scholarly journals ISO Observations of AGB Stars in the Small Magellanic Cloud

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.

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

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.

scholarly journals Dust Size Effect On IR Colors Of AGB Stars

2008 ◽  
Vol 4 (S252) ◽  
pp. 263-264
Author(s):  
Huan Wang ◽  
B. W. Jiang ◽  
R. Szczerba
Keyword(s):  
Size Effect ◽  
Loss Rate ◽  
Near Infrared ◽  
Mass Loss Rate ◽  
Mie Theory ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Agb Stars ◽  
Ir Sources ◽  
The Difference

AbstractWith the Mie theory and the radiative transfer model, we studied the effect of dust size on the infrared color indexes concerning special filters used in the space infrared missions and typical filters in the near-infrared, of AGB stars with typical oxygen-rich and carbon-rich dust shells. It is found the most affected bands are the near-infrared bands JHK and the Spitzer IRAC bands, meanwhile the wavebands with reference wavelength longer than 10 μm is little affected. The effect increases fast with the mass loss rate. We also discussed the potential to distinguish the O-rich and C-rich dusts, and the difference in IR colors between the AGB stars and other IR sources like YSOs and galaxies.

scholarly journals The Mass Loss Rate of SK 80 (07Iaf) in the Small Magellanic Cloud

1986 ◽  
Vol 116 ◽  
pp. 269-270
Author(s):  
A J Willis ◽  
I D Howarth ◽  
K Nandy ◽  
D H Morgan
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Optical Spectra ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Small Magellanic Cloud ◽  
Ob Stars

The star SK 80 in the SMC is classified as 07Iaf by Walborn (1976) who notes that it is the only confirmed Of star in that Galaxy known to date. A knowledge of the mass loss properties of OB stars in the Magellanic Clouds is of interest because of the recent evidence that such stars show reduced mass loss properties than their galactic counterparts (Hutchings 1980) and for Of stars because of the possible link between such stars and Pop I transition WNL stars (Conti 1976).We have secured HIRES IUE and optical spectra of SK 80 and have attempted to derive the mass loss rate from these data.

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

2020 ◽  
Vol 498 (3) ◽  
pp. 3283-3301 ◽  
Author(s):  
Giada Pastorelli ◽  
Paola Marigo ◽  
Léo Girardi ◽  
Bernhard Aringer ◽  
Yang Chen ◽  
...  
Keyword(s):  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Stellar Populations ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Asymptotic Giant Branch ◽  
Star Formation History ◽  
Spectral Energy ◽  
Agb Stars ◽  
The Third

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.

Mass‐Loss Rate and He/H Abundance of the Erupting Component in the Small Magellanic Cloud System HD 5980

1998 ◽  
Vol 499 (2) ◽  
pp. 889-897 ◽  
Author(s):  
G. Koenigsberger ◽  
M Pena ◽  
W. Schmutz ◽  
S. Ayala
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Magellanic Cloud ◽  
Cloud System ◽  
Small Magellanic Cloud

scholarly journals Are the silicate crystallinities of oxygen-rich evolved stars related to their mass loss rates?

2018 ◽  
Vol 14 (S343) ◽  
pp. 425-426
Author(s):  
Biwei Jiang ◽  
Jiaming Liu ◽  
Aigen Li
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Evolved Stars ◽  
Loss Rates

AbstractA sample of 28 oxygen-rich evolved stars is selected based on the presence of crystalline silicate emission features in their ISO/SWS spectra. The crystallinity, measured as the flux fraction of crystalline silicate features, is found not to be related to mass loss rate that is derived from fitting the spectral energy distribution.

