High-resolution spectroscopy of globular cluster post-Asymptotic 
 Giant Branch stars

Mooney, C. J.; Rolleston, W. R. J.; Keenan, F. P.; Dufton, P. L.; Smoker, J. V.; Ryans, R.; Aller, L. H.; Trundle, C.

doi:10.1051/0004-6361:20040084

Cited by 18 publications

(19 citation statements)

References 51 publications

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“…For the early-type stars the stellar features were normally broad (cf. Mooney et al 2002Mooney et al , 2004 and hence easily removed in the normalisation process. Finally, Cols.…”

Section: Flames-giraffe Archive Sample Towards Open Clusters In the Mmentioning

confidence: 99%

The large- and small-scale Ca II K structure of the Milky Way from observations of Galactic and Magellanic sightlines

Smoker

Keenan

2015

A&A

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Aims. The large and small-scale (pc) structure of the Galactic interstellar medium can be investigated by utilising spectra of earlytype stellar probes of known distances in the same region of the sky. This paper determines the variation in line strength of Ca ii at 3933.661 Å as a function of probe separation for a large sample of stars, including a number of sightlines in the Magellanic Clouds. Methods. FLAMES-GIRAFFE data taken with the Very Large Telescope towards early-type stars in 3 Galactic and 4 Magellanic open clusters in Ca ii are used to obtain the velocity, equivalent width, column density, and line width of interstellar Galactic calcium for a total of 657 stars, of which 443 are Magellanic Cloud sightlines. In each cluster there are between 43 and 111 stars observed.Additionally, FEROS and UVES Ca ii K and Na i D spectra of 21 Galactic and 154 Magellanic early-type stars are presented and combined with data from the literature to study the calcium column density -parallax relationship.Results. For the four Magellanic clusters studied with FLAMES, the strength of the Galactic interstellar Ca ii K equivalent width on transverse scales from ∼0.05−9 pc is found to vary by factors of ∼1.8−3.0, corresponding to column density variations of ∼0.3−0.5 dex in the optically-thin approximation. Using FLAMES, FEROS, and UVES archive spectra, the minimum and maximum reduced equivalent widths for Milky Way gas are found to lie in the range ∼35−125 mÅ and ∼30−160 mÅ for Ca ii K and Na i D, respectively.The range is consistent with a previously published simple model of the interstellar medium consisting of spherical cloudlets of filling factor ∼0.3, although other geometries are not ruled out. Finally, the derived functional form for parallax (π) and Ca ii column density (N CaII ) is found to be π(mas) = 1/(2.39 × 10 −13 × N CaII (cm −2 ) + 0.11). Our derived parallax is ∼25 per cent lower than predicted by Megier et al. (2009, A&A, 507, 833) at a distance of ∼100 pc and ∼15 percent lower at a distance of ∼200 pc, reflecting inhomogeneity in the Ca ii distribution in the different sightlines studied.

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“…For the early-type stars the stellar features were normally broad (cf. Mooney et al 2002Mooney et al , 2004 and hence easily removed in the normalisation process. Finally, Cols.…”

Section: Flames-giraffe Archive Sample Towards Open Clusters In the Mmentioning

confidence: 99%

The large- and small-scale Ca II K structure of the Milky Way from observations of Galactic and Magellanic sightlines

Smoker

Keenan

2015

A&A

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“…Therefore, NGC 6712 has almost certainly contributed stars to the disk and/or halo. Previous abundance analyses of NGC 6712 only considered one post-AGB star (Jasniewicz et al 2004;Mooney et al 2004), whose composition may not reflect the composition of the cluster due to the rich nucleosynthesis occurring in the late phases of stellar evolution. In this paper, we present the first detailed chemical abundance analysis of bright red-giant stars in this tidally disrupted globular cluster.…”

Section: Introductionmentioning

confidence: 99%

Chemical Abundances in Giant Stars of the Tidally Disrupted Globular Cluster NGC 6712 from High‐Resolution Infrared Spectroscopy

Yong

Meléndez

Cunha

et al. 2008

Astrophysical Journal

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We present abundances of C, N, O, F, Na, and Fe in six giant stars of the tidally disrupted globular cluster NGC 6712. The abundances were derived by comparing synthetic spectra with high-resolution infrared spectra obtained with the Phoenix spectrograph on the Gemini South telescope. We find large star-to-star abundance variations of the elements C, N, O, F, and Na. NGC 6712 and M4 are the only globular clusters in which F has been measured in more than two stars, and both clusters reveal F abundance variations whose amplitude is comparable to or exceeds that of O, a pattern which may be produced in M k 5 M AGB stars. Within the limited samples, the F abundance in globular clusters is lower than in field and bulge stars at the same metallicity. NGC 6712 and Pal 5 are tidally disrupted globular clusters whose red giant members exhibit O and Na abundance variations not seen in comparable metallicity field stars. Therefore, globular clusters such as NGC 6712 and Pal 5 cannot contribute many field stars and/or field stars do not form in environments with chemical enrichment histories like those of NGC 6712 and Pal 5. Although our sample size is small, from the amplitude of the O and Na abundance variations we infer a large initial cluster mass and tentatively confirm that NGC 6712 was once one of the most massive globular clusters in our Galaxy.

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“…There are several types of evolved A-type stars in globular clusters including blue straggler stars, interacting binaries, A and B type horizontal branch (HB) stars (Moehler 2005), A-type post-HB and post-AGB stars , Jasniewicz et al 2004, Mooney et al 2004. In earlier surveys some were classified as UV-bright stars (Zinn et al 1972).…”

Section: A-type Post-hb and Post-agb Stars In Globular Clusters And Rmentioning

confidence: 99%

“…Chemical composition studies of B, A, and F type UV-bright stars in globular clusters reveal that some of them are post-AGB A and F stars showing evidence for third dredgeup and overabundance of carbon and s-process elements for example ROA 24 in ω Cen (Gonzalez & Wallerstein 1994), while some show severe carbon deficiency indicating that they left the AGB before the third dredgeup occurred for example ZNG 1 in M10, ROA 5701 in ω Cen and Barnard 29 in M13 , Jasniewicz et al 2004, Mooney et al 2004.…”

Section: A-type Post-hb and Post-agb Stars In Globular Clusters And Rmentioning

confidence: 99%

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Evolved A-type stars

Parthasarathy

2004

Proc. IAU

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High-resolution spectroscopy of globular cluster post-Asymptotic Giant Branch stars

Cited by 18 publications

References 51 publications

The large- and small-scale Ca II K structure of the Milky Way from observations of Galactic and Magellanic sightlines

The large- and small-scale Ca II K structure of the Milky Way from observations of Galactic and Magellanic sightlines

Chemical Abundances in Giant Stars of the Tidally Disrupted Globular Cluster NGC 6712 from High‐Resolution Infrared Spectroscopy

Evolved A-type stars

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