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21 results on '"Deacon, N.R."'

1. A global cloud map of the nearest known brown dwarf

Author

Crossfield, I.J.M., Biller, B., Schlieder, J.E., Deacon, N.R., Bonnefoy, M., Homeier, D., Allard, F., Buenzli, E., Henning, Th., Brandner, W., Goldman, B., and Kopytova, T.

Subjects
Astronomical research, Brown dwarfs -- Observations -- Natural history, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Brown dwarfs--substellar bodies more massive than planets but not massive enough to initiate the sustained hydrogen fusion that powers self-luminous stars (1, 2)--are born hot and slowly cool as they [...]

Published
2014

2. A search for southern ultracool dwarfs in young moving groups

Author

Deacon N.R., Jones H.R.A., Burningham B., Jenkins J.S., Galvez-Ortiz M.C., Pinfield D.J., Clarke J.R.A., Pokorny R.S., Barnes J.R., and Day-Jones A.C.

Subjects
Physics, QC1-999
Abstract

We have constructed an 800-strong red object catalogue by cross-referencing optical and infrared catalogues with an extensive proper motion catalogue compiled for red objects in the southern sky to obtain proper motions. We have applied astrometric and photometric constraints to the catalogue in order to select ultracool dwarf moving group candidates. 132 objects were found to be candidates of a moving group. From this candidate list we present initial results. Using spectroscopy we have obtained reliable spectral types and space motions, and by association with moving groups we can infer an age and composition. the further study of the remainder of our candidates will provide a large sample of young brown dwarfs and confirmed members will provide benchmark ultracool dwarfs. These will make suitable targets of AO planet searches.

Published
2011
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3. Understanding sub-stellar populations using wide-field infrared surveys

Author

Hewett P.C., Ishi M., McMahon R.G., Lucas P.W., Jones H.R.A., Warren S.J., Mortlock D.J., Dupuy T., Huelamo N., West A.A., Deacon N.R., Lodieu N., Homeier D., Liu M.C., Tinney C.G., Tamura M., Beaumont H., Leggett S.K., Burningham B., Day-Jones A.C., Pinfield D.J., Zapatero-Osorio M.R., Martin E.L., Venemans B.P., Barrado D., Zhang Z., and Morales-Calderon M.

Subjects
Physics, QC1-999
Abstract

This paper discusses benchmark brown dwarfs in various environments, and focuses on those in wide binary systems. We present a summary of the recently discovered T dwarf population from the UKIDSS Large Area Survey, and describe the constraints that it places on our knowledge of the sub-stellar initial mass function. We also present some exciting results from our ongoing search for wide companions to this sample, that has so far revealed an M4-T8.5 binary system at ∼12 parsecs and also the first ever Tdwarf-white dwarf binary system. The T dwarfs in these binaries have their properties constrained by the primary object and are thus benchmark objects that are already testing the predictions of theoretical model atmospheres.

Published
2011
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4. A Pan-STARRS 1 study of the relationship between wide binarity and planet occurrence in the Kepler field

Author

Flewelling, H., Chambers, K.C., Wainscoat, R.J., Hodapp, K.W., Burgett, W.S., Tonry, J.L., Kraus, A.L., Deacon, N.R., Kaiser, N., Mann, A.W., Magnier, E.A., and Waters, C.

Abstract

The NASA Kepler mission has revolutionized time-domain astronomy and has massively expanded the number of known extrasolar planets. However, the effect of wide multiplicity on exoplanet occurrence has not been tested with this data set. We present a sample of 401 wide multiple systems containing at least one Kepler target star. Our method uses Pan- STARRS 1 and archival data to produce an accurate proper motion catalogue of the Kepler field. Combined with Pan-STARRS 1 SED fits and archival proper motions for bright stars, we use a newly developed probabilistic algorithm to identify likely wide binary pairs which are not chance associations. As byproducts of this we present stellar SED templates in the Pan-STARRS 1 photometric system and conversions from this system to Kepler magnitudes. We find that Kepler target stars in our binary sample with separations above 6 arcsec are no more or less likely to be identified as confirmed or candidate planet hosts than a weighted comparison sample of Kepler targets of similar brightness and spectral type. Therefore we find no evidence that binaries with projected separations greater than 3000 au affect the occurrence rate of planets with P < 300 d around FGK stars.

