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Physics and Astronomy


We have mapped the distribution of young and old stars in the gaseous H i warp of NGC 4565. We find a clear correlation of young stars (< 600 Myr) with the warp but no coincident old stars (> 1 Gyr), which places an upper limit on the age of the structure. The formation rate of the young stars, which increased ∼ 300 Myr ago relative to the surrounding regions, is (6.3+2.5 −1.5) × 10−5 M yr−1 kpc−2. This implies a ∼ 60 ± 20 Gyr depletion time of the H i warp, similar to the timescales calculated for the outer H i disks of nearby spiral galaxies. While some stars associated with the warp fall into the asymptotic giant branch (AGB) region of the color–magnitude diagram, where stars could be as old as 1 Gyr, further investigation suggests that they may be interlopers rather than real AGB stars. We discuss the implications of these age constraints for the formation of H i warps and the gas fueling of disk galaxies.


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Original Publication Information

Radburn-Smith, David J., et al. "Constraining the Age of the NGC 4565 HI Disk Warp: Determining the Origin of Gas Warps." 2014. The Astrophysical Journal 780(1): 12 pp.