2006/01/01 by Andrew A. West, Andrew West, John J. Bochanski +6 · 69 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Disc #Galactic plane #Galaxy #Galaxy formation and evolution #Luminosity #Physics #Stars #Stellar, planetary, and galactic studies #Thick disk #Thin disk #astro-ph
paper · pdf · doi:10.1086/508652
published in The Astronomical Journal 132(6), 2507-2512 (Institute of Physics) · 6 pages, accepted for publication in AJ
openalex publication_date 2006/01/01 · arxiv created 2006/08/31 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a spectroscopic study and dynamical analysis of ∼2600 M7 dwarfs. We confirm our previous finding that the fraction of magnetically active stars decreases with vertical distance from the Galactic plane. We also show that the mean luminosity of the Hα emission has a small but statistically significant decrease with distance. Using space motions for ∼1300 stars and a simple one-dimensional dynamical simulation, we demonstrate that the drop in the activity fraction of M7 dwarfs can be explained by thin disk dynamical heating and a rapid decrease of magnetic activity at a mean stellar age of ∼6-7 Gyr.