Published
2016
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5. 2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary

Author

Deacon, N.R., primary, Magnier, E.A., additional, Liu, Michael C., additional, Schlieder, Joshua E., additional, Aller, Kimberly M., additional, Best, William M.J., additional, Bowler, Brendan P., additional, Burgett, W.S., additional, Chambers, K.C., additional, Draper, P.W., additional, Flewelling, H., additional, Hodapp, K.W., additional, Kaiser, N., additional, Metcalfe, N., additional, Sweeney, W.E., additional, Wainscoat, R.J., additional, and Waters, C., additional

Published
2017
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6. Prospecting in ultracool dwarfs: Measuring the metallicities of mid- and late-m dwarfs

Author

Mann, A.W., Brewer, J.M., Magnier, E.A., Deacon, N.R., Gaidos, E., Liu, M.C., Aller, K.M., and Ansdell, M.

Abstract

Metallicity is a fundamental parameter that contributes to the physical characteristics of a star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult to measure their metallicities using techniques that have been commonly used for Sun-like stars. Although there has been significant progress in developing empirical methods to measure M dwarf metallicities over the last few years, these techniques have been developed primarily for early- to mid-M dwarfs. We present a method to measure the metallicity of mid- to late-M dwarfs from moderate resolution (R ∼ 2000) K-band (≃ 2.2 μm) spectra. We calibrate our formula using 44 wide binaries containing an F, G, K, or early-M primary of known metallicity and a mid- to late-M dwarf companion. We show that similar features and techniques used for early-M dwarfs are still effective for late-M dwarfs. Our revised calibration is accurate to ∼0.07 dex for M4.5-M9.5 dwarfs with -0.58 < [Fe/H] < +0.56 and shows no systematic trends with spectral type, metallicity, or the method used to determine the primary star metallicity. We show that our method gives consistent metallicities for the components of M+M wide binaries. We verify that our new formula works for unresolved binaries by combining spectra of single stars. Lastly, we show that our calibration gives consistent metallicities with the Mann et al. study for overlapping (M4-M5) stars, establishing that the two calibrations can be used in combination to determine metallicities across the entire M dwarf sequence.

Published
2014
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7. LHS 2803B: A very wide mid-T dwarf companion to an old M dwarf identified from Pan-STARRS1

Author

Redstone, J.A., Chambers, K.C., Hodapp, K.W., Magnier, E.A., Tonry, J.L., Deacon, N.R., Morgan, J.S., Burgett, W.S., Price, P.A., Wainscoat, R.J., Liu, M.C., Kaiser, N., Mann, A.W., Kudritzki, R.-P., and Bowler, B.P.

Abstract

We report the discovery of a wide (1400 AU projected separation), common proper motion companion to the nearby M dwarf LHS 2803 (PSO J207.0300-13.7422). This object was discovered during our census of the local T dwarf population using Pan-STARRS1 and Two Micron All Sky Survey data. Using the Infrared Telescope Facility/SpeX near-infrared spectroscopy, we classify the secondary to be spectral type T5.5. University of Hawaii 2.2m/SuperNova Integral Field Spectrograph optical spectroscopy indicates that the primary has a spectral type of M4.5, with approximately solar metallicity and no measurable Hα emission. We use this lack of activity to set a lower age limit for the system of 3.5Gyr. Using a comparison with chance alignments of brown dwarfs and nearby stars, we conclude that the two objects are unlikely to be a chance association. The primary's photometric distance of 21pc and its proper motion implies thin disk kinematics. Based on these kinematics and its metallicity, we set an upper age limit for the system of 10Gyr. Evolutionary model calculations suggest that the secondary has a mass of 72±47 MJup, temperature of 1120 ± 80K, and log g = 5.4 ± 0.1dex. Model atmosphere fitting to the near-IR spectrum gives similar physical parameters of 1100K and log g = 5.0.

Published
2012
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8. A search for southern ultracool dwarfs in young moving groups

Author

Clarke, J.R.A., Pinfield, D.J., Galvez-Ortiz, M.C., Jenkins, J.S., Burningham, B., Deacon, N.R., Jones, H.R.A., Pokorny, R.S., Barnes, J.R., Day-Jones, A.C., Clarke, J.R.A., Pinfield, D.J., Galvez-Ortiz, M.C., Jenkins, J.S., Burningham, B., Deacon, N.R., Jones, H.R.A., Pokorny, R.S., Barnes, J.R., and Day-Jones, A.C.

