The effect of stellar activity on the spectroscopic stellar parameters of the young solar twin HIP 36515

Galarza, Jhon Yana; Meléndez, Jorge; Válio, Adriana; Reggiani, Henrique; Carlos, M.; Ponte, Geisa; Spina, L.; Haywood, R. D.

doi:10.1093/mnrasl/slz153

Cited by 51 publications

(47 citation statements)

References 39 publications

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“…Some trends might be even more pronounced, as we are dealing with PMS stars, which might not have model spectra calculated as carefully and rigorously as main sequence stars. Chromospheric activity (Carter 1989;Yana Galarza et al 2019) and strong magnetic fields (Basri et al 1992;Johns-Krull et al 1999;Spina et al 2020) are known to influence PMS stars significantly. (iv) Biased photometric temperature and gravity could have an effect as well, although it must be minor, as this is the only effect we thoroughly analysed.…”

Section: Evaluation Of Systematic Effectsmentioning

confidence: 99%

The GALAH survey: Chemical homogeneity of the Orion complex

Kos

Bland-Hawthorn

Buder

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Due to its proximity, the Orion star forming region is often used as a proxy to study processes related to star formation and to observe young stars in the environment they were born in. With the release of Gaia DR2, the distance measurements to the Orion complex are now good enough that the three dimensional structure of the complex can be explored. Here we test the hypothesis that, due to non-trivial structure and dynamics, and age spread in the Orion complex, the chemical enrichment of youngest stars by early core-collapse supernovae can be observed. We obtained spectra of 794 stars of the Orion complex with the HERMES spectrograph at the Anglo Australian telescope as a part of the GALAH and GALAH-related surveys. We use the spectra of ∼300 stars to derive precise atmospheric parameters and chemical abundances of 25 elements for 15 stellar clusters in the Orion complex. We demonstrate that the Orion complex is chemically homogeneous and that there was no self-pollution of young clusters by core-collapse supernovae from older clusters; with a precision of 0.02 dex in relative alpha-elements abundance and 0.06 dex in oxygen abundance we would have been able to detect pollution from a single supernova, given a fortunate location of the SN and favourable conditions for ISM mixing. We estimate that the supernova rate in the Orion complex was very low, possibly producing no supernova by the time the youngest stars of the observed population formed (from around 21 to 8 Myr ago).

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Section: Evaluation Of Systematic Effectsmentioning

confidence: 99%

The GALAH survey: Chemical homogeneity of the Orion complex

Kos

Bland-Hawthorn

Buder

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…Moreover, these authors demonstrate that such variations of EWs depend on the optical depth of line formation and, marginally, on the Landè g L factor, which measures the sensitivity of a spectral line to magnetic fields. Spina et al (2020) conducted the same study as Yana Galarza et al (2019) to a sample of 211 solar-analogue stars observed with High Accuracy Radial velocity Planet Searcher (HARPS) and find similar results. Yana Galarza et al (2019), Baratella et al (2020), and Spina et al (2020) demonstrate how iron lines forming in the upper layers of the photosphere of young stars can yield higher abundances due to the possible influence of the more intense chromospheric or photospheric magnetic fields.…”

Section: Introductionmentioning

confidence: 78%

“…Recently, Yana Galarza et al (2019) show that the observed EWs of iron lines vary with the activity phase of the young solar analogue HD 59967 (age ∼400 Myr). In particular, they find that the line strength increases when the star is more active, producing variations of ξ and iron abundance along with the stellar cycle.…”

