Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud

ABSTRACT Reliable models of the thermally pulsing asymptotic giant branch (TP-AGB) phase are of critical importance across astrophysics, including our interpretation of the spectral energy distribution of galaxies, cosmic dust production, and enrichment of the interstellar medium. With the aim of improving sets of stellar isochrones that include a detailed description of the TP-AGB phase, we extend our recent calibration of the AGB population in the Small Magellanic Cloud (SMC) to the more metal-rich Large Magellanic Cloud (LMC). We model the LMC stellar populations with the trilegal code, using the spatially resolved star formation history derived from the VISTA survey. We characterize the efficiency of the third dredge-up by matching the star counts and the Ks-band luminosity functions of the AGB stars identified in the LMC. In line with previous findings, we confirm that, compared to the SMC, the third dredge-up in AGB stars of the LMC is somewhat less efficient, as a consequence of the higher metallicity. The predicted range of initial mass of C-rich stars is between Mi ≈ 1.7 and 3 M⊙ at Zi = 0.008. We show how the inclusion of new opacity data in the carbon star spectra will improve the performance of our models. We discuss the predicted lifetimes, integrated luminosities, and mass-loss rate distributions of the calibrated models. The results of our calibration are included in updated stellar isochrones publicly available.

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Luminosities and mass-loss rates of Local Group AGB stars and red supergiants

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731089 ◽

2018 ◽

Vol 609 ◽

pp. A114 ◽

Cited By ~ 24

Author(s):

M. A. T. Groenewegen ◽

G. C. Sloan

Keyword(s):

Radiative Transfer ◽

Mass Loss ◽

Local Group ◽

Mass Loss Rate ◽

Large Fraction ◽

Large Magellanic Cloud ◽

Asymptotic Giant Branch ◽

Spectral Energy ◽

Agb Stars ◽

Evolved Stars

Context. Mass loss is one of the fundamental properties of asymptotic giant branch (AGB) stars, and through the enrichment of the interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking. Aims. We aim to investigate mass loss and luminosity in a large sample of evolved stars in several Local Group galaxies with a variety of metalliticies and star-formation histories: the Small and Large Magellanic Cloud, and the Fornax, Carina, and Sculptor dwarf spheroidal galaxies (dSphs). Methods. Dust radiative transfer models are presented for 225 carbon stars and 171 oxygen-rich evolved stars in several Local Group galaxies for which spectra from the Infrared Spectrograph on Spitzer are available. The spectra are complemented with available optical and infrared photometry to construct spectral energy distributions. A minimization procedure was used to determine luminosity and mass-loss rate (MLR). Pulsation periods were derived for a large fraction of the sample based on a re-analysis of existing data. Results. New deep K-band photometry from the VMC survey and multi-epoch data from IRAC (at 4.5 μm) and AllWISE and NEOWISE have allowed us to derive pulsation periods longer than 1000 days for some of the most heavily obscured and reddened objects. We derive (dust) MLRs and luminosities for the entire sample. The estimated MLRs can differ significantly from estimates for the same objects in the literature due to differences in adopted optical constants (up to factors of several) and details in the radiative transfer modelling. Updated parameters for the super-AGB candidate MSX SMC 055 (IRAS 00483−7347) are presented. Its current mass is estimated to be 8.5 ± 1.6 M⊙, suggesting an initial mass well above 8 M⊙ in agreement with estimates based on its large Rubidium abundance. Using synthetic photometry, we present and discuss colour-colour and colour-magnitude diagrams which can be expected from the James Webb Space Telescope.

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Comparative Studies of the Dust around Red Supergiant and Oxygen-Rich Asymptotic Giant Branch Stars in the Local Universe

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316005883 ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 470-471

Author(s):

B. A. Sargent ◽

S. Srinivasan ◽

A. Speck ◽

K. Volk ◽

F. Kemper ◽

...

