Winds are predicted to be ubiquitous in low-mass, actively star-forminggalaxies. Observationally, winds have been detected in relatively few localdwarf galaxies, with even fewer constraints placed on their timescales. Here,we compare galactic outflows traced by diffuse, soft X-ray emission fromChandra Space Telescope archival observations to the star formation historiesderived from Hubble Space Telescope imaging of the resolved stellar populationsin six starburst dwarfs. We constrain the longevity of a wind to be of order 25Myr based on galaxies whose starburst activity has already declined, although alarger sample is needed to confirm this result. Compared to estimates fromspiral galaxies, we find a higher average efficiency for converting themechanical energy of stellar feedback to thermal, soft X-ray emission. Theoutflows have likely been sustained for timescales comparable to the durationof the starbursts (i.e., 100's Myr), after taking into account the time for thedevelopment and cessation of the wind. The wind timescales imply that materialis driven to larger distances in the circumgalactic medium than previouslythought from assuming 5-10 Myr starburst durations, and that less material isrecycled back to the host galaxy on short timescales. In the detected outflows,the expelled hot gas shows various morphologies which are not consistent with asimple biconical outflow structure. The sample and analysis are part of alarger program, the STARBurst IRregular Dwarf Survey (STARBIRDS), aimed atunderstanding the lifecycle and impact of starburst activity in low-masssystems.

Spiral arms are the most singular features in disc galaxies. These structurescan exhibit different patterns, namely grand design and flocculent arms, witheasily distinguishable characteristics. However, their origin and themechanisms shaping them are unclear. The overall role of spirals in thechemical evolution of disc galaxies is another unsolved question. Inparticular, it has not been fully explored if the \hii\,regions of spiral armspresent different properties from those located in the interarm regions. Herewe analyse the radial oxygen abundance gradient of the arm and interarm starforming regions of 63 face-on spiral galaxies using CALIFA Integral FieldSpectroscopy data. We focus the analysis on three characteristic parameters ofthe profile: slope, zero-point, and scatter. The sample is morphologicallyseparated into flocculent versus grand design spirals and barred versusunbarred galaxies. We find subtle but statistically significant differencesbetween the arm and interarm distributions for flocculent galaxies, suggestingthat the mechanisms generating the spiral structure in these galaxies may bedifferent to those producing grand design systems, for which no significantdifferences are found. We also find small differences in barred galaxies, notobserved in unbarred systems, hinting that bars may affect the chemicaldistribution of these galaxies but not strongly enough as to be reflected inthe overall abundance distribution. In light of these results, we propose barsand flocculent structure as two distinct mechanisms inducing differences in theabundance distribution between arm and interarm star forming regions.

We analyze the intracluster medium (ICM) and circumgalactic medium (CGM) in 7X-ray detected galaxy clusters using spectra of background QSOs from HST/COSand HST/STIS, optical spectroscopy of the cluster galaxies from MMT/Hectospecand SDSS, and X-ray imaging/spectroscopy from XMM-Newton and Chandra. Opticalspectroscopy reveals many galaxies at small impact parameters (<300 kpc) to theQSO sightlines and within ~1000 km/s of the cluster redshifts; we report a verylow covering fraction of H I absorption in the CGM of these cluster galaxies,f_c = 18% +14%/-9%, to stringent detection limits (log N(HI) < 13 cm^-2) inmost cases. As field galaxies have H I covering fractions of ~100% at similarradii, the dearth of CGM H I in our data indicates that the cluster environmenthas effectively stripped or gravitationally heated and overionized the gaseoushalos of these member galaxies. Second, we assess the contribution of warm-hot(10^5 - 10^6 K) gas to the ICM as traced by O VI and broad Ly-alpha (BLA)absorption, which would potentially bring the cluster baryon content closer tothe universal baryon mass fraction (~17%). Despite the high S/N of our data, wedo not detect O VI in any cluster, and we only detect BLA features in the QSOspectrum probing one cluster. We estimate that the total column density ofmaterial in the warm-hot phase along this line of sight totals to ~3% of thatcontained in the hot T > 10^7 K X-ray emitting phase. These features may tracepre-shocked material outside the cluster. Comparing halo gas properties inregions ranging from the low-density 'field' to galaxy groups and high-densityclusters, we find that the CGM is progressively depleted of H I with increasingenvironmental density, where galaxy clusters are extreme sites where the CGM ismost severely transformed. This transformation may play a key role inenvironmental galaxy quenching.