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

Wiegert, J.; Groenewegen, M. A. T.; Jorissen, A.; Decin, L.; Danilovich, T.

doi:10.1051/0004-6361/202038029

Cited by 7 publications

(3 citation statements)

References 74 publications

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“…´-10 6 M e yr −1 , similar to values previously derived using DUSTY modeling when accounting for the different assumptions for the distance (Bogdanov & Taranova 2001). 9 These mass loss rates, however, should be used with caution because incorrect model geometry can have a considerable impact on the derived mass loss rates (Wiegert et al 2020). Additionally, the system's outburst(s) may result in more-significant episodic mass loss.…”

Section: D Radiative Transfer Modelingmentioning

confidence: 99%

A Multiwavelength Study of the Symbiotic Mira HM Sge with SOFIA and HST

Goldman,

Sankrit,

Montiel

et al. 2024

ApJ

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We have targeted the dusty symbiotic Mira system HM Sge with four instruments from the IR to the UV. We have used these observations along with archival observations to study how the system has been evolving after its 1975 nova-like outburst. We have detected rovibrational water emission in a symbiotic system for the first time using new EXES high-spectral-resolution infrared spectroscopy. The features, detected in emission, have velocities consistent with the systemic velocity but do not show any clear evidence of high-velocity outflows. Mid-infrared photometry and grism spectroscopy show that the oxygen-rich asymptotic giant branch dust and dust output have shown little to no change over the past 39 years. In the optical/UV, we detect three main [N ii] nebular features that were detected 22 years ago. Two of these features show a small amount of movement, corresponding to average outflows speeds of 38 and 78 km s−1 since they were previously observed; some previously detected [N ii] features are no longer visible. New UV spectroscopy has shown that the nebular environment continues to steadily relax after the system’s 1975 outburst. The data suggest, however, that the temperature of the hot component has increased from 200,000 K in 1989 to greater than 250,000 K now. Our new and archival observations suggest that the evolution of the system after its outburst is swift with little to no major changes after a period of a couple of years.

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Section: D Radiative Transfer Modelingmentioning

confidence: 99%

A Multiwavelength Study of the Symbiotic Mira HM Sge with SOFIA and HST

Goldman,

Sankrit,

Montiel

et al. 2024

ApJ

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“…This opens up the question of an alternative, non-isotropic, dust density distribution for the DE sources as, for instance, suggested by Decin et al (2019) for evolved OH/IR stars. This can be analysed along the lines of Wiegert et al (2020), but it would lead too far to test this out in detail in this paper. The conclusion for now is that there is no obvious way to produce the amount of emission we see with significantly less dust, and hence increase the R gd .…”

Section: Objects With Detached Dust Csesmentioning

confidence: 99%

CO line observations of OH/IR stars in the inner Galactic Bulge: Characteristics of stars at the tip of the AGB

