A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions
Emission lines of singly charged ions populate many astrophysical spectra. However, the interpretation of the line intensities (usually line ratios) often depends on the transition rates of the decays of very long-lived low-lying levels. For example, the line ratio of two electric-dipole forbidden t...
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2020-05-01
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| author | Elmar Träbert |
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| description | Emission lines of singly charged ions populate many astrophysical spectra. However, the interpretation of the line intensities (usually line ratios) often depends on the transition rates of the decays of very long-lived low-lying levels. For example, the line ratio of two electric-dipole forbidden transitions in the 3s<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>2</mn> </msup> </semantics> </math> </inline-formula>3p<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>3</mn> </msup> </semantics> </math> </inline-formula> ground configuration of singly ionized sulfur (ion S<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>+</mo> </msup> </semantics> </math> </inline-formula>, spectrum S II) has been interpreted in terms of a density diagnostic for planetary nebulae, i.e., for densities in the order of 10<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>4</mn> </msup> </semantics> </math> </inline-formula> cm<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics> </math> </inline-formula>. The predicted lifetimes of the <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>2</mn> </msup> </semantics> </math> </inline-formula>D<inline-formula> <math display="inline"> <semantics> <msubsup> <mrow></mrow> <mrow> <mn>3</mn> <mo>/</mo> <mn>2</mn> <mