“First there is a mountain, then there is no mountain, then there is”
‘There Is a Mountain‘ by Donovan
Rock and Roll Hall of Fame member Donovan Leitch was inspired by a Buddhist saying to write those lyrics about finding one’s true nature. If a mountain can disappear, can something bigger … like a star? That the question astronomers are pondering after a massive star in a strange dwarf galaxy suddenly blinked out of existence and left nothing behind to indicate what happened or where it went. The next lines of the song compares it to a caterpillar shedding its skin to transform into a butterfly. Did this star shed its life and transform into something else other than a black hole? If so, this would be a first. Is it? Donovan? Buddhists?
“We investigate a suspected very massive star in one of the most metal-poor dwarf galaxies, PHL 293B. Excitingly, we find the sudden disappearance of the stellar signatures from our 2019 spectra, in particular the broad H lines with P Cygni profiles that have been associated with a massive luminous blue variable (LBV) star.”
In a research paper published this week in the Monthly Notices of the Royal Astronomical Society, astronomers from around the world reveal how the massive star they had studied between 2001 and 2011 suddenly disappeared when they went for a look in 2019. Located in the Kinman Dwarf (PHL 293B) galaxy in the Aquarius constellation about 75 million light years from Earth, this was a luminous blue variable star about 2.5 million times brighter than the Sun and in the latter stages of its life – although certainly not on its deathbed. Or so they thought.
“It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion.”
Where was the supernova explosion?
In a European Southern Observatory (ESO) press release announcing the study, team leader and PhD student Andrew Allan of Trinity College Dublin describes using the ESPRESSO instrument (Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations) of the ESO’s Very Large Telescope (VLT) and the VLT’s four 8-metre telescopes simultaneously in August 2019. Finding no sign of the star, they suspected and error and switched to the VLT’s X-shooter instrument (“the ultimate weapon in intermediate resolution spectroscopy across a wide wavelength range, from the ultraviolet (UV) to the near-infrared (NIR)”) and still found no sign of the massive luminous star. With the Kinman Dwarf galaxy being too far away to see individual stars, they went back to older data which gave the astronomers a clue to what they had really been looking at.
“The old data indicated that the star in the Kinman Dwarf could have been undergoing a strong outburst period that likely ended sometime after 2011. Luminous blue variable stars such as this one are prone to experiencing giant outbursts over the course of their life, causing the stars’ rate of mass loss to spike and their luminosity to increase dramatically.”
Ah-ha! The luminous blue variable star was luminous because it was in a last blast of brightness and on its way out in 2011, or already “going gently into the night,” as team member Jose Groh, also of Trinity College Dublin, described it. As a result, the star may have dimmed considerably and is now blocked by a dust cloud. Or, the star collapsed into a black hole without producing a supernova – something only known to have occurred once before. As expected, the astronomers hope it’s the latter option, but can’t prove it because they can’t see the black hole … yet.
“Planned to begin operations in 2025, ESO’s Extremely Large Telescope (ELT) will be capable of resolving stars in distant galaxies such as the Kinman Dwarf, helping to solve cosmic mysteries such as this one.”
Will it come back?
Will they find a non-supernova black hole where the star was first? Donovan?
“Caterpillar sheds his skin to find a butterfly within.”
Then what?
“First there is a mountain, then there is no mountain, then there is”
Astronomy, like Buddhism and rock singers, can be comforting and frustrating at the same time.
from Mysterious Universe https://ift.tt/31CLtle
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