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.

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 HELP: modelling the spectral energy distributions of Herschel detected galaxies in the ELAIS N1 field

2018 ◽  
Vol 620 ◽  
pp. A50 ◽  
Author(s):  
K. Małek ◽  
V. Buat ◽  
Y. Roehlly ◽  
D. Burgarella ◽  
P. D. Hurley ◽  
...  
Keyword(s):  
Near Infrared ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Mass Star ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
The Impact ◽  
Attenuation Laws ◽  
Peculiar Galaxies

Aims. The Herschel Extragalactic Legacy Project (HELP) focuses on the data from ESA’s Herschel mission, which covered over 1300 deg2 and is preparing to publish a multi-wavelength catalogue of millions of objects. Our main goal is to find the best approach to simultaneously fitting spectral energy distributions (SEDs) of millions of galaxies across a wide redshift range to obtain homogeneous estimates of the main physical parameters of detected infrared (IR) galaxies. Methods. We perform SED fitting on the ultraviolet(UV)/near-infrared(NIR) to far-infrared(FIR) emission of 42 047 galaxies from the pilot HELP field: ELAIS N1. To do this we use the latest release of CIGALE, a galaxy SED fitting code relying on energy balance, to deliver the main physical parameters such as stellar mass, star formation rate, and dust luminosity. We implement additional quality criteria to the fits by calculating χ2 values for the stellar and dust part of the spectra independently. These criteria allow us to identify the best fits and to identify peculiar galaxies. We perform the SED fitting of ELAIS N1 galaxies by assuming three different dust attenuation laws separately allowing us to test the impact of the assumed law on estimated physical parameters. Results. We implemented two additional quality value checks for the SED fitting method based on stellar mass estimation and energy budget. This method allows us to identify possible objects with incorrect matching in the catalogue and peculiar galaxies; we found 351 possible candidates of lensed galaxies using two complementary χ2s criteria (stellar and infrared χ2s) and photometric redshifts calculated for the IR part of the spectrum only. We find that the attenuation law has an important impact on the stellar mass estimate (on average leading to disparities of a factor of two). We derive the relation between stellar mass estimates obtained by three different attenuation laws and we find the best recipe for our sample. We also make independent estimates of the total dust luminosity parameter from stellar emission by fitting the galaxies with and without IR data separately.

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 How to disentangle geometry and mass-loss rate from AGB-star spectral energy distributions

2020 ◽  
Vol 642 ◽  
pp. A142 ◽  
Author(s):  
J. Wiegert ◽  
M. A. T. Groenewegen ◽  
A. Jorissen ◽  
L. Decin ◽  
T. Danilovich
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Asymptotic Giant Branch ◽  
Spectral Energy ◽  
High Angular Resolution ◽  
Circumstellar Envelope ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
The Impact

Context. High-angular-resolution observations of asymptotic giant branch (AGB) stars often reveal non-spherical morphologies for the gas and dust envelopes. Aims. We aim to make a pilot study to quantify the impact of different geometries (spherically symmetric, spiral-shaped, and disc-shaped) of the dust component of AGB envelopes on spectral energy distributions (SEDs), mass estimates, and subsequent mass-loss rate (MLR) estimates. We also estimate the error made on the MLR if the SED is fitted by an inappropriate geometrical model. Methods. We use the three-dimensional Monte-Carlo-based radiative-transfer code RADMC-3D to simulate emission from dusty envelopes with different geometries (but fixed spatial extension). We compare these predictions with each other, and with the SED of the AGB star EP Aqr that we use as a benchmark since its envelope is disc-like and known to harbour spiral arms, as seen in CO. Results. The SEDs involving the most massive envelopes are those for which the different geometries have the largest impact, primarily on the silicate features at 10 and 18 μm. These different shapes originate from large differences in optical depths. Massive spirals and discs appear akin to black bodies. Optically thick edge-on spirals and discs (with dust masses of 10−4 and 10−5 M⊙) exhibit black-body SEDs that appear cooler than those from face-on structures and spheres of the same mass, while optically thick face-on distributions appear as warmer emission. We find that our more realistic models, combined spherical and spiral distributions, are 0.1 to 0.5 times less massive than spheres with similar SEDs. More extreme, less realistic scenarios give that spirals and discs are 0.01 to 0.05 times less massive than corresponding spheres. This means that adopting the wrong geometry for an AGB circumstellar envelope may result in a MLR that is incorrect by as much as one to two orders of magnitude when derived from SED fitting.

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 Spectral Energy Distributions, Ages, and Metallicities of Star Clusters in M33

2001 ◽  
Vol 122 (4) ◽  
pp. 1796-1806 ◽  
Author(s):  
Jun Ma ◽  
Xu Zhou ◽  
Xu Kong ◽  
Hong Wu ◽  
Jiansheng Chen ◽  
...  
Keyword(s):  
Star Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions
Sign in / Sign up

Export Citation Format

Share Document