A<i>SPITZER</i>SEARCH FOR COLD DUST WITHIN GLOBULAR CLUSTERS

Barmby, P.; Boyer, Martha L.; Woodward, C. E.; Gehrz, R. D.; Loon, Jacco Th. van; Fazio, G. G.; Marengo, Massimo; Polomski, Elisha

doi:10.1088/0004-6256/137/1/207

Cited by 30 publications

(36 citation statements)

References 64 publications

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“…Several of these have now been observed in GCs: notably Pease 1 (K648) in M15 (Pease 1928), but also IRAS 18333−2357 (GJJC1) in M22 (Gillett et al 1989), JaFu1 in Pal6 and JaFu2 in NGC 6441 (Jacoby et al 1997). The fact that, out of all the clusters observed to date, only M15 shows convincing evidence of hosting an observable ICM (Boyer et al 2006; Barmby et al 2009), could be due to a random effect, rather than due to M15's particularly low metallicity. This implies that the diffuse matter seen in M15 could merely be a diffusing planetary nebula that was ejected ≳10 4 yr ago; however, its large mass (≳0.3 M ⊙ ) would suggest that a single such event is unlikely to be the sole producer of this much material.…”

Section: Discussionmentioning

confidence: 94%

Giants in the globular cluster ω Centauri: dust production, mass-loss and distance

McDonald

Loon

Decin

et al. 2009

Monthly Notices of the Royal Astronomical Society

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115

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We present spectral energy distribution modelling of 6875 stars in ω Centauri, obtaining stellar luminosities and temperatures by fitting literature photometry to state‐of‐the‐art marcs stellar models. By comparison to four different sets of isochrones, we provide a new distance estimate to the cluster of 4850 ± 200 (random error) ± 120 (systematic error) pc, a reddening of E(B−V) = 0.08 ± 0.02 (random) ± 0.02 (systematic) mag and a differential reddening of ΔE(B−V) < 0.02 mag for an age of 12 Gyr. Several new post‐early‐AGB candidates are also found. Infrared excesses of stars were used to measure total mass‐loss rates for individual stars down to ∼7 × 10−8 M⊙ yr−1. We find a total dust mass‐loss rate from the cluster of 1.3 ±0.80.5× 10−9 M⊙ yr−1, with the total gas mass‐loss rate being > 1.2 ±0.60.5× 10−6 M⊙ yr−1. Half of the cluster's dust production and 30 per cent of its gas production comes from the two most extreme stars – V6 and V42 – for which we present new Gemini/T‐ReCS mid‐infrared spectroscopy, possibly showing that V42 has carbon‐rich dust. The cluster's dust temperatures are found to be typically ≳550 K. Mass‐loss apparently does not vary significantly with metallicity within the cluster, but shows some correlation with barium enhancement, which appears to occur in cooler stars, and especially on the anomalous RGB. Limits to outflow velocities, dust‐to‐gas ratios for the dusty objects and the possibility of short‐time‐scale mass‐loss variability are also discussed in the context of mass‐loss from low‐metallicity stars. The ubiquity of dust around stars near the RGB tip suggests significant dusty mass‐loss on the RGB; we estimate that typically 0.20–0.25 M⊙ of mass‐loss occurs on the RGB. From observational limits on intracluster material, we suggest the dust is being cleared on a time‐scale of ≲105 yr.

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Section: Discussionmentioning

confidence: 94%

Giants in the globular cluster ω Centauri: dust production, mass-loss and distance

McDonald

Loon

Decin

et al. 2009

Monthly Notices of the Royal Astronomical Society

Self Cite

115

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“…the old massive GCs (de Grijs et al 2005). The majority of the studied Galactic GCs are found to be devoid of dust, which is unexpected considering evolutionary effects on their stellar population (Barmby et al 2009;Priestley et al 2011). The evolution of GCs is affected by the geometry and mass of their host galaxy (e.g., Madrid et al 2014).…”

