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Related papers: Lithium in the Intermediate-Age Open Cluster, NGC …

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We have identified a large number of possible very low mass members of the cluster IC2391 based primarily on their location in an I versus (R-I)_C CM diagram. We have obtained new photometry and low resolution ($\Delta \lambda = 2.7$ \AA)…

Astrophysics · Physics 2007-05-23 D. Barrado y Navascues , J. R. Stauffer , B. M. Patten

HYDRA spectra of 287 stars in the field of NGC 2506 from the turnoff through the giant branch are analyzed. With previous data, 22 are identified as probable binaries; 90 more are classified as potential non-members. Spectroscopic analyses…

Solar and Stellar Astrophysics · Physics 2018-03-21 B. J. Anthony-Twarog , D. B. Lee-Brown , C. P. Deliyannis , B. A. Twarog

Spectroscopy of 333 NGC 6819 stars and Gaia astrometry are used to map Li evolution from the giant branch tip to 0.5 mag below the Li dip. Isochrone comparison with [Fe/H] = -0.04, based upon neural network spectroscopic analysis, produces…

Solar and Stellar Astrophysics · Physics 2019-10-09 C. P. Deliyannis , B. J. Anthony-Twarog , D. B. Lee-Brown , B. A. Twarog

We present FLAMES/GIRAFFE spectroscopy obtained at the Very Large Telescope (VLT). Using these observations we have been able for the first time to observe the Li I doublet in the Main Sequence stars of a Globular Cluster. We also observed…

Astrophysics of Galaxies · Physics 2015-05-14 J. I. González Hernández , P. Bonifacio , E. Caffau , M. Steffen , H. -G. Ludwig , N. Behara , L. Sbordone , R. Cayrel , S. Zaggia

High-dispersion spectra of 89 potential members of the old, super-metal-rich open cluster, NGC 6253, have been obtained with the HYDRA multi-object spectrograph. Based upon radial-velocity measurements alone, 47 stars at the turnoff of the…

Astrophysics of Galaxies · Physics 2015-05-18 B. J. Anthony-Twarog , C. P. Deliyannis , B. A. Twarog , J. D. Cummings , R. M. Maderak

The prediction of the PLANCK-constrained primordial lithium abundance in the Universe is in discordance with the observed Li abundances in warm Population II dwarf and subgiant stars. Among the physically best motivated ideas, it has been…

We report discovery of significant depletion of Li on the surfaces of F dwarf stars in the 150-Myr-old open cluster M35, analagous to a feature in the 700-Myr-old Hyades cluster that has been referred to as the ``Li gap.'' We have caught…

Astrophysics · Physics 2009-11-10 Aaron Steinhauer , Constantine P. Deliyannis

Thanks to the high multiplex and efficiency of Giraffe at the VLT we have been able for the first time to observe the Li I doublet in the Main Sequence (MS) stars of a Globular Cluster. At the same time we observed Li in a sample of…

Astrophysics of Galaxies · Physics 2015-05-14 J. I. González Hernández , P. Bonifacio , E. Caffau , M. Steffen , H. -G. Ludwig , N. Behara , L. Sbordone , R. Cayrel , S. Zaggia

During Big Bang nucleosynthesis (BBN) in the first 15 minutes of the Universe some $^7$Li was created along with isotopes of H and He. The determination of that primordial value of Li can help constrain the conditions at that time. The…

Solar and Stellar Astrophysics · Physics 2024-06-26 Ann Merchant Boesgaard , Constantine P. Deliyannis

We present lithium abundances for ~50 X-ray selected candidate members of the 30-50 Myr old open clusters IC 2602 and IC 2391. These data enlarge and extend to cooler temperatures previous Li surveys of these clusters by Stauffer et al.…

Astrophysics · Physics 2009-11-06 S. Randich , R. Pallavicini , G. Meola , J. R. Stauffer , Suchitra C. Balachandran

We present a detailed chemical analysis of 22 stars along the colour-magnitude sequence of the intermediate-age (1.7 Gyr) open cluster IC 4651. We find for the cluster a well-defined Fe abundance of [Fe/H]= 0.10 +/- 0.03 (internal errors),…

Astrophysics · Physics 2009-11-10 L. Pasquini , S. Randich , M. Zoccali , V. Hill , C. Charbonnel , B. Nordstrom

We present high resolution observations (FWHM=15 km/sec) of the Li region in 5 stars belonging to the old (14 Gyrs), metal rich ([Fe/H]=-0.7) globular cluster 47Tuc. At the ESO NTT telescope we obtained EMMI spectra for three V about 17.4…

Astrophysics · Physics 2011-05-23 Luca Pasquini , Paolo Molaro

Open clusters (OC) of 1-3 Gyr age contain intermediate-to-low-mass stars in evolutionary phases of multiple relevance to understanding Li evolution. Stars leaving the main sequence (MS) from the hot side of the Lithium dip (LD) at a fixed…

Solar and Stellar Astrophysics · Physics 2020-06-22 B. A. Twarog , B. J. Anthony-Twarog , C. P. Deliyannis , A. Steinhauer

We present new high resolution spectroscopic observations of the intermediate age (~2 Gyr) open cluster NGC 752. We investigate the Li vs. Teff distribution and we obtain a new accurate determination of the cluster metallicity. We compare…

Astrophysics · Physics 2009-11-10 P. Sestito , S. Randich , R. Pallavicini

Lithium abundances in open clusters provide an effective way of probing mixing processes in the interior of solar-type stars and convection is not the only mixing mechanism at work. To understand which mixing mechanisms are occurring in…

Solar and Stellar Astrophysics · Physics 2016-05-25 Matthieu Castro , Tharcísyo Duarte , Giancarlo Pace , José Dias do Nascimento

We have obtained intermediate-resolution optical spectroscopy of 44 candidate very low mass members of the nearby young open cluster IC2391. Of these, 26 spectra are totally new, 14 were already analyzed in a previous paper and another four…

Astrophysics · Physics 2016-07-01 David Barrado y Navascues , John R. Stauffer , Ray Jayawardhana

The so-called lithium depletion boundary (LDB) provides a secure and independent tool for deriving the ages of young open clusters.In this context, our goal is to determine membership for a sample of 147 photometrically selected candidates…

Astrophysics · Physics 2009-11-13 S. Manzi , S. Randich , W. J. de Wit , F. Palla

Most Globular Clusters are believed to host a single stellar populations. They can thus be considered a good place to study the Spite plateau and probe for possible evolutionary modifications of the Li content. We want to determine the Li…

Astrophysics of Galaxies · Physics 2015-05-14 J. I. Gonzalez Hernandez , P. Bonifacio , E. Caffau , M. Steffen , H. -G. Ludwig , N. T. Behara , L. Sbordone , R. Cayrel , S. Zaggia

We present the abundance measurements of several elements (Fe, Ca, Na, Ni, Ti, Al, Cr, Si) for 20 solar--type stars belonging to four Galactic open clusters: NGC 3680, IC 4651, Praesepe, and M 67. Oxygen abundances were in addition measured…

Astrophysics · Physics 2009-11-13 G. Pace , L. Pasquini , P. François

We address the existence and origin of the lithium (Li) desert, a region in the Li - T_eff plane sparsely populated by stars. Here we analyze some of the explanations that have been suggested for this region, including mixing in the late…

Solar and Stellar Astrophysics · Physics 2018-06-13 Claudia Aguilera-Gómez , Iván Ramírez , Julio Chanamé