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2 results

  • 16 - Extragalactic Surveys: CANON and PHANGS-ALMA

  • from Part VI - External Galaxies
  • Duncan MacKay, University of Kent, Canterbury, Mark Thompson, University of Leeds, James Urquhart, University of Kent, Canterbury
  • Book:
    Case Studies in Star Formation
    Published online:
    11 April 2023
    Print publication:
    13 April 2023, pp 255-266

  • Summary

    Two extra-Galactic surveys are considered. The first takes observations of nearly 200 GMCs across a small sample of local galaxies in the CANON CO survey. In spite of the local nature of the sample, results confirm essential facts about molecular gas distribution in galaxies other than our own, including a confirmed linear relationship between GMC virial mass and CO luminosity, which implies a constant CO-H2 conversion factor and supports a virialization assumption. The second survey, PHANGS-ALMA (Physics at High Angular Resolution in Nearby Galaxies with the Atacama Large Millimetre-submillimetre Array), maps CO emission from galaxies up to 17 Mpc away, with resolutions of 1″–1.5″ encompassing active star-forming galaxies down to total stellar masses ~5 × 109 M☉. Within 11 of those target galaxies considered here, the results offer tens of thousands of measurements at GMCs scales between 20 and 130 pc, comparable to Galactic-scale observations, and one outcome is confirmation of a positive correlation between GMC surface densities and velocity distributions.

  • Comparing Parametric and Nonparametric Statistical Methods for Studying the Velocity Distributions of Population I Stars

  • F. Arenou, M. L. Bougeard
  • Journal:
    Symposium - International Astronomical Union / Volume 156 / 1993
    Published online by Cambridge University Press:
    07 August 2017, pp. 265-269
    Print publication:
    1993
    • Article
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  • This Paper investigates population I star samples from the viewpoint of the velocity distributions, each being viewed as a mixture. To obtain information on the class centers, clustering techniques are first applied. Secondly, we use a parametric maximum likelihood formulation that we solve by Redner-Walker's E.M. algorithm. The obtained results are compared and discussed from an astrophysical viewpoint.