Researches of Stellar Populations in Star Clusters

Abstract Binary stars are common in the universe, but binary fractions are various in different star clusters and galaxies. Studies have shown that binary fraction affects the integrated spectral energy distributions obviously, in particular in the UV band. It affects spectral fitting of many star clusters and galaxies significantly. However, previous works usually take a fixed binary fraction, i.e., 0.5, and this is far from getting accurate results. Therefore, it is important to model the integrated spectral energy distributions of stellar populations with various binary fractions. This work presents a modeling of spectral energy distributions of simple stellar populations with binary fractions of 0.3, 0.7, and 1.0. The results are useful for different kinds of spectral studies.

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On the precision of full-spectrum fitting of simple stellar populations – I. Well-sampled populations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2515 ◽

2020 ◽

Vol 498 (2) ◽

pp. 2814-2832

Author(s):

Randa Asa’d ◽

Paul Goudfrooij

Keyword(s):

Random Noise ◽

Star Clusters ◽

Stellar Populations ◽

Asymptotic Giant Branch ◽

Full Spectrum ◽

Red Giant ◽

Set Up ◽

Age Range ◽

Spectrum Fitting ◽

Giant Branch Stars

ABSTRACT We investigate the precision of the ages and metallicities of 21 000 mock simple stellar populations (SSPs) determined through full-spectrum fitting. The mock SSPs cover an age range of 6.8 < log (age/yr) < 10.2, for three wavelength ranges in the optical regime, using both Padova and MIST isochrone models. Random noise is added to the model spectra to achieve S/N ratios between 10 and 100 per wavelength pixel. We find that for S/N ≥ 50, this technique can yield ages of SSPs to an overall precision of ∆log (age/yr)∼01 for ages in the ranges 7.0 ≤ log (age/yr) ≤ 8.3 and 8.9 ≤ log (age/yr) ≤ 9.4. For the age ranges of 8.3 ≤ log (age/yr) ≤ 8.9 and log (age/yr) ≥ 9.5, which have significant flux contributions from asymptotic giant branch and red giant branch stars, respectively, the age uncertainty rises to about ±0.3 dex. The precision of age and metallicity estimation using this method depends significantly on the S/N and the wavelength range used in the fitting. We quantify the systematic differences in age predicted by the MIST and Padova isochrone models, due to their different assumptions about stellar physics in various important (i.e. luminous) phases of stellar evolution, which needs to be taken in consideration when comparing ages of star clusters obtained using these popular models. Knowing the strengths and limitations of this technique is crucial in interpreting the results obtained for real star clusters and for deciding the optimal instrument set-up before performing the observations.

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Globular clusters and their link with stellar populations in the Milky Way

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319007361 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 19-23

Author(s):

David Yong

Keyword(s):

Chemical Evolution ◽

Globular Clusters ◽

Milky Way ◽

Star Clusters ◽

Stellar Populations ◽

Chemical Compositions ◽

Chemical Abundance ◽

Chemical Enrichment ◽

Similarities And Differences ◽

Insight Into

AbstractObservations of stellar chemical compositions enable us to identify connections between globular clusters and stellar populations in the Milky Way. In particular, chemical abundance ratios provide detailed insight into the chemical enrichment histories of star clusters and the field populations. For some elements, there are striking differences between field and cluster stars which reflect different nucleosynthetic processes and/or chemical evolution. The goal of this talk was to provide an overview of similarities and differences in chemical compositions between globular clusters and the Milky Way as well as highlighting a few areas for further examination.

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Testing spectral models for stellar populations with star clusters - I. Methodology

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2009.16153.x ◽

2010 ◽

Vol 403 (2) ◽

pp. 780-796 ◽

Cited By ~ 37

Author(s):

Roberto Cid Fernandes ◽

Rosa M. González Delgado

Keyword(s):

Star Clusters ◽

Stellar Populations ◽

Spectral Models

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Star Clusters and Stellar Populations of the M31 Disk as Viewed by HST

Symposium - International Astronomical Union ◽

10.1017/s0074180900223577 ◽

2002 ◽

Vol 207 ◽

pp. 149-151

Author(s):

Benjamin F. Williams ◽

Paul W. Hodge

Keyword(s):

Star Clusters ◽

Stellar Populations ◽

Young Star ◽

Young Stars ◽

New Method ◽

Data Archive ◽

Stellar Photometry ◽

Identification Method ◽

Ob Associations ◽

Young Star Clusters

We present a new method for finding associations of young stars in M31 using broadband WFPC2 data from the HST data archive. Applying our identification method to 13 WFPC2 fields, covering an area of ∼60 arcmin2, has revealed 80 new candidate young star clusters in these portions of the M31 disk. Most of these clusters are small (≳5 pc) young (∼10–200 Myr) star groups located within large OB associations. We have estimated the reddening values and the ages of each candidate individually by fitting isochrones to the stellar photometry. We provide a catalogue of the candidates including rough approximations of their reddenings and ages.

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Star Clusters in Local Group Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900108551 ◽

1995 ◽

Vol 164 ◽

pp. 181-192

Author(s):

Edward W. Olszewski

Keyword(s):

Stellar Population ◽

Local Group ◽

Star Clusters ◽

Stellar Populations ◽

Cluster Systems ◽

Star Forming ◽

Long Time ◽

History Of ◽

Individual Objects

In this paper I will try to give the flavor of two different concepts of stellar population, namely, the population of cluster systems within galaxies, and the stellar populations within individual clusters. I hope to show, in concert with other papers in this volume, that a generic vision of Population I and II has been outdated for a long time. I believe that it is still proper to talk about populations within individual objects; in the case of galaxies, one might make a correspondence of populations with the important star forming events in the history of a galaxy.

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