Keck Spectra of Brown Dwarf Candidates and a Precise Determination of the Lithium Depletion Boundary in the α Persei Open Cluster

Stauffer, J. R.; Barrado, D.; Bouvier, J.; Morrison, Heather; Harding, Paul; Luhman, K. L.; Stanke, T.; McCaughrean, M. J.; Terndrup, D. M.; Allen, Lori; Assouad, Patrick

doi:10.1086/308069

Cited by 131 publications

(112 citation statements)

References 33 publications

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“…Many searches have been geared towards discovering new BDs in nearby open clusters. Within the open clusters, BDs have been identified as both isolated free-floating objects (for example, Comerón 2003;Stauffer et al 1999) and members of double and multiple systems (Basri & Martín 1999;Reid & Mahoney 2000). The richest of the observable open clusters are the Pleiades (age ∼120 Myr), where more than 160 BD candidates have been discovered (Jameson et al 2002;Moraux et al 2003;Hodgkin 2003, and references therein).…”

Section: Introductionmentioning

confidence: 99%

The mass function of the Coma Berenices open cluster below 0.2 M_⊙: a search for low-mass stellar and substellar members

Melnikov

Eislöffel

2012

A&A

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Context. Little is known about the population of the Coma Berenices open cluster (age ∼500 Myr) below 0.2 M , and statistics show that there is a prominent deficit of very low-mass objects in this mass range compared to younger open clusters with ages of <250 Myr. Aims. We search for very low-mass stars and substellar objects (brown dwarfs) in the Coma open cluster to derive the present-day cluster mass function below 0.2 M .Methods. An imaging survey of the Coma open cluster in the R-and I-bands was carried out with the 2k × 2k CCD Schmidt camera at the 2-m telescope in Tautenburg. We performed a photometric selection of the cluster member candidates by combining results of our survey with 2MASS JHK s photometry. We also analysed low-resolution optical spectroscopic observations of a sample of 14 of our stellar cluster member candidates to estimate their spectral types and luminosity.Results. We present a photometric survey covering 22.5 deg 2 around the Coma open cluster centre with a completeness limit of 21. m 5 in the R-band and 20. m 5 in the I-band. Using optical/IR colour−magnitude diagrams, we identify 82 very low-mass cluster member candidates in the magnitude range 14. m 7 < I < 20. m 1. Five of them have luminosities and colour indices consistent with brown dwarfs. We calculate a mass spectrum of the very low-mass end of the cluster under the assumption that all selected candidates are probable cluster members. The calculated present-day mass function (dN/dm ≈ m −α ) can be divided into two parts with a slope of α = 0.6 in the mass interval 0.2 > M > 0.14 M and α ∼ 0 in 0.14 > M > 0.06 M . Conclusions. Our analysis of the spectroscopy of 14 objects shows that they are very low-mass MV-dwarfs of spectral type and luminosity consistent with Coma open cluster membership. This suggests that the membership probability of our other candidates may be high. Our results suggest that the mass function of the Coma open cluster can be traced towards substellar objects, but comparison with a mass spectra of younger clusters indicates that the Coma open cluster has probably lost its lowest mass members by means of dynamical evolution.

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Section: Introductionmentioning

confidence: 99%

The mass function of the Coma Berenices open cluster below 0.2 M_⊙: a search for low-mass stellar and substellar members

Melnikov

Eislöffel

2012

A&A

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“…3). We should keep in mind that the lithium test applied to the α Per cluster yielded a value larger than the turn-off main-sequence method (90 Myr versus 50 Myr; Stauffer et al 1999). …”

Section: The Age Of the Clustermentioning

confidence: 94%

“…Cruz et al 2003), as companions to low-mass stars (Burgasser et al 2003;Gizis et al 2003;Close et al 2003;Bouy et al 2003), in star-forming regions (Lucas & Roche 2000;Briceño et al 2002;Luhman et al 2003), and in open clusters (Bouvier et al 1998;Zapatero Osorio et al 2000;Barrado y Navascués et al 2001a;Barrado y Navascués et al 2002;Oliveira et al 2003, and references therein). Since the discovery of the first BDs in the Pleiades (Rebolo et al 1995(Rebolo et al , 1996, numerous open clusters have been targeted in the optical and in the near-infrared to uncover their low-mass and substellar populations, including the Pleiades (Bouvier et al 1998;Tej et al 2002;Dobbie et al 2002;Moraux et al 2003), α Per (Stauffer et al 1999;Barrado y Navascués et al 2002), M 35 (Barrado y Navascués et al 2001a, IC 2391 (Barrado y Navascués et al 2001b), and NGC 2547 (Oliveira et al 2003).…”

