Metallicity calibrations for dwarf stars and giants in the Geneva photometric system

Netopil, M.

doi:10.1093/mnras/stx1077

Cited by 19 publications

(9 citation statements)

References 83 publications

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“…On the basis of 12 main-sequence stars, we find the metallicity [Fe/H] NLTE = −0.10 ± 0.02 dex and [Fe/H] LTE = −0.09 ± 0.03 dex. This estimate is consistent, within the uncertainties, with estimates based on the analysis of high-resolution spectra by Santos et al (2012), Conrad et al (2014), andNetopil (2017). Fritzewski et al (2019) reported the metallicity of [Fe/H] of −0.07 ± 0.10 dex using lower-resolution near-IR spectra.…”

Section: Ngc 3532supporting

confidence: 89%

Non-LTE chemical abundances in Galactic open and globular clusters

Kovalev

Bergemann

Ting

et al. 2019

A&A

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Aims. We study the effects of non-local thermodynamic equilibrium (NLTE) on the determination of stellar parameters and abundances of Fe, Mg, and Ti from the medium-resolution spectra of FGK stars. Methods. We extend the Payne fitting approach to draw on NLTE and LTE spectral models. These are used to analyse the spectra of the Gaia-ESO benchmark stars and the spectra of 742 stars in 13 open and globular clusters in the Milky Way: NGC 3532, NGC 5927, NGC 2243, NGC 104, NGC 1851, NGC 2808, NGC 362, M2, MGC 6752, NGC 1904 Results. Our approach accurately recovers effective temperatures, surface gravities, and abundances of the benchmark stars and clusters members. The differences between NLTE and LTE are significant in the metal-poor regime, [Fe/H] −1. The NLTE [Fe/H] values are systematically higher, whereas the average NLTE [Mg/Fe] abundance ratios are ∼ 0.15 dex lower, compared to LTE. Our LTE measurements of metallicities and abundances of stars in Galactic clusters are in a good agreement with the literature. Yet, for most clusters, our study yields the first estimates of NLTE abundances of Fe, Mg and Ti. Conclusions. All clusters investigated in this work are homogeneous in Fe and Ti, with the intra-cluster abundance variations of less then 0.04 dex. NGC 2808, NGC 4833, M2 and M 15 show significant dispersions in [Mg/Fe]. Contrary to common assumptions, the NLTE analysis changes the mean abundance ratios in the clusters, but it does not influence the intra-cluster abundance dispersions.

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Section: Ngc 3532supporting

confidence: 89%

Non-LTE chemical abundances in Galactic open and globular clusters

Kovalev

Bergemann

Ting

et al. 2019

A&A

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“…The estimated equatorial velocity and rotation period are also close to the solar values (e.g., v sin i = 2.4 km s −1 , P rot = 21.4 d, Hojjatpanah et al 2020). The metal content is slightly higher than the solar value with different estimates ranging from [Fe/H]=0.31 to 0.37 (Netopil 2017;C ¸elebi et al 2019). The star does not have companions of stellar mass, with observational limits in separation and magnitude difference ranging from ρ = 0.03 ′′ at ∆mag = 0 to ρ = 1.5 ′′ at ∆mag = 3.0 (Tokovinin 2014).…”

Section: δ Pav a Nearby Solar Twinsupporting

confidence: 72%

Looking for astrometric signals below 20 m/s: A candidate exo-Jupiter in $δ$ Pav

Makarov,

Zacharias,

Finch

2021

Preprint

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We use a combination of Hipparcos space mission data with the USNO dedicated ground-based astrometric program URAT-Bright designed to complement and verify Gaia results for the brightest stars in the south to estimate the small perturbations of observed proper motions caused by exoplanets. One of the 1423 bright stars in the program, δ Pav, stands out with a small proper motion difference between our long-term estimate and Gaia EDR3 value, which corresponds to a projected velocity of (−17, +13) m s −1 . This difference is significant at a 0.994 confidence in the RA component, owing to the proximity of the star and the impressive precision of proper motions. The effect is confirmed by a comparison of long-term EDR3-Hipparcos and short-term Gaia EDR3 proper motions at a smaller velocity, but with formally absolute confidence. We surmise that the close Solar analog δ Pav harbors a long-period exoplanet similar to Jupiter.

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“…Basic physical parameters of the primary G0V star have been determined by Netopil (2017) and by Luck (2017). The two studies give similar values for T eff and log g. We tabulate Luck's values, and use the differences between the two studies to estimate uncertainties.…”

Section: Physical Parameters Of the Starsmentioning

confidence: 99%

Discovery of a Sirius-like binary system with a very strongly magnetic white dwarf

Landstreet

Bagnulo

2020

A&A

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Binary systems containing a magnetic white dwarf and a main-sequence star are considered extremely rare, perhaps non-existent. In the course of a search of magnetic fields in high-mass white dwarfs we have discovered a Sirius-like wide binary system composed of a main-sequence G0 star and an M ∼ 1.1 M white dwarf with a huge (hundreds of MG) magnetic field. This star, WDS J03038+0608B, shows a circular polarisation amplitude of 5 % in the continuum, with no evidence of variability in a 1 d timescale, little or no linear polarisation in the blue part of the spectrum, and about 2 % linear polarisation in the red part of the optical spectrum. A search in the literature reveals the existence of at least four more binary systems that include a magnetic white dwarf and a non-degenerate companion; three such systems passed unremarked in previous studies. We estimate that up to a few percent of magnetic white dwarfs may be found to occur in wide binary pairs. However, at least four of the five known binary systems with a magnetic white dwarf are too widely separated to be expected to evolve into systems experiencing Roche-lobe overflow, and cannot be considered as progenitors of magnetic cataclysmic variable (AM Her and DQ Her) systems.

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Metallicity calibrations for dwarf stars and giants in the Geneva photometric system

Cited by 19 publications

References 83 publications

Non-LTE chemical abundances in Galactic open and globular clusters

Non-LTE chemical abundances in Galactic open and globular clusters

Looking for astrometric signals below 20 m/s: A candidate exo-Jupiter in $δ$ Pav

Discovery of a Sirius-like binary system with a very strongly magnetic white dwarf

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