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Rotational velocity, lithium abundance, and the mass depth of the outer convective zone are key parameters in the study of the processes at work in the stellar interior, in particular when examining the poorly understood processes operating…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. D. do Nascimento , J. S. da Costa , J. R. De Medeiros

The rotational evolution of a young stellar population can give informations about the rotation pattern of more evolved clusters. Combined with rotational period values of thousands of young stars and theoretical propositions about the…

Solar and Stellar Astrophysics · Physics 2021-11-18 Maria Jaqueline Vasconcelos , Jérôme Bouvier , Florian Gallet , Edson A. Luz Filho

We test the predictions of spectral synthesis models based on seven different massive-star prescriptions against Legacy ExtraGalactic UV Survey (LEGUS) observations of eight young massive clusters in two local galaxies, NGC 1566 and NGC…

I present the results of a programme to monitor the strengths of the Li I 6708A, K I 7699A and chromospheric Halpha lines in a group of cool Pleiades stars. Consistent instrumentation and analysis techniques are used to show that there is…

Astrophysics · Physics 2009-10-31 R. D. Jeffries

We compute rotating 1D stellar evolution models that include a modified temperature gradient in convection zones and criterion for convective instability inspired by rotating 3D hydrodynamical simulations performed with the MUSIC code. In…

Solar and Stellar Astrophysics · Physics 2021-10-27 Thomas Constantino , Isabelle Baraffe , Thomas Goffrey , Jane Pratt , Thomas Guillet , Dimitar Vlaykov , Louis Amard

Using data from the HATNet survey for transiting exoplanets we measure photometric rotation periods for 368 Pleiades stars with 0.4 Msun < M < 1.3 Msun. We detect periodic variability for 74% of the cluster members in this mass range that…

Solar and Stellar Astrophysics · Physics 2010-06-07 Joel D. Hartman , Gáspár Á Bakos , Géza Kovács , Robert W. Noyes

In the presence of rotation-induced mixing, element diffusion still occurs in stellar radiative zones, although at a slower rate than in the case of a complete stability of the stellar gas. As a consequence, helium settling leads to…

Astrophysics · Physics 2009-11-07 Sylvie Vauclair , Sylvie Theado

B-type stars are known to rotate at various velocities, including very fast rotators near the critical velocity as the Be stars. In this paper, we provide stellar models covering the mass range between 1.7 to 15 Msun, which includes the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Cyril Georgy , Sylvia Ekström , Anahí Granada , Georges Meynet , Nami Mowlavi , Patrick Eggenberger , André Maeder

We study the radial dependence in stellar populations of 33 nearby early-type galaxies with central stellar velocity dispersions sigma* > 150 km/s. We measure stellar population properties in composite spectra, and use ratios of these…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Jenny E Greene , Jeremy D Murphy , Genevieve J Graves , James E Gunn , Sudhir Raskutti , Julia M Comerford , Karl Gebhardt

Eclipsing binaries with M-type components are still rare objects. Strong observational biases have made that today only a few eclipsing binaries with component masses below 0.6 Msun and well-determined fundamental properties are known.…

Astrophysics · Physics 2009-11-11 Ignasi Ribas

We present NLTE Li abundances for 88 stars in the metallicity range -3.5 < [Fe/H] < -1.0. The effective temperatures are based on the infrared flux method with improved E(B-V) values obtained mostly from interstellar NaI D lines. The Li…

Solar and Stellar Astrophysics · Physics 2015-05-19 Jorge Melendez , Luca Casagrande , Ivan Ramirez , Martin Asplund , William Schuster

At least 10-15% of nearby sun-like stars have known Jupiter-mass planets. In contrast, very few planets are found in mature open and globular clusters such as the Hyades and 47 Tuc. We explore here the possibility that this dichotomy is due…

Astrophysics · Physics 2009-05-12 R. Spurzem , M. Giersz , D. C. Heggie , D. N. C. Lin

We critically examine the constraints on internal angular momentum transport which can be inferred from the spin down of open cluster stars. The rotation distribution inferred from rotation velocities and periods are consistent for larger…

Solar and Stellar Astrophysics · Physics 2014-11-20 Pavel A. Denissenkov , Marc Pinsonneault , Donald M. Terndrup , Grant Newsham

We present the Pre-Main-Sequence (PMS) evolutionary tracks of stars with 0.0065~5.0Ms. The models were evolved from the PMS stellar birthline to the onset of hydrogen burning in the core. The convective turnover timescales which enables an…

Astrophysics · Physics 2016-07-20 Youn Kil Jung , Yong-Cheol Kim

We analyze the physical properties of stellar clusters that are detected in massive star-forming regions in the MYStIX project--a comparative, multiwavelength study of young stellar clusters within 3.6 kpc that contain at least one O-type…

Lithium abundances determined by spectral synthesis from both the 6708A resonance line and the 6104 subordinate line are reported for 11 late-type Pleiades stars, including spectra previously analysed by Russell (1996). We report a 0.7 dex…

Astrophysics · Physics 2009-11-07 A. Ford , J. Jeffries , B. Smalley

We investigate the viability of a model in which the chemical anomalies among Globular Cluster stars are due to accretion of gas onto the protostellar discs of low mass stars. This model has been suggested as a way to reduce the large…

Solar and Stellar Astrophysics · Physics 2015-06-22 Francesca D'Antona , Paolo Ventura , Thibaut Decressin , Enrico Vesperini , Annibale D'Ercole

WIYN/Hydra spectroscopy (at R~15,000) of the moderately metal-rich Praesepe and Hyades open clusters was used to study their main sequence (MS) iron ([Fe/H]) and lithium (A(Li)) abundances. Self-consistent [Fe/H] and Li analyses of these…

Solar and Stellar Astrophysics · Physics 2017-03-08 Jeffrey D. Cummings , Constantine P. Deliyannis , Ryan M. Maderak , Aaron Steinhauer

We compare the properties of recent samples of the lithium abundances in halo stars to one another and to the predictions of theoretical models including rotational mixing, and we examine the data for trends with metal abundance. We find…

Astrophysics · Physics 2008-11-26 M. H. Pinsonneault , G. Steigman , T. P. Walker , V. K. Narayanan

The period versus mass diagrams (i.e., rotational sequences) of open clusters provide crucial constraints for angular momentum evolution studies. However, their memberships are often heavily contaminated by field stars, which could…

Solar and Stellar Astrophysics · Physics 2021-12-08 Diego Godoy-Rivera , Marc H. Pinsonneault , Luisa M. Rebull