Searching for signatures of planet formation in stars with circumstellar debris discs

Maldonado, J.; Eiroa, C.; Villaver, E.; Montesinos, B.; Mora, A.

doi:10.1051/0004-6361/201525764

Cited by 70 publications

(102 citation statements)

References 96 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The authors concluded that the T c trend depends on the Galactic chemical evolution (GCE) and suggested that the difference in T c slopes, observed between planet hosting solar analogs and solar analogs without detected planets, may reflect their age difference. Maldonado et al (2015) and Maldonado & Villaver (2016) also confirmed the correlation of the T c trend with age, and further suggested a significant correlation with the stellar radius and mass. Önehag et al (2014) in turn showed that while the Sun shows a different T c trend when compared to the solarfield twins, it shows a very similar abundance trend with T c when compared to the stars from the open cluster M 67.…”

Section: Introductionsupporting

confidence: 55%

ζ²Reticuli, its debris disk, and its lonely stellar companionζ¹Ret

Adibekyan

Delgado-Mena

Figueira

et al. 2016

A&A

View full text Add to dashboard Cite

Context. Several studies have reported a correlation between the chemical abundances of stars and condensation temperature (known as T c trend). Very recently, a strong T c trend was reported for the ζ Reticuli binary system, which consists of two solar analogs. The observed trend in ζ 2 Ret relative to its companion was explained by the presence of a debris disk around ζ 2 Ret. Aims. Our goal is to re-evaluate the presence and variability of the T c trend in the ζ Reticuli system and to understand the impact of the presence of the debris disk on a star. Methods. We used very high-quality spectra of the two stars retrieved from the HARPS archive to derive very precise stellar parameters and chemical abundances. We derived the stellar parameters with the classical (nondifferential) method, while we applied a differential line-by-line analysis to achieve the highest possible precision in abundances, which are fundamental to explore for very tiny differences in the abundances between the stars. Results. We confirm that the abundance difference between ζ 2 Ret and ζ 1 Ret shows a significant (∼2σ) correlation with T c . However, we also find that the T c trends depend on the individual spectrum used (even if always of very high quality). In particular, we find significant but varying differences in the abundances of the same star from different individual high-quality spectra. Conclusions. Our results for the ζ Reticuli system show, for example, that nonphysical factors, such as the quality of spectra employed and errors that are not accounted for, can be at the root of the T c trends for the case of individual spectra.

show abstract

Section: Introductionsupporting

confidence: 55%

ζ²Reticuli, its debris disk, and its lonely stellar companionζ¹Ret

Adibekyan

Delgado-Mena

Figueira

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…We also added individual objects with activity periods reported by Metcalfe et al (2010), DeWarf et al (2010), and Egeland et al (2015). We also included the parameters of HD 45184 that were determined by different literature works (Sousa et al 2008;Bensby et al 2014;Battistini & Bensby 2015;Maldonado et al 2015;Nissen 2015;Spina et al 2016). These are shown as blue filled circles with error bars.…”