Keyword(s):

Globular Clusters ◽

Milky Way ◽

Mass Loss Rate ◽

Dust Emission ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Asymptotic Giant Branch ◽

Asymptotic Giant Branch Stars ◽

Agb Stars ◽

Circumstellar Environments

AbstractWe analyze the dust emission features seen in Spitzer Space Telescope Infrared Spectrograph (IRS) spectra of red supergiant (RSG) and oxygen-rich asymptotic giant branch (AGB) stars in the Large Magellanic Cloud and Small Magellanic Cloud galaxies and in various Milky Way globular clusters. The spectra come from the Spitzer Legacy program SAGE-Spectroscopy (PI: F. Kemper), the Spitzer program SMC-Spec (PI: G. Sloan), and other archival Spitzer-IRS programs. The broad 10 and 20 micron emission features attributed to amorphous dust of silicate composition seen in the spectra show evidence for systematic differences in the centroid of both emission features between O-rich AGB and RSG populations. Radiative transfer modeling using the GRAMS grid of models of AGB and RSG stars suggests that the centroid differences are due to differences in dust properties. We investigate differences in dust composition, size, shape, etc that might be responsible for these spectral differences. We explore how these differences may arise from the different circumstellar environments around RSG and O-rich AGB stars and assess effects of varying metallicity (LMC versus SMC versus Milky Way globular cluster) and other properties (mass-loss rate, luminosity, etc.) on the dust originating from these stars. BAS acknowledges funding from NASA ADAP grant NNX13AD54G.

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Red supergiant stars in the Large Magellanic Cloud

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832833 ◽

2018 ◽

Vol 616 ◽

pp. A175 ◽

Cited By ~ 10

Author(s):

Ming Yang ◽

Alceste Z. Bonanos ◽

Bi-Wei Jiang ◽

Jian Gao ◽

Meng-Yao Xue ◽

...

Keyword(s):

Time Series ◽

Time Series Data ◽

Spectral Energy Distribution ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Asymptotic Giant Branch ◽

Series Data ◽

Spectral Energy ◽

Evolutionary Stage ◽

Evolutionary Models

The characteristics of infrared properties and mid-infrared (MIR) variability of red supergiant (RSG) stars in the Large Magellanic Cloud (LMC) are analyzed based on 12 bands of near-infrared (NIR) to MIR co-added data from 2MASS, Spitzer and WISE, and ∼6.6 yr of MIR time-series data collected by the ALLWISE and NEOWISE-R projects. 773 RSGs candidates were compiled from the literature and verified by using the color-magnitude diagram (CMD), spectral energy distribution (SED) and MIR variability. About 15% of valid targets in the IRAC1–IRAC2/IRAC2–IRAC3 diagram may show polycyclic aromatic hydrocarbon (PAH) emission. We show that arbitrary dereddening Q parameters related to the IRAC4, S9W, WISE3, WISE4, and MIPS24 bands could be constructed based on a precise measurement of MIR interstellar extinction law. Several peculiar outliers in our sample are discussed, in which one outlier might be a RSG right before the explosion or an extreme asymptotic giant branch (AGB) star in the very late evolutionary stage based on the MIR spectrum and photometry. There are 744 identified RSGs in the final sample having both the WISE1- and WISE2-band time-series data. The results show that the MIR variability is increasing along with the increasing of brightness. There is a relatively tight correlation between the MIR variability, mass loss rate (MLR; in terms of KS–WISE3 color), and the warm dust or continuum (in terms of WISE4 magnitude/flux), where the MIR variability is evident for the targets with KS–WISE3 > 1.0 mag and WISE4 < 6.5 mag, while the rest of the targets show much smaller MIR variability. The MIR variability is also correlated with the MLR for which targets with larger variability also show larger MLR with an approximate upper limit of −6.1 M⊙ yr−1. Both the variability and the luminosity may be important for the MLR since the WISE4-band flux is increasing exponentially along with the degeneracy of luminosity and variability. The identified RSG sample has been compared with the theoretical evolutionary models and shown that the discrepancy between observation and evolutionary models can be mitigated by considering both variability and extinction.

