DUST IS FORMING ALONG THE RED GIANT BRANCH OF 47 Tuc

Origlia, L.; Rood, Robert T.; Fabbri, S.; Ferraro, F. R.; Pecci, F. Fusi; Rich, R. Michael; Dalessandro, E.

doi:10.1088/0004-637x/718/1/522

Cited by 31 publications

(37 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…as much as 2.5 mag) than the RGB tip, as already suggested by Origlia et al (2010) based on evidence for "historic" mass loss from dust emission in 47 Tuc.…”

Section: Discussionsupporting

confidence: 66%

See 1 more Smart Citation

Modelling chromospheric line profiles as diagnostics of velocity fields inω Centauri red giant stars

Vieytes

Mauas

Cacciari

et al. 2010

A&A

View full text Add to dashboard Cite

Context. Mass loss of ∼0.1−0.3 M from Population II red giant stars (RGB) is a requirement of stellar evolution theory in order to account for several observational evidences in globular clusters. Aims. The aim of this study is to detect the presence of outward velocity fields, which are indicative of mass outflow, in six luminous red giant stars of the stellar cluster ω Cen. Methods. We compare synthetic line profiles computed using relevant model chromospheres to observed profiles of the Hα and Ca II K lines. The spectra were taken with UVES (R = 45 000) and the stars were selected so that three of them belong to the metalrich population and three to the metal-poor population, and sample as far down as 1 to 2.5 mag fainter than the respective RGB tips. Results. We do indeed reveal the presence of low-velocity outward motions in four of our six targets, without any apparent correlation with astrophysical parameters.Conclusions. This provides direct evidence that outward velocity fields and mass motions exist in RGB stars as much as 2.5 mag fainter than the tip. On the assumption that the mass outflow may eventually lead to mass loss from the star, we estimate mass-loss rates of some 10 −9 −10 −10 M yr −1 that are compatible with the stellar evolution requirements. These rates seem to be correlated with luminosity rather than metallicity.

show abstract

“…as much as 2.5 mag) than the RGB tip, as already suggested by Origlia et al (2010) based on evidence for "historic" mass loss from dust emission in 47 Tuc.…”

Section: Discussionsupporting

confidence: 66%

“…These conclusions, however, were revised by Origlia et al (2010) in 47 Tuc where the use of a better dust indicator allowed them to detect dust at fainter magnitudes along the RGB.…”

Section: Introductionmentioning

confidence: 99%

Modelling chromospheric line profiles as diagnostics of velocity fields inω Centauri red giant stars

Vieytes

Mauas

Cacciari

et al. 2010

A&A

View full text Add to dashboard Cite

show abstract

“…2 and 3. In addition, in a few suspect cases we performed the same procedure using HST images in the F814W band, as already done in Origlia et al (2010). This provides the most solid evidence that the IR excess is not due to blends.…”

Section: Appendix A: Impact Of Crowding and Photometric Errorsmentioning

confidence: 94%

“…Indeed, in relatively warm and low luminosity giants, like lowmass RGB stars, the fractional contribution of warm, optically thin dust emission from a CS envelope is not negligible in the 3-5 μm spectral range. Hence, as detailed in Origlia et al (2010), a combination of near-and mid-IR colors like (K − 5.8) and (K − 8), is more effective in tracing the possible presence of small amounts of warm dust around low-mass RGB stars than the pure Spitzer-IRAC (3.6−8) color, which is mostly sensitive to detect relatively large amount of cold dust around the coolest (hence the most luminous) giants. Since the 8 μm IRAC band is the most sensitive to warm dust and the least contaminated by photospheric emission, we use the (K − 8) 0 color as a primary diagnostic to select stars with possible dust excess.…”

Section: Color-magnitude and Color-color Diagramsmentioning

confidence: 99%

“…We combined Spitzer-IRAC photometry with high-resolution near-IR photometry from the ground and used (K-IRAC) colors as diagnostics of possible circumstellar dust excess. Results for 47 Tuc have been published in Origlia et al (2007Origlia et al ( , 2010, while those for the complex stellar system ω Cen will be presented in a forthcoming paper.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An empirical mass-loss law for Population II giants from theSpitzer-IRAC survey of Galactic globular clusters

Origlia

Ferraro

Fabbri

et al. 2014

A&A

View full text Add to dashboard Cite

Aims. The main aim of the present work is to derive an empirical mass-loss (ML) law for Population II stars in first and second ascent red giant branches. Methods. We used the Spitzer InfraRed Array Camera (IRAC) photometry obtained in the 3.6-8 μm range of a carefully chosen sample of 15 Galactic globular clusters spanning the entire metallicity range and sampling the vast zoology of horizontal branch (HB) morphologies. We complemented the IRAC photometry with near-infrared data to build suitable color-magnitude and color-color diagrams and identify mass-losing giant stars. Results. We find that while the majority of stars show colors typical of cool giants, some stars show an excess of mid-infrared light that is larger than expected from their photospheric emission and that is plausibly due to dust formation in mass flowing from them. For these stars, we estimate dust and total (gas + dust) ML rates and timescales. We finally calibrate an empirical ML law for Population II red and asymptotic giant branch stars with varying metallicity. We find that at a given red giant branch luminosity only a fraction of the stars are losing mass. From this, we conclude that ML is episodic and is active only a fraction of the time, which we define as the duty cycle. The fraction of mass-losing stars increases by increasing the stellar luminosity and metallicity. The ML rate, as estimated from reasonable assumptions for the gas-to-dust ratio and expansion velocity, depends on metallicity and slowly increases with decreasing metallicity. In contrast, the duty cycle increases with increasing metallicity, with the net result that total ML increases moderately with increasing metallicity, about 0.1 M every dex in [Fe/H]. For Population II asymptotic giant branch stars, we estimate a total ML of ≤0.1 M , nearly constant with varying metallicity.

show abstract

Production of dust by massive stars at high redshift

Gall

Hjorth

Andersen

2011

Astron Astrophys Rev

193

206

View full text Add to dashboard Cite

The large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift pose a challenge to galaxy formation models and theories of cosmic dust formation. At z > 6 only stars of relatively high mass (> 3 Msun) are sufficiently short-lived to be potential stellar sources of dust. This review is devoted to identifying and quantifying the most important stellar channels of rapid dust formation. We ascertain the dust production efficiency of stars in the mass range 3-40 Msun using both observed and theoretical dust yields of evolved massive stars and supernovae (SNe) and provide analytical expressions for the dust production efficiencies in various scenarios. We also address the strong sensitivity of the total dust productivity to the initial mass function. From simple considerations, we find that, in the early Universe, high-mass (> 3 Msun) asymptotic giant branch stars can only be dominant dust producers if SNe generate <~ 3 x 10^-3 Msun of dust whereas SNe prevail if they are more efficient. We address the challenges in inferring dust masses and star-formation rates from observations of high-redshift galaxies. We conclude that significant SN dust production at high redshift is likely required to reproduce current dust mass estimates, possibly coupled with rapid dust grain growth in the interstellar medium.Comment: 72 pages, 9 figures, 5 tables; to be published in The Astronomy and Astrophysics Revie

show abstract

DUST IS FORMING ALONG THE RED GIANT BRANCH OF 47 Tuc

Cited by 31 publications

References 8 publications

Modelling chromospheric line profiles as diagnostics of velocity fields inω Centauri red giant stars

Modelling chromospheric line profiles as diagnostics of velocity fields inω Centauri red giant stars

An empirical mass-loss law for Population II giants from theSpitzer-IRAC survey of Galactic globular clusters

Production of dust by massive stars at high redshift

Contact Info

Product

Resources

About