On the origin of fluorine in the Milky Way

Renda, Agostino; Fenner, Yeshe; Gibson, Brad K.; Karakas, Amanda I.; Lattanzio, John C.; Campbell, Simon; Chieffi, A.; Cunha, Kátia; Smith, Verne V.

doi:10.1111/j.1365-2966.2004.08215.x

Cited by 97 publications

(133 citation statements)

References 25 publications

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“…Meynet & Arnould (2000) identified He-burning in Wolf-Rayet stars, where the same reactions as those in AGB stars could occur, as the third potential source. The contribution of each site to the evolution of 19 F in the Galaxy is not known, but the inclusion of all three sources in a Galactic chemical evolution model resulted in satisfactory agreement between the model prediction and the available observational data (Renda et al 2004;Cunha & Smith 2005).…”

Section: Introductionmentioning

confidence: 99%

Fluorine in the Carbon‐Enhanced Metal‐Poor Star HE 1305+0132

Schuler¹,

Cunha²,

Smith³

2008

AIP Conference Proceedings

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The fluorine abundance of the Carbon-Enhanced Metal-Poor (CEMP) star HE 1305+0132 has been derived by analysis of the molecular HF (1-0) R9 line at 2.3357 µm in a high-resolution (R = 50, 000) spectrum obtained with the Phoenix spectrometer and Gemini-South telescope. Our abundance analysis makes use of a CNO-enhanced ATLAS12 model atmosphere characterized by a metallicity and CNO enhancements determined utilizing medium-resolution (R = 3, 000) optical and near-IR spectra. The effective iron abundance is found to be [Fe/H] = −2.5, making HE 1305+0132 the most Fe-deficient star, by more than an order of magnitude, for which the abundance of fluorine has been measured. Using spectral synthesis, we derive a super-solar fluorine abundance of A( 19 F) = 4.96 ± 0.21, corresponding to a relative abundance of [F/Fe] = +2.90. A single line of the Phillips C 2 system is identified in our Phoenix spectrum, and along with multiple lines of the first-overtone vibration-rotation CO (3-1) band head, C and O abundances of A( 12 C) = 8.57 ± 0.11 and A( 16 O) = 7.04 ± 0.14 are derived. We consider the striking fluorine overabundance in the framework of the nucleosynthetic processes thought to be responsible for the C-enhancement of CEMP stars and conclude that the atmosphere of HE 1305+0132 was polluted via mass transfer by a primary companion during its asymptotic giant branch phase. This is the first study of fluorine in a CEMP star, and it demonstrates that this rare nuclide can be a key diagnostic of nucleosynthetic processes in the early Galaxy.

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Section: Introductionmentioning

confidence: 99%

Fluorine in the Carbon‐Enhanced Metal‐Poor Star HE 1305+0132

Schuler¹,

Cunha²,

Smith³

2008

AIP Conference Proceedings

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“…The aforementioned observational results combined with theoretical models currently indicate that all three suggested sources of fluorine contributed to the observed abundances of this element in different epochs of the evolution of the Galaxy (Renda et al 2004;Kobayashi et al 2011). However, the relative contributions of the three F productors remains disputed.…”

Section: Introductionmentioning

confidence: 99%

Fluorine abundances in dwarf stars of the solar neighbourhood

Recio–Blanco

Laverny

Worley

et al. 2012

A&A

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Context. In spite of many observational efforts to characterize the chemical evolution of our Galaxy, not much is known about the origin of fluorine (F). Models suggest that the F found in the Galaxy might have been produced mainly in three different ways, namely, Type II supernovae, asymptotic giant branch nucleosynthesis, or in the core of Wolf-Rayet stars. Only a few observational measurements of F abundances are available in the literature and mostly for objects whose characteristics might hamper an accurate determination of fluorine abundance (e.g., complex mixing and nucleosynthesis processes, external/internal contamination). Aims. We acquire data using the high-resolution IR-spectrograph CRIRES and gather FEROS data from the European Southern Observatory archive. The classical method of spectral synthesis in local thermodynamic equilibrium has been used to perform the abundance analysis. Methods. We derive the F abundances of nine cool main-sequence dwarfs in the solar neighbourhood, based on an unblended line of the HF molecule at 2.3 microns. In addition, we study the s-process elements of five of these stars. Results. Several of the analysed stars seem to be slightly fluorine enhanced with respect to the Sun, although no correlation is found between the F abundance and the iron content. In addition, the most fluorine enriched stars are also yttrium and zirconium enriched, which suggests that AGB fluorine nucleosynthesis is the dominant source of fluorine production for the observed stars. Nevertheless, the correlation between [F/Fe] and the s-elements is rather weak and possibly masked by the uncertainties in the F abundance measurements. Finally, we compare our derived F abundances to previous measurements of alpha-element and ironpeak element abundances. Type II core collapse supernovae do not appear to be the main site of F production for our targets, as no correlation seems to exist between the [F/Fe] and the [α/Fe] ratios.

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“…Nuclear production in AGB stars contributes to the chemical evolution of galaxies (e.g., Travaglio et al 2004;Renda et al 2004). The chemical yields support the interpreted stellar abundances from dwarf spheroidal galaxy satellites of the Milky Way relative to stellar abundances of Galactic halo stars (Venn et al 2004;Geisler et al 2005).…”

Section: Agb Evolutionmentioning

confidence: 99%

Hydrodynamic Simulations of He Shell Flash Convection

Herwig

Freytag

Hueckstaedt

et al. 2006

ApJ

105

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We present the first hydrodynamic, multidimensional simulations of He shell flash convection. We investigate the properties of shell convection immediately before the He luminosity peak during the 15th thermal pulse of a stellar evolution track with initially 2 solar masses and metallicity Z ¼ 0:01. This choice is a representative example of a low-mass asymptotic giant branch thermal pulse. We construct the initial vertical stratification with a set of polytropes to resemble the stellar evolution structure. Convection is driven by a constant volume heating in a thin layer at the bottom of the unstable layer. We calculate a grid of two-dimensional simulations with different resolutions and heating rates, plus one low-resolution three-dimensional run. The flow field is dominated by large convective cells that are centered in the lower half of the convection zone. It generates a rich spectrum of gravity waves in the stable layers both above and beneath the convective shell. The magnitude of the convective velocities from our one-dimensional mixing-length theory model and the rms-averaged vertical velocities from the hydrodynamic model are consistent within a factor of a few. However, the velocity profile in the hydrodynamic simulation is more asymmetric and decays exponentially inside the convection zone. Both g-modes and convective motions cross the formal convective boundaries, which leads to mixing across the boundaries. Our resolution study shows consistent flow structures among the higher resolution runs, and we see indications for convergence of the vertical velocity profile inside the convection zone for the highest resolution simulations. Many of the convective properties, in particular the exponential decay of the velocities, depend only weakly on the heating rate. However, the amplitudes of the gravity waves increase with both the heating rate and the resolution.

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On the origin of fluorine in the Milky Way

Cited by 97 publications

References 25 publications

Fluorine in the Carbon‐Enhanced Metal‐Poor Star HE 1305+0132

Fluorine in the Carbon‐Enhanced Metal‐Poor Star HE 1305+0132

Fluorine abundances in dwarf stars of the solar neighbourhood

Hydrodynamic Simulations of He Shell Flash Convection

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