Olofsson

Khouri

Sargent

et al. 2022

A&A

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Context. OH/IR stars are examples of late stellar evolution on the asymptotic giant branch (AGB), and they are, as such, important objects to study. They are also excellent probes of stellar populations, in particular in regions of high interstellar extinction such as the central regions of our Galaxy. Aims. Our goal is to characterise the stellar and circumstellar properties of high-mass-loss-rate OH/IR stars in the inner Galactic Bulge using the Atacama Large Millimeter/submillimeter Interferometer (ALMA). Methods. Rotational lines of 12 CO and 13 CO, as well as a millimetre-wave continuum, have been observed for a sample of 22 OH/IR stars in directions within 2 • of the Galactic Centre. Photometry data (≈ 1−30 µm) have been gathered from the literature to construct spectral energy distributions (SEDs) and to determine pulsational variability. Radiative transfer models have been used to interpret the line and photometry data. Results. All stars in the sample were detected in at least one CO line, and eight objects were detected in 324 GHz continuum. Based on luminosity criteria, the sample is divided into 17 objects that most likely lie within the inner Galactic Bulge, and five objects that are most likely foreground objects. The median luminosity of the inner-Galactic-Bulge sub-sample, 5600 L , corresponds to an initial mass in the range 1.2 − 1.6 M , indicating that these inner-Galactic-Bulge OH/IR stars descend from solar-type stars. The objects in this sub-sample are further divided into two classes based on their SED characteristics: Eleven objects have SEDs that are well matched by models invoking dust envelopes extending from a few stellar radii and outwards, while six objects are better modelled as having detached dust envelopes with inner radii in the range 200 − 600 au and warmer central stars. The former objects have periodic variability, while the latter objects are predominantly non-periodic. The median gas-mass-loss rate, gas terminal expansion velocity, gas-to-dust mass ratio, and circumstellar 12 CO/ 13 CO abundance ratio have been estimated to be 2×10 −5 M yr −1 , 18 km s −1 , 200 (excluding the sources with detached dust envelopes, which show markedly lower gas-to-dust ratios), and 5, respectively, for the inner-Galactic-Bulge sub-sample. All line brightness distributions are resolved at an angular scale of ≈ 0 . 15, but only two objects show a structure in their circumstellar envelopes at our resolution and sensitivity. In both cases, this structure takes the form of a cavity and a bipolar morphology. Conclusions. The inner-Galactic-Bulge sub-sample consists of high mass-loss-rate stars that descend from solar-type progenitors and that lie near the tip of the AGB. Some of the sample stars may have recently ceased mass loss and, hence, have begun to evolve beyond the AGB, as evidenced by a change in circumstellar characteristics and indications of warmer central stars. The inferred very low stellar 12 C/ 13 C isotope ratios are indicative of CNO-cycle nuclear processing, and they are most like...

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“…The investigations of AGB stars by several authors have led to a better understanding of this important phase of stellar evolution (e.g., Habing 1996;Lançon et al 1999;Piovan et al 2003;Herwig 2005;Woitke 2006; Karakas & Lattanzio 2007;Poelarends et al 2008;Ramstedt et al 2008;Weiss & Ferguson 2009;Karakas 2010;Ventura & Marigo 2010;Ventura et al 2012;Di Criscienzo et al 2013;García-Hernández et al 2013;Girardi et al 2013;Placco et al 2013;Kalirai et al 2014;Cristallo et al 2015;Battino et al 2016;Goldman et al 2017;Brunner et al 2019;Goldman et al 2019;McDonald & Trabucchi 2019;Girardi et al 2020;Pastorelli et al 2020;Wiegert et al 2020). However, the overall impact of TP-AGB 4 stars on stellar populations of galaxies is not well understood, and has been a matter of debate during the last fifteen years (e.g., Marigo et al 2010;Marigo 2015).…”

Section: Introductionmentioning

confidence: 99%

On the Thermally Pulsing Asymptotic Giant Branch Contribution to the Light of Nearby Disk Galaxies

Martínez-García,

Bruzual,

González-Lópezlira

et al. 2020

Preprint

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The study of the luminosity contribution from TP-AGB stars to the stellar populations of galaxies is crucial to determine their physical parameters (e.g., stellar mass and age). We use a sample of 84 nearby disk galaxies to explore diverse stellar population synthesis models with different luminosity contributions from TP-AGB stars. We fit the models to optical and NIR photometry, on a pixel by pixel basis. The statistics of the fits show a preference for a low luminosity contribution (i.e., high mass-to-light ratio in the NIR) from TP-AGB stars. Nevertheless, for 30-40% of the pixels in our sample a high luminosity contribution (hence low mass-to-light ratio in the NIR) from TP-AGB stars is favored. According to our findings, the mean TP-AGB star luminosity contribution in nearby disk galaxies may vary with Hubble type. This may be a consequence of the variation of the TP-AGB mass-loss rate with metallicity, if metal-poor stars begin losing mass earlier than metal-rich stars, because of a pre-dust wind that precedes the dust-driven wind.

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

Cited by 7 publications

References 74 publications

A Multiwavelength Study of the Symbiotic Mira HM Sge with SOFIA and HST

A Multiwavelength Study of the Symbiotic Mira HM Sge with SOFIA and HST

CO line observations of OH/IR stars in the inner Galactic Bulge: Characteristics of stars at the tip of the AGB

On the Thermally Pulsing Asymptotic Giant Branch Contribution to the Light of Nearby Disk Galaxies

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