Section: Introductionmentioning

confidence: 99%

A deep wide-field optical survey in the young open cluster Collinder 359

Lodieu

Bouvier

James

et al. 2006

A&A

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We present the first deep, optical, wide-field imaging survey of the young open cluster Collinder 359, complemented by near-infrared follow-up observations. This study is part of a large programme aimed at examining the dependence of the mass function on environment and time. We have surveyed 1.6 square degrees in the cluster, in the I and z filters, with the CFH12K camera on the Canada-France-Hawaii 3.6-m telescope down to completeness and detection limits in both filters of 22.0 and 24.0 mag, respectively. Based on their location in the optical (I − z, I) colour-magnitude diagram, we have extracted new cluster member candidates in Collinder 359 spanning 1.3−0.03 M , assuming an age of 60 Myr and a distance of 450 pc for the cluster. We have used the 2MASS database as well as our own near-infrared photometry to examine the membership status of the optically-selected cluster candidates. Comparison of the location of the most massive members in Collinder 359 in a (B − V, V) diagram with theoretical isochrones suggests that Collinder 359 is older than α Per but younger than the Pleiades. We discuss the possible relationship between Collinder 359 and IC 4665 as both clusters harbour similar parameters, including proper motion, distance, and age.

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“…This technique was first proposed by Rebolo et al (1992) and Magazzu et al (1993) (see also Pozio 1991), and successfully applied to the Pleiades , see also (Basri et al 1996), Alpha Persei (Stauffer et al 1999;Basri & Martín 1999) IC2391 (Barrado y Navascués et al 1999a, see also for an update Barrado y Navascués et al (2004b). In the case of the Pleiades, it yields an age of 125±8 Myr or 130±20 Myr.…”

Section: Dwarfs: the Lithium Depletion Boundarymentioning

confidence: 99%

“…Figure 17 contains a CMD for the Alpha Per cluster, modified after Stauffer et al (1999). Green solid circles are used for clusters members with lithium (for this range and age, very-low mass stars close to the substellar boundary), whereas blue empty circles represent members without lithium on their surface.…”

Section: Dwarfs: the Lithium Depletion Boundarymentioning

confidence: 99%

Clusters: Age Scales for Stellar Physics

Barrado

2016

EAS Publications Series

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Abstract. Ages are key to truly understand a large plethora of astrophysical phenomena. On the other hand, stellar clusters are open windows to understand stellar evolution, specifically, the change with time and mass of different stellar properties. As such, they are our laboratories where different theories can be tested, but without accurate ages, our knowledge would impaired. We revisit here a large number of age-dating techniques and discuss their advantages and draw-backs. In addition, a step-by step process is suggested in order to built a coherent age scale ladder, minimizing the error budget and the sources of uncertainty.

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Keck Spectra of Brown Dwarf Candidates and a Precise Determination of the Lithium Depletion Boundary in the α Persei Open Cluster

Cited by 131 publications

References 33 publications

The mass function of the Coma Berenices open cluster below 0.2 M_⊙: a search for low-mass stellar and substellar members

The mass function of the Coma Berenices open cluster below 0.2 M_⊙: a search for low-mass stellar and substellar members

A deep wide-field optical survey in the young open cluster Collinder 359

Clusters: Age Scales for Stellar Physics

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Keck Spectra of Brown Dwarf Candidates and a Precise Determination of the Lithium Depletion Boundary in the α Persei Open Cluster

Cited by 131 publications

References 33 publications

The mass function of the Coma Berenices open cluster below 0.2 M⊙: a search for low-mass stellar and substellar members

The mass function of the Coma Berenices open cluster below 0.2 M⊙: a search for low-mass stellar and substellar members

A deep wide-field optical survey in the young open cluster Collinder 359

Clusters: Age Scales for Stellar Physics

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Product

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The mass function of the Coma Berenices open cluster below 0.2 M_⊙: a search for low-mass stellar and substellar members

The mass function of the Coma Berenices open cluster below 0.2 M_⊙: a search for low-mass stellar and substellar members