The Substellar Members of the Pleiades

Dobbie, P. D.; Jameson, R. F.; Osborne, Samantha; Hodgkin, S. T.; Pinfield, D. J.

doi:10.1017/s007418090021053x

Cited by 18 publications

(27 citation statements)

References 4 publications

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“…The mass function is approximately linear across the entire mass spectrum probed by our study (Fig. 9) and in agreement with estimated IMF for the Pleiades (α= 0.6–1.0; Martín, Zapatero Osorio & Rebolo 1998; Tej et al 2002; Dobbie et al 2002a; Moraux et al 2003), α Per (0.59 ± 0.05; Barrado y Navascués et al 2002) and σ Orionis (0.8 ± 0.4; Béjar et al 2001). Optical surveys in open clusters derived contamination level of the order of 30–45 per cent (Barrado y Navascués et al 2002), even in proper motion samples (Moraux et al 2001).…”

Section: Discussionsupporting

confidence: 88%

“…Finally, filled circles correspond to a ‘smoothed’ mass function by counting the number of objects per magnitude bin by steps of 0.5 mag. Overplotted are mass functions from the literature for the Pleiades (Martín et al 1998; Dobbie et al 2002a; Tej et al 2002; Moraux et al 2003), α Per (Barrado y Navascués et al 2002), σ Orionis (Béjar et al 2001) and the Trapezium Cluster (Muench et al 2002; Slesnick et al 2004).…”

Section: Discussionmentioning

confidence: 99%

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New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data

Lodieu

Hambly

Jameson

et al. 2007

Monthly Notices of the Royal Astronomical Society

146

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We present first results from a deep (J= 18.7), wide‐field (6.5 deg2) infrared (ZY JHK) survey in the Upper Sco association conducted within the science verification phase of the United Kingdom Infrared Telescope Infrared Deep Sky Survey Galactic Cluster Survey (GCS). Cluster members define a sequence well separated from field stars in the (Z−J, Z) colour–magnitude diagram. We have selected a total of 164 candidates with J= 10.5–18.7 mag from the (Z−J, Z) and (Y−J, Y) diagrams. We further investigated the location of those candidates in the other colour–magnitude and colour–colour diagrams to weed out contaminants. The cross‐correlation of the GCS catalogue with the Two‐Micron All‐Sky Survey data base confirms the membership of 116 photometric candidates down to 20 Jupiter masses as they lie within a 2σ circle centred on the association mean motion. The final list of cluster members contains 129 sources with masses between 0.3 and 0.007 M⊙. We extracted a dozen new low‐mass brown dwarfs below 20 MJup, the limit of previous surveys in the region. Finally, we have derived the mass function in Upper Sco over the 0.3–0.01 M⊙ mass range, best fit by a single segment with a slope of index α= 0.6 ± 0.1, in agreement with previous determination in open clusters.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data

Lodieu

Hambly

Jameson

et al. 2007

Monthly Notices of the Royal Astronomical Society

146

View full text Add to dashboard Cite

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“…The mass function appears to keep rising at such low masses with a slope index which agrees, within the uncertainties, with the values inferred from earlier studies (e.g. Dobbie et al 2002a; Moraux et al 2003; Lodieu et al 2007b).…”

Section: Introductionsupporting

confidence: 89%

Testing the fragmentation limit in the Upper Sco association★

Lodieu¹,

Hambly²,

Dobbie³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We present the results of a deep (J∼ 21 at 5σ) infrared photometric survey of a 0.95‐deg2 area in the central region of the Upper Sco association. The photometric observations consist of a deep Y+J‐band image obtained with the Wide Field Camera on the United Kingdom Infra‐Red Telescope (UKIRT) with part coverage in Z complemented by the methane ON and OFF imaging survey conducted with the Wide‐field InfraRed Camera on the Canada–France–Hawaii Telescope. We have selected five potential T‐type objects belonging to the Upper Sco association on the basis of their blue methane colours and their J− CH4 off colours. We have also identified a sample of seven to eight Upper Sco member candidates bridging the gap between known cluster M types and our new T‐type candidates. These candidates were selected based on their positions in various colour–magnitude diagrams, and they follow the sequence of known Upper Sco members identified in the UKIRT Infrared Deep Sky Survey Galactic Clusters Survey. We present additional membership constraints using proper motion estimates from the multiple epochs available with us. We also present optical and near‐infrared spectra obtained with the X‐Shooter spectrograph on the Very Large Telescope for five L‐type candidates covering the 0.6–2.5 m wavelength range, none of which is confirmed as a young brown dwarf. We discuss the lack of detection of new candidate members as well as the possible turn‐down in the Upper Sco mass function as we are approaching the fragmentation limit.

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“… From left‐ to right‐hand side, coverage used in the Pleiades open cluster to derive PMs: coverage in ZYJHK from the UKIDSS GCS DR1, INT optical survey (e.g. Dobbie et al 2002a) and CFHT I CFHT and Z CFHT study (Moraux et al 2003). Only one in 10 sources are plotted for the GCS coverage.…”

Section: Surveys and Data Setsmentioning

confidence: 99%

A wide deep infrared look at the Pleiades with UKIDSS: new constraints on the substellar binary fraction and the low-mass initial mass function

Lodieu¹,

Dobbie²,

Deacon³

et al. 2007

Monthly Notices of the Royal Astronomical Society

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We present the results of a deep wide‐field near‐infrared survey of 12 deg2 of the Pleiades conducted as part of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Galactic Cluster Survey (GCS). We have extracted over 340 high‐probability proper motion (PM) members down to 0.03 M⊙ using a combination of UKIDSS photometry and PM measurements obtained by cross‐correlating the GCS with data from the Two Micron All Sky Survey, the Isaac Newton Telescope and the Canada–France–Hawaii Telescope. Additionally, we have unearthed 73 new candidate brown dwarf (BD) members on the basis of five‐band UKIDSS photometry alone. We have identified 23 substellar multiple system candidates out of 63 candidate BDs from the (Y−K, Y) and (J−K, J) colour–magnitude diagrams, yielding a binary frequency of 28–44 per cent in the 0.075−0.030 M⊙ mass range. Our estimate is three times larger than the binary fractions reported from high‐resolution imaging surveys of field ultracool dwarfs and Pleiades BDs. However, it is marginally consistent with our earlier ‘peculiar’ photometric binary fraction of 50 ± 10 per cent presented by Pinfield et al., in good agreement with the 32–45 per cent binary fraction derived from the recent Monte Carlo simulations of Maxted & Jeffries and compatible with the 26 ± 10 per cent frequency recently estimated by Basri & Reiners. A tentative estimate of the mass ratios from photometry alone seems to support the hypothesis that binary BDs tend to reside in near equal‐mass ratio systems. In addition, the recovery of four Pleiades members targeted by high‐resolution imaging surveys for multiplicity studies suggests that half of the binary candidates may have separations below the resolution limit of the Hubble Space Telescope or current adaptive optics facilities at the distance of the Pleiades (a ∼7 au). Finally, we have derived luminosity and mass functions from the sample of photometric candidates with membership probabilities. The mass function is well modelled by a lognormal peaking at 0.24 M⊙ and is in agreement with previous studies in the Pleiades.

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The Substellar Members of the Pleiades

Cited by 18 publications

References 4 publications

New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data

New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data

Testing the fragmentation limit in the Upper Sco association★

A wide deep infrared look at the Pleiades with UKIDSS: new constraints on the substellar binary fraction and the low-mass initial mass function

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