Massive stars are not like your car keys. They are not likely to disappear beneath a pile of email in your kitchen counter tops, or wind up in the washing machine. However a huge star that astronomers were celebrating for a decade appears to be completely missing.
The celebrity, at the very late stages of its life span, was shining brightly between 2001 and 2011, when distinct groups of astronomers were frequently observing it to acquire more information about how stars end their own lives. However, in observations obtained 2019, the celebrity’s signature was totally absent.
Subsequently the mystery deepened. When investigators return through archival data from 2011 and 2016, searching for some hint regarding the celebrity’s disappearance, its light was current in the prior, but lacking at the latter. But after 2011, the star disappeared with no trace.
And there is a very exciting possibility – the star fell down into a black hole, with no supernova which has been thought an essential part of these occasions.
“If accurate,” stated astrophysicist Andrew Allan of Trinity College Dublin in Ireland,”this could be the first direct detection of such a monster celebrity ending its life this way.”
It is somewhat hard to work out precisely what happened, however. Everything went down into a dwarf galaxy named PHL 293B, 75 million light-years away. At the space, making individual stars is hopeless – we just don’t possess the tech.
But, there is a kind of star known as a luminous blue variable which has a recognisable light touch. These stars are enormous – to the supergiant or even hypergiant scale – and in the conclusion of their lifetimes. Therefore, they are incredibly unstable and bright, and their light may fluctuate dramatically in both spectrum and brightness as they experience outbursts and eruptions.
At the prior observations of the dwarf galaxy, that this touch was present, signaling a superstar between 2.5 and 3.5 million times as bright as the Sun. So as soon as the group turned four of those European Southern Observatory’s Very Large Telescope optical telescopes towards PHL 293B at August 2019, the lack was shocking.
“It will be extremely strange for this huge star to evaporate without creating a bright supernova explosion,” Allan stated .
In the past few decades, however, evidence has begun to emerge that celebrities can really collapse into black holes without experiencing a supernova explosion. In 2017, a newspaper was printed on a similar happening at a galaxy 22 million light-years off – a red giant star that brightened suddenly before stripping out of existence, leading astronomers to hypothesise that the celebrity had experienced a collapsed supernova before falling.
According to their observations, the group considers that the superstar in PHL 293B has been at an eruptive condition between 2001 and 2011. From this stage, there are two major possibilities.
The first is that the celebrity grew marginally fresher, and eventually become shrouded in a cloud of dust as it circulates material to the area around it much like the dust cloud which could (or might not) have obscured Milky Way’s red giant star Betelgeuse before this season. Within this situation, the celebrity might have lasted erupting supporting its own cloud of dust – we simply can not see it because, well, cloud of dust.
Near-infrared observations involving 2009 and 2019 ruled out a cloud of warm dust, but mid-infrared observations which may confirm or rule out cooler dust are not yet been removed, so this situation is still very much on the desk.
In another situation, the eruption might have become the star’s death throes, ending suddenly at a certain stage later 2011 since the star collapsed to a black hole. If the celebrity had a first mass involving 85 and 120 times the Sun – only under the selection of a pair-instability supernova, where the star has been blown to smithereens rather than collapsing.
It is not impossible that the celebrity failed an undetected supernova, but such a huge star as a luminous blue variable would be expected to make a supernova afterglow that excels from the sky for five or more years after the kaboom.
“We might have discovered among the very massive stars of the local Universe moving quietly into the night,” stated astrophysicist Jose Groh of Trinity College Dublin.
It is impossible to know for sure with the recent statistics. Just future observations across a variety of wavelengths can shed light onto the puzzle of the lost celebrity.
The study was published in the Monthly Notices of the Royal Astronomical Society.