SDSS-V Local Volume Mapper (LVM): Helix Nebula public data, Data Analysis Pipeline data products

TL;DR

This paper presents a detailed, spatially resolved spectroscopic analysis of the Helix Nebula using SDSS-V LVM data, revealing ionization structure, faint lines, and physical conditions across the nebula.

Contribution

It introduces the first wide-field, hexagonally sampled emission-line maps of the Helix Nebula with the LVM Data Analysis Pipeline, enabling detailed spatial analysis.

Findings

Revealed ionization stratification from core to envelope

Detected faint auroral and diagnostic lines across the nebula

Confirmed low dust content and homogeneous temperature and density

Abstract

We present a spatially resolved spectroscopic analysis of the Helix Nebula (NGC 7293) using data from the SDSS-V Local Volume Mapper (LVM), by applying the recently developed LVM Data Analysis Pipeline (LVM-DAP). Covering the full optical range (3600-9800 {\AA}) over a contiguous ~ 0.5 degree field, the LVM data provide the first hexagonally sampled, wide-field emission-line maps of all major ionic species in this archetypal planetary nebula. The resulting flux, kinematic, and line-ratio maps reveal the well-known ionization stratification of the nebula, from the compact He++ core to the bright [O III] ring and the extended low-ionization envelope, enabling a detailed comparison with classical aperture spectroscopy. Owing to the sensitivity and uniform spatial sampling of the LVM, numerous faint auroral and diagnostic lines are detected across the nebula, including [O III] 4363, [N II] 5755, and He I lines, allowing precise measurements of weak-line morphology. The derived radial trends confirm the remarkably low dust content and the overall homogeneity of electron temperature and density across the main ring. Ionized-gas kinematics traced by H{\alpha} further support the scenario of a slowly expanding, limb-brightened shell consistent with previous studies. This work demonstrates the diagnostic power of LVM spectroscopy for extended nebulae and highlights its capability to recover both global and spatially resolved physical conditions across complex ionized structures.