our Sun won't terminate as the typical planetary nebula

An artist’s illustration of a planetary nebula engulfing its orbiting planets. 

Credit: Regulus36/deviantart

Textbooks often cite that planetary nebulae (PNe, plural) represent an endstate for lower-mass single stars.

But conversely, recent research suggests that most PNe stem from binary systems.

The lowest mass star theorized to form the typical PN is near 1 solar mass, and thus without a companion the Sun may not surpass the mass limit required to generate the hot glowing (ionized) nebula typically tied to PNe.

New research continues to question our original understanding of how the Sun's life may end.

A new study spearheaded by G. Jacoby aimed in part to test that binary hypothesis by searching for PNe in star clusters occupying M31.

The team remarked that, "while the binary interaction model explains some of the anomalies associated with the observed planetary nebula population, this theory awaits final confirmation."

"The traditional theory states that the progenitors of PNe are low- to intermediate-mass single stars …

However, this theory does not provide a natural explanation for the non-spherical morphologies observed for the great majority of PNe, nor their low rate of formation.

For these and other inconsistencies, a new paradigm has been developed, wherein most PNe are shaped via the interaction … with a binary companion," said Jacoby et al. 2013.

The advantage of finding a PN in a star cluster is that its fundamental parameters (e.g., progenitor mass, age, chemical composition) can be inferred from cluster membership.

"It is difficult to probe the different PN formation scenarios using field stars, since one has almost no prior information about the properties of the PN progenitors. However, within star clusters, the situation is different, as both the age and metallicity of the progenitor can be accessed," said the Jacoby team.

The problem with using PNe in the field is that their parameters are poorly constrained, in part because distances to the objects are notoriously uncertain. "… the situation in distance determinations for Galactic PNe is not very satisfactory.

It is estimated that this distance scale can be accurate on average to 35-50%," said Zhang 1995.

In recent years parallax measurements from the Hubble Space Telescope (Benedict et al. 2009) and the US Naval Observatory (Harris et al. 2007) have provided improved distances for some of the nearest PNe, and certain refined methods for estimating PNe distances may yield uncertainties as good as 20 to 30% (Frew and Parker 2006, Frew 2008, Stanghellini et al. 2008).