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We have mapped the distribution of young and old stars in the gaseous HI 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) x 10^-5 M_sol/yr/kpc^2. This implies a ~60+/-20 Gyr depletion time of the HI warp, similar to the timescales calculated for the outer HI 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 HI warps, and the gas fueling of disk galaxies.
We present 21-cm observations and models of the neutral hydrogen in NGC 4565, a nearby, edge-on spiral galaxy, as part of the Westerbork Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) survey. These models provide insight concerning both the morpholog
We present detections of 21-cm emission from neutral hydrogen (HI) in the circumgalactic medium (CGM) of the local edge-on galaxies NGC 891 and NGC 4565 using the Robert C. Byrd Green Bank Telescope (GBT). With our 5$sigma$ sensitivity of $8.2 times
The NGC 5903 galaxy group is a nearby (~30 Mpc) system of ~30 members, dominated by the giant ellipticals NGC 5903 and NGC 5898. The group contains two unusual structures, a ~110 kpc long HI filament crossing NGC 5903, and a ~75 kpc wide diffuse, ste
We propose an innovative method for measuring the neutral hydrogen (HI) content of an optically-selected spectroscopic sample of galaxies through cross-correlation with HI intensity mapping measurements. We show that the HI-galaxy cross-power spectru
New deep VLA D array HI observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To investigate the 3D structure of the atomic gas disk, we made different