Mystery of the Missing Star: A Cosmic Investigation
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Chapter 1: The Disappearing Star
Utilizing the Very Large Telescope (VLT) situated in the Atacama Desert of Northern Chile, astronomers have uncovered a puzzling phenomenon: a massive, unstable star has vanished from a remote dwarf galaxy. This intriguing case revolves around a star last observed in 2011. Could its disappearance be due to dust obscuring its visibility, or might this investigation unveil secrets regarding black holes?
This captivating illustration depicts what the luminous blue variable star in the Kinman Dwarf galaxy might have looked like prior to its enigmatic disappearance. The Kinman Dwarf galaxy, located 75 million light-years away, has become the focus of astronomers eager to solve this cosmic mystery. The star, which was nearly three times more luminous than our sun, has left researchers with two potential explanations for its sudden absence.
Could it be that the star simply dimmed significantly due to dust obstruction? Or does this disappearance hint at a deeper cosmic enigma? Might the star have collapsed into a black hole without a spectacular supernova event to mark its end?
PhD student Andrew Allan from Trinity College Dublin, likens his role to that of a detective, pursuing clues to unravel this cosmic riddle. The findings were published in the Monthly Notices of the Royal Astronomical Society.
The initial clue indicating the star's absence came when Allan and his international team identified it as an excellent candidate for studying the life cycles of massive stars.
This image, captured by NASA/ESA's Hubble Space Telescope in 2011, shows the Kinman Dwarf galaxy (PHL 293B) before the star's disappearance. Although the galaxy is too distant for astronomers to resolve individual stars, they could detect the signatures of the massive star during observations from 2001 to 2011. These signatures, however, were absent in more recent data.
When the team directed the VLT towards the star's last known position, they were astonished to find no trace of it.
“We were taken aback to discover that the star had vanished!” — Andrew Allan
Due to the vast distance of 75 million light-years, distinguishing individual stars within the Kinman Dwarf galaxy is impossible. However, astronomers can identify the spectral signatures of these stars, which is crucial in determining when one of these signatures goes missing.
During the 2001 to 2011 observations, the presence of a luminous blue variable star was detectable in the galaxy's light. This star was approximately 2.5 times brighter than our sun. Despite the inherent instability of blue variable stars, which often exhibit dramatic changes in brightness and spectra, researchers have been able to identify the remnants of such objects.
To conduct their initial observations in August 2019, the team utilized the ESPRESSO instrument attached to the VLT. When they failed to locate the star's signature with this powerful device, they proceeded to use the VLT’s X-Shooter instrument for further investigation. This follow-up confirmed their initial findings.
The absence of the expected traces in their data left the researchers stunned.
Section 1.1: The Quest for Answers
With the star's disappearance confirmed, the astronomers faced a pressing question: What could have happened to it?
“It would be highly unusual for such a massive star to disappear without a bright supernova explosion,” — Andrew Allan
The team recognized that there might be valuable insights regarding the star's fate hidden within the data collected from 2001 to 2011. This is akin to a detective examining a missing person’s last known location for leads.
In particular, the researchers revisited data from 2002 and 2009 sourced from the X-Shooter and UVES instruments archived at the ESO Science Archive Facility. “The comparison between the high-resolution UVES spectra from 2002 and our 2019 observations with ESPRESSO provided significant insights,” explains Andrea Mehner, a staff astronomer at ESO in Chile who contributed to the study.
The archived data revealed that the missing star had undergone a significant outburst phase, likely concluding sometime after 2011. Such intense activity is characteristic of blue variable stars, whose massive outbursts can result in rapid mass loss and dramatic spikes in luminosity.
This leads astronomers to propose two possible scenarios for the star's disappearance. One possibility relates directly to this intense outburst phase.
They hypothesize that the mass loss could have rendered the star less luminous. Additionally, the material ejected during this phase might have formed a dust cloud around the already dimmer star, further concealing it from view.
This would account for the star's disappearance without the typical supernova event.
Alternatively, the blue variable star might have collapsed into a black hole, bypassing the usual supernova explosion. If this hypothesis holds true, it could challenge our understanding of stellar death and the formation of black holes, revealing more profound cosmic questions.
JWST Solves a Mystery of a Star That Vanished In 2015
The first video discusses how the James Webb Space Telescope contributes to uncovering the mystery surrounding the disappearance of stars, including those that went missing years ago.
Going Dark: The Mystery of Vanishing Stars
The second video explores the enigma of stars that have seemingly vanished, delving into potential explanations and the implications for our understanding of the universe.
Clearly, the investigation into the mystery of the missing star is far from concluded. Fortunately, further research into this stellar enigma is set to progress. The ESO’s Extremely Large Telescope (ELT), which is scheduled to commence operations in 2025, promises to possess the capability to resolve individual stars. Based on these discoveries, the ELT will likely focus on the Kinman Dwarf galaxy to uncover the fate of the missing star.
Jose Groh from Trinity College Dublin summarizes:
“We may have detected one of the most massive stars of the local Universe going gently into the night.”
Original research: Allen, A.P., Groh, J.H., Mehner, A., et al, [2020], ‘The possible disappearance of a massive star in the low metallicity galaxy PHL 293B,’ Monthly Notices of the Royal Astronomical Society.