Section: Introductionmentioning

confidence: 99%

The GAPS Programme at TNG

Baratella

D’Orazi

Biazzo

et al. 2020

A&A

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Context. The detailed chemical composition of stars is important in many astrophysical fields, among which is the characterisation of exoplanetary systems. Previous studies seem to indicate an anomalous chemical pattern of the youngest stellar population in the solar vicinity that has sub-solar metal content. This can influence various observational relations linking the properties of exoplanets to the characteristics of the host stars, for example the giant planet-metallicity relation. Aims. In this framework, we aim to expand our knowledge of the chemical composition of intermediate-age stars and understand whether these peculiarities are real or related to spectroscopic analysis techniques. Methods. We analysed high-resolution optical and near-infrared spectra of intermediate-age stars (<700 Myr) that have been observed simultaneously with HARPS-N and GIANO-B spectrographs in GIARPS mode. To overcome issues related to the young ages of the stars, we applied a new spectroscopic method that uses titanium lines to derive the atmospheric parameters, in particular surface gravities and microturbulence velocity parameter. We derived abundances of C I, Na I, Mg I, Al I, Si I, Ca I, Ti I, Ti II, Cr I, Cr II, Fe I, Fe II, Ni I, and Zn I. Results. The lack of systematic trends between elemental abundances and effective temperatures validates our methods. However, we observed that the coolest stars in the sample, where Teff < 5400 K, display higher abundances for the ionised species, in particular Cr II, and for high-excitation potential C I lines. Conclusions. We found a positive correlation between the higher abundances measured of C I and Cr II and the activity index log RHK′. Instead, we found no correlations between the C abundances obtained from CH molecular band at 4300 Å and both effective temperatures and activity. Thus, we suggest that these are better estimates for C abundances in young and cool stars. Finally, we found an indication of an increasing abundance ratio [X/H] with the condensation temperature for HD 167389, indicating possible episodes of planet engulfment.

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“…Adibekyan et al 2012;Delgado Mena et al 2017;Hojjatpanah et al 2019). This method can be also utilised to investigate the variation of magnetic field strength during stellar activity cycles for active stars with sufficiently long spectroscopic time-series (Alvarado-Gómez et al 2018;Yana Galarza et al 2019). One can also envisage incorporating Zeeman intensification of the Fe i lines studied here into Doppler imaging inversions with the goal of simultaneously reconstructing both cool spot maps and distributions of small-scale magnetic field intensity ).…”

Section: Discussionmentioning

confidence: 99%

Hidden magnetic fields of young suns

Kochukhov

Hackman

Lehtinen

et al. 2020

A&A

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Global magnetic fields of active solar-like stars are nowadays routinely detected with spectropolarimetric measurements and are mapped with Zeeman-Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities, polarimetry captures only a tiny fraction of the magnetic flux and cannot assess the overall stellar surface magnetic field if it is dominated by a smallscale component. Analysis of Zeeman broadening in high-resolution intensity spectra can reveal these hidden complex magnetic fields. Historically, there were very few attempts to obtain such measurements for G dwarf stars due to the difficulty of disentangling Zeeman effect from other broadening mechanisms affecting spectral lines. Here we developed a new magnetic field diagnostic method based on relative Zeeman intensification of optical atomic lines with different magnetic sensitivity. Using this technique we obtained 78 field strength measurements for 15 Sun-like stars, including some of the best-studied young solar twins. We find that the average magnetic field strength B f drops from 1.3-2.0 kG in stars younger than about 120 Myr to 0.2-0.8 kG in older stars. The mean field strength shows a clear correlation with the Rossby number and with the coronal and chromospheric emission indicators. Our results suggest that magnetic regions have roughly the same local field strength B ≈ 3.2 kG in all stars, with the filling factor f of these regions systematically increasing with stellar activity. Comparing our results with the spectropolarimetric analyses of global magnetic fields in the same stars, we find that ZDI recovers about 1% of the total magnetic field energy in the most active stars. This figure drops to just 0.01% for the least active targets.

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The effect of stellar activity on the spectroscopic stellar parameters of the young solar twin HIP 36515

Cited by 51 publications

References 39 publications

The GALAH survey: Chemical homogeneity of the Orion complex

The GALAH survey: Chemical homogeneity of the Orion complex

The GAPS Programme at TNG

Hidden magnetic fields of young suns

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