Stuart D. Ryder

Publications (3)1.69 Total impact

• Article: The Circumnuclear Starburst in M83

  Stuart D. Ryder, Robert G. Sharp, Johan H. Knapen, Lisa M. Mazzuca, Ian R. Parry
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  ABSTRACT: We present results from near-infrared integral-field spectroscopy of the circumnuclear starburst in M83, using the CIRPASS instrument on Gemini South. The combination of Pa[beta], CO (6,3), and [Fe II] equivalent width measurements over large contiguous regions allows us to track the spatial propagation of star formation across the ringlet, which is too heavily obscured to be properly analysed at optical wavelengths. We find the clearest evidence yet for an age gradient, with the youngest clusters found closest to where the dust lane crosses the ringlet. We discuss the implications for gas fueling by the bar. [copyright] 2005 American Institute of Physics
  09/2005;
• Article: Circumnuclear Star Formation in M100

  Stuart D. Ryder, Johan H. Knapen
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  ABSTRACT: Near-infrared (JHK) images of the nucleus of the barred spiral galaxy M100 (NGC 4321) have been obtained using a high-bandwidth tip-tilt secondary and fast guider system on the 3.8 m United Kingdom Infrared Telescope (UKIRT). The resulting images, with a resolution of 0.34″ at K, reveal for the first time a host of compact ‘knots’, which appear to be the result of a recent burst (or bursts) of star formation. Confirmation of this comes from K-band spectroscopy of these knots with CGS4 on UKIRT, which shows Brγ emission and CO absorption features. A comparison with starburst evolutionary models suggests ages for these knots of between 17 and 27 Myr, and a stellar population dominated by late-type supergiants.
  Astrophysics and Space Science 02/2001; 276(2):405-412. · 1.69 Impact Factor
• Article: Resolving Circumnuclear Star Formation in M100 with Image Stabilisation at

  Stuart D. Ryder, Johan H. Knapen
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  ABSTRACT: Near-infrared (JHK) images of the nucleus of the barred spiral galaxy M100 (NGC 4321) have been obtained using a high-bandwidth tip-tilt secondary and fast guider system on the 3.8m United Kingdom Infrared Telescope (UKIRT). The resulting images, with a resolution of 0: 00 34 at K, reveal for the first time a host of compact "knots", which appear to be the result of a recent burst (or bursts) of star formation. Confirmation of this comes from K-band spectroscopy of these knots with CGS4 on UKIRT, which shows Brfl emission and CO absorption features. A comparison with starburst evolutionary models suggests ages for these knots of 15--25 Myr, and a stellar population dominated by late-type supergiants. 1 The Upgraded UKIRT In an effort to deliver image quality which is as close as possible to the diffraction limit (FWHM = 0: 00 11 at =2.2 ¯m), the 3.8m United Kingdom Infrared Telescope (UKIRT) has been upgraded with the addition of several new features (Hawarden et al. 1998), inc...
  12/1998;