According to observations by the Hubble Space Telescope, the Bat Man Nebula has faded and changed its shape in about 20 years. The sudden change in temperature experienced by the central star seems to be the cause of this unprecedented and rapid deterioration.
A star usually takes millions of years to be born, and its adult stage lasts for billions of years. If its mass is very light or medium, such as our sun, there will be a period of time when the hydrogen in the nuclear is exhausted as fuel, it will expand and discharge its outer layer.
These layers illuminated by the stellar nucleus will produce a Planetary nebula, The beautiful object expands brightness while dimming, and finally disappears in tens of thousands of years.
A new study with the participation of researchers from the Advanced Scientific Research Council (CSIC) revealed something unprecedented: In just two decades, Stingray Nebula, The smallest known, is closed.
This stingray nebula, also known as Hen 3-1357Recognized as the youngest planetary nebula in 1998: According to calculations, the core of the central star has only produced enough energy for 20 years to ionize the gas envelope formed by the outer layer.
The data also shows that given its low mass, the central star is warming faster than expected.
Its size is only one-tenth of the usual size of a planetary nebula, but the luxury of this cosmic stingray does not end there. This new work shows that in the past two decades, Hen3-1357 has gradually disappeared, and the gas layer surrounding the central star has also gradually disappeared.
Dramatic and very rare change
He pointed out: “These changes are huge and strange changes.” Martin A. Guerrero,researcher Andalusian Institute of Astrophysics (IAA-CSIC) The person participating in the task. He added: “We are witnessing the real-time evolution of the nebula, and there will be changes in a few years. We have never seen this so clearly.”
Compare by Hubble Space Telescope Data obtained in 2016 and 1996 (allowing observation of its shape for the first time) showed how it lost its luster and changed its shape.
The gas fluorescent tentacles and filaments in the central area have almost disappeared, and the curved edges indicate that their association with the stingray has almost disappeared.
Researchers have recorded unprecedented changes in the nitrogen, hydrogen, and oxygen emitted by the dying star in the center of the nebula. Between 1996 and 2016, oxygen emissions in particular reduced brightness by nearly a thousand times.
He said: “You have seen the changes in the nebula before, but what we are seeing here is the change in the basic structure of the nebula.” Bruce BalickHe is a researcher at the University of Washington in Seattle, USA, and he is the leader of this research.
Barrick emphasized: “In most cases, the nebula is growing, but here, its shape is changing and weakening on an unprecedented time scale.” In fact, the shiny elliptical inner ring seems to fade away. And shrink. “
The phenomena observed from the ground show signs of changes in the brightness of other planetary nebulae over time, but these signs have not been confirmed so far.
Guerrero said: “Due to the optical stability of the Hubble Space Telescope, we are pretty sure that the brightness of this nebula will change over time. This can only be confirmed by the visual acuity of the telescope.”
The rise and fall of the central star’s temperature
The researchers pointed out that the rapid changes in the nebula are a response to it. Central Star SAO 244567In a short period of time from 1971 to 2002, its surface temperature soared to 60,000 degrees, ten times the temperature of the sun.
Since then, it has gradually dropped to 22,000 degrees, so the star cannot produce enough photons to maintain the ionization of the nebula.
In 2016, a group of researchers proposed that this star will experience once flash helium, The helium-rich layer immediately adjacent to the star’s surface enters a sudden fusion process, which causes the upper layer to expand and cool.
Guerrero said: “In the final stages of stellar evolution, they are very rare events, but they cause fascinating non-equilibrium processes in nebula ionization, just like we studied in HuBi 1.”
“This is a planetary nebula in an advanced composite state, because the cooling time of the gas is longer than that of Hen3-1357. He concluded that at this point, it is difficult to know the final destination. Maybe the central star will heat up again and cause The ionization nebula ionizes, or the star will never warm up, and Hen3-1357 will become a failed planetary nebula.”
B. Balick, MA Guerrero, G. Ramos-Larios. “The fall of the youngest planetary nebula, Hen3-1357”. Astrophysical Journal2020 year