scholarly journals Modeling of Integrated Spectral Energy Distributions of Stellar Populations with Various Binary Fractions

2021 ◽  
Vol 2068 (1) ◽  
pp. 012048
Author(s):  
Zhongmu Li ◽  
Chen Yan
Keyword(s):  
Binary Stars ◽  
Star Clusters ◽  
Stellar Populations ◽  
Spectral Studies ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Spectral Fitting ◽  
The Universe

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.

scholarly journals Photometric characterization of multiple populations in star clusters: the impact of the first dredge-up

2020 ◽  
Vol 492 (3) ◽  
pp. 3459-3464 ◽  
Author(s):  
Maurizio Salaris ◽  
Chris Usher ◽  
Silvia Martocchia ◽  
Emanuele Dalessandro ◽  
Nate Bastian ◽  
...  
Keyword(s):  
Star Clusters ◽  
Light Element ◽  
Element Abundance ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Multiple Populations ◽  
Red Giant ◽  
The Impact

ABSTRACT The existence of star-to-star light-element abundance variations (multiple populations, MPs) in massive Galactic and extragalactic star clusters older than about 2 Gyr is by now well established. Photometry of red giant branch (RGB) stars has been and still is instrumental in enabling the detection and characterization of cluster MPs, through the appropriate choices of filters, colours, and colour combinations that are mainly sensitive to N and – to a lesser degree – C stellar surface abundances. An important issue not yet properly addressed is that the translation of the observed widths of the cluster RGBs to abundance spreads must account for the effect of the first dredge-up on the surface chemical patterns, hence on the spectral energy distributions of stars belonging to the various MPs. We have filled this gap by studying theoretically the impact of the dredge-up on the predicted widths of RGBs in clusters hosting MPs. We find that for a given initial range of N abundances, the first dredge-up reduces the predicted RGB widths in N-sensitive filters compared to the case when its effect on the stellar spectral energy distributions is not accounted for. This reduction is a strong function of age and has also a dependence on metallicity. The net effect is an underestimate of the initial N-abundance ranges from RGB photometry if the first dredge-up is not accounted for in the modelling, and also the potential determination of spurious trends of N-abundance spreads with age.

Panchromatic characterisation of accreting black holes in dusty star-forming galaxies

2019 ◽  
Vol 15 (S356) ◽  
pp. 26-26
Author(s):  
Gabriela Calistro Rivera
Keyword(s):  
Galactic Nuclei ◽  
Spectral Energy ◽  
X Rays ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Nuclear Activity ◽  
Star Forming ◽  
History Of ◽  
Fully Bayesian ◽  
The Universe

AbstractAlthough AGN do not typically dominate the bolometric emission of dusty star forming galaxies, large AGN fractions (sometimes > 40%) have been observed in various sub-millimeter surveys. These diagnostics have been however mostly based on X-ray counterpart selections and a complete multiwavength census of the fraction of AGN hosts is needed. I will present new advances in the modelling of panchromatic spectral energy distributions (SEDs) of active galactic nuclei (AGN), based on our publicly available code AGNfitter (Calistro-Rivera et al.2016). AGNfitter implements a fully Bayesian Markov Chain Monte Carlo method to fit the spectral energy distributions of AGNs pushing the wavelengths frontiers from the radio to the X-rays. I will present a recent application of AGNfitter on dusty star forming galaxies in the ALESS submillimeter survey to obtain an unbiased multiwavelength characterisation of the nuclear activity buried in dusty star formation. Our method reveals a significantly larger contribution of AGN activity to the emission in these galaxies than previously observed based on X-rays diagnostics. Our method represents a unique tool to potentially characterise an unbiased accretion history of the Universe when applied to larger populations of star-forming galaxies.

scholarly journals Spectral Energy Distributions and Age Estimates of 78 Star Clusters in M33

2002 ◽  
Vol 123 (6) ◽  
pp. 3141-3153 ◽  
Author(s):  
Jun Ma ◽  
Xu Zhou ◽  
Jiansheng Chen ◽  
Hong Wu ◽  
Zhaoji Jiang ◽  
...  
Keyword(s):  
Star Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Age Estimates

scholarly journals SPECTRAL ENERGY DISTRIBUTIONS AND MASSES OF 304 M31 OLD STAR CLUSTERS

2015 ◽  
Vol 149 (2) ◽  
pp. 56 ◽  
Author(s):  
Jun Ma ◽  
Song Wang ◽  
Zhenyu Wu ◽  
Tianmeng Zhang ◽  
Hu Zou ◽  
...  
Keyword(s):  
Star Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions

scholarly journals Hot Stellar Populations in the M31 Bulge

1993 ◽  
Vol 153 ◽  
pp. 415-416
Author(s):  
Henry C. Ferguson ◽  
Arthur F. Davidsen
Keyword(s):  
Stellar Populations ◽  
Spectral Energy ◽  
Horizontal Branch ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Relative Contribution ◽  
Uv Emission

We investigate the possibility that the Far-UV spectral energy distributions (SED's) of M31 and NGC 1399 differ only in the relative contribution from classical PAGB stars and in the amount of extinction. A good fit to the M31 spectrum is obtained for E(B-V) = 0.11 if about 65% of the flux comes from PAGB stars and the rest from stars of the type producing the far-UV emission in NGC1399. We speculate that the UV continuum in both galaxies is dominated by stars in post-horizontal branch phases of evolution, with a distribution of post-HB masses governed primarily by the metallicity and metallicity spread of the population. This hypothesis can qualitatively explain both the relative fluxes of UV rising branches in NGC1399 and M31 and the shapes of their SED's.

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