Oldest Planetary Nebula Hosted by 500-Million-Old Galactic Cluster: All the Details

Astronomers have discovered the oldest visible planetary nebula (PN) in a 500-million-year-old Galactic Open Cluster (OC). A rare celestial gem has been found in a cluster called M37 and is believed to be of high astrophysical value. Planetary nebulae (PNe) are luminous envelopes ejected from dying stars that glow with different colors and shapes that provide a spectacular sight for astronomers. This discovery has been made by a team of researchers from the University of Hong Kong. They found that PN has a kinematic age of 70,000 years.

Recently tarnished The PN, named IPHASX J055226.2+323724, is only the third planetary nebula out of a total of ~4,000 PNe known in our Galaxy to show a connection between a PN and an OC. Additionally, it is said to be the oldest PN discovered by astronomers to date.

They estimated the age by analyzing how fast the nebula was expanding as determined by the PN emission lines. They also assumed that the speed has remained effectively the same since the beginning and that time has passed since the nebular shell was first ejected by the dying star.

The recently observed planetary nebula IPHASX J055226.2+323724
Photo credit: University of Hong Kong

Although the planetary nebula is very old, it is still a blink of an eye relative to the parent star, which is millions of years old. The researchers say that the “Grand Old Dame” resides in a stellar cluster whose atmosphere allows the team to determine powerful additional parameters that are not possible for the general galactic PN population.

These parameters include estimates of the mass of the progenitor star of the PN at the termination of the stellar main sequence. Researchers can also estimate the residual mass of the central star from which the PNe were ejected through theoretical isochrones and observe the properties of the hot, blue central star.

Using this method, the team determined the size of the star when the PN gas shell was born, as well as its residual mass.

“I am very excited to be able to work on these fascinating rare cases of OC-PN associations as they continue to yield important science results, as all three cases we have found are of butterfly (bipolar) PN size. are very faint and highly evolved, and all have type-1 chemistry in their emission lines, and of course, all have intermediate to high progenitor masses. said Former HKU PhD student Dr Vasiliki Fragkou. She is also the first author of the study Published In Astrophysical Journal Letters.