ISOCAM Observations of Galactic Globular Clusters: Mass Loss along the Red Giant Branch

Origlia, L.; Ferraro, F. R.; Pecci, F. Fusi; Rood, Robert T.

doi:10.1086/339857

Cited by 77 publications

(99 citation statements)

References 56 publications

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“…2 shows that the FIR spectral energy distribution (SED) of NGC 7078 is clearly inconsistent with the Rayleigh-Jeans tail of emission by its stellar content, the measured FIR emission exceeding the extrapolated stellar continuum by some three orders of magnitude. We also note that the magnitude and wavelength at which the excess is seen means that it is very unlikely to be due to the contribution of circumstellar dust (Origlia et al 2002). The only plausible explanation for the excess is emission by intra-cluster dust in the GC core.…”

Section: Resultsmentioning

confidence: 80%

“…Penny et al (1997) and Hopwood et al (1998) upper limits only, but Hopwood et al reported a marginal detection at 850 µm in the core of the metal-rich GC NGC 6356. Origlia et al (2002) carried out a deep survey of several GCs with ISOCAM. They concluded that prolific mass-loss occurs primarily near the tip of the red giant branch, is episodic, and does not seem to depend strongly on the GC metallicity.…”

Section: Introductionmentioning

confidence: 99%

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Far infra-red emission from NGC 7078: First detection of intra-cluster dust in a globular cluster

Evans

Stickel

Loon

et al. 2003

A&A

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Abstract. Improved data analysis of far infrared imaging data of the globular cluster NGC 7078 obtained with the ISO instrument ISOPHOT at 60 µm, 70 µm and 90 µm has detected the thermal emission from dust in its core, the first secure detection of intra-cluster dust in a globular cluster. The amount of dust is broadly consistent with mass-loss from evolved, metal-deficient stars in NGC 7078 in the time since it last crossed the Galactic plane.

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Section: Resultsmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Far infra-red emission from NGC 7078: First detection of intra-cluster dust in a globular cluster

Evans

Stickel

Loon

et al. 2003

A&A

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“…The NGC 362, NGC 6388, and M 15 clusters were previously observed with ISOCAM by Origlia et al (2002).…”

Section: Mass-losing Stars: Previous Identificationsmentioning

confidence: 76%

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

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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.

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“…Because T eff is derived spectroscopically, the gravity is recomputed through the Stefan-Boltzmann equation in each iteration according to the new value of T eff . The mass value of 0.82 M ⊙ is appropriate for RGB stars but probably too high for AGB stars, because of mass loss phenomena during the RGB phase (Rood 1973;Origlia et al 2002Origlia et al , 2007Origlia et al , 2014. In 6 Note that Simmerer et al (2013) adopted as solar reference value 7.56 obtained from their own solar analysis, while we used 7.50 by Grevesse & Sauval (1998).…”

Section: Analysis With Photometric Gravitiesmentioning

confidence: 99%

The Origin of the Spurious Iron Spread in the Globular Cluster NGC 3201

Mucciarelli

Lapenna

Massari

et al. 2015

ApJ

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NGC 3201 is a globular cluster suspected to have an intrinsic spread in the iron content. We re-analysed a sample of 21 cluster stars observed with UVES-FLAMES at the Very Large Telescope and for which Simmerer et al. found a 0.4 dex wide [Fe/H] distribution with a metal-poor tail. We confirmed that when spectroscopic gravities are adopted, the derived [Fe/H] distribution spans ∼0.4 dex. On the other hand, when photometric gravities are used, the metallicity distribution from Fe I lines remains large, while that derived from Fe II lines is narrow and compatible with no iron spread. We demonstrate that the metal-poor component claimed by Simmerer et al. is composed by asymptotic giant branch stars that could be affected by non local thermodynamical equilibrium effects driven by iron overionization. This leads to a decrease of the Fe I abundance, while leaving the Fe II abundance unaltered. A similar finding has been already found in asymptotic giant branch stars of the globular clusters M5 and 47 Tucanae. We conclude that NGC 3201 is a normal cluster, with no evidence of intrinsic iron spread.

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ISOCAM Observations of Galactic Globular Clusters: Mass Loss along the Red Giant Branch

Cited by 77 publications

References 56 publications

Far infra-red emission from NGC 7078: First detection of intra-cluster dust in a globular cluster

Far infra-red emission from NGC 7078: First detection of intra-cluster dust in a globular cluster

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

The Origin of the Spurious Iron Spread in the Globular Cluster NGC 3201

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