The Ca ii triplet in red giant spectra: [Fe/H] determinations and the role of [Ca/Fe]

Costa, G. S. Da

doi:10.1093/mnras/stv2315

Cited by 31 publications

(6 citation statements)

References 46 publications

(96 reference statements)

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“…The equivalent width of the Ca II triplet absorption feature provides an independent estimate of [Fe/H] ([Fe/H] CaT ) for comparison to Fe H phot [ ] (e.g., Armandroff & Da Costa 1991;Battaglia et al 2008;Starkenburg et al 2010;Da Costa 2016). However, estimates of [Fe/H] based on Ca II equivalent width measurements in spectroscopic studies of M31 halo stars typically have large uncertainties (e.g., Gilbert et al 2014), due to a combination of relatively low spectral signal-to-noise ratio (S/N) and limited precision resulting from measuring the equivalent width of only two or three absorption lines that are frequently affected by night sky lines at the velocities typical of M31 halo stars.…”

Section: Introductionmentioning

confidence: 99%

Elemental Abundances in M31: Iron and Alpha Element Abundances in M31’s Outer Halo*

Gilbert

Wojno

Kirby

et al. 2020

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We present [Fe/H] and [α/Fe] abundances, derived using spectral synthesis techniques, for stars in M31's outer stellar halo. The 21 [Fe/H] measurements and 7 [α/Fe] measurements are drawn from fields ranging from 43 to 165kpc in projected distance from M31. We combine our measurements with existing literature measurements, and compare the resulting sample of 23 stars with [Fe/H] and 9 stars with [α/Fe] measurements in M31's outer halo with [α/Fe] and [Fe/H] measurements, also derived from spectral synthesis, in M31's inner stellar halo (r<26 kpc) and dSph galaxies. The stars in M31's outer halo have [α/Fe] patterns that are consistent with the largest of M31's dSph satellites (AndI and AndVII). These abundances provide tentative evidence that the [α/Fe] abundances of stars in M31's outer halo are more similar to the abundances of Milky Way halo stars than to the abundances of stars in M31's inner halo. We also compare the spectral synthesis-based [Fe/H] measurements of stars in M31's halo with previous photometric [Fe/H] estimates, as a function of projected distance from M31. The spectral synthesis-based [Fe/H] measurements are consistent with a large-scale metallicity gradient previously observed in M31's stellar halo to projected distances as large as 100kpc. Unified Astronomy Thesaurus concepts: Galaxies (573); Local Group (929); Andromeda Galaxy (39); Galaxy stellar halos (598); Stellar abundances (1577)

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Section: Introductionmentioning

confidence: 99%

Elemental Abundances in M31: Iron and Alpha Element Abundances in M31’s Outer Halo*

Gilbert

Wojno

Kirby

et al. 2020

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“…This corresponds to a large electron spin-polarization 0.1 < µ B B 0 /k B T < 1 even at a considerable distance from the neutron star surface. While the electron temperature may not be of relativistic magnitude, the particle interactions with the pulsar fields nevertheless induce relativistic motion in the atmosphere [48,49]. For electrons at the pulsar or magnetar surface, on the other hand, the degeneracy makes the particles strongly relativistic with a Fermi temperature of the order T F ∼ 10 12 K [50], which, depending on the magnetic field, corresponds to a degree of spin polarization 0.0001…”

Section: Discussionmentioning

confidence: 99%

Relativistic kinetic theory for spin-1/2 particles: Conservation laws, thermodynamics, and linear waves

et al. 2019

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We study a recently derived fully relativistic kinetic model for spin-1/2 particles. Firstly, the full set of conservation laws for energy, momentum and angular momentum are given, together with an expression for the (non-symmetric) stress-energy tensor. Next, the thermodynamic equilibrium distribution is given in different limiting cases. Furthermore, we address the analytical complexity that arises when the spin-and momentum eigenfunctions are coupled in linear theory, by calculating the linear dispersion relation for such a case. Finally, we discuss the model and give some context by comparing with potentially relevant phenomena that are not included, such as radiation reaction and vacuum polarization.

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“…comm. ;Carretta et al 2009;Yong et al 2009;Simpson & Cottrell 2013;Marino et al 2014;Navin et al 2015;Da Costa 2016).…”

Section: Globular and Open Clustersmentioning

confidence: 99%

“…Targets in ω Cen were taken from Bellini et al (2009), and in NGC 7099, targets were taken from Da Costa (2016). We were only able to observe between 10 and 173 cluster members in any single configuration, given the magnitude limits and the limitations of the fibre positioner (2dF fibres cannot be placed closer together on the sky than 30 ).…”

Section: Globular and Open Clustersmentioning

confidence: 99%

The GALAH survey: observational overview andGaiaDR1 companion

Martell

Sharma

Buder

et al. 2016

Mon. Not. R. Astron. Soc.

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190

135

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The Ca ii triplet in red giant spectra: [Fe/H] determinations and the role of [Ca/Fe]

Abstract: Measurements are presented and analyzed of the strength of the Ca ii triplet lines in red giants in Galactic globular and open clusters, and in a sample of red giants in the LMC disk that have significantly different [Ca/Fe]

Cited by 31 publications

References 46 publications

Elemental Abundances in M31: Iron and Alpha Element Abundances in M31’s Outer Halo*

Elemental Abundances in M31: Iron and Alpha Element Abundances in M31’s Outer Halo*

Relativistic kinetic theory for spin-1/2 particles: Conservation laws, thermodynamics, and linear waves

The GALAH survey: observational overview andGaiaDR1 companion

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