White dwarf missing in planetary nebula

Let's see this as a case of the missing dwarf. A group of astronomers must perform interstellar field investigations. They had two suspects, signs of attack and assault, but there were no corpses. The southern planetary nebula named Su WT 2 is the scene of this case, about 6,500 light-years away from Earth in the direction of the constellation Centaurus.

SuWt 2 has gas rings that shine on the edges. Many translucent lobes expand perpendicular to the ring, making the most faint parts of the nebula bear an hourglass shape. These glowing things are thought to take energy from a burned star and become a white dwarf. But we don't see that white dwarf anywhere.

The mystery became even more confusing when researchers used the ultraviolet observation method using NASA's International Ultraviolet Explorer satellite in early 1990. They hoped to find signs of a dim star. but extremely hot. However, satellites do not detect any ultraviolet radiation.

Instead, at the center of the nebula is two suspicious objects: a pair of tightly wrapped stars that are twisted about 5 days apart, both are not white dwarfs . These stars are hotter than our sun (classifying their spectrum at A level), but they are still not hot enough to make the nebula shine. Only a single stream of ultraviolet radiation, such as a missing white dwarf, can do that.

This is a photo of planetary nebula SuWt 2, showing the ring-shaped bright structure surrounding a central bright star.The true central star is a double system in which the two stars completely surround each other every 5 days.The contact of these stars and a larger star produces matter that forms the nebula that creates the ring structure.The burnt core of the giant companion star has not been found inside the nebula.The nebula is located 6500 light-years away from Earth in the direction of the constellation Centaurus.This color photo was taken on January 31, 1995 with the 1.5m diameter telescope of the National Science Foundation at Cerro Tololo Inter-American Observatory (CTIO), Chile.CTIO is part of the National Optical Astronomical Observatory, with Headquarters in Tucson, Arizona.(Photo: NASA, NOAO, H. Bond and K. Exter (STScI / AURA))

The study was conducted by Katrina Exter and Howard Bond of the Space Telescope Science Research Institute in Baltimore, Maryland, and a group of British and American partners. Their extensive spectroscopic and photometric research on this pair shows that both stars are larger than the main sequence of stars with the same weight. That may mean they have begun to evolve into red giants. Both stars seem to spin more slowly than expected, they are expected to always face the same side, but not.

Astronomers give a simple explanation for these events: the central stars of SuWt 2 were born into a family of 3 brothers, with two stars twisting around each other closely and one The giant star follows its orbit outward. This provides space for a giant star to evolve into a red giant, which in turn submerges the star A. is tightly enclosed within the red giant, which scientists call 'a general envelope'. ', the star twists gradually into the center, making this envelope rotate faster. Finally, the outer layers of red giant stars are pushed out in orbit, producing circular nebulae as we see it today. The two star A's slow rotation may be the result of being mistreated by its giant brother.

Observations from the ground were obtained thanks to a telescope at Cerro Tololo Inter-American Observatory, Chile; New Technology telescope at South Europe Observatory, Chile; Anglo-Australian telescope, Australia; and South Africa Observatory.

Ultraviolet radiation from the hot core of the red giant star causes the nebula to glow. If this core reaches the required weight, it will shrink and cool quickly into a faint white dwarf, which is the reason for the current invisible.

Their research results are presented on June 3 at the 212th meeting of the American Scientific Community in St. Louis. Louis. Other members of the group include Keivan Stassun (Vanderbilt University, Tennesse), Pierre Maxted and Barry Smalley (Keele University, England) and Don Pollaco (Queen's University, England).