The metal-rich abundance pattern – spectroscopic properties and abundances for 107 main-sequence stars

Ivanyuk, O.; Jenkins, James S.; Pavlenko, Ya. V.; Jones, H. R. A.; Pinfield, D. J.

doi:10.1093/mnras/stx647

Cited by 24 publications

(42 citation statements)

References 58 publications

(122 reference statements)

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“…The high-resolution and high-S/N of the CHEPS spectra from HARPS allows Ivanyuk et al (2017) the study of chemical abundances like Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the atmospheres of metal-rich dwarfs. Gravities in the atmospheres of subgiants are lower in comparison to dwarfs, however, we carried out the same procedure for the lithium abundance determination for the stars of both groups.…”

Section: Observations and Data Acquisitionmentioning

confidence: 99%

“…We used the stellar atmospheric parameters (effective temperatures T eff , gravities log g, microturbulent velocities V m , rotational velocities V sin i and abundances of Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn determined for the 107 stars of CHEPS sample by Ivanyuk et al (2017), who used our procedure of finding the best fit of the synthetic absorption line profiles to the observed spectra using ABEL8 programme (Pavlenko 2017). We used the model atmospheres computed by Ivanyuk et al (2017) using SAM12 programme (Pavlenko 2003).…”

Section: Abundances Analysismentioning

confidence: 99%

“…We used the model atmospheres computed by Ivanyuk et al (2017) using SAM12 programme (Pavlenko 2003). Model atmospheres, synthetic spectra were computed for the same set of input parameters.…”

Section: Abundances Analysismentioning

confidence: 99%

“…Rotational velocity was varied around the values found by Ivanyuk et al (2017) to obtain the best fit to the observed Li lines. In most cases, differences of our V sin i with Ivanyuk et al (2017) does not exceed ±0.5 km s −1 .…”

Section: Abundances Analysismentioning

confidence: 99%

“…This approach allowed us to minimise effects of blending by lines of other atoms and even CN, which depends on the unknown yet C and N abundances. In this work abundances of C and N and other non-analysed elements by Ivanyuk et al (2017) were scaled following [Fe/H]. The updated atomic line list VALD-2 (Kupka et al 1999) was used in our synthetic spectra computations, see Yakovina et al (2011) …”

Section: Abundances Analysismentioning

confidence: 99%

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A detailed study of lithium in 107 CHEPS dwarf stars

Pavlenko

Jenkins

Ivanyuk

et al. 2018

A&A

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Context. We report results from lithium abundance determinations using high resolution spectral analysis of the 107 metal-rich stars from the Calan-Hertfordshire Extrasolar Planet Search programme. Aims. We aim to set out to understand the lithium distribution of the population of stars taken from this survey. Methods. The lithium abundance taking account of non-local thermodynamical equilibrium effects was determined from the fits to the Li I 6708 Å resonance doublet profiles in the observed spectra. Results. We find that a) fast rotators tend to have higher lithium abundances; b) log N(Li) is higher in more massive and hot stars; c) log N(Li) is higher in stars of lower log g; d) stars with the metallicities >0.25 dex do not show the lithium lines in their spectra; e) most of our planet hosts rotate slower; and f) a lower limit of lithium isotopic ratio is 7 Li/ 6 Li > 10 in the atmospheres of two stars with planets (SWP) and two non-SWP stars. Conclusions. Measurable lithium abundances were found in the atmospheres of 45 stars located at distances of 20−170 pc from the Sun, for the other 62 stars the upper limits of log N(Li) were computed. We found well defined dependences of lithium abundances on T eff , V sin i, and less pronounced for the log g. In case of V sin i we see two sequences of stars: with measurable lithium and with the upper limit of log N(Li). About 10% of our targets are known to host planets. Only two SWP have notable lithium abundances, so we found a lower proportion of stars with detectable Li among known planet hosts than among stars without planets. However, given the small sample size of our planet-host sample, our analysis does not show any statistically significant differences in the lithium abundance between SWP and stars without known planets.

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Section: Observations and Data Acquisitionmentioning

confidence: 99%

Section: Abundances Analysismentioning

confidence: 99%

Section: Abundances Analysismentioning

confidence: 99%

Section: Abundances Analysismentioning

confidence: 99%

Section: Abundances Analysismentioning

confidence: 99%

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A detailed study of lithium in 107 CHEPS dwarf stars

Pavlenko

Jenkins

Ivanyuk

et al. 2018

A&A

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Flare activity and photospheric analysis of Proxima Centauri

Pavlenko

Mascareño

Rebolo

et al. 2017

A&A

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Context. We present the analysis of emission lines in high-resolution optical spectra of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V. Aims. We carry out the detailed analysis of observed spectra to get a better understanding of the physical conditions of the atmosphere of this star. Methods. We identify the emission lines in a serie series of 147 high-resolution optical spectra of the star at different levels of activity and compare them with the synthetic spectra computed over a wide spectral range. Results. Our synthetic spectra computed with the PHOENIX 2900/5.0/0.0 model atmosphere fits pretty well the observed optical-to-near-infrared spectral energy distribution. However, modelling strong atomic lines in the blue spectrum (3900-4200Å) requires implementing additional opacity. We show that high temperature layers in Proxima Centauri consist in at least three emitting parts: a) a stellar chromosphere where numerous emission lines form. We suggest that some emission cores of strong absorption lines of metals form there; b) flare regions above the chromosphere, where hydrogen Balmer lines up to high transition levels (10-2) form; c) a stellar wind component with Vr = −30 kms −1 seen in some Balmer lines as blue shifted emission lines. We believe that the observed He line at 4026Å in emission can be formed in that very hot region. Conclusions. We show, that real structure of the atmosphere of Proxima is rather complicated. The photosphere of the star is best fit by a normal M5 dwarf spectrum. On the other hand emission lines form in the chromosphere, flare regions and extended hot envelope.

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Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars (SPECIES)

Soto¹,

Jenkins²

2018

A&A

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Context. The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and characteristics of their companion(s). Aims. Our aims were to develop a community tool that allows the automated calculation of stellar parameters for a large number of stars, using high resolution echelle spectra and minimal photometric magnitudes, and introduce the first catalogue of these measurements in this work. Methods. We measured the equivalent widths of several iron lines and used them to solve the radiative transfer equation assuming local thermodynamic equilibrium in order to obtain the atmospheric parameters (T eff , [Fe/H], log g and ξ t ). We then used these values to derive the abundance of 11 chemical elements in the stellar photosphere (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu and Zn). Rotation and macroturbulent velocity were obtained using temperature calibrators and synthetic line profiles to match the observed spectra of five absorption lines. Finally, by interpolating in a grid of MIST isochrones, we are able to derive the mass, radius and age for each star using a Bayesian approach. Results. Our SPECIES code obtains bulk parameters that are in good agreement with measured values from different existing catalogues, including when different methods are used to derive them. We find excellent agreement with previous works that used similar methodologies, in particular when the T eff is calculated using model fitting to the spectra themselves. We find discrepancies in the chemical abundances for some elements with respect to other works, which could be produced by differences in T eff , or in the line list or the atomic line data used to derive them. We also obtained analytic relations to describe the correlations between different parameters, and we implemented new methods to better handle these correlations, which provides a better description of the uncertainties associated with the measurements.

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The metal-rich abundance pattern – spectroscopic properties and abundances for 107 main-sequence stars

Cited by 24 publications

References 58 publications

A detailed study of lithium in 107 CHEPS dwarf stars

A detailed study of lithium in 107 CHEPS dwarf stars

Flare activity and photospheric analysis of Proxima Centauri

Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars (SPECIES)

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