The Spectral Energy Distribution and Mass‐Loss Rate of the A‐Type Supergiant Deneb

2002 ◽  
Vol 570 (1) ◽  
pp. 344-368 ◽  
Author(s):  
J. P. Aufdenberg ◽  
P. H. Hauschildt ◽  
E. Baron ◽  
T. E. Nordgren ◽  
A. W. Burnley ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Spectral Energy

scholarly journals 2-D Radiation Transfer Model of Non-Spherically Symmetric Dust Shell in Proto-Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 139-140
Author(s):  
Kate Y. L. Su ◽  
Kevin Volk ◽  
Sun Kwok
Keyword(s):  
Radiation Transfer ◽  
Spectral Energy Distribution ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Radiative Transfer Model ◽  
Spectral Energy ◽  
Transfer Model ◽  
Agb Stars ◽  
Dust Shell ◽  
Radiation Transfer Model

Resent high-resolution optical imaging has directly revealed reflection nebulosity around proto-planetary nebulae (PPNs), the transition objects between asymptotic giant branch (AGB) stars and planetary nebulae (Sahai et al. 1998, Su et al. 1998, Ueta et al. 2000, Su et al. 2001). The existence of bipolar nebulae observed in the PPN phase suggests the presence of asymmetry in the AGB circumstellar dust shell. In order to model these objects, a self-consistent radiation transfer model is necessary. As a first attempt, we construct an approximate two-dimensional dust radiative transfer model to simultaneously fit the spectral energy distribution (SED) and images of a centrally-heated dust envelope.

scholarly journals UVIT-HST-Gaia-VISTA study of KRON 3 in the Small Magellanic Cloud: A cluster with an extended red clump in UV

2021 ◽  
Author(s):  
P K Nayak ◽  
A Subramaniam ◽  
S Subramanian ◽  
S Sahu ◽  
C Mondal ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Variable Mass ◽  
Intrinsic Property ◽  
Small Variation ◽  
Magellanic Cloud ◽  
Spectral Energy ◽  
Small Range ◽  
Small Magellanic Cloud ◽  
Red Clump

Abstract We have demonstrated the advantage of combining multi-wavelength observations, from the ultraviolet (UV) to near-infrared, to study Kron 3, a massive star cluster in the Small Magellanic Cloud. We have estimated the radius of the cluster Kron 3 to be 2${_{.}^{\prime}}$0 and for the first time, we report the identification of NUV-bright red clump (RC) stars and the extension of the RC in colour and magnitude in the NUV versus (NUV−optical) colour-magnitude diagram (CMD). We found that extension of the RC is an intrinsic property of the cluster and it is not due to contamination of field stars or differential reddening across the field. We studied the spectral energy distribution of the RC stars, and estimated a small range in temperature ∼5000–5500 K, luminosity ∼60–90 L⊙ and radius ∼8.0–11.0 R⊙ supporting their RC nature. The range of UV magnitudes amongst the RC stars (∼23.3 to 24.8 mag) is likely caused by the combined effects of variable mass loss, variation in initial helium abundance (Yini = 0.23 to 0.28), and a small variation in age (6.5-7.5 Gyr) and metallicity ([Fe/H] = −1.5 to −1.3). Spectroscopic follow-up observations of RC stars in Kron 3 are necessary to confirm the cause of the extended RC.

Calibrating TP-AGB stellar models and chemical yields through resolved stellar populations in the Small Magellanic Cloud

2018 ◽  
Vol 14 (S343) ◽  
pp. 269-272
Author(s):  
Giada Pastorelli ◽  
Paola Marigo ◽  
Léo Girardi ◽  
Keyword(s):  
Mass Loss ◽  
Magellanic Cloud ◽  
Star Formation History ◽  
Agb Stars ◽  
Population Synthesis ◽  
Small Magellanic Cloud ◽  
Luminosity Functions ◽  
Formation History ◽  
Best Fitting ◽  
The Impact

AbstractMost of the physical processes driving the TP-AGB evolution are not yet fully understood and they need to be modelled with parameterised descriptions. We present the results of the on-going calibration of the TP-AGB phase based on a complete sample of AGB stars in the Small Magellanic Cloud (SAGE-SMC survey). We computed large grids of TP-AGB models with several combinations of third dredge-up and mass-loss prescriptions with the COLIBRI code. The SMC AGB population is modelled with the population synthesis code TRILEGAL according to the space-resolved star formation history derived with the deep photometry from the VISTA survey of the Magellanic Clouds. We put quantitative constraints on the efficiencies of the third dredge-up and mass loss by requiring the models to reproduce the star counts and the luminosity functions of the observed Oxygen-, Carbon-rich and extreme-AGB stars and we investigate the impact of the best-fitting prescriptions on the chemical yields.

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