The Hyades lithium problem revisited

Swenson, Fritz J.; Faulkner, John; Rogers, F. J.; Iglesias, Carlos A.

doi:10.1086/173985

Cited by 111 publications

(125 citation statements)

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“…Ages were taken from Hillenbrand (1997) for the ONC and from Park et al (2000) for NGC 2264. Listed are the PMS evolution model employed in the study from which the cluster age was taken (SF94 = Swenson et al 1994;DM97 = D'Antona & Mazzitelli 1994;BC98-I, II = Baraffe et al 1998), the deduced cluster ages, and, if the same model was applied in both clusters, the resulting age ratio (t NGC 2264 /t ONC ). the PMS evolution model used.…”

Section: The Age Ratio Of Ngc 2264 and Oncmentioning

confidence: 99%

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Rotational evolution of low mass stars: The case of NGC 2264

Lamm¹,

Mundt²,

Bailer‐Jones³

et al. 2005

A&A

115

218

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Abstract. Our study is based on an extensive photometric monitoring program in the young (2-4 Myr) open cluster NGC 2264 by Lamm et al. (2004a). This program resulted in a sample of 405 periodic variables which are most likely pre-main sequence (PMS) members of the cluster. The periodic variability of these stars results from the rotational modulation of the light by stellar spots. In this paper we investigate the rotation period evolution of young stars. This is done by comparing the period distribution of the older NGC 2264 with that of the younger Orion Nebular Cluster (ONC, age: ∼1 Myr) which is known from the literature. The age ratio between the two clusters was estimated on the basis of PMS models to be about 2 +0.75 −0.5 . We find that the period distribution of NGC 2264 is similar in form to the ONC but shifted to shorter periods. In both clusters the period distribution depends strongly on the mass and it is bimodal for higher mass stars with M > ∼ 0.25 M while it is unimodal for lower mass stars with M < ∼ 0.25 M . In addition the lower mass stars rotate much faster on average than the higher mass stars. Quantitative comparison between the period distributions of both clusters suggests that a large fraction (about 80%) of stars have spun up from the age of the ONC to the age of NGC 2264. Based on this estimate and the estimated age ratio between the two clusters we find that the average spin up by a factor of 1.5−1.8 from the age of the ONC to the age of NGC 2264 is consistent with a decreasing stellar radius and conservation of angular momentum, for most stars. However, within NGC 2264 we did not find any significant spin up from the younger to older stars in the cluster. We also found indications for some ongoing disk-locking in NGC 2264, in particular for the higher mass stars. Our analysis of the period distribution suggests that about 30% of the higher mass stars in NGC 2264 could be magnetically locked into co-rotation with their inner disk. In the case of the lower mass stars, disk-locking seems to be less important for the rotational evolution of the stars. This interpretation is supported by the analysis of the stars' Hα emission. This analysis indicates that the locking period of the higher mass stars is about P = 8 days. For the lower mass stars this analysis indicates a locking period of about 2-3 days. We argue that the latter stars are probably not "completely" locked to their disk and propose an evolution scenario for these stars which we call "moderate angular momentum loss". In this scenario angular momentum is continuously removed from the stars but at a rate too low to lock the stars with a constant rotation period. We have done a detailed comparison with the recently published rotational period study of NGC 2264 of Makidon et al. (2004). Even though their obtained period distribution of their quality 1 data on NGC 2264 is indistinguishable within the statistical errors from ours, we come to quite different conclusions about the interpretation. One major reason for these discrepanci...

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Section: The Age Ratio Of Ngc 2264 and Oncmentioning

confidence: 99%

“…For the age determination of the ONC, Hillenbrand (1997) used the two PMS evolution models by Swenson et al (1994;hereafter SF94) and D'Antona & Mazzitelli (1994;hereafter DM94). These two PMS evolution models were also used for the age determination of NGC 2264 by Park et al (2000).…”

Section: Modelmentioning

confidence: 99%

Rotational evolution of low mass stars: The case of NGC 2264

Lamm¹,

Mundt²,

Bailer‐Jones³

et al. 2005

A&A

115

218

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“…Li depletion ceases as the SCZ recedes toward the surface and its base cools. Independent of the details of the (standard) input physics, SSET robustly predicts that no further Li depletion occurs during the MS for AFG dwarfs (e.g., Deliyannis et al 1990;Pinsonneault et al 1990;Swenson et al 1994;Chaboyer et al 1995), whereas KM dwarfs can continue to deplete Li as they evolve beyond the ZAMS. The predicted Li-T e relation is modified very slightly as models evolve to slightly higher T e over time.…”

Section: Introductionmentioning

confidence: 98%

Lithium in the Intermediate-Age Open Cluster, NGC 3680

Anthony-Twarog

Deliyannis

Twarog

et al. 2009

The Astronomical Journal

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“…IM Lup is a pre-main-sequence star located in the Lupus II cloud for which Wichmann et al (1998) report a distance of 190 ± 27 pc using Hipparcos parallaxes. From its M0 spectral type and estimated bolometric luminosity of 1.3 ± 0.3 L , Hughes et al (1994) derive a mass of 0.4 M and an age of 0.6 Myr using evolutionary tracks from Swenson et al (1994), or 0.3 M and 0.1 Myr adopting the tracks of D 'Antona & Mazzitelli (1994). In Pinte et al (2008), a much higher value of 1 M is derived using tracks of Baraffe et al (1998).…”

Section: Introductionmentioning

confidence: 99%

A break in the gas and dust surface density of the disc around the T Tauri star IM Lupi

Panić¹,

Hogerheijde²,

Wilner

et al. 2009

A&A

118

124

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Aims. We study the distribution and physical properties of molecular gas in the disc around the T Tauri star IM Lup on scales close to 200 AU. We investigate how well the gas and dust distributions compare and work towards a unified disc model that can explain both gas and dust emission. Methods. 12 CO, 13 CO, and C 18 O J = 2−1 line emission, as well as the dust continuum at 1.3 mm, is observed at 1. 8 resolution towards IM Lup using the Submillimeter Array. A detailed disc model based on the dust emission is tested against these observations with the aid of a molecular excitation and radiative transfer code. Apparent discrepancies between the gas and dust distribution are investigated by adopting simple modifications to the existing model. Results. The disc is seen at an inclination of 54 • ± 3 • and is in Keplerian rotation around a 0.8-1.6 M star. The outer disc radius traced by molecular gas emission is 900 AU, while the dust continuum emission and scattered light images limit the amount of dust present beyond 400 AU and are consistent with the existing model that assumes a 400 AU radius. Our observations require a drastic density decrease close to 400 AU with the vertical gas column density at 900 AU in the range of 5 × 10 20 -10 22 cm −2 . We derive a gas-to-dust mass ratio of 100 or higher in disc regions beyond 400 AU. Within 400 AU from the star our observations are consistent with a gas-to-dust ratio of 100 but other values are not ruled out.

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The Hyades lithium problem revisited

Cited by 111 publications

References 0 publications

Rotational evolution of low mass stars: The case of NGC 2264

Rotational evolution of low mass stars: The case of NGC 2264

Lithium in the Intermediate-Age Open Cluster, NGC 3680

A break in the gas and dust surface density of the disc around the T Tauri star IM Lupi

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