Browsing Physics & Atmospheric Science by Author "Lewis, G. F."

Now showing items 1-20 of 22

  • The bi-variate luminosity-color distribution of IRAS galaxies, and implications for the high redshift Universe 

    Chapman, S. C.; Helou, G.; Lewis, G. F.; Dale, D. A. (2003-05)
    We present a characterization of the local luminosity-color, bi-variate distribution of IRAS galaxies from the 1.2Jy sample, selected at 60 micron. The S60/S100 infrared color is used as the best single parameter description ...

  • Deep Gemini/GMOS imaging of an extremely isolated globular cluster in the Local Group 

    Mackey, A. D.; Ferguson, A. M. N.; Irwin, M. J.; Martin, N. F.; Huxor, A. P.; Tanvir, N. R.; Chapman, S. C.; Ibata, R. A.; Lewis, G. F.; McConnachie, A. W. (2009-09-08)
    We report on deep imaging of a remote M31 globular cluster, MGC1, obtained with Gemini/GMOS. Our colour-magnitude diagram for this object extends ~5 magnitudes below the tip of the red giant branch and exhibits features ...

  • Density Variations in the NW Star Stream of M31 

    Carlberg, R. G.; Richer, Harvey B.; McConnachie, Alan W.; Irwin, Mike; Ibata, Rodrigo A.; Dotter, Aaron L.; Chapman, Scott; Fardal, Mark; Ferguson, A. M. N.; Lewis, G. F.; Navarro, Julio F.; Puzia, Thomas H.; Valls-Gabaud, David (2011-02-17)
    The Pan Andromeda Archeological Survey (PAndAS) CFHT Megaprime survey of the M31-M33 system has found a star stream which extends about 120 kpc NW from the center of M31. The great length of the stream, and the likelihood ...

  • Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy 

    Martin, N. F.; Ibata, R. A.; Irwin, M. J.; Chapman, S.; Lewis, G. F.; Ferguson, A. M. N.; Tanvir, N.; McConnachie, A. W. (2006-10-01)
    We present the discovery of three faint dwarf galaxies and a globular cluster in the halo of the Andromeda galaxy (M31), found in our MegaCam survey that spans the southern quadrant of M31, from a projected distance of ~50 ...

  • Dynamics in the satellite system of Triangulum: Is AndXXII a dwarf satellite of M33? 

    Chapman, S. C.; Widrow, L.; Collins, M. L. M.; Dubinski, J.; Ibata, R. A.; Penarrubia, J.; Rich, M.; Ferguson, A. M. N.; Irwin, M. J.; Lewis, G. F.; Martin, N.; McConnachie, A.; Tanvir, N. (2012-06-25)
    We present results from a spectroscopic survey of the dwarf spheroidal And XXII and the two extended clusters EC1 and EC2. These three objects are candidate satellites of the Triangulum galaxy, M33, which itself is likely ...

  • Exploring the Properties of the M31 Halo Globular Cluster System 

    Huxor, A. P.; Ferguson, A. M. N.; Tanvir, N. R.; Irwin, M. J.; Mackey, A. D.; Ibata, R. A.; Bridges, T.; Chapman, S. C.; Lewis, G. F. (2011-02-02)
    Following on from our discovery of a significant population of M31 outer halo globular clusters (GCs), and updates to the Revised Bologna Catalogue of M31 GCs, we investigate the GC system of M31 out to an unprecedented ...

  • Further multiwavelength observations of the SSA22 Ly_alpha emitting `blob' 

    Chapman, S. C.; Scott, D.; Windhorst, R. A.; Frayer, D. T.; Borys, C.; Lewis, G. F.; Ivison, R. J. (2004-05)
    We present new follow-up observations of the sub-mm luminous Ly_alpha-emitting object in the SSA22 z=3.09 galaxy overdensity, referred to as `Blob 1' by Steidel et al.(2000). In particular we discuss high resolution Hubble ...

  • The Haunted Halos of Andromeda and Triangulum: A panorama of galaxy formation in action 

    Ibata, R.; Martin, N. F.; Irwin, M.; Chapman, S.; Ferguson, A. M. N.; Lewis, G. F.; McConnachie, A. W. (2007-12-20)
    We present a deep photometric survey of M31, conducted with the CFHT and INT, covering the inner 50 kpc of the galaxy, the Southern quadrant out to 150 kpc, and extending to M33. This is the first systematic panoramic study ...

  • An HST/ACS View of the Inhomogeneous Outer Halo of M31 

    Richardson, J. C.; Ferguson, A. M. N.; Mackey, A. D.; Irwin, M. J.; Chapman, S. C.; Huxor, A.; Ibata, R. A.; Lewis, G. F.; Tanvir, N. R. (2009-03-19)
    We present a high precision photometric view of the stellar populations in the outer halo of M31, using data taken with the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). We analyse the field populations ...

  • Inside the whale: the structure and dynamics of the isolated Cetus dwarf spheroidal 

    Lewis, G. F.; Ibata, R. A.; Chapman, S. C.; McConnachie, A.; Irwin, M. J.; Tolstoy, E.; Tanvir, N. R. (2007-02-05)
    This paper presents a study of the Cetus dwarf, an isolated dwarf galaxy within the Local Group. A matched-filter analysis of the INT/WFC imaging of this system reveals no evidence for significant tidal debris that could ...