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ISO Observations of AGB Stars in the Small Magellanic Cloud

Symposium - International Astronomical Union ◽

10.1017/s0074180900203963 ◽

1999 ◽

Vol 192 ◽

pp. 95-99

Author(s):

J.A.D.L. Blommaert ◽

M.A.T. Groenewegen ◽

M. R. Cioni ◽

H. J. Habing ◽

J.Th. van Loon ◽

...

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Spectral Energy Distribution ◽

Magellanic Cloud ◽

Radiative Transfer Model ◽

Spectral Energy ◽

Transfer Model ◽

Agb Stars ◽

Small Magellanic Cloud

We used ISOCAM and ISOPHOT to observe the spectral energy distribution between 3.6 and 60 μm of AGB stars in the Small Magellanic Cloud detected by IRAS. CAM-CVF spectra are made which enable us to establish the carbon- or oxygen-rich nature of the stars.We are in the process of analysing this data using a radiative transfer model. This will provide us with accurate determinations of luminosity and mass loss rate. Combining the results on the SMC, LMC and Galaxy we hope to address the open question of the metallicity dependencies of the mass loss rate. This in turn is important in the ejection of matter by AGB stars into the interstellar medium.

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Asymptotic Giant Branch Stars in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900200855 ◽

1991 ◽

Vol 148 ◽

pp. 363-364

Author(s):

Neill Reid ◽

J. R. Mould

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Asymptotic Giant Branch ◽

Red Giants ◽

Asymptotic Giant Branch Stars ◽

Agb Stars ◽

Satellite Systems ◽

Luminosity Functions ◽

Theoretical Predictions

Since the pioneering objective prism surveys by Westerlund (1960) and Blanco et al. (1980), the Magellanic Clouds have proved a fruitful site for exploring the evolution of AGB stars. We have used photometric techniques to extend the prism C-star surveys to M- and S-type AGB stars, constructing luminosity functions and obtaining spectra of individual stars for comparison with theoretical predictions. We have concentrated on the Large Magellanic Cloud (LMC), but we have recently obtained observations of luminous red giants in a region of the Small Magellanic Cloud (SMC). In this paper we compare the results from these studies of the two satellite systems.

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Ammonia in circumstellar environment of V Cyg

Advances in Astronomy and Space Physics ◽

10.17721/2227-1481.10.7-11 ◽

2020 ◽

Vol 10 (1) ◽

pp. 7-11

Author(s):

B. Etmański ◽

M. Schmidt ◽

R. Szczerba

Keyword(s):

Background Radiation ◽

Spectral Energy Distribution ◽

Careful Analysis ◽

Asymptotic Giant Branch ◽

Spectral Energy ◽

Agb Stars ◽

Circumstellar Envelopes ◽

Theoretical Predictions ◽

Red Supergiants ◽

Molecular Lines

The HIFI instrument on board of the Herschel Space Observatory (HSO) has been very successful in detecting molecular lines from the circumstellar envelopes around evolved stars, like massive red supergiants, Asymptotic Giant Branch (AGB) and post-AGB stars, as well as the planetary nebulae. Among others, ammonia have been found in the circumstellar envelopes of C-rich AGB stars in amounts that significantly exceeded the theoretical predictions for C-rich stars. Few scenarios have been proposed to resolve this problem: formation of ammonia behind the shock front and photochemical processes in the inner part of the envelope partly transparent to UV background radiation due to the clumpy structure of the gas and formation of ammonia on dust grains. Careful analysis of observations may help to put the constraints on one or another mechanism of ammonia formation. Here, we present results of the non-LTE radiative transfer modeling of ammonia transitions including the crucial process of radiative pumping via the v2=1 vibrational band (at ∼10 μm) for V Cyg. Only the ground-based ammonia transition NH3 J = 10-00 at 572.5 GHz has been observed by HIFI. Therefore, to determine the abundance of ammonia we estimate the photodissociation radius of NH3 using chemical model of the envelope consistent with the dust grain properties concluded from the spectral energy distribution.

