Unusual Shell Around Red Supergiant DFK 52 Puzzles Astronomers
Astronomers have discovered a massive shell of gas and dust surrounding the red supergiant star DFK 52, presenting a mystery regarding its origin. Observations from the Atacama Large Millimeter/submillimeter Array (ALMA) revealed the unusual structure, indicating the star underwent important mass loss relatively recently.
The shell is unusually large and cold, extending far from the star. This contrasts with typical wind models for red supergiants, suggesting DFK 52 has experienced a unique history. The star is expected to eventually end its life as a Type II supernova.
Researchers are currently investigating the cause of this dramatic expulsion of material. One leading hypothesis involves a yet-undiscovered companion star that may have disturbed the star’s atmosphere and triggered the mass loss. “To us, it’s a mystery as to how the star managed to expel so much material in such a short timeframe. Maybe, like Betelgeuse seems to, it has a companion star that’s still to be discovered,” explained Moritz Siebert. The idea of a stellar companion gaining traction as a potential explanation.
another possibility is an unstable phase within DFK 52 itself, leading to episodic mass loss, a phenomenon observed or inferred in other massive stars nearing the end of their lives. However, the specific triggers for such events remain a topic of ongoing research.
The presence of dense gas and dust near a star can considerably impact the appearance of a supernova. When ejected material collides with surrounding material, it can brighten the event and create distinctive features in the early light spectrum. A 2017 study of supernova SN 2013fs demonstrated this effect, revealing a dense circumstellar medium shed shortly before the explosion.
While DFK 52’s shell is farther out than that observed around SN 2013fs, it confirms the star has a history of substantial mass loss. Further increases in mass loss before the star’s demise could result in a particularly bright and noticeable supernova.
DFK 52 shares similarities with well-known red supergiants like Betelgeuse and Antares. Like these stars,it is indeed massive,swollen,and cool,and is predicted to end its life as a type II supernova. Betelgeuse’s dimming in late 2019 and early 2020, attributed to a dust cloud formed by ejected material, illustrates the dynamic nature of these stars.DFK 52 appears less luminous than some extreme red supergiants but possesses a larger,colder envelope at a greater distance,hinting at an unusual evolutionary path.the research team plans to conduct further observations to search for a companion star and to map the 3D structure of the shell in greater detail.Analyzing the gas chemistry and dust properties will also help clarify the sequence of events that led to the outburst.
“if this is a typical red supergiant, it could explode sometime in the next million years,” stated study co-author Elvire De Beck. “We’re planning more observations to understand what’s happening, and to find out whether this might be the Milky Way’s next supernova.”
The study was published in Astronomy and Astrophysics.Image Credit: ALMA (ESO/NAOJ/NRAO)/M. Siebert et al.
