Browsing University of Hertfordshire by Author "Riaz, Basmah"

Now showing items 1-12 of 12

    • BROWN DWARF DISKS AT AGES OF 5-10 Myr 

      Riaz, Basmah; Lodieu, Nicolas; Gizis, John E. (2009-11-10)
      We present Spitzer/IRAC and MIPS 24 mu m observations for 28 brown dwarfs in the Upper Scorpius (UppSco) region. We find a disk fraction of 10.7%-(+ 8.7%)(3.3%) . One object shows a small excess at 24 mu m but none at ...

    • Characterizing the disk around the TW Hydrae Association brown dwarf 2MASSW J1207334-393254 

      Riaz, Basmah; Gizis, John E. (2007-05-20)
      We present detailed modeling of the disk around the TW Hydrae Association (TWA) brown dwarf 2MASSW J1207334 - 393254 (2M1207), using Spitzer observations from 3.6 to 24 mu m. The spectral energy distribution (SED) does not ...

    • Erratum: "Identification of New M Dwarfs in the Solar Neighborhood" (AJ, 132, 866 [2006]) 

      Riaz, Basmah; Gizis, John E.; Harvin, James (2007-03)

    • First Confirmed Detection of a Bipolar Molecular Outflow from a Young Brown Dwarf 

      Phan-Bao, Ngoc; Riaz, Basmah; Lee, Chin-Fei; Tang, Ya-Wen; Ho, Paul T. P.; Martin, Eduardo L.; Lim, Jeremy; Ohashi, Nagayoshi; Shang, Hsien (2008-12-20)
      Studying the earliest stages in the birth of stars is crucial for understanding how they form. Brown dwarfs with masses between that of stars and planets are not massive enough to maintain stable hydrogen-burning fusion ...

    • Herschel PACS and SPIRE observations of TW Hydrae association brown dwarf disks 

      Riaz, Basmah; Gizis, John (2012)
      We present Herschel SPIRE observations of the TW Hydrae association (TWA) brown dwarf disks SSSPM J1102-3431 (SS1102) and 2MASSW J1207334-393254 (2M1207). Both disks are undetected in the SPIRE 200-500 μm bands. We analyzed ...

    • Hubble Space Telescope search for M subdwarf binaries 

      Riaz, Basmah; Gizis, John E.; Samaddar, Debasmita (2008-01-10)
      We present HSTACS observations of 19 nearby M subdwarfs in a search for binary systems. Other than the wide common proper-motion pair LHS 2140/2139, none of our sdM and esdM targets are found to be binaries. Our survey is ...

    • Identification of new M dwarfs in the solar neighborhood 

      Riaz, Basmah; Gizis, John E.; Harvin, James (2006-08)
      We present the results from a spectroscopic study of 1080 nearby active M dwarfs, selected by correlating the Two Micron All Sky Survey and ROSAT catalogs. We have derived the spectral types and estimated distances for all ...

    • Infrared Observations of a Mid-L Dwarf with Strong Hα Emission 

      Riaz, Basmah; Gizis, John E. (2007-04-10)
      We present Spitzer/IRAC observations of the L5 dwarf, 2MASSI J1315309-264951 (2M 1315). This ultracool dwarf is known to display strong emission in the H alpha line. The spectral energy distribution (SED) for this object ...

    • New brown dwarf disks in the TW Hydrae association 

      Riaz, Basmah; Gizis, John E. (2008-07-10)
      In our analysis of Spitzer IRS archival data on the stellar and substellar members of the TW Hydrae association (TWA), we have discovered two new brown dwarf disks: a flat, optically thick disk around SSSPM J1102 - 3431 ...

    • Spitzer observations of nearby M dwarfs 

      Riaz, Basmah; Mullan, D. J.; Gizis, John E. (2006-10-20)
      We present Spitzer IRAC and MIPS observations for a sample of eight M dwarfs: six dMe, one dM, and one sdMe star. All of our targets are found to have SEDs that are fitted within the error bars by a purely photospheric ...

    • Very low-luminosity Class I/flat outflow sources in sigma Orionis 

      Riaz, Basmah; Thompson, M.A.; Whelan, E.T.; Lodieu, N. (2015-01-21)
      We present an optical to submillimetre multiwavelength study of two very low-luminosity Class I/flat systems, Mayrit 1701117 and Mayrit 1082188, in the σ Orionis cluster. We performed moderate-resolution (R ∼ 1000) optical ...

    • Young stellar objects in NGC 6823 

      Riaz, Basmah; Martin, E.L.; Tata, R.; Monin, J-L; Phan-Bao, Ngoc; Bouy, H. (2011)
      NGC 6823 is a young open cluster that lies at a distance of ∼2 kpc in the Vulpecula OB1 association. Previous studies using CCD photometry and spectroscopy have identified a Trapezium system of bright O- and B-type stars ...