Search for associations containing young stars (SACY)

Almeida, P. Viana; Santos, N. C.; Melo, C.; Eiff, M. Ammler‐von; Torres, C. A. O.; Quast, G.; Gameiro, J. F.; Sterzik, M.

doi:10.1051/0004-6361/200811194

Cited by 71 publications

(57 citation statements)

References 38 publications

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“…The same scenario for the origin of metal-rich planet hosts were proposed in some other papers (e.g. Ecuvillon et al 2007;Santos et al 2008;Viana Almeida et al 2009). …”

Section: Kinematics Of Planet-hosting Starssupporting

confidence: 68%

Overabundance ofα-elements in exoplanet-hosting stars

Adibekyan

Santos

Sousa

et al. 2012

A&A

Self Cite

125

115

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We present the results for a chemical abundance analysis between planet-hosting and stars without planets for 12 refractory elements for a total of 1111 nearby FGK dwarf stars observed within the context of the HARPS GTO programs. Of these stars, 109 are known to harbour high-mass planetary companions and 26 stars are hosting exclusively Neptunians and super-Earths. We found that the [X/Fe] ratios for Mg, Al, Si, Sc, and Ti both for giant and low-mass planet hosts are systematically higher than those of comparison stars at low metallicities ([Fe/H] < ∼ from −0.2 to 0.1 dex depending on the element). The most evident discrepancy between planet-hosting and stars without planets is observed for Mg. Our data suggest that the planet incidence is greater among the thick disk population than among the thin disk for mettallicities bellow −0.3 dex. After examining the [α/Fe] trends of the planet host and non-host samples we conclude that a certain chemical composition, and not the Galactic birth place of the stars, is the determinating factor for that. The inspection of the Galactic orbital parameters and kinematics of the planet-hosting stars shows that Neptunian hosts tend to belong to the "thicker" disk compared to their high-mass planet-hosting counterparts. We also found that Neptunian hosts follow the distribution of high-α stars in the UW vs. V velocities space, but they are more enhanced in Mg than high-α stars without planetary companions. Our results indicate that some metals other than iron may also have an important contribution to planet formation if the amount of iron is low. These results may provide strong constraints for the models of planet formation, especially for planets with low mass.

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“…The same scenario for the origin of metal-rich planet hosts were proposed in some other papers (e.g. Ecuvillon et al 2007;Santos et al 2008;Viana Almeida et al 2009). …”

Section: Kinematics Of Planet-hosting Starssupporting

confidence: 68%

Overabundance ofα-elements in exoplanet-hosting stars

Adibekyan

Santos

Sousa

et al. 2012

A&A

Self Cite

125

115

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“…In particular, the surface gravities were determined for the weak-line T Tauri stars (WTTS; James et al 2006;Santos et al 2008) as well as for the post-T Tauri stars (Viana Almeida et al 2009). Stars of both types are finishing their contraction phase and approaching the Main Sequence.…”

Section: Discussionmentioning

confidence: 99%

An in-depth analysis of the RZ Piscium atmosphere

Potravnov

Гринин

Ilyin³

et al. 2014

A&A

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The star RZ Psc is one of the most unusual members of the UX Ori star family. It demonstrates all properties that are typical of these stars (the light variability, high linear polarization in deep minima, the blueing effect), but until recently there has been no obvious evidence of its youth. Recently, we have shown that RZ Psc is in the transitional evolutionary stage between stars with the primordial and debris disks. In this paper we present the results of the quantitative analysis of the star's spectrum. Using the high-resolution (R = 46 000) spectrum of RZ Psc obtained with Nordic Optical Telescope, we determined T eff = 5350 ± 150 K, log g = 4.2 ± 0.2, [M/H] = −0.3 ± 0.05. These parameters agree well with the same ones as for the stars recently passed the T Tauri star evolutionary stage. This supports our previous suggestion about the evolutionary status of RZ Psc as the post-T Tauri and post-UX Ori star.

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“…We made the assumption that the objects have solar abundances. This is likely the case given the recent metallicity measurements in Chameleon I (James et al 2006;Santos et al 2008), Taurus (Santos et al 2008), Ursa Major group (Ammler-von Eiff & Guenther 2009;Biazzo et al 2012), and young associations (Viana Almeida et al 2009;Biazzo et al 2012;Barenfeld et al 2013). We also analyzed the TWA 22 A and B spectra using the BT-SETTL grids and the GAIA-COND library (Brott & Hauschildt 2005).…”

Section: The Librariesmentioning

confidence: 99%

A library of near-infrared integral field spectra of young M–L dwarfs

Bonnefoy

Chauvin

Lagrange

et al. 2014

A&A

144

204

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Context. At young ages, low surface gravity affects the atmospheric properties of ultracool dwarfs. The impact on medium-resolution near-infrared (NIR) spectra has only been slightly investigated at the M-L transition so far. Aims. We present a library of NIR (1.1-2.45 µm) medium-resolution (R ∼ 1500-2000) integral field spectra of 15 young M6−L0 dwarfs. We aim at deriving updated NIR spectral type, luminosity, and physical parameters (T eff , log g, M, L/L ) for each source. This work also aims at testing the latest generation of BT-SETTL atmospheric models. Methods. We estimated spectral types using spectral indices and the spectra of young objects classified in the optical. We used the 2010 and 2012 releases of the BT-SETTL synthetic spectral grid and cross-checked the results with the DRIFT-PHOENIX models to derive the atmospheric properties of the sources. Results. We do not find significant differences between the spectra of young companions and those of young isolated brown dwarfs in the same spectral type range. We derive infrared spectral types L0 ± 1, L0 ± 1, M9.5 ± 0.5, M9.5 ± 0.5, M9.25 ± 0.25, M8 +0.5 −0.75 , and M8.5 ± 0.5 for AB Pic b, Cha J110913-773444, USco CTIO 108B, GSC 08047-00232 B, DH Tau B, CT Cha b, and HR7329B, respectively. The BT-SETTL and DRIFT-PHOENIX models yield close T eff and log g estimates for each source. The models seem to show a 600 +600 −300 K drop in the effective temperature at the M-L transition. Assuming the former temperatures are correct, we then derive new mass estimates that confirm that DH Tau B, USco CTIO 108B, AB Pic b, KPNO Tau 4, OTS 44, and Cha1109 lie inside or at the boundary of the planetary mass range. We combine the empirical luminosities of the M9.5-L0 sources to the T eff to derive semi-empirical radii estimates that do not match "hot-start" evolutionary models predictions at 1-3 Myr. We use complementary data to demonstrate that atmospheric models are able to reproduce the combined optical and infrared spectral energy distribution, together with the NIR spectra of these sources simultaneously. But the models still fail to represent the dominant features in the optical. This issue raises doubts on the ability of these models to predict effective temperatures from NIR spectra alone. Conclusions. The library provides templates for characterizing other young and late type objects. The study advocates the use of photometric and spectroscopic information over a broad range of wavelengths to study the properties of very low-mass young companions to be detected with the planet imagers (Subaru/SCExAO, LBT/LMIRCam, Gemini/GPI, VLT/SPHERE).

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Search for associations containing young stars (SACY)

Cited by 71 publications

References 38 publications

Overabundance ofα-elements in exoplanet-hosting stars

Overabundance ofα-elements in exoplanet-hosting stars

An in-depth analysis of the RZ Piscium atmosphere

A library of near-infrared integral field spectra of young M–L dwarfs

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