Low-mass stars and brown dwarfs in Praesepe

Baker, D.; Jameson, R. F.; Casewell, Sarah L.; Deacon, N. R.; Lodieu, N.; Hambly, N. C.

doi:10.1111/j.1365-2966.2010.17302.x

Cited by 20 publications

(34 citation statements)

References 43 publications

(71 reference statements)

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“…Kraus & Hillenbrand (2007) identify 1050 ± 30 Praesepe members earlier than spectral type M5, corresponding to 550 ± 40 M . The mass-function in Praesepe agrees well with the present-day MF for field stars (Kraus & Hillenbrand 2007;Boudreault et al 2010;Baker et al 2010). Adams et al (2002) state the half-mass radius to be 1.…”

Section: Praesepesupporting

confidence: 70%

Inverse dynamical population synthesis

Marks

Kroupa

2012

A&A

244

302

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Binary populations in young star clusters show multiplicity fractions both lower and up to twice as high as those observed in the Galactic field. We follow the evolution of a population of binary stars in dense and loose star clusters starting with an invariant initial binary population and a formal multiplicity fraction of unity, and demonstrate that these models can explain the observed binary properties in Taurus, ρ Ophiuchus, Chamaeleon, Orion, IC 348, Upper Scorpius A, Praesepe, and the Pleiades. The model needs to consider solely different birth densities for these regions. The evolved theoretical orbital-parameter distributions are highly probable parent distributions for the observed ones. We constrain the birth conditions (stellar mass, M ecl , and half-mass radius, r h ) for the derived progenitors of the star clusters and the overall present-day binary fractions allowed by the present model. The results compare very well with properties of molecular cloud clumps on the verge of star formation. Combining these with previously and independently obtained constraints on the birth densities of globular clusters, we identify a weak stellar mass -half-mass radius correlation for cluster-forming cloud clumps, r h /pc ∝ (M ecl /M ) 0.13 ± 0.04 . The ability of the model to reproduce the binary properties in all the investigated young objects, covering present-day densities from 1−10 stars pc −3 (Taurus) to 2 × 10 4 stars pc −3 (Orion), suggests that environment-dependent dynamical evolution plays an important role in shaping the present-day properties of binary populations in star clusters, and that the initial binary properties may not vary dramatically between different environments.

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Section: Praesepesupporting

confidence: 70%

Inverse dynamical population synthesis

Marks

Kroupa

2012

A&A

244

302

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“…Lodieu et al 2007b; Pinfield et al 2008; Burningham et al 2010). While the MFs of the more aged populations like Praesepe (Kraus & Hillenbrand 2007; Baker et al 2010; Boudreault et al 2010) or the field (Metchev et al 2008; Burningham et al 2010; Reylé et al 2010; Kirkpatrick et al 2011) show gradients consistent with the Pleiades lognormal, power‐law fits to the very young Upper Sco ( x =−0.4 ± 0.08; Lodieu et al 2011) and σ Orionis ( x =−0.5 ± 0.2; Lodieu et al 2009) clusters are flatter. This may be evidence of a variation in the substellar IMF, or simply an artefact of systematic errors in the evolutionary model predictions at very young ages or age spreads.…”

Section: The Initial Mass Functionmentioning

confidence: 93%

Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey - I. The Pleiades★

Lodieu

Deacon

Hambly

2012

Monthly Notices of the Royal Astronomical Society

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We present the results of a deep wide‐field near‐infrared survey of the entire Pleiades cluster recently released as part of the UKIRT Infrared Deep Sky Survey (UKIDSS) Galactic Clusters Survey (GCS) Data Release 9 (DR9). We have identified a sample of ∼1000 Pleiades cluster member candidates combining photometry in five near‐infrared passbands and proper motions derived from the multiple epochs provided by the UKIDSS GCS DR9. We also provide revised membership for all previously published Pleiades low‐mass stars and brown dwarfs in the past decade recovered in the UKIDSS GCS DR9 Pleiades survey based on the new photometry and astrometry provided by the GCS. We find no evidence of K‐band variability in the Pleiades members larger than ∼0.08 mag. In addition, we infer a substellar binary frequency of 22–31 per cent in the 0.075–0.03 M⊙ range for separations less than ∼100 au. We employed two independent but complementary methods to derive the cluster luminosity and mass functions: a probabilistic analysis and a more standard approach consisting of stricter astrometric and photometric cuts. We found that the resulting luminosity and mass functions obtained from both methods are very similar. We derive the Pleiades mass function in the 0.6–0.03 M⊙ range and found that it is best reproduced by a lognormal representation with a mean characteristic mass of 0.20 ± 0.05 M⊙, in agreement with earlier studies and the extrapolation of the field mass function.

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“…CMDs showing previously reported members of Praesepe recovered in UKIDSS DR9 GCS. Previously known members are taken from Jones & Cudworth (), Hambly et al (), Hodgkin et al (), González‐García et al (), Kraus & Hillenbrand (), Baker et al (), Boudreault et al () and Wang et al (). The filled dots are the objects which have a proper motion consistent with Praesepe membership (3σ astrometric selection), while the objects presented with the crosses do not.…”

Section: Cross‐match With Previous Surveysmentioning

confidence: 99%

Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey - III. Praesepe

Boudreault¹,

Lodieu²,

Deacon³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Over the past decades open clusters have been the subject of many studies. Such studies are crucial considering that the universality of the initial mass function is still a subject of current investigations. Praesepe is an interesting open cluster for the study of the stellar and substellar mass function (MF), considering its intermediate age and its nearby distance. Here we present the results of a wide-field, near-infrared study of Praesepe using the Data Release 9 of the United Kingdom Infrared Telescope Infrared Deep Sky Survey Galactic Clusters Survey. We obtained cluster candidates of Praesepe based on a 3σ astrometric and five-band photometric selection. We derived a binary frequency for Praesepe of 25.6 ± 3.0 per cent in the 0.2-0.45 M mass range, 19.6 ± 3.0 per cent for 0.1-0.2 M and 23.2 ± 5.6 per cent for 0.07-0.1 M . We also studied the variability of the cluster candidates of Praesepe, and we conclude that seven objects could be variable. We inferred the luminosity function of Praesepe in the Z and J bands and derived its MF. We observe that our determination of the MF of Praesepe differs from previous studies: while previous MFs present an increase from 0.6 to 0.1 M , our MF shows a decrease. We looked at the MF of Praesepe in two different regions of the cluster, i.e. within and beyond 1. • 25, and we observed that both regions present an MF which decrease to lower masses. We compared our results with the Hyades, the Pleiades and α Per MF in the mass range 0.072-0.6 M and showed that the Praesepe MF is more similar to α Per although they are, respectively, of ages ∼85 and ∼600 Myr. Even though of similar age, the Praesepe remains different than the Hyades, with a decrease in the MF of only ∼0.2 dex from 0.6 down to 0.1 M , compared to ∼1 dex for the Hyades.

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Low-mass stars and brown dwarfs in Praesepe

Cited by 20 publications

References 43 publications

Inverse dynamical population synthesis

Inverse dynamical population synthesis

Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey - I. The Pleiades★

Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey - III. Praesepe

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