We identified the open cluster (OC) groups using Gaia data by analyzing the close correlations in three-dimensional (3D) spatial, 3D velocity, and age. N-body simulation results reveal that these OC groups are gradually dispersing into independent clusters. For G1 and G2, correlations between cluster ages and distances from predicted supernova (SN) explosion sites, combined with pulsar associations, strongly suggest feedback-driven sequential star formation. These results highlight the role of stellar feedback in hierarchical star formation.

Mrk 71 is the closest Green Pea analog, dominated by Knot A, a young, metal-poor super star cluster that is a strong candidate Lyman continuum (LyC) emitter. Broad, faint emission-line wings tracing > 3000 km/s gas of unknown origin have been observed in Mrk 71. We analyze spatially-resolved [O III] and Hα emission-line profiles obtained with GMOS-N IFU, and find that the broad wings a) exhibit a wind kinematic structure originating from Knot A; b) have symmetric, power-law line profiles; and c) cannot be explained by supernovae or stellar winds. On the other hand, the radiation energy, ionization parameter, and stellar surface density, associated with Knot A signal radiation-dominated feedback. We show that a clumpy, LyC and/or Lyα-driven superwind from Knot A can reproduce the observed broad wings. Our finding thus strongly suggests that LyC escapes from Knot A, which may also occur in other Green Pea LyC emitters.

Feedback from stars and active galactic nuclei is the main driver of the cosmic baryon cycle. In this summary, I give a brief overview of the different (stellar) feedback processes that impact the conditions and the evolution of the cold interstellar medium and of the recent theoretical and computational works on the topic. In particular, the feedback from massive stars, i.e. ionizing radiation, radiation pressure, stellar winds, and supernovae are key regulators of the local star formation process in cold molecular clouds. The relative impact of the different feedback processes is currently debated, but it seems evident that pre-supernova feedback is essential. Also, the strong shocks associated with stellar winds and supernovae are engines for the acceleration of cosmic rays, which in turn influence the chemistry and dynamics of the surrounding cold gas. Together these processes drive galactic outflows that contribute to regulating the galaxy ecosystem.

Massive stars have far-reaching feedback effects that alter the surrounding environment on local, global, and cosmic scales. Spectral analyses of massive stars with adequate stellar-atmosphere models are important to study massive star feedback in detail. We discuss the most recent UV and optical studies of massive metal-poor stars, including those with metallicities ranging from half to one twentieth of solar, connected with large-scale ISM structures in the Magellanic Clouds and the tidal Magellanic Bridge. We present ionizing fluxes from massive stars with low metallicity along with mechanical energy, and we further compare these to the observed energetics in the ISM. The results give hints on the leakage of hot gas and ionizing photons in the Magellanic Clouds. The paper outlines feedback from individual massive stars to population-level collective feedback, the significance of various feedback mechanisms (radiation, wind, supernova), and the influence by the physical conditions of the ISM.

Weak mechanical feedback from young, metal-poor super star clusters promotes suppression of potential energy-driven outflows. These conditions are predicted to elevate C IV 1550 nebular emission. We present the first nebular C IV imaging of a nearby star-forming complex. The observations are obtained with the Hubble Space Telescope using ACS/SBC, targeting Mrk 71, a starburst complex in the local, metal-poor galaxy NGC 2366. This system is a spatially resolved analog of the Green Pea galaxies and a candidate Lyman continuum emitter.

HI and CO observations indicate that the cold gas in galaxies is very turbulent. However, the turbulent energy is expected to be quickly dissipated, implying that some energy source is needed to explain the observations. The nature of such turbulence was long unclear, as even the main candidate, supernova (SN) feedback, seemed insufficient. Other mechanisms have been proposed, but without reaching a general consensus. The key novelty of our work is considering that the gas disc thickness and flaring increase the dissipation timescale of turbulence, thus reducing the energy injection rate required to sustain it. In excellent agreement with the theoretical expectations, we found that the fraction of the SN energy (a.k.a. SN coupling efficiency) needed to maintain the cold gas turbulence is ∼ 1%, solving a long-standing conundrum.

Feedback from supernovae (SNe) is an essential mechanism that self-regulates the growth of galaxies. We build an SN feedback model based on high-resolution simulations of superbubble and SN-driven outflows for the physical understanding of the galaxy–CGM connection. Using an Eulerian hydrodynamic code Athena++, we find universal scaling relations for the time evolution of superbubble momentum, when the momentum and time are scaled by those at the shell-formation time. We then develop an SN feedback model utilizing Voronoi tessellation, and implement it into the GADGET3-Osaka smoothed particle hydrodynamic code. We show that our stochastic thermal feedback model produces galactic outflow that carries the metals high above the galactic plane but with weak suppression of star formation. Additional mechanical feedback further suppresses star formation. Therefore, we argue that both thermal and mechanical feedback is necessary for the SN feedback model of galaxy evolution when an individual SN bubble is unresolved.