SDSS-V LVM: Revealing the Physical and Chemical Structure of the Helix Nebula
18 affiliations
- 1Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México , 58090 Morelia, Michoacán ,
- 2Universidad Nacional Autónoma de México. Instituto de Astronomía . A.P. 70-264, 04510. Ciudad de México ,
- 3Universidad Nacional Autónoma de México. Instituto de Astronomía . A.P. 106, 22800. Ensenada, B.C. ,
- 4Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México , Av. Universidad s/n, 62210 Cuernavaca, Morelos ,
- 5Instituto de Astrofísica de Canarias , Vía Láctea s/n, 38205, La Laguna, Tenerife ,
- 6Institute of Astrophysics, Facultad de Ciencias Exactas, Universidad Andrés Bello, Sede Concepción , Talcahuano ,
- 7Universidad de Chile Departamento de Astronomía, , Camino del Observatorio 1515, Las Condes, Santiago ,
- 8Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales , Av. Ejército Libertador 441, Santiago ,
- 9Universidad de La Serena Department of Astronomy, , Av. Raul Bitran 1302, La Serena ,
- 10University of Colorado , Boulder, CO 80309 ,
- 11Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg , Mönchhofstr. 12-14, D-69120 Heidelberg ,
- 12Universidad Nacional Autónoma de México , Facultad de Ciencias, Av. Universidad 3000, 04510, Cd. de
- 13University of Utah Department of Physics and Astronomy, , 270 S. 1400 E. #E2108, Salt Lake City, UT 84112 ,
- 14New York University Abu Dhabi , PO Box 129188, Abu Dhabi ,
- 15Center for Astrophysics and Space Science (CASS), New York University Abu Dhabi , PO Box 129188, Abu Dhabi ,
- 16Sternberg Astronomical Institute, Lomonosov Moscow State University , Universitetskij pr., 13, Moscow, 119234 ,
- 17Universidad de Chile , Av. Libertador Bernardo O’Higgins 1058 ,
- 18Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101 ,
Abstract
We present a spatially contiguous spectroscopic analysis of the physical and chemical structure of the Helix Nebula (NGC 7293, PNG 036.1-57.1) using integral-field observations from the SDSS-V Local Volume Mapper (LVM). The nearly complete nebular coverage allows us to map extinction, electron density and temperature, ionisation structure, and chemical abundances within a common dataset. We reconstruct calibrated datacubes from the LVM row-stacked spectra and measure 41 optical emission lines from hydrogen, helium, and collisionally excited ions. The Helix is globally a low-density nebula, with characteristic electron densities of ∼102 cm−3, but shows a strongly structured thermal distribution. Te([O III]) exhibits a U-shaped radial profile, decreasing from the central cavity to intermediate radii and rising toward the outer nebula, while Te([N II]) increases outward and Te([O II]) decreases. These contrasting behaviours show that different diagnostics trace distinct ionisation zones. The spatially resolved abundance analysis yields a near-solar oxygen abundance, 12 + log (O/H) ≃ 8.7, consistent with an approximately chemically homogeneous nebula once ionisation structure is considered. Simulated long-slit extractions show that inferred O/H depends systematically on slit orientation and can remain biased after ionisation correction, demonstrating the importance of spatial coverage in strongly stratified nebulae. We also find sulfur systematically deficient relative to other α-elements, consistent with the planetary-nebula sulfur anomaly. These results highlight the power of wide-field integral-field spectroscopy for linking the thermal, ionisation, and chemical structure of extended planetary nebulae.
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BibTeX
@article{orozcoduarte2026sdssv,
title = {{SDSS-V LVM: Revealing the Physical and Chemical Structure of the Helix Nebula}},
author = {R Orozco-Duarte and J E Méndez-Delgado and J A Toalá and L Sabin and C Morisset and S F Sánchez and H Ibarra-Medel and W J Henney and A Z Lugo-Aranda and A Singh and E J Johnston and A Roman-Lopes and C G Román-Zúñiga and I Cruz-Gonzalez and Guy S Stringfellow and M Peña and A Wofford and E Egorova and O Aranguré and L C Castañeda-Carlos and S Torres-Peimbert and L Hernández-Martínez and J R Brownstein and R de J Zermeño and I Yu Katkov and Oleg V Egorov and A J Mejía-Narváez and G A Blanc and Mónica A Villa-Durango},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = nov,
doi = {10.1093/mnras/stag2118},
url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2118/9013658},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - SDSS-V LVM: Revealing the Physical and Chemical Structure of the Helix Nebula
AU - R Orozco-Duarte
AU - J E Méndez-Delgado
AU - J A Toalá
AU - L Sabin
AU - C Morisset
AU - S F Sánchez
AU - H Ibarra-Medel
AU - W J Henney
AU - A Z Lugo-Aranda
AU - A Singh
AU - E J Johnston
AU - A Roman-Lopes
AU - C G Román-Zúñiga
AU - I Cruz-Gonzalez
AU - Guy S Stringfellow
AU - M Peña
AU - A Wofford
AU - E Egorova
AU - O Aranguré
AU - L C Castañeda-Carlos
AU - S Torres-Peimbert
AU - L Hernández-Martínez
AU - J R Brownstein
AU - R de J Zermeño
AU - I Yu Katkov
AU - Oleg V Egorov
AU - A J Mejía-Narváez
AU - G A Blanc
AU - Mónica A Villa-Durango
PY - 2026
DA - 2026/11/05
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag2118
UR - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2118/9013658
AB - We present a spatially contiguous spectroscopic analysis of the physical and chemical structure of the Helix Nebula (NGC 7293, PNG 036.1-57.1) using integral-field observations from the SDSS-V Local Volume Mapper (LVM). The nearly complete nebular coverage allows us to map extinction, electron density and temperature, ionisation structure, and chemical abundances within a common dataset. We reconstruct calibrated datacubes from the LVM row-stacked spectra and measure 41 optical emission lines from hydrogen, helium, and collisionally excited ions. The Helix is globally a low-density nebula, with characteristic electron densities of ∼102 cm−3, but shows a strongly structured thermal distribution. Te([O III]) exhibits a U-shaped radial profile, decreasing from the central cavity to intermediate radii and rising toward the outer nebula, while Te([N II]) increases outward and Te([O II]) decreases. These contrasting behaviours show that different diagnostics trace distinct ionisation zones. The spatially resolved abundance analysis yields a near-solar oxygen abundance, 12 + log (O/H) ≃ 8.7, consistent with an approximately chemically homogeneous nebula once ionisation structure is considered. Simulated long-slit extractions show that inferred O/H depends systematically on slit orientation and can remain biased after ionisation correction, demonstrating the importance of spatial coverage in strongly stratified nebulae. We also find sulfur systematically deficient relative to other α-elements, consistent with the planetary-nebula sulfur anomaly. These results highlight the power of wide-field integral-field spectroscopy for linking the thermal, ionisation, and chemical structure of extended planetary nebulae.
SN - 0035-8711
SN - 1365-2966
ER -