Utilizing the powerful capabilities of NASA's Chandra X-ray spacecraft, astronomers have conducted a thorough investigation of a potential super-star cluster, designated HSO BMHERICC J72.971176-69.391112, affectionately known as H72.97−69.39. Their recent observations have unveiled a remarkable discovery: the presence of diffuse hot gas enveloping this intriguing cluster, as detailed in a paper published on the pre-print server arXiv on February 21.
Super-star clusters (SSCs) stand as formidable entities in the cosmos, representing very massive young open clusters (OCs) that evolve into the illustrious globular clusters (GCs) over time. These clusters teem with a profusion of youthful, massive stars that orchestrate the ionization of surrounding interstellar atomic hydrogen, manifesting as luminous HII regions. The scrutiny of SSCs proves invaluable to astronomers, offering key insights into the formation and evolution of GCs and the galaxies that host them.
Nestled approximately 160,000 light years away, H72.97−69.39 emerges as a highly-embedded contender within the star-forming domain of N79 within the expansive Large Magellanic Cloud (LMC). With an estimated age of less than 500,000 years, H72.97−69.39 finds itself in the nascent throes of formation, boasting an accelerating star-formation rate and a bolometric luminosity reaching a staggering two million solar luminosities.
Despite prior scrutiny across optical, infrared, and submillimeter wavelengths, H72.97−69.39 has remained largely unexplored in the realm of X-rays. Motivated by this intriguing knowledge gap, a team of astronomers led by Trinity Webb of the Ohio State University (OSU) embarked on a quest to harness the capabilities of Chandra to unveil the enigmatic X-ray emissions emanating from this celestial ensemble.
“Here we study the X-ray emission of H72.97−69.39 with the Chandra X-ray Observatory, and we explore stellar-wind feedback at an early stage in star formation,” the researchers articulated in their published findings.
Through meticulous Chandra observations, astronomers discerned the presence of diffuse X-ray emissions encircling H72.97−69.39. The discerned X-ray emission sprawls across an expanse of approximately 10 arcseconds in radius, indicative of hot gas generated by stellar-wind feedback during the formative stages of this celestial marvel.
Remarkably, the X-ray emission exudes a distinct hardness, dominated by photons surpassing the 1.2 keV threshold. This phenomenon hints at a notable hot gas temperature, a substantial absorbing column enshrouding the locale, or a potential contribution from a non-thermal/power-law component. Additionally, the spatial distribution of X-rays appears to juxtapose the dense carbon monoxide gas, suggestive of the hot gas preferentially occupying lower-density cavities within the region.
Further analyses unveiled that the X-ray luminosity of H72.97−69.39 resides one order of magnitude below anticipated levels if the shock-heated gas were constrained by a cool shell. In such a scenario, the shell would undergo thermal conduction-induced heating and eventual evaporation. This intriguing outcome underscores the profound energy loss occurring even in the embryonic stages of massive star cluster formation, signifying the substantial dissipation of wind energy.
In summary, the pioneering observations of H72.97−69.39 with Chandra have unveiled a tapestry of cosmic phenomena, shedding light on the intricate interplay between stellar-wind feedback and the emergent dynamics within nascent super-star clusters. These revelations not only enrich our understanding of early-stage cluster formation but also pave the way for deeper explorations into the enigmatic realms of cosmic evolution and stellar dynamics.