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Two Different Stellar Populations in the Large Magellanic Cloud?

Symposium - International Astronomical Union ◽

10.1017/s0074180900109325 ◽

1995 ◽

Vol 164 ◽

pp. 415-415

Author(s):

JU. Frantsman ◽

I. Shmeld

Keyword(s):

Neutron Capture ◽

Stellar Populations ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Agb Stars ◽

Helium Burning ◽

Stellar Interior ◽

Processed Material ◽

Evolutionary Scheme ◽

Simple Picture

The evolution of stars on the AGB has been explained as episodic helium burning and neutron capture nucleosynthesis in the stellar interior, followed by the mixing of a portion of the processed material into the envelope of a star. The simple stellar evolutionary scheme M–MS–S–SC–N had been accepted. However in recent years extensive observations of AGB stars have shown that evolution of the AGB is more complicated than painted in such a simple picture.

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The mass-loss, expansion velocities, and dust production rates of carbon stars in the Magellanic Clouds

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1255 ◽

2019 ◽

Vol 487 (1) ◽

pp. 502-521 ◽

Cited By ~ 10

Author(s):

Ambra Nanni ◽

Martin A T Groenewegen ◽

Bernhard Aringer ◽

Stefano Rubele ◽

Alessandro Bressan ◽

...

Keyword(s):

Mass Loss ◽

Mass Loss Rate ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Spectral Energy ◽

Carbon Stars ◽

Dust Production ◽

Production Rates ◽

Total Dust

ABSTRACT The properties of carbon stars in the Magellanic Clouds (MCs) and their total dust production rates are predicted by fitting their spectral energy distributions (SED) over pre-computed grids of spectra reprocessed by dust. The grids are calculated as a function of the stellar parameters by consistently following the growth for several dust species in their circumstellar envelopes, coupled with a stationary wind. Dust radiative transfer is computed taking as input the results of the dust growth calculations. The optical constants for amorphous carbon are selected in order to reproduce different observations in the infrared and optical bands of Gaia Data Release 2. We find a tail of extreme mass-losing carbon stars in the Large Magellanic Cloud (LMC) with low gas-to-dust ratios that is not present in the Small Magellanic Cloud (SMC). Typical gas-to-dust ratios are around 700 for the extreme stars, but they can be down to ∼160–200 and ∼100 for a few sources in the SMC and in the LMC, respectively. The total dust production rate for the carbon star population is ∼1.77 ± 0.45 × 10−5 M⊙ yr−1, for the LMC, and ∼2.52 ± 0.96 × 10−6 M⊙ yr−1, for the SMC. The extreme carbon stars observed with the Atacama Large Millimeter Array and their wind speed are studied in detail. For the most dust-obscured star in this sample the estimated mass-loss rate is ∼6.3 × 10−5 M⊙ yr−1. The grids of spectra are available at:1 and included in the SED-fitting python package for fitting evolved stars.2

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The VMC Survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937271 ◽

2020 ◽

Vol 636 ◽

pp. A48

Author(s):

M. A. T. Groenewegen ◽

A. Nanni ◽

M.-R. L. Cioni ◽

L. Girardi ◽

R. de Grijs ◽

...

