Issue |
A&A
Volume 689, September 2024
|
|
---|---|---|
Article Number | A14 | |
Number of page(s) | 9 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202450325 | |
Published online | 27 August 2024 |
Detection of the [C I] λ8727 emission line
Low-ionization structures in NGC 7009
1
Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens,
GR 15236
Penteli, Greece
Corresponding author; stavrosakras@gmail.com
2
Instituto de Física e Química, Universidade Federal de Itajubá,
Av. BPS 1303, Pinheirinho,
37500-903,
Itajubá, MG, Brazil
3
European Southern Observatory,
Karl-Schwarzschild Strasse 2,
85748
Garching, Germany
4
Observatório do Valongo, Universidade Federal do Rio de Janeiro,
Ladeira Pedro Antonio 43,
20080-090,
Rio de Janeiro, Brazil
5
Instituto de Astrofísica de Canarias,
38205
La Laguna, Tenerife, Spain
6
Departamento de Astrofísica, Universidad de La Laguna,
38206
La Laguna, Tenerife, Spain
Received:
11
April
2024
Accepted:
14
July
2024
We report the first spatially resolved detection of the near-infrared [C I] λ8727 emission from the outer pair of low-ionization structures in the planetary nebula NGC 7009 from data obtained by the Multi Unit Spectroscopic Explorer integral field unit. This atomic carbon emission marks the transition zone between ionized and neutral gas and for the first time offers direct evidence that LISs are photodominated regions. The outer LIS pair exhibits intense [C I] λ8727 emission, but He I λ8733 is absent. Conversely, the inner pair of knots shows both lines, likely due to the host nebula emission. Furthermore, the [C I] λ8727 line is absent in the host nebula emission, but He I λ8733 is present. Although the origin of the [C I] λ8727 line is still debated, its detection supports the scenario of photoevaporated dense molecular clumps.
Key words: shock waves / ISM: atoms / photon-dominated region (PDR) / planetary nebulae: individual: NGC 7009
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.