Temperature Variations from HST Spectroscopy of NGC 1976
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| Format: | Artículo científico |
| Langue: | en |
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Universidad Nacional Autónoma de México
2003
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| _version_ | 1876452345147031552 |
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| author | X. W. Liu |
| author_facet | X. W. Liu |
| contents | Temperature Variations from HST Spectroscopy of NGC 1976 X. W. Liu K. P. M. Blagrave J. F. Nguyen R. H. Rubin R. J. Dufour P. G. Martin J. A. Baldwin G. J. Ferland Física, Astronomía y Matemáticas H II Regions ISM: Abundances ISM: Individual (Orion Nebula) We present HST/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ux ratio [O III] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (t2A) across the nebula. We also measure the intrinsic line ux ratio [N II] 5756/6585 in order to estimate Te and t2A in the N+ region. The interpretation of the [N II] data is not as clear cut as the [O III] data because of a higher sensitivity to knowledge of the electron density (Ne). We present results from binning the data along the various slits into tiles that are 0.5" square. The average [O III] temperature for our four HST/STIS slits varies from 7678 K to 8358 K; t2A varies from 0.00682 to 0.0176. When we use Ne of 8000 (for slits 1 and 2) and 3000 cm_3 (for slits 4 and 5) with Lennon & Burke (1994) collision strengths, the average [N II] temperature for each of the four slits varies from 8979 K to 9761 K; t2 A varies from 0.00551 to 0.0172. The measurements of Te reported here are an average along each line of sight. Therefore, despite finding remarkablylow t2A, we cannot rule out significantly larger temperature uctuations along the line of sight. The result that the average [N II] Te exceeds the average [O III] Te confirms what has been previously found for Orion and what is expected on theoretical grounds. 2003 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57101829 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.18 |
| format | Artículo científico |
| id | redalyc_57101829 |
| institution | Redalyc |
| language | en |
| publishDate | 2003 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Temperature Variations from HST Spectroscopy of NGC 1976 X. W. Liu Física, Astronomía y Matemáticas H II Regions ISM: Abundances ISM: Individual (Orion Nebula) Temperature Variations from HST Spectroscopy of NGC 1976 X. W. Liu K. P. M. Blagrave J. F. Nguyen R. H. Rubin R. J. Dufour P. G. Martin J. A. Baldwin G. J. Ferland Física, Astronomía y Matemáticas H II Regions ISM: Abundances ISM: Individual (Orion Nebula) We present HST/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ux ratio [O III] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (t2A) across the nebula. We also measure the intrinsic line ux ratio [N II] 5756/6585 in order to estimate Te and t2A in the N+ region. The interpretation of the [N II] data is not as clear cut as the [O III] data because of a higher sensitivity to knowledge of the electron density (Ne). We present results from binning the data along the various slits into tiles that are 0.5" square. The average [O III] temperature for our four HST/STIS slits varies from 7678 K to 8358 K; t2A varies from 0.00682 to 0.0176. When we use Ne of 8000 (for slits 1 and 2) and 3000 cm_3 (for slits 4 and 5) with Lennon & Burke (1994) collision strengths, the average [N II] temperature for each of the four slits varies from 8979 K to 9761 K; t2 A varies from 0.00551 to 0.0172. The measurements of Te reported here are an average along each line of sight. Therefore, despite finding remarkablylow t2A, we cannot rule out significantly larger temperature uctuations along the line of sight. The result that the average [N II] Te exceeds the average [O III] Te confirms what has been previously found for Orion and what is expected on theoretical grounds. 2003 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57101829 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.18 |
| title | Temperature Variations from HST Spectroscopy of NGC 1976 |
| topic | Física, Astronomía y Matemáticas H II Regions ISM: Abundances ISM: Individual (Orion Nebula) |
| url | https://www.redalyc.org/articulo.oa?id=57101829 |