2018/11/12 by Ed Elson, E. C. Elson, Sié Kam +4 · 12 citations
Environmental Science · Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Estimator #Galaxies: Formation, Evolution, Phenomena #Galaxy #Molecular cloud #Physics #Plant Water Relations and Carbon Dynamics #Power law #Saturation (graph theory) #Star (game theory) #Star formation #Stars #Statistics #astro-ph.GA
paper · pdf · doi:10.1093/mnras/sty3091
published in Monthly Notices of the Royal Astronomical Society 483(1), 931-946 (Oxford University Press) · 16 pages, 13 figures, accepted for publication in MNRAS
arxiv created 2018/11/12 · openalex publication_date 2018/11/13 · arxiv updated 2018/11/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
For the Local Group Scd galaxy M 33 this paper presents a multiscale study of the relationship between the monochromatic star formation rate (SFR) estimator based on 12 |μ|m emission and the total SFR estimator based on a combination of far-ultraviolet and 24 |μ|m emission. We show the 12 |μ|m emission to be a linear estimator of total SFR on spatial scales from 782 pc down to 49 pc, over almost four magnitudes in SFR. These results therefore extend to sub-kpc length-scales the analogous results from other studies for global length-scales. We use high-resolution H i and 12CO(J = 2 − 1) image sets from the literature to compare the star formation to the neutral gas. For the full range of length-scales we find well-defined power-law relationships between 12 |μ|m-derived SFR surface densities and neutral gas surface densities. For the H2 gas component almost all correlations are consistent with being linear. No evidence is found for a breakdown in the star formation law at small length-scales in M 33 reported by other authors. We show that the average star formation efficiency in M 33 is roughly 10−9 yr−1 and that it remains constant down to giant molecular cloud length-scales. Toomre and shear-based models of the star formation threshold are shown to inaccurately account for the star formation activity in the inner disc of M 33. Finally, we clearly show that the H i saturation limit of ≈9 M|\odot pc-2| reported in the literature for other galaxies is not an intrinsic property of M 33 – it is systematically introduced as an artefact of spatially smoothing the data.