Abstract

Contains fulltext : 76167.pdf (preprint version ) (Open Access)

Published
2010

9. The IPHAS-POSS-I proper motion survey of the Galactic plane

Author

Deacon, N.R., Groot, P.J., Drew, J.E., Greimel, R., Hambly, N.C., Irwin, M.J., Aungwerojwit, A., Drake, J., Steeghs, D., Deacon, N.R., Groot, P.J., Drew, J.E., Greimel, R., Hambly, N.C., Irwin, M.J., Aungwerojwit, A., Drake, J., and Steeghs, D.

Abstract

Contains fulltext : 75740.pdf (publisher's version ) (Open Access) Contains fulltext : 75740.pdf (preprint version ) (Open Access)

Published
2009

10. The UV-Excess survey of the northern Galactic plane

Author

Groot, P.J., Verbeek, K., Groot, E de, Besselaar, E.J.M. van den, Deacon, N.R., Ham, W.C.P. van, Hu, H., Morales-Rueda, L., Nelemans, G.A., Oosting, T., Schellart, P., et al., Groot, P.J., Verbeek, K., Groot, E de, Besselaar, E.J.M. van den, Deacon, N.R., Ham, W.C.P. van, Hu, H., Morales-Rueda, L., Nelemans, G.A., Oosting, T., Schellart, P., and et al.

Abstract

Contains fulltext : 75754_pre.pdf (preprint version ) (Open Access) Contains fulltext : 75754.pdf (publisher's version ) (Open Access)

Published
2009

13. Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey

Author

Pinfield, D.J., Burningham, B., Tamura, M., Leggett, S.K., Lodieu, N., Lucas, P.W., Mortlock, D.J., Warren, S.J., Homeier, D., Ishii, M., Deacon, N.R., McMahon, R.G., Hewett, P.C., Osori, M.R.Z., Martin, E.L., Jones, H.R.A., Venemans, B.P., Day-Jones, A.C., Dobbie, P.D., Folkes, S.L., Dye, S., Allard, F., Baraffe, I., Navascues, D. Barrado Y, Casewell, S.L., Chiu, K., Chabrier, G., Clarke, F., Hodgkin, S.T., Magazzu, A., McCaughrean, M.J., Nakajima, T., Pavlenko, Y., Tinney, C.G., Pinfield, D.J., Burningham, B., Tamura, M., Leggett, S.K., Lodieu, N., Lucas, P.W., Mortlock, D.J., Warren, S.J., Homeier, D., Ishii, M., Deacon, N.R., McMahon, R.G., Hewett, P.C., Osori, M.R.Z., Martin, E.L., Jones, H.R.A., Venemans, B.P., Day-Jones, A.C., Dobbie, P.D., Folkes, S.L., Dye, S., Allard, F., Baraffe, I., Navascues, D. Barrado Y, Casewell, S.L., Chiu, K., Chabrier, G., Clarke, F., Hodgkin, S.T., Magazzu, A., McCaughrean, M.J., Nakajima, T., Pavlenko, Y., and Tinney, C.G.

Abstract

Contains fulltext : 72398.pdf ( ) (Open Access)

Published
2008

15. Multiplicity of cool dwarfs

Author

Dupuy, T.J., primary, Allen, P.R., additional, Kraus, A.L., additional, Biler, B., additional, Blake, C.H., additional, Davison, C., additional, Deacon, N.R., additional, Duchêne, G., additional, Geller, A.M., additional, King, R.R., additional, Law, N.M., additional, Nguyen, D.C., additional, Reipurth, B., additional, Winters, J.G., additional, and Zhang, Z.H., additional

Published
2013
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16. A wide deep infrared look at the Pleiades with UKIDSS: new constraints on the substellar binary fraction and the low-mass initial mass function

Author

Lodieu, N., Dobbie, P.D., Deacon, N.R., Hodgkin, S.T., Hambly, N.C., Jameson, R.F., Lodieu, N., Dobbie, P.D., Deacon, N.R., Hodgkin, S.T., Hambly, N.C., and Jameson, R.F.

