations of more distant open clusters are clearly needed to obtain a more profound picture at Galactocentric distances beyond 10 000 pc. Conclusions. Only a combination of all available photometric and spectroscopic data will shed more light on how the local and global Galactic properties are correlated with metallicity.

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“…It is interesting to note that in a QCD, stars with the same spectral type, but different "normal" reddening, lie on a straight line parallel to the x-axis, as shown in Figure 2. By using an appropriate set of photometric filters, e.g., the automated two-dimensional classification from multicolor photometry in the Vilnius system [38][39][40][41][42], it would be possible to make a stellar classification with a set of reddening-free Q parameters. To calculate the standard error (σ Q ), we should consider that the Q parameter depends on the accuracy of the magnitudes and the color-excess ratio.…”

Section: Reddening-free Q Parametermentioning

confidence: 99%

Reddening-Free Q Parameters to Classify B-Type Stars with Emission Lines

Aidelman

Cidale

2023

Galaxies

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The emission-line B-type stars constitute a heterogeneous group. Many of these stars show similar optical spectroscopic features and color indices, making it difficult to classify them adequately by means of photometric and spectroscopic techniques. Thus, it is relevant to deal with appropriate classification criteria to avoid as many selection effects as possible. For this purpose, we analyzed different reddening-free Q parameters, taking advantage of the Gaia and 2MASS photometric surveys, for both main sequence and emission-line B-type stars. Along with this work, we provided various criteria to search for normal and emission-line B-type stars, using different color–color, Q–color, and Q–Q diagrams. It was also possible to identify stars in different transition phases (i.e., (Rp−J) vs. (J−Ks) diagrams) and to classify them according to their NIR radiation excesses (i.e., the (Bp−Rp) vs. (H−Ks) diagram). Other diagrams, such as the QJKHK vs. (H−Ks) or QBpJHK vs. (Bp−Ks), were very useful to search for and classify different classes of B-type stars with emission lines. These diagrams highlighted the presence of several stars, classified as CBe, with large color excesses that seemed to be caused by the presence of dust in their envelopes. Therefore, these stars would be misclassified. Three groups of HAeBe stars with different intrinsic dust properties were also distinguished. The amount of intrinsic dust emission in the diverse groups of emission-line stars was well-recognized via the QJHK vs. QBpRpHK diagram. The different selection criteria are very important tools for automated designs of machine learning and optimal search algorithms.

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A study of dust cloud parameters by Vilnius photometry

Cited by 5 publications

References 3 publications

Vilnius CCD photometry of NGC 4755 and 47 Tuc

Vilnius CCD photometry of NGC 4755 and 47 Tuc

On the metallicity of open clusters

Reddening-Free Q Parameters to Classify B-Type Stars with Emission Lines

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