Planet signatures and effect of the chemical evolution of the Galactic thin-disk stars

Spina, L.; Meléndez, Jorge; Ramírez, Iván

doi:10.1051/0004-6361/201527429

Cited by 67 publications

(87 citation statements)

References 61 publications

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“…Along this line, hints of a correlation between the T C slopes and the stellar age have already been reported (Adibekyan et al 2014;Maldonado et al 2015;Nissen 2015;Spina et al 2016). Adibekyan et al (2014) use the stellar mean galactocentric distance as a proxy of the stellar birthplace -finding tentative evidence of a correlation with the T C slope.…”

Section: Discussionmentioning

confidence: 67%

“…Finally, we note that, while general trends between the T C slopes and evolutionary parameters may be present, it does not exclude other processes, such as planetary formation, planet engulfment, or dust-gas segregation in protoplanetary discs that may affect the stellar photospheric abundance of refractory elements relative to volatiles (Gaidos 2015;Spina et al 2016).…”

Section: Discussionmentioning

confidence: 89%

“…We note that the correlations were performed using all stars (planet and non-planet hosts) together. Less massive (Nissen 2015;Spina et al 2016). Following this line of reasoning, a comparison of the stellar masses and ages between planet hosts and non-planet hosts were performed.…”

Section: Trends With Evolutionary Propertiesmentioning

confidence: 99%

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Evolved stars and the origin of abundance trends in planet hosts

Maldonado

Villaver

2016

A&A

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Context. Detailed chemical abundance studies have revealed different trends between samples of planet and non-planet hosts. Whether these trends are related to the presence of planets or not is strongly debated. At the same time, tentative evidence that the properties of evolved stars with planets may be different from what we know for main-sequence hosts has recently been reported. Aims. We aim to test whether evolved stars with planets show any chemical peculiarity that could be related to the planet formation process. Methods. In a consistent way, we determine the metallicity and individual abundances of a large sample of evolved (subgiants and red giants) and main-sequence stars that are with and without known planetary companions, and discuss their metallicity distribution and trends. Our methodology is based on the analysis of high-resolution échelle spectra (R 57 000) from 2−3 m class telescopes. It includes the calculation of the fundamental stellar parameters, as well as individual abundances of C, O , Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, and Zn. Results. No differences in the [X/Fe] vs. condensation temperature (T C ) slopes are found between the samples of planet and nonplanet hosts when all elements are considered. However, if the analysis is restricted to only refractory elements, differences in the T C -slopes between stars with and without known planets are found. This result is found to be dependent on the stellar evolutionary stage, as it holds for main-sequence and subgiant stars, while there seems to be no difference between planet and non-planet hosts among the sample of giants. A search for correlations between the T C -slope and the stellar properties reveals significant correlations with the stellar mass and the stellar age. The data also suggest that differences in terms of mass and age between main-sequence planet and non-planet hosts may be present. Conclusions. Our results are well explained by radial mixing in the Galaxy. The sample of giants contains stars that are more massive and younger than their main-sequence counterparts. This leads to a sample of stars that are possibly less contaminated by stars that were not born in the solar neighbourhood, leading to no chemical differences between planet and non-planet hosts. The sample of main-sequence stars may contain more stars from the outer disc (specially the non-planet host sample) which might lead to the differences observed in the chemical trends.

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Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 89%

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Evolved stars and the origin of abundance trends in planet hosts

Maldonado

Villaver

2016

A&A

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“…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

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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.

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“…Campante et al 2015), dust and planets around giant branch stars (Bonsor et al 2014;Trifonov et al 2015;Lillo-Box, Barrado & Correia 2016;Wittenmyer et al 2016), and polluted white dwarfs at a variety of cooling ages (Koester, Gänsicke & Farihi 2014;Hollands et al, in preparation) all provide necessary constraints. Main-sequence planetary studies have now begun to utilize white dwarf atmosphere chemical signatures in their planetary formation models (Carter-Bond et al 2012;Morlok et al 2014;Bergin et al 2015;Ramírez et al 2015;Mordasini et al 2016;Spina, Meléndez & Ramírez 2016), and future missions such as PLATO will further enable comparisons with well-constrained stellar ages (Veras et al 2015b). Full-lifetime simulations incorporating all of the necessary physics ( fig.…”

Section: M P O Rta N C E O F D E T E R M I N I N G Fat Ementioning

confidence: 99%

The unstable fate of the planet orbiting the A star in the HD 131399 triple stellar system

Veras

Mustill

Gänsicke

2016

Mon. Not. R. Astron. Soc.

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Validated planet candidates need not lie on long-term stable orbits, and instability triggered by post-main-sequence stellar evolution can generate architectures which transport rocky material to white dwarfs, hence polluting them. The giant planet HD 131399Ab orbits its parent A star at a projected separation of about 50-100 au. The host star, HD 131399A, is part of a hierarchical triple with HD 131399BC being a close binary separated by a few hundred au from the A star. Here, we determine the fate of this system, and find the following: (i) Stability along the main sequence is achieved only for a favourable choice of parameters within the errors. (ii) Even for this choice, in almost every instance, the planet is ejected during the transition between the giant branch and white dwarf phases of HD 131399A. This result provides an example of both how the free-floating planet population may be enhanced by similar systems and how instability can manifest in the polluted white dwarf progenitor population.

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Planet signatures and effect of the chemical evolution of the Galactic thin-disk stars

Cited by 67 publications

References 61 publications

Evolved stars and the origin of abundance trends in planet hosts

Evolved stars and the origin of abundance trends in planet hosts

Discovery of an activity cycle in the solar analog HD 45184

The unstable fate of the planet orbiting the A star in the HD 131399 triple stellar system

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