The venerable Hubble Space Telescope captured an incredible star that is shining with the intensity of 1 million suns, just in time for its 31st anniversary in space Saturday (April 24).
The price for shining so brightly is a shorter lifetime for AG Carinae, a bright blue star which will only last for a few million years. That’s nothing compared with our relatively stable sun’s 10-billion-year lifetime. But astronomers are mesmerized by the incoming signs of destruction from AG Carinae nonetheless.
“I like studying these kinds of stars because I am fascinated by their instability. They are doing something weird,” Kerstin Weis, a variable blue star expert at Ruhr University in Bochum, Germany, said in a statement.
The image from Hubble shows a nebula (a gas cloud) that happened during one of the larger outbursts from the variable star. The star is fighting to stay intact, with radiation pressure pushing outward and gravity compressing inward. As the forces spar against each other, the star expands and contracts. Sometimes the star gets so big that it blows layers of gas into space, before barely coming back together again.
The weird physics of AG Carinae becomes all the more precious to us when we realize how rare this star is. Only 50 known luminous blue variable stars are present in the Local Group of galaxies that includes our own galaxy, the Milky Way. Moreover, this swaying back and forth between billowing large and compressing again is a phase that only lasts a few tens of thousands of years, a mere blink in the universe’s overall 13.77-billion-year-old lifespan.
The star is fairly quiet for the time being, but you can see the effects of its powerful stellar wind (or charged particles) flowing into space and crashing into the nebula, which is moving a little slower than the gas. This creates a “snowplow” effect when the hot wind carves a cavity into the cooler, slower nebula.
Hubble is also a precious gem in astronomy due to its ability to observe objects again and again in its decades of spaceflight. The telescope’s long lifetime comes in large part due to several astronaut crews who visited the observatory several times between 1993 and 2009, performing vital repairs and upgrades that will keep the observatory operating well into this decade at the least.
Once Hubble finally runs out of fuel or power, there is a successor on the way shortly. NASA plans to send its James Webb Space Telescope into the black in October this year, following many years of delays due to technical and budgetary issues. Webb will have a larger mirror able to peer even further back into the universe’s history; it also is adept at viewing stars and exoplanets. The drawback, however, is Webb will be situated too far away from Earth for astronaut crews to visit.