Special Talk

• Special Talks

  Speaker: Peter Zeidler (STScI)
  Title: Sub-stellar Cluster Populations at Low Metallicities - the Discovery of the First Extra-Galactic Young Brown Dwarf Population​​​​​​​
  Abstract: We present our discovery of the first young, low-metallicity Brown Dwarfs in NGC 602 a young star cluster outside the Milky Way. Using JWST NIRCam photometry, we detected this rich population of 64 Brown Dwarf candidates between 50 to 87 Jupiter masses. Located in the Small Magellanic Cloud (SMC), NGC 602 is a rare nearby low-metallicity example of massive star formation (SF) in isolation. Even with its unfavorable location in the wing of the SMC, a remote low gas-density region, the O and B-star rich cluster shows a high SF rate, comparable to well-studied regions in the Milky Way and the Magellanic Clouds. Despite the rareness in the Local Group, SF in galactic streams is a common phenomenon at high redshifts and in interacting galaxies thus NGC 602 is an example for star cluster formation under conditions similar to the Cosmic Noon. Our detected Brown Dwarfs, the first of their kind, follow a spatial distribution similar to the rich cluster pre-main-sequence (PMS) located in three “stream-like” features from the North and North East toward the central cluster. Thus, we conclude that these Brown Dwarfs and the PMS stars originate from the same SF episode about 2 Myr ago. Based on these results and with the synergy of space and ground-based telescopes (i.e., HST, JWST, VLT/MUSE) we are now able to study the impact of stellar winds and feedback processes on the young stellar population across all masses as well as the gas. This allows us to investigate how star clusters form at low metallicities, how they might drive star formation outwards into the clouds, and test the recurring fundamental questions in SF theories: Is the initial mass function, the very core evidence of how the Universe turns gas into stars, universal, even in the sub-stellar regime and across time.

  Speaker: Adarsh Ranjan (STScI)
  Title: Probing Enrichment Timescales in M83, a Grand-Design Starburst​​​​​​​
  Abstract: To understand how stars influence their surrounding interstellar medium (ISM), it is crucial to study them through spatially resolved spectra of individual star clusters. Only by resolving these regions in detail can we begin to answer fundamental questions such as: How rapidly does chemical enrichment occur? and What factors control the timescales and efficiency of metal enrichment in the ISM? In this work, we focus on young massive star clusters within M83—a nearby, grand-design starburst galaxy known for its rich star-forming environment and high (super-solar) metallicity. M83 provides an ideal setting to study how stellar feedback shapes the ISM in chemically evolved galaxies. We carry out a co-spatial, multi-wavelength spectroscopic analysis using rest-frame ultraviolet data from HST/COS and optical data from VLT/MUSE. This approach allows us to trace both neutral and ionized gas phases around the young massive star-clusters, offering a more complete picture of the enrichment process. While other similar studies have looked at relatively metal-poor galaxies, our study will be the first of it's kind to look at metal-rich galaxy. In my talk, I will share new findings on how the abundances of key elements such as nitrogen and oxygen vary between these gas phases (ionized and neutral). These variations reveal how different stellar populations (varying in stellar-age, type, metallicity and cluster-mass) and galactic environment (galactocentric distance, location) - contribute to enrichment in distinct ways.