# The Class of Jsolated Stars and Luminous Planetary Nebulae in old stellar populations

## TL;DR

This paper proposes a new class of stars called Jsolated stars, which have lower mass loss rates due to lack of angular momentum increase from companions, explaining bright planetary nebulae in old populations.

## Contribution

It introduces the concept of Jsolated stars with distinct mass loss rates, offering a new perspective on late stellar evolution and planetary nebula luminosities.

## Key findings

- Jsolated stars likely have lower mass loss rates.
- Lower mass loss rates can explain bright PNe in old populations.
- Combining higher AGB luminosities with low mass loss rates accounts for observations.

## Abstract

We suggest that stars whose angular momentum (J) does not increase by a companion, star or planet, along their post-main sequence evolution have much lower mass loss rates along their giant branches. Their classification to a separate group can bring insight on their late evolution stages. We here term these Jsolated stars. We argue that the mass loss rate of Jsolated stars is poorly determined because the mass loss rate expressions on the giant branches are empirically based on samples containing stars that experience strong binary interaction, with stellar or sub-stellar companions, e.g., planetary nebula (PN) progenitors. We use our earlier claim for a low mass loss rate of asymptotic giant branch (AGB) stars that are not spun-up by a stellar or substellar companion to show that we can account for the enigmatic finding that the brightest PNe in old stellar populations reach the same luminosity as the brightest PNe in young populations. It is quite likely that the best solution to the existence of bright PNe in old stellar populations is the combination of higher AGB luminosities, as obtained in some new stellar models, and the lower mass loss rates invoked here.