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Home > Seminars > Archive of past UTINAM seminars > 2013

Ronin Wu

Physics Revealed by Broad-range CO Ladders and Fine-structure Lines in the M83 galaxy

Tuesday November 26 2013, 14:00

Library of the observatory

Ronin Wu, Service d’Astrophysique du CEA, Saclay


M83 is a face-on grand-design galaxy situated 4.5 Mpc away in the southern hemisphere. Structure-wise, it is very similar to our Milky-way, and its face-on orientation makes it ideal to study the star-forming regions in its nucleus and along the spiral arms. We present a 3’x3’ spectral-mapping observation of M83, using the Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) of the Herschel Space Observatory. This poster focuses on the presentation of following results.

  • The CO spectral line energy distribution (SLED):
    The warm CO lines covered in this wavelength include J=4-3 to J=13-12 transitions, which allows us to determine the peak CO ladder intensities and beyond. We model the physical conditions in the objects (N(CO), Tkin, n(H2)) using a large velocity gradient (LVG) code. The CO transitions from J=1-0 to J=4-3 observed with the ground-based telescopes, when available, are included in our study.
  • [NII]205μm line and star formation rate (SFR):
    The [NII]205μm map from M83 is compared to the SFR calculated with FUV and 24 μm maps. The relationship between the CO J=1-0 line and SFR are also shown as a comparison.