VizieR Online Data Catalog: A full-sky 20pc census of stars & BDs (Kirkpatrick+, 2024)
Abstract
A complete accounting of nearby objects-from the highest-mass white dwarf progenitors down to low-mass brown dwarfs-is now possible, thanks to an almost complete set of trigonometric parallax determinations from Gaia, ground-based surveys, and Spitzer follow-up. We create a census of objects within a Sun-centered sphere of 20pc radius and check published literature to decompose each binary or higher-order system into its separate components. The result is a volume-limited census of ~3600 individual star formation products useful in measuring the initial mass function across the stellar (<8Mȯ) and substellar (>~5MJup) regimes. Comparing our resulting initial mass function to previous measurements shows good agreement above 0.8Mȯ and a divergence at lower masses. Our 20pc space densities are best fit with a quadripartite power law, {xi}(M)=dN/dM∝M-α, with long-established values of α=2.3 at high masses (0.55<M<8.00Mȯ), and α=1.3 at intermediate masses (0.22<M<0.55Mȯ), but at lower masses, we find α=0.25 for 0.05<M<0.22Mȯ, and α=0.6 for 0.01<M<0.05Mȯ. This implies that the rate of production as a function of decreasing mass diminishes in the low-mass star/high-mass brown dwarf regime before increasing again in the low-mass brown dwarf regime. Correcting for completeness, we find a star to brown dwarf number ratio of, currently, 4:1, and an average mass per object of 0.41Mȯ.
(23 data files).- Publication:
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VizieR Online Data Catalog
- Pub Date:
- June 2024
- Bibcode:
- 2024yCat..22710055K
- Keywords:
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- Stars: brown dwarf;
- Spectral types;
- Stars: distances;
- Photometry: infrared;
- Parallaxes: trigonometric;
- Exoplanets;
- Radial velocities