Abstract

Contains fulltext : 35239.pdf ( ) (Open Access), 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 Msolar 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 Msolar 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 ca

Published
2007

17. Southern infrared proper motion survey. II. A sample of low mass stars with mu >= 0.1'/ yr

Author

Deacon, N.R., Hambly, N.C., Deacon, N.R., and Hambly, N.C.

Abstract

Contains fulltext : 36474.pdf (preprint version ) (Open Access) Contains fulltext : 36474..pdf (publisher's version ) (Open Access), We present details of the second part of the Southern Infrared Proper Motion Survey (SIPS). Here accurate relative astrometry allows us to reduce the minimum proper motion to 0.1 arcsec per year. This yields 6904 objects with proper motions between our minum cut and half an arcsecond a year. A small overspill sample with proper motions greater than this is also included. We examine our sample to identify interesting individual objects such as common proper motion binaries, potential L dwarfs and candidate nearby stars. Finally we show our survey is incomplete due to many factors, factors which we will take into account when simulating these survey results in the next paper in this series. Full Tables 7 and 8 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/468/163

Published
2007

18. Two T dwarfs from the UKIDSS early data release

Author

Kendall, T.R., Tamura, M., Tinney, C.G., Martín, E.L., Ishii, M., Pinfield, D.J., Lucas, P.W., Jones, H.R.A., Leggett, S.K., Dye, S., Hewett, P.C., Allard, F., Baraffe, I., Navascués, D. Barrado Y, Carraro, G., Casewell, S.L., Chabrier, G., Chappelle, R.J., Clarke, F., Day-Jones, A., Deacon, N.R., Dobbie, P.D., Folkes, S., Hambly, N.C., Hodgkin, S.T., Nakajima, T., Jameson, R.F., Lodieu, N., Magazzù, A., McCaughrean, M.J., Pavlenko, Y.V., Tadashi, N., Osorio, M.R. Zapatero, Kendall, T.R., Tamura, M., Tinney, C.G., Martín, E.L., Ishii, M., Pinfield, D.J., Lucas, P.W., Jones, H.R.A., Leggett, S.K., Dye, S., Hewett, P.C., Allard, F., Baraffe, I., Navascués, D. Barrado Y, Carraro, G., Casewell, S.L., Chabrier, G., Chappelle, R.J., Clarke, F., Day-Jones, A., Deacon, N.R., Dobbie, P.D., Folkes, S., Hambly, N.C., Hodgkin, S.T., Nakajima, T., Jameson, R.F., Lodieu, N., Magazzù, A., McCaughrean, M.J., Pavlenko, Y.V., Tadashi, N., and Osorio, M.R. Zapatero

Abstract

Contains fulltext : 36642.pdf ( ) (Open Access) Contains fulltext : 36642.pdf (publisher's version ) (Open Access), Context: We report on the first ultracool dwarf discoveries from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release (LAS EDR), in particular the discovery of T dwarfs which are fainter and more distant than those found using the 2MASS and SDSS surveys. Aims: We aim to show that our methodologies for searching the ~27 deg2 of the LAS EDR are successful for finding both L and T dwarfs via cross-correlation with the Sloan Digital Sky Survey (SDSS) DR4 release. While the area searched so far is small, the numbers of objects found shows great promise for near-future releases of the LAS and great potential for finding large numbers of such dwarfs. Methods: Ultracool dwarfs are selected by combinations of their YJH(K) UKIDSS colours and SDSS DR4 z-J and i-z colours, or, lower limits on these red optical/infrared colours in the case of DR4 dropouts. After passing visual inspection tests, candidates have been followed up by methane imaging and spectroscopy at 4 m and 8 m-class facilities. Results: Our main result is the discovery following CH4 imaging and spectroscopy of a T4.5 dwarf, ULAS J 1452+0655, lying ~80 pc distant. A further T dwarf candidate, ULAS J 1301+0023, has very similar CH4 colours but has not yet been confirmed spectroscopically. We also report on the identification of a brighter L0 dwarf, and on the selection of a list of LAS objects designed to probe for T-like dwarfs to the survey J-band limit. Conclusions: Our findings indicate that the combination of the UKIDSS LAS and SDSS surveys provide an excellent tool for identifying L and T dwarfs down to much fainter limits than previously possible. Our discovery of one confirmed and one probable T dwarf in the EDR is consistent with expectations from the previously measured T dwarf density on the sky.

