Astronomers recently witnessed yet another ho-hum explosion of a star, or so they had thought..
Stars are fairly common near the centers of pairs of colliding galaxies, as are supermassive black holes. What happens when the two objects approach each other? The story begins when the star that is central to this week’s story appeared to fall right on top of a black hole, at which point it released large amounts of X-rays.
This signature is typical of an exploding star, which is also a relatively common phenomenon in the centers of galaxies. On tracking this supernova over a ten-year period, however, the star did not show the attributes typical of others. It did not fade away over time as its energy dissipated, but instead formed into a long radio jet similar in appearance to a jet trail of an airplane passing overhead.
According to the results of a long-term study led by Seppo Mattila of the University of Turku in Finland, and Miguel Perez-Torres of the Astrophysical Institute of Andalusia in Spain, the answer to the mysterious circumstances of this stellar death is far from pedestrian.
By analyzing the radio jet and other observations taken in infrared colors, or heat, they discovered that the black hole that neighbored the ill-fated star was not a passive observer of the supernova. Rather, the scenario that fits the data best is that a portion of the star was consumed by the supermassive black hole, while another portion was stretched like taffy by the black hole into a long spaghetti-like stream of stellar material which we now see as the radio jet.
This is a rare detection of what astronomers call a “tidal disruption event,” in which a black hole is caught disrupting a star. Such events may be relatively common especially in the centers of galaxies, and also usually hidden from our view.