Age Determinations of the Hyades, Praesepe, and Pleiades via MESA Models with Rotation

Gossage, Seth; Conroy, Charlie; Dotter, Aaron; Choi, Jieun; Rosenfield, Philip; Cargile, Phillip A.; Dolphin, Andrew E.

doi:10.3847/1538-4357/aad0a0

Cited by 141 publications

(134 citation statements)

References 124 publications

(150 reference statements)

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“…The Hyades cluster age of our models shown in Fig. 1, is 588 Myrs, in good agreement with Gossage et al (2018) (in particular with their model for a rotation of Ω/Ωc = 0.6) and references given therein. A long-standing literature age of the Hyades is 625 Myrs (Perryman et al (1998)).…”

Section: Derivation Of the Exact States Of Evolutionsupporting

confidence: 90%

Magnetic activity and evolution of the four Hyades K giants

Schröder

Mittag

Jack

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We determine the exact physical parameters of the four Hyades cluster K giants, using their parallaxes and atmospheric modeling of our red-channel TIGRE high-resolution spectra. Performing a comparison with well-tested evolutionary tracks, we derive exact masses and evolutionary stages. At an age of 588 (±60) Myrs and with a metallicity of Z=0.03 (consistent with the spectroscopic abundances), we find HD 27371 and HD 28307, the two less bright K giants, at the onset of central helium-burning, entering their blue loops with a mass of 2.62 M ⊙ , while the slightly brighter stars HD 28305 and HD 27697 are already exiting their blue loop. Their more advanced evolution suggests a higher mass of 2.75 M ⊙ .Notably, this pairing coincides with the different activity levels, which we find for these four stars from chromospheric activity monitoring with TIGRE and archival Mount Wilson data as well as from ROSAT coronal detections: The two less evolved K giants are the far more active pair, and we confidently confirm their rotation with periods of about 142 days. This work therefore provides some first, direct evidence of magnetic braking during the 130 Myrs lasting phase of central helium-burning, similar to what has long been known to occur to cool main-sequence stars.

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Section: Derivation Of the Exact States Of Evolutionsupporting

confidence: 90%

Magnetic activity and evolution of the four Hyades K giants

Schröder

Mittag

Jack

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…However, still some discrepancies are found in the age value, usually quoted between 600-800 Myr depending on methodology and models used (e.g. Brandt & Huang 2015;Gossage et al 2018).…”

Section: Chemical Taggingmentioning

confidence: 99%

“…The Hyades and NGC 2632 have been considerably observed in the past (e.g. Gebran et al 2010;Boesgaard et al 2013;Gossage et al 2018, among many others). Both appear to have similar in age, between 600 and 800 Myr, and metallicity ∼ +0.15 dex.…”

Section: Introductionmentioning

confidence: 99%

Differential abundances of open clusters and their tidal tails: Chemical tagging and chemical homogeneity

Casamiquela

Tarricq

Soubiran

et al. 2020

A&A

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Context. Well studied Open Clusters (OCs) of the Solar neighbourhood are frequently used as reference objects to test galactic and stellar theories. For that purpose their chemical composition needs to be known with a high level of confidence. It is also important to clarify if each OC is chemically homogeneous and if it has a unique chemical signature. Aims. The aims of this work are (1) to determine accurate and precise abundances of 22 chemical species (from Na to Eu) in the Hyades, Praesepe and Rupecht 147 using a large number of stars at different evolutionary states, (2) to evaluate the level of chemical homogeneity of these OCs, (3) to compare their chemical signatures. Methods. We gathered ∼800 high resolution and high signal-to-noise spectra of ∼100 members in the three clusters, obtained with the latest memberships based on Gaia DR2 data. We build a pipeline which computes atmospheric parameters and strictly line-by-line differential abundances among twin stars in our sample. With this method we are able to reach a very high precision in the abundances (0.01-0.02 dex in most of the elements). Results. We find large differences in the absolute abundances in some elements, which can be attributed to diffusion, NLTE effects or systematics in the analysis. For the three OCs, we find strong correlations in the differential abundances between different pairs of elements. According to our experiment with synthetic data, this can be explained by some level of chemical inhomogeneity. We compare differential abundances of several stars from the Hyades and Praesepe tails: the stars that differ more in chemical abundances also have distinct kinematics, even though they have been identified as members of the tail. Conclusions. It is possible to obtain high precision abundances using a differential analysis even when mixing spectra from different instruments. With this technique we find that the Hyades and Preasepe have the same chemical signature when G dwarfs and K giants are considered. Despite a certain level of inhomogeneity in each cluster, it is still possible to clearly distinguish the chemical signature of the older cluster Ruprecht 147 when compared to the Hyades and Praesepe.

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“…In this context, the lack of an eMSTO in NGC2509 may be related to the characteristics of the stellar rotation distribution of the cluster. In order to investigate this hypothesis, we present here some modelling efforts done with the MIST stellar evolution framework (Choi et al 2016;Dotter 2016;Choi et al 2018;Gossage et al 2018), which includes the effects of rotation. We began with a qualitative analysis of the stellar rotation distribution in NGC 2509.…”

Section: Stellar Rotation Distributionmentioning

confidence: 99%

Extended main sequence turnoffs in open clusters as seen by Gaia – II. The enigma of NGC 2509

Ovelar

Gossage

Kamann

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We investigate the morphology of the colour-magnitude diagram (CMD) of the open cluster NGC 2509 in comparison with other Galactic open clusters of similar age using Gaia photometry. At ∼ 900 Myr Galactic open clusters in our sample allshow an extended main sequence turn off (eMSTO) with the exception of NGC 2509, which presents an exceptionally narrow CMD. Our analysis of the Gaia data rules out differential extinction, stellar density, and binaries as a cause for the singular MSTO morphology in this cluster. We interpret this feature as a consequence of the stellar rotation distribution within the cluster and present the analysis with MIST stellar evolution models that include the effect of stellar rotation on which we based our conclusion. In particular, these models point to an unusually narrow range of stellar rotation rates (Ω/Ω crit,ZAMS = [0.4, 0.6]) within the cluster as the cause of this singular feature in the CMD of NGC 2509. Interestingly, models that do not include rotation are not as good at reproducing the morphology of the observed CMD in this cluster.

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Age Determinations of the Hyades, Praesepe, and Pleiades via MESA Models with Rotation

Cited by 141 publications

References 124 publications

Magnetic activity and evolution of the four Hyades K giants

Magnetic activity and evolution of the four Hyades K giants

Differential abundances of open clusters and their tidal tails: Chemical tagging and chemical homogeneity

Extended main sequence turnoffs in open clusters as seen by Gaia – II. The enigma of NGC 2509

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