Section: Discussionmentioning

confidence: 99%

Discovery of an activity cycle in the solar analog HD 45184

Flores

González

Arancibia

et al. 2016

A&A

View full text Add to dashboard Cite

Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca ii H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims. We aim to detect activity cycles in solar-analog stars and determine whether they can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184 using HARPS spectra. The temporal coverage and high quality of the spectra allow us to detect both long-and short-term activity variations. Methods. We analysed the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. To search for line-core flux variations, we focused on Ca ii H&K and Balmer Hα and Hβ lines, which are typically used as optical chromospheric activity indicators. We calculated the HARPS-S index from Ca ii H&K lines and converted it into the Mount Wilson scale. In addition, we also considered the equivalent widths of Balmer lines as activity indicators. Moreover, we analysed the possible variability of Fe ii and other metallic lines in the optical spectra. The spectral variations were analysed for periodicity using the Lomb-Scargle periodogram. Results. We report for the first time a long-term 5.14-yr activity cycle in the solar-analog star HD 45184 derived from Mount Wilson S index. This makes HD 45184 one of most similar stars to the Sun with a known activity cycle. The variation is also evident in the first lines of the Balmer series, which do not always show a correlation with activity in solar-type stars. Notably, unlike the solar case, we also found that the equivalent widths of the high photospheric Fe ii lines (4924 Å, 5018 Å and 5169 Å) are modulated (±2 mÅ) by the chromospheric cycle of the star. These metallic lines show variations above 4σ in the rms spectrum, while some Ba ii and Ti ii lines present variations at 3σ level, which could be considered as marginal variations. From short-term modulation of the S index we calculate a rotational period of 19.98 days, which agrees with its mean chromospheric activity level. We also clearly show that the activity cycles of HD 45184 can be detected in both Fe ii and Balmer lines.

show abstract

“…The works of Meléndez et al (2009) and Ramírez et al (2009) have triggered several papers investigating relations between [X/Fe]-T C slopes and the existence of planets around stars (Gonzalez et al 2010;González Hernández et al 2010, 2013Schuler et al 2011;Adibekyan et al 2014;Maldonado et al 2015). The results obtained are not very conclusive, partly because the stars included span wider ranges in T eff , log g, and [Fe/H] than the solar twins in Meléndez et al (2009) making the abundance ratios less precise and introducing a dependence of the derived [X/Fe]-T C slopes on possible corrections for Galactic evolution effects.…”

Section: Introductionmentioning

confidence: 99%

High-precision abundances of elements in solar twin stars

Nissen

2015

A&A

252

304

View full text Add to dashboard Cite

Context. High-precision determinations of abundances of elements in the atmospheres of the Sun and solar twin stars indicate that the Sun has an unusually low ratio between refractory and volatile elements. This has led to the suggestion that the relation between abundance ratios, [X/Fe], and elemental condensation temperature, T C , can be used as a signature of the existence of terrestrial planets around a star. Aims. HARPS spectra with S /N 600 for 21 solar twin stars in the solar neighborhood and the Sun (observed via reflected light from asteroids) are used to determine very precise (σ ∼ 0.01 dex) differential abundances of elements in order to see how well [X/Fe] is correlated with T C and other parameters such as stellar age. Methods. Abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, Cr, Fe, Ni, Zn, and Y are derived from equivalent widths of weak and medium-strong spectral lines using MARCS model atmospheres with parameters determined from the excitation and ionization balance of Fe lines. Non-LTE effects are considered and taken into account for some of the elements. In addition, precise (σ 0.8 Gyr) stellar ages are obtained by interpolating between Yonsei-Yale isochrones in the log g -T eff diagram. Results. It is confirmed that the ratio between refractory and volatile elements is lower in the Sun than in most of the solar twins (only one star has the same [X/Fe]-T C distribution as the Sun), but for many stars, the relation between [X/Fe] and T C is not well defined.

show abstract

Searching for signatures of planet formation in stars with circumstellar debris discs

Cited by 70 publications

References 96 publications

ζ²Reticuli, its debris disk, and its lonely stellar companionζ¹Ret

ζ²Reticuli, its debris disk, and its lonely stellar companionζ¹Ret

Discovery of an activity cycle in the solar analog HD 45184

High-precision abundances of elements in solar twin stars

Contact Info

Product

Resources

About

Searching for signatures of planet formation in stars with circumstellar debris discs

Cited by 70 publications

References 96 publications

ζ2Reticuli, its debris disk, and its lonely stellar companionζ1Ret

ζ2Reticuli, its debris disk, and its lonely stellar companionζ1Ret

Discovery of an activity cycle in the solar analog HD 45184

High-precision abundances of elements in solar twin stars

Contact Info

Product

Resources

About

ζ²Reticuli, its debris disk, and its lonely stellar companionζ¹Ret

ζ²Reticuli, its debris disk, and its lonely stellar companionζ¹Ret