text: 83,111,1347539745371516936,1908579919,Alexa,"The timing feels a little weird on this but...I have a new paper out the arxiv today looking at the stellar population gradients of the Dragonfly 44! They're pretty weird! <LINK> <LINK> Here's how DF44 looks with respect to other dwarf galaxies <LINK> The upshot of all this is that the internal properties of DF44 (the stellar pops and the kinematics from @DokkumPieter's earlier paper using the same amazing KCWI data) suggest a very different SFH than we see in what I like to call the ""canonical"" dwarf population. @brant_robertson Thanks! It was a lot of fun working on it",https://arxiv.org/abs/2101.02220,"We use the Keck Cosmic Web Imager integral-field unit spectrograph to: 1) measure the global stellar population parameters for the ultra-diffuse galaxy (UDG) Dragonfly 44 (DF44) to much higher precision than previously possible for any UDG, and 2) for the first time measure spatially-resolved stellar population parameters of a UDG. We find that DF44 falls below the mass--metallicity relation established by canonical dwarf galaxies both in and beyond the Local Group. We measure a flat radial age gradient ($m_{\rm age} \sim +0.01_{-0.08}^{+0.07}$ log Gyr kpc$^{-1}$) and a flat-to-positive metallicity gradient ($m_{\rm [Fe/H]} \sim +0.08_{-0.11}^{+0.11}$ dex kpc$^{-1}$), which are inconsistent with the gradients measured in similarly pressure-supported dwarf galaxies. We also measure a flat-to-negative [Mg/Fe] gradient ($m_{\rm [Mg/Fe]} \sim -0.18_{-0.17}^{+0.17}$ dex kpc$^{-1}$) such that the central $1.5$ kpc of DF44 has stellar population parameters comparable to metal-poor globular clusters. Overall, DF44 does not have internal properties similar to other dwarf galaxies and is inconsistent with it having been puffed up through a prolonged, bursty star-formation history, as suggested by some simulations. Rather, the evidence indicates that DF44 experienced an intense epoch of ""inside-out"" star formation and then quenched early and catastrophically, such that star-formation was cut off more quickly than in canonical dwarf galaxies. ","Spatially Resolved Stellar Spectroscopy of the Ultra-diffuse Galaxy