O/H-N/O: The curious case of NGC 4670
We use integral field spectroscopic (IFS) observations fromGemini Multi-Object Spectrograph North (GMOS-N) of a group of four HII regions and the surrounding gas in the central region of the blue compact dwarf (BCD) galaxy NGC 4670. At spatial scales of ~9 pc, we map the spatial distribution of a va...
| Autores: | , , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2018 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/197108 |
| Acesso em linha: | http://hdl.handle.net/10261/197108 |
| Access Level: | acceso abierto |
| Palavra-chave: | Galaxies: individual: NGC 4670 Galaxies: abundances Galaxies: dwarf HII regions |
| Resumo: | We use integral field spectroscopic (IFS) observations fromGemini Multi-Object Spectrograph North (GMOS-N) of a group of four HII regions and the surrounding gas in the central region of the blue compact dwarf (BCD) galaxy NGC 4670. At spatial scales of ~9 pc, we map the spatial distribution of a variety of physical properties of the ionized gas: internal dust attenuation, kinematics, stellar age, star formation rate, emission-line ratios, and chemical abundances. The region of study is found to be photoionized. Using the robust direct T method, we estimate metallicity, nitrogen-to-oxygen ratio, and helium abundance of the four HII regions. The same parameters are also mapped for the entire region using the HII-CHImistry code. We find that log(N/O) is increased in the region where the Wolf-Rayet bump is detected. The region coincides with the continuum region, around which we detect a slight increase in He abundance. We estimate the number of WC4, WN2-4, and WN7-9 stars from the integrated spectrum of WR bump region. We study the relation between log(N/O) and 12 + log(O/H) using the spatially resolved data of the field of view as well as the integrated data of the HII regions from 10 BCDs. We find an unexpected negative trend between N/O and metallicity. Several scenarios are explored to explain this trend, including nitrogen enrichment, and variations in star formation efficiency via chemical evolution models.© 2018 The Author(s). |
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