  • The kinematic footprints of five stellar streams in Andromeda's halo 

    Chapman, S. C.; Ibata, R.; Irwin, M.; Koch, A.; Letarte, B.; Martin, N.; Collins, M.; Lewis, G. F.; McConnachie, A.; Penarrubia, J.; Rich, R. M.; Trethewey, D.; Ferguson, A. M. N.; Huxor, A.; Tanvir, N. (2008-10)
    (abridged) We present a spectroscopic analysis of five stellar streams (`A', `B', `Cr', `Cp' and `D') as well as the extended star cluster, EC4, which lies within streamC, all discovered in the halo of M31 from our ...

  • The kinematic identification of a thick stellar disc in M31 

    Collins, M. L. M.; Chapman, S. C.; Ibata, R. A.; Irwin, M. J.; Rich, R. M.; Ferguson, A. M. N.; Lewis, G. F.; Tanvir, N.; Koch, A. (2010-10-25)
    We present the first characterization of a thick disc component in the Andromeda galaxy (M31) using kinematic data from the DEIMOS multi-object spectrograph instrument on Keck II. Using 21 fields in the South West of the ...

  • A kinematically selected, metal-poor stellar halo in the outskirts of M31 

    Chapman, S. C.; Ibata, R.; Lewis, G. F.; Ferguson, A. M. N.; Irwin, M.; McConnachie, A.; Tanvir, N. (2006-12-10)
    We present evidence for a metal-poor, [Fe/H]$\sim-1.4$ $\sigma$=0.2 dex, stellar halo component detectable at radii from 10 kpc to 70 kpc, in our nearest giant spiral neighbor, the Andromeda galaxy. This metal-poor sample ...

  • The nucleus of the Sagittarius dSph galaxy and M54: a window on the process of galaxy nucleation 

    Bellazzini, M.; Ibata, R. A.; Chapman, S. C.; Mackey, A. D.; Monaco, L.; Irwin, M. J.; Martin, N. F.; Lewis, G. F.; Dalessandro, E. (2008-09-01)
    We present the results of a thorough study of the nucleus of the Sgr dwarf spheroidal galaxy and of the bright globular cluster M54 that resides within the same nucleus (Sgr,N). We have obtained accurate radial velocities ...

  • The Properties of Microjansky Radio Sources in the HDF-N, SSA13, and SSA22 Fields 

    Chapman, S. C.; Barger, A. J.; Cowie, L. L.; Scott, D.; Borys, C.; Capak, P.; Fomalont, E. B.; Lewis, G. F.; Richards, E. A.; Steffen, A. T.; Wilson, G.; Yun, M. (2003-03)
    (abridged) We present multiwavelength observations for a large sample of microjansky radio sources detected in ultradeep 1.4GHz maps centered on the Hubble Deep Field-North (HDF-N) and the Hawaii Survey Fields SSA13 and ...

  • The Recent Stellar Archeology of M31 - The Nearest Red Disk Galaxy 

    Davidge, T. J.; McConnachie, A. W.; Fardal, M. A.; Fliri, J.; Valls-Gabaud, D.; Chapman, S. C.; Lewis, G. F.; Rich, R. M. (2012-03-27)
    We examine the star-forming history (SFH) of the M31 disk during the past few hundred Myr. The luminosity functions (LFs) of main sequence stars at distances R_GC > 21 kpc (i.e. > 4 disk scale lengths) are matched by models ...

  • The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI 

    Collins, M. L. M.; Chapman, S. C.; Rich, R. M.; Ibata, R. A.; Irwin, M. J.; Peñarrubia, J.; Arimoto, N.; Brooks, A. M.; Ferguson, A. M. N.; Lewis, G. F.; McConnachie, A. W.; Venn, K. (2011-03-10)
    While the satellites of the Milky Way (MW) have been shown to be largely consistent in terms of their mass contained within one half--light radius (M_{half}) with a "Universal" mass profile, a number of M31 satellites are ...

  • Slicing The Monoceros Overdensity with Suprime-Cam 

    Conn, Blair C.; Noël, Noelia E. D.; Rix, Hans-Walter; Lane, R. R.; Lewis, G. F.; Irwin, M. J.; Martin, N. F.; Ibata, R. A.; Dolphin, A.; Chapman, S. (2012-05-14)
    We derive distance, density and metallicity distribution of the stellar Monoceros Overdensity (MO) in the outer Milky Way, based on deep imaging with the Subaru Telescope. We applied CMD fitting techniques in three stripes ...

  • A spectroscopic survey of EC4, an Extended Cluster in Andromeda's halo 

    Collins, M. L. M.; Chapman, S. C.; Irwin, M.; Ibata, R.; Martin, N. F.; Ferguson, A. M. N.; Huxor, A.; Lewis, G. F.; Mackey, A. D.; McConnachie, A. W.; Tanvir, N. (2009-03-26)
    We present a spectroscopic survey of candidate red giant branch stars in the extended star cluster, EC4, discovered in the halo of M31 from our CFHT/MegaCam survey, overlapping the tidal streams, Stream Cp and Stream Cr. ...

  • Strangers in the night: Discovery of a dwarf spheroidal galaxy on its first Local Group infall 

    Chapman, S. C.; Penarrubia, J.; Ibata, R.; McConnachie, A.; Martin, N.; Irwin, M.; Blain, A.; Lewis, G. F.; Letarte, B.; Lo, K.; Ludlow, A.; O'neil, K. (2007-06-20)
    We present spectroscopic observations of the AndXII dwarf spheroidal galaxy using DEIMOS/Keck-II, showing it to be moving rapidly through the Local Group (-556 km/s heliocentric velocity, -281 km/s relative to Andromeda ...