Section: Cavity and Sscsmentioning

confidence: 98%

Probing the interstellar medium of NGC 1569 with Herschel★

Lianou

Barmby

Rémy-Ruyer

et al. 2014

Monthly Notices of the Royal Astronomical Society

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NGC 1569 has some of the most vigorous star formation among nearby galaxies. It hosts two super star clusters (SSCs) and has a higher star formation rate (SFR) per unit area than other starburst dwarf galaxies. Extended emission beyond the galaxy's optical body is observed in warm and hot ionised and atomic hydrogen gas; a cavity surrounds the SSCs. We aim to understand the impact of the massive star formation on the surrounding interstellar medium in NGC 1569 through a study of its stellar and dust properties. We use Herschel and ancillary multiwavelength observations, from the ultraviolet to the submillimeter regime, to construct its spectral energy distribution, which we model with magphys on ∼300 pc scales at the SPIRE 250 µm resolution. The multiwavelength morphology shows low levels of dust emission in the cavity, and a concentration of several dust knots in its periphery. The extended emission seen in the ionised and neutral hydrogen observations is also present in the far-infrared emission. The dust mass is higher in the periphery of the cavity, driven by ongoing star formation and dust emission knots. The SFR is highest in the central region, while the specific SFR is more sensitive to the ongoing star formation. The region encompassing the cavity and SSCs contains only 12 per cent of the dust mass of the central starburst, in accord with other tracers of the interstellar medium. The gas-to-dust mass ratio is lower in the cavity and fluctuates to higher values in its periphery.

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“…There is a notable lack of detections of intracluster material with the Spitzer Space Telescope. Only two clusters of the many observed with Spitzer have "possible" detections of intracluster material (Boyer et al 2006;Barmby et al 2009). One suggestion for removal of intracluster material is ram-pressure stripping by the galactic halo (Frank & Gisler 1976, Okada et al 2007), but Spitzer observations cannot confirm the expected relation between cluster kinematics and the presence (or upper limit) of dust (Barmby et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Fast Winds and Mass Loss From Metal-Poor Field Giants

Dupree

Smith

Strader

2009

The Astronomical Journal

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Echelle spectra of the infrared He i λ10830 line were obtained with NIRSPEC on the Keck 2 telescope for 41 metal-deficient field giant stars including those on the red giant branch (RGB), asymptotic giant branch (AGB), and red horizontal branch (RHB). The presence of this He i line is ubiquitous in stars with T eff 4500 K and M V fainter than −1.5, and reveals the dynamics of the atmosphere. The line strength increases with effective temperature for T eff 5300 K in RHB stars. In AGB and RGB stars, the line strength increases with luminosity. Fast outflows ( 60 km s −1 ) are detected from the majority of the stars and about 40% of the outflows have sufficient speed as to allow escape of material from the star as well as from a globular cluster. Outflow speeds and line strengths do not depend on metallicity for our sample ([Fe/H]= −0.7 to −3.0), suggesting the driving mechanism for these winds derives from magnetic and/or hydrodynamic processes. Gas outflows are present in every luminous giant, but are not detected in all stars of lower luminosity indicating possible variability. Mass loss rates ranging from ∼3 × 10 −10 to ∼6 × 10 −8 M yr −1 estimated from the Sobolev approximation for line formation represent values with evolutionary significance for red giants and RHB stars. We estimate that 0.2 M will be lost on the RGB, and the torque of this wind can account for observations of slowly rotating RHB stars in the field. About 0.1-0.2 M will be lost on the RHB itself. This first empirical determination of mass loss on the RHB may contribute to the appearance of extended horizontal branches in globular clusters. The spectra appear to resolve the problem of missing intracluster material in globular clusters. Opportunities exist for "wind smothering" of dwarf stars by winds from the evolved population, possibly leading to surface pollution in regions of high stellar density.

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ASPITZERSEARCH FOR COLD DUST WITHIN GLOBULAR CLUSTERS

Cited by 30 publications

References 64 publications

Giants in the globular cluster ω Centauri: dust production, mass-loss and distance

Giants in the globular cluster ω Centauri: dust production, mass-loss and distance

Probing the interstellar medium of NGC 1569 with Herschel★

Fast Winds and Mass Loss From Metal-Poor Field Giants

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