Astronomers conducted an astro-photometric study of Messier 37, an open cluster. One of the most important findings of this research is the presence of a large and evolved planetary nebula in Messier 37. The research was detailed in a paper published on the arXiv.org pre-print repository on August 12.
Planetary nebulae (PNe) are expanding shells of gas and dust ejected from stars during their evolution from main sequence stars to red giants or white dwarfs. They are uncommon, but crucial for astronomers studying the chemical evolution of stars and galaxies.
Messier 37 (also known as M37 or NGC 2099) is the brightest and richest open cluster (OC) in the constellation Auriga, located approximately 4,500 light years away. It has a radius of about 10 to 13 light years, a mass of about 1,500 solar masses, and over 500 known stars.
A team of astronomers led by Vasiliki Fragkou of the National Autonomous University of Mexico has now presented evidence confirming that a PN known as IPHASX J055226.2+323724, discovered in 2008, is a component of Messier 37. Furthermore, the likely central star of this PN is a white dwarf identified as a high-probability proper motion member of Messier 37.
“Sabin (2008) discovered and classified the nebula as a PN candidate using IPHAS [INT Photometric H-Alpha Survey] imagery. We present new, high-resolution radial velocity data that confirm this unusual OC-PN connection “The researchers wrote about it in their paper.
The ESA’s Gaia satellite’s consistent radial velocities and proper motions for the confirmed planetary nebula’s central star and cluster stars support the hypothesis that IPHASX J055226.2+323724 is a member of Messier 37. This scenario is also supported by the PN positional proximity within the cluster tidal radius, reddening, and distance agreement.
According to the research, IPHASX J055226.2+323724 is a large (5.2 light years in radius), bipolar, evolved (around 78,000 years old) PN with a low surface brightness. The PN’s internal structure is patchy, and its emission line spectra suggest Type-I (nitrogen enriched) chemistry. The central star of the nebula is a white dwarf with a final mass of about 0.63 solar masses.
In summarising the findings, the authors noted that IPHASX J055226.2+323724 is only the third known PN in a Galactic open cluster. They went on to say that its evolved state gives important clues about the maximum observable lifetime of PNe in general.
“This planetary nebula also appears to have the largest kinematical age ever determined, implying increased visibility lifetimes when clustered,” the researchers concluded.