Long-period variables in the Magellanic Clouds - Supergiants, AGB stars, supernova precursors, planetary nebula precursors, and enrichment of the interstellar medium

Wood, P. R.; Bessell, M. S.; Fox, Mark

doi:10.1086/161265

Cited by 293 publications

(267 citation statements)

References 0 publications

Supporting

Mentioning

252

Contrasting

Unclassified

Order By: Relevance

“…In consequence, despite its high luminosity -M K S = −9.55 mag, more typical of RSGs than AGB stars -we have to conclude that HV 838 is a very luminous AGB star. This is in agreement with its position in the period/luminosity diagram (Wood et al 1983) and the presence of a significant Li  6707 Å line (Smith et al 1995).…”

Section: Objects Of Particular Interestsupporting

confidence: 89%

“…In addition, Soszyñski et al (2009) observed an amplitude in I of 2.5 mag, too large for a RSG (Groenewegen et al 2009). HV 2572 is therefore a luminous AGB star, with M K S = −10.1 mag (above the upper M K S limit in the Wood et al 1983 luminosity-period diagram). Therefore, we have opted to classify it as M7.5 II-III.…”

Section: Objects Of Particular Interestmentioning

confidence: 90%

See 1 more Smart Citation

A new survey of cool supergiants in the Magellanic Clouds

González-Fernández

Dorda

Negueruela

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. In this study we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. Methods. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership in the clouds. Results. Around two hundred new red supergiants have been detected, hinting at a yet to be observed large population. Using nearand mid-infrared photometry we study the brightness distribution of these stars, the onset of mass-loss, and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid-and near-infrared photometry to improve the observational efficiency of similar programs to this.

show abstract

Section: Objects Of Particular Interestsupporting

confidence: 89%

Section: Objects Of Particular Interestmentioning

confidence: 90%

A new survey of cool supergiants in the Magellanic Clouds

González-Fernández

Dorda

Negueruela

et al. 2015

A&A

View full text Add to dashboard Cite

show abstract

“…3.3). We have thus as a first step investigated whether pulsating model atmospheres of Mira variables can provide a good fit to our RSG stars as well, although the stellar parameters, in particular mass and luminosity, are very different and variability amplitudes of RSGs are typically lower by a factor of 2−3 compared to Miras (Wood et al 1983). We used the recent CODEX model series by Ireland et al (2008Ireland et al ( , 2011 and, as an example, have found best-fit models to the data of V602 Car as shown in Fig.…”

Section: Pulsation Modelsmentioning

confidence: 99%

“…Currently, the mechanism of mass loss of RSG stars and semi-regular or irregular AGBs is not known in detail. Nevertheless, in the case of Mira-variable AGB stars (mass-loss rates of 10 −6 M /yr -10 −4 M /yr, Wood et al 1983Wood et al , 1992, this mechanism is better understood. The theoretical models that explain the Mira massloss process are based on pulsations that extend the atmospheres to radii where dust can form, and subsequently on radiative pressure on dust grains that drives the wind (e.g., Bladh et al 2013).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

What causes the large extensions of red supergiant atmospheres?

Arroyo-Torres

Wittkowski²,

Chiavassa

et al. 2015

A&A

Self Cite

108

View full text Add to dashboard Cite

Aims. This research has two main goals. First, we present the atmospheric structure and the fundamental parameters of three red supergiants (RSGs), increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. Methods. We carried out spectro-interferometric observations of the RSGs V602 Car, HD 95687, and HD 183589 in the near-infrared K-band (1.92−2.47 μm) with the VLTI/AMBER instrument at medium spectral resolution (R ∼ 1500). To categorize and comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3D convection, and new 1D self-excited pulsation models of RSGs. Results. Our near-infrared flux spectra of V602 Car, HD 95687, and HD 183589 are well reproduced by the PHOENIX model atmospheres. The continuum visibility values are consistent with a limb-darkened disk as predicted by the PHOENIX models, allowing us to determine the angular diameter and the fundamental parameters of our sources. Nonetheless, in the case of V602 Car and HD 95686, the PHOENIX model visibilities do not predict the large observed extensions of molecular layers, most remarkably in the CO bands. Likewise, the 3D convection models and the 1D pulsation models with typical parameters of RSGs lead to compact atmospheric structures as well, which are similar to the structure of the hydrostatic PHOENIX models. They can also not explain the observed decreases in the visibilities and thus the large atmospheric molecular extensions. The full sample of our RSGs indicates increasing observed atmospheric extensions with increasing luminosity and decreasing surface gravity, and no correlation with effective temperature or variability amplitude. Conclusions. The location of our RSG sources in the Hertzsprung-Russell diagram is confirmed to be consistent with the red limits of recent evolutionary tracks. The observed extensions of the atmospheric layers of our sample of RSGs are comparable to those of Mira stars. This phenomenon is not predicted by any of the considered model atmospheres including available 3D convection and new 1D pulsation models of RSGs. This confirms that neither convection nor pulsation alone can levitate the molecular atmospheres of RSGs. Our observed correlation of atmospheric extension with luminosity supports a scenario of radiative acceleration on Doppler-shifted molecular lines.

show abstract

Envelopes of red giant stars

Wannier

Cool Stars, Stellar Systems, and the Sun

View full text Add to dashboard Cite

Long-period variables in the Magellanic Clouds - Supergiants, AGB stars, supernova precursors, planetary nebula precursors, and enrichment of the interstellar medium

Cited by 293 publications

References 0 publications

A new survey of cool supergiants in the Magellanic Clouds

A new survey of cool supergiants in the Magellanic Clouds

What causes the large extensions of red supergiant atmospheres?

Envelopes of red giant stars

Contact Info

Product

Resources

About