The Nearby Evolved Stars Survey II: Constructing a volume-limited sample and first results from the James Clerk Maxwell Telescope

TL;DR

The paper presents the construction of a volume-limited sample of ~850 evolved stars within 3 kpc, using sub-mm observations from JCMT and APEX, revealing new insights into dust production and envelope properties.

Contribution

It introduces a new distance estimation metric for evolved stars and provides first results from the NESS survey, including dust production rates and envelope characteristics.

Findings

Most dust is produced by highly enshrouded objects in the Galactic Plane.

Estimated total dust production rate is 4.7×10⁻⁵ M☉/yr.

Sub-mm fluxes are higher and spectral indices shallower than models predict.

Abstract

The Nearby Evolved Stars Survey (NESS) is a volume-complete sample of $\sim$850 Galactic evolved stars within 3\,kpc at (sub-)mm wavelengths, observed in the CO $J = $ (2$-$1) and (3$-$2) rotational lines, and the sub-mm continuum, using the James Clark Maxwell Telescope and Atacama Pathfinder Experiment. NESS consists of five tiers, based on distances and dust-production rate (DPR). We define a new metric for estimating the distances to evolved stars and compare its results to \emph{Gaia} EDR3. Replicating other studies, the most-evolved, highly enshrouded objects in the Galactic Plane dominate the dust returned by our sources, and we initially estimate a total DPR of $4.7\times 10^{-5}$ M$_\odot$ yr$^{-1}$ from our sample. Our sub-mm fluxes are systematically higher and spectral indices are typically shallower than dust models typically predict. The 450/850 $\mu$m spectral indices are consistent with the blackbody Rayleigh--Jeans regime, suggesting a large fraction of evolved stars have unexpectedly large envelopes of cold dust.