Keyword(s):

Mass Loss ◽

Mass Loss Rate ◽

Magellanic Clouds ◽

Asymptotic Giant Branch ◽

Young Stellar Objects ◽

Spectral Energy ◽

Pulsation Period ◽

Agb Stars ◽

Be Stars ◽

Large Variability

Context. Variability is a key property of stars on the asymptotic giant branch (AGB). Their pulsation period is related to the luminosity and mass-loss rate of the star. Long-period variables (LPVs) and Mira variables are the most prominent of all types of variability of evolved stars. The reddest, most obscured AGB stars are too faint in the optical and have eluded large variability surveys. Aims. We obtained a sample of LPVs by analysing K-band light curves (LCs) of a large number of sources in the direction of the Magellanic Clouds with the colours expected for red AGB stars ((J − K) > 3 mag or equivalent in other colour combinations). Methods. Selection criteria were derived based on colour-colour and colour-magnitude diagrams from the combination of the VISTA Magellanic Cloud (VMC) survey, Spitzer IRAC and AllWISE data. After eliminating LPVs with known periods shorter than 450 days, a sample of 1299 candidate obscured AGB stars was selected. K-band LCs were constructed by combining the epoch photometry available in the VMC survey with literature data, were analysed for variability, and fitted with a single period sine curve to derive mean magnitudes, amplitudes, and periods. A subset of 254 stars are either new variables, known variables where the period we find is better determined than the literature value, or variables with periods longer than 1000 days. The spectral energy distributions (SEDs) of these stars were fitted to a large number of templates. For this purpose the SEDs and Spitzer IRS spectra of some non-AGB stars (Be stars, HII regions and young stellar objects – YSOs) were also fitted to have templates of the most likely contaminants in the sample. Results. A sample of 217 likely LPVs is found. Thirty-four stars have periods longer than 1000 days, although some of them have alternative shorter periods. The longest period of a known Mira in the Magellanic Clouds from Optical Gravitational Lensing Experiment data (with P = 1810 d) is derived to have a period of 2075 d based on its infrared LC. Two stars are found to have longer periods, but both have lower luminosities and smaller pulsation amplitudes than expected for Miras. Mass-loss rates and luminosities are estimated from the template fitting. Period-luminosity relations are presented for carbon (C-) and oxygen (O-) rich Miras that appear to be extensions of relations derived in the literature for shorter periods. The fit for the C stars is particularly well defined (with 182 objects) and reads Mbol = (−2.27 ± 0.20) ⋅ log P + (1.45 ± 0.54) mag with an rms of 0.41 mag. Thirty-four stars show pulsation properties typical of Miras while the SEDs indicate that they are not. Overall, the results of the LC fitting are presented for over 200 stars that are associated with YSOs.

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Long-term evolution of AGB wind envelopes: Insights from hydrodynamical models

Symposium - International Astronomical Union ◽

10.1017/s0074180900203306 ◽

1999 ◽

Vol 191 ◽

pp. 379-388

Author(s):

M. Steffen ◽

D. Schönberner ◽

R. Szczerba

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Alternative Mechanism ◽

Agb Stars ◽

Hydrodynamical Simulations ◽

Thermal Pulses

Up to now, hydrodynamical models of dust-driven AGB winds do not generally take into account the ‘long-term’ changes of the stellar parameters (on stellar evolution time scales of 103 to 105 yrs), although it is well known that the luminosity and (very likely) the mass loss rate undergo significant variations when so called ‘thermal pulses’ occur on the upper AGB. In this review we demonstrate that time-dependent radiation hydrodynamics calculations are needed to understand the formation, structure, and spectral energy distribution of detached dust shells detected by IRAS and ISO. Combined with appropriate models, these observations can reveal part of the previous mass loss history on the AGB and allow an empirical check of presently adopted mass loss laws.Based on insights from hydrodynamical simulations, we discuss the two competing scenarios that have been put forward to explain the origin of the very thin molecular shells recently discovered around some carbon stars. We find that the signature of a short mass loss ‘eruption’ broadens quickly with time due to the related velocity gradient across the shell. Hence, this scenario is not considered a likely explanation of detached CO shells. On the other hand, the alternative mechanism, interaction of winds, is shown to be capable of producing very thin shells of greatly enhanced gas density in the dusty outflows from AGB stars by sweeping up matter at the interface between both type of winds.

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