Surprises Unveiled: Hubble Space Telescope Revisits a Star that Erupted 40 Years Ago

Hubble Space Telescope: Astronomers have delved back into the peculiar case of HM Sagittae (HM Sge), a binary star system that erupted spectacularly 40 years ago. With fresh data from NASA’s Hubble Space Telescope, the retired Stratospheric Observatory for Infrared Astronomy (SOFIA), and archival data from other missions, scientists have uncovered new surprises in this unique stellar system.
The Unusual Nova of HM Sagittae
In 1975, HM Sge dramatically brightened 250 times between April and September. Unlike typical novae that fade within months or years, HM Sge maintained its brightness for decades. Recent observations show the system has become hotter but intriguingly dimmer, defying conventional expectations.
A Symbiotic Star System
HM Sge is a symbiotic star system where a white dwarf and a dust-producing giant star orbit each other. The white dwarf pulls gas from the giant star, forming a hot accretion disk around it. Occasionally, this disk undergoes thermonuclear explosions as the hydrogen buildup reaches a critical point. These explosions offer vital insights into the dynamics of stellar evolution in binary systems.
New Findings from Hubble Space and SOFIA
In 2021, Steven Goldman, Ravi Sankrit, and their team utilized Hubble and SOFIA to observe HM Sge from infrared to ultraviolet (UV) wavelengths. Hubble’s UV data revealed a strong emission line of highly ionized magnesium, absent in 1990 spectra. This suggests the white dwarf and accretion disk’s temperature has risen from under 400,000 degrees Fahrenheit in 1989 to over 450,000 degrees Fahrenheit.
SOFIA’s Contributions
SOFIA, which retired in 2022, provided crucial data on water, gas, and dust around the system. Infrared spectra showed the giant star resumed normal dust production within a few years of the explosion but has dimmed recently. SOFIA also detected water moving at 18 miles per second, likely the speed of the accretion disk around the white dwarf. The gas bridge between the stars now spans about 2 billion miles.
Collaboration with Amateur Astronomers
The team partnered with the American Association of Variable Star Observers (AAVSO), involving amateur astronomers worldwide in monitoring HM Sge. These observations have revealed changes not seen since the initial outburst 40 years ago, highlighting the importance of continuous monitoring for understanding stellar systems.http://indiatoday.com
The Rarity and Significance of HM Sagittae
Symbiotic stars like HM Sge are rare, and observing a nova-like explosion in such a system is even rarer. This unique event provides a wealth of data for astrophysicists. The changes observed in HM Sge over the past decades offer insights into the behavior and evolution of binary star systems, helping researchers understand the complex interactions between white dwarfs and their giant companions.
Future Research Directions
The recent findings have paved the way for further research. Astronomers will continue monitoring HM Sge with both space-based and ground-based telescopes, focusing on the system’s energetics and long-term changes. Understanding HM Sge can shed light on the fundamental processes driving stellar evolution in binary systems.
Conclusion
The study of HM Sagittae highlights the dynamic nature of our universe and the importance of long-term astronomical research. The surprising changes in this binary star system emphasize the need for continuous observation. As technology advances, astronomers will uncover more mysteries of stars like HM Sge, deepening our understanding of stellar evolution and the forces shaping our galaxy. viralenews.com