BD+48 740—Li OVERABUNDANT GIANT STAR WITH A PLANET: A CASE OF RECENT ENGULFMENT?

Adamów, M.; Niedzielski, A.; Villaver, E.; Nowak, G.; Wolszczan, A.

doi:10.1088/2041-8205/754/1/l15

Cited by 88 publications

(82 citation statements)

References 45 publications

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“…127 hosts a brown dwarf of 19.8 M J at a distance of 2.4 AU with a period of 678 days (LM07). One can then speculate that a possible explanation for the enhanced Li observed in this star is the engulfment of a putative short-period planet that previously existed in the system as might be the case of other Li-rich planet hosts presented in Adamów et al (2012Adamów et al ( , 2014.…”

Section: Ngc 4349 No 127mentioning

confidence: 87%

Searching for Li-rich giants in a sample of 12 open clusters

Delgado-Mena

Tsantaki

Sousa

et al. 2016

A&A

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Aims. The aim of this work is to search for Li-rich giants in a sample of clusters where planets have been searched, thus we can study the planet engulfment scenario to explain Li replenishment using a proper comparison sample of stars without detected giant planets. Methods. We derived Li abundances for a sample of 67 red giant stars in 12 different open clusters using standard spectral synthesis techniques and high-resolution spectra (from HARPS and UVES). We also determined masses, ages, and radius from PARSEC stellar isochrones to constrain the evolutionary stage of these stars. Results. We found three stars in different clusters with clearly enhanced Li abundances compared to other stars within the cluster. Interestingly, the only two stars with a detected substellar companion in our sample belong to that group. One of the planet hosts, NGC 2423 No. 3, might lie close to the luminosity bump on the HR diagram, a phase where Li production by the Cameron-Fowler process is supported by extra-mixing to bring fresh Li up to the surface. On the other hand, NGC 4349 No. 127 is a more massive and more evolved giant that does not seem to be in the evolutionary phase where other Li-rich stars are found. We discuss the possibility that the Li enhancement of this star is triggered by the engulfment of a planet, considering that close-in planets hardly survive the RGB tip and the early AGB phases.

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Section: Ngc 4349 No 127mentioning

confidence: 87%

Searching for Li-rich giants in a sample of 12 open clusters

Delgado-Mena

Tsantaki

Sousa

et al. 2016

A&A

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“…1), as derived by the comparison with isochrones from the Girardi et al (2002) collection and adopting the K98 parameters in terms of distance, reddening and age (4 Gyr). Other cases of lithium-rich giants associated with the red-clump phase have been suggested (Ruchti et al 2011;Kumar et al 2011;Adamów et al 2012b;Martell & Shetrone 2013), but, being field stars, they lacked any firm determination of their evolutionary status.…”

Section: Discussionmentioning

confidence: 98%

“…Planet engulfment can be advocated to explain lithium-rich giants, and some suggestive cases have been presented (see, e.g., Adamów et al 2012a). However, accretion of a planet or a brown dwarf in the stellar envelope would not be able to increase the surface abundance above the Population I value.…”

Section: Introductionmentioning

confidence: 99%

A super lithium-rich red-clump star in the open cluster Trumpler 5

Monaco

Boffin

Bonifacio

et al. 2014

A&A

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Context. The existence of lithium-rich low-mass red giant stars still represents a challenge for stellar evolution models. Stellar clusters are privileged environments for this kind of investigation. Aims. To investigate the chemical abundance pattern of the old open cluster Trumpler 5, we observed a sample of four red-clump stars with high-resolution optical spectrographs. One of them (#3416) reveals extremely strong lithium lines in its spectrum. Methods. One-dimensional, local thermodynamic equilibrium analysis was performed on the spectra of the observed stars. A 3D-NLTE analysis was performed to derive the lithium abundance of star #3416. Results. Star #3416 is super Li-rich with A(Li) = 3.75 dex. The lack of 6 Li enrichment ( 6 Li/ 7 Li < 2%), the low carbon isotopic ratio ( 12 C/ 13 C = 14 ± 3), and the lack of evidence for radial velocity variation or enhanced rotational velocity (v sin i = 2.8 km s −1 ) all suggest that lithium production has occurred in this star through the Cameron & Fowler mechanism. Conclusions. We identified a super Li-rich core helium-burning, red-clump star in an open cluster. Internal production is the most likely cause of the observed enrichment. Given the expected short duration of a star's Li-rich phase, enrichment is likely to have occurred at the red clump or in the immediately preceding phases, namely during the He-flash at the tip of the red giant branch (RGB) or while ascending the brightest portion of the RGB.

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“…The first two stars are members of binary systems (Abt 1981;Meisel 1968), where the latter is in addition chromospherically active (e.g., Strassmeier 1994). The reason for absolute RV discrepancy for TYC 3304-00090-1 is discussed in more detail in Adamów et al (2012).…”

Section: Comparison With Literature Datamentioning

confidence: 97%

The Penn State-Toruń Centre for Astronomy Planet Search stars

Zieliński

Niedzielski

Wolszczan

et al. 2012

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Aims. We present basic atmospheric parameters (T eff , log g, v t , and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ∼1000 star sample observed within the Penn State-Toruń Centre for Astronomy Planet Search with the High Resolution Spectrograph of the 9.2 m Hobby-Eberly Telescope. The stellar parameters (luminosities, masses, radii) are key to properly interpreting newly discovered low-mass companions, while a systematic study of the complete sample will create a basis for future statistical considerations concerning the appearance of low-mass companions around evolved low-and intermediate-mass stars. Methods. The atmospheric parameters were derived using a strictly spectroscopic method based on the LTE analysis of equivalent widths of Fe I and Fe II lines. With existing photometric data and the Hipparcos parallaxes, we estimated stellar masses and ages via evolutionary tracks fitting. The stellar radii were calculated from either estimated masses and the spectroscopic log g or from the spectroscopic T eff and estimated luminosities. The absolute radial velocities were obtained by cross-correlating spectra with a numerical template. Results. We completed the spectroscopic analysis for 332 stars, 327 of which were found to be giants. A simplified analysis was applied to the remaining 16 stars, which had incomplete data. The results show that our sample is composed of stars with effective temperatures ranging from 4055 K to 6239 K, with log g between 1.39 and 4.78 (5 dwarfs were identified). The estimated luminosities are between log L/L = −1.0 and 3 and lead to masses ranging from 0.6 to 3.4 M . Only 63 stars with masses larger than 2 M were found. The radii of our stars range from 0.6 to 52 R with the vast majority between 9−11 R . The stars in our sample are generally less metal-abundant than the Sun with median [Fe/H] = −0.15. The estimated uncertainties in the atmospheric parameters were found to be comparable to those reached in other studies. However, due to lack of precise parallaxes, the stellar luminosities and, in turn, the masses are far less precise, within 0.2 M in best cases and 0.3 M on average.

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BD+48 740—Li OVERABUNDANT GIANT STAR WITH A PLANET: A CASE OF RECENT ENGULFMENT?

Cited by 88 publications

References 45 publications

Searching for Li-rich giants in a sample of 12 open clusters

Searching for Li-rich giants in a sample of 12 open clusters

A super lithium-rich red-clump star in the open cluster Trumpler 5

The Penn State-Toruń Centre for Astronomy Planet Search stars

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