Published
2007

19. Eight new T4.5-T7.5 dwarfs discovered in the UKIDSS Large Area Survey Data Release 1

Author

Lodieu, N., Pinfield, D.J., Leggett, S.K., Jameson, R.F., Mortlock, D.J., Warren, S.J., Burningham, B., Lucas, P.W., Chiu, K., Liu, M.C., Venemans, B.P., McMahon, R.G., Allard, F., Baraffe, I., Navascués, D.B. Y, Carraro, G., Casewell, S.L., Chabrier, G., Chappelle, R.J., Clarke, F., Day-Jones, A.C., Deacon, N.R., Dobbie, P.D., Folkes, S.L., Hambly, N.C., Hewett, P.C., Hodgkin, S.T., Jones, H.R.A., Kendall, T.R., Magazzù, A., Martín, E.L., McCaughrean, M.J., Nakajima, T., Pavlenko, Y., Tamura, M., Tinney, C.G., Osorio, M.R. Zapatero, Lodieu, N., Pinfield, D.J., Leggett, S.K., Jameson, R.F., Mortlock, D.J., Warren, S.J., Burningham, B., Lucas, P.W., Chiu, K., Liu, M.C., Venemans, B.P., McMahon, R.G., Allard, F., Baraffe, I., Navascués, D.B. Y, Carraro, G., Casewell, S.L., Chabrier, G., Chappelle, R.J., Clarke, F., Day-Jones, A.C., Deacon, N.R., Dobbie, P.D., Folkes, S.L., Hambly, N.C., Hewett, P.C., Hodgkin, S.T., Jones, H.R.A., Kendall, T.R., Magazzù, A., Martín, E.L., McCaughrean, M.J., Nakajima, T., Pavlenko, Y., Tamura, M., Tinney, C.G., and Osorio, M.R. Zapatero

Abstract

Contains fulltext : 34817.pdf ( ) (Open Access), We present eight new T4.5-T7.5 dwarfs identified in the UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) Data Release 1 (DR1). In addition we have recovered the T4.5 dwarf SDSSJ020742.91+000056.2 and the T8.5 dwarf ULASJ003402.77-005206.7. Photometric candidates were picked up in two-colour diagrams over 190deg2 (DR1) and selected in at least two filters. All candidates exhibit near-infrared spectra with strong methane and water absorption bands characteristic of T dwarfs and the derived spectral types follow the unified scheme of Burgasser et al.. We have found six new T4.5-T5.5 dwarfs, one T7 dwarf, one T7.5 dwarf and recovered a T4.5 dwarf and a T8.5 dwarf. We provide distance estimates which lie in the 15-85pc range; the T7.5 and T8.5 dwarfs are probably within 25pc of the Sun. We conclude with a discussion of the number of T dwarfs expected after completion of the LAS, comparing these initial results to theoretical simulations. Based on observations made with the United Kingdom Infrared Telescope, operated by the Joint Astronomy Centre on behalf of the UK Particle Physics and Astronomy Research Council. E-mail: nlodieu@iac.es ‡ Alfred P. Sloan Research Fellow.

Published
2007

20. Understanding sub-stellar populations using wide-field infrared surveys

Author

Pinfield, D.J., primary, Day-Jones, A.C., additional, Burningham, B., additional, Leggett, S.K., additional, Beaumont, H., additional, Tamura, M., additional, Tinney, C.G., additional, Liu, M.C., additional, Homeier, D., additional, Lodieu, N., additional, Deacon, N.R., additional, West, A.A., additional, Huelamo, N., additional, Dupuy, T., additional, Mortlock, D.J., additional, Warren, S.J., additional, Jones, H.R.A., additional, Lucas, P.W., additional, Ishi, M., additional, McMahon, R.G., additional, Hewett, P.C., additional, Zapatero-Osorio, M.R., additional, Martin, E.L., additional, Venemans, B.P., additional, Barrado, D., additional, Zhang, Z., additional, and Morales-Calderon, M., additional

Published
2011
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21. A search for southern ultracool dwarfs in young moving groups

Author

Clarke, J.R.A., primary, Pinfield, D.J., additional, Galvez-Ortiz, M.C., additional, Jenkins, J.S., additional, Burningham, B., additional, Deacon, N.R., additional, Jones, H.R.A., additional, Pokorny, R.S., additional, Barnes, J.R., additional, and Day-Jones, A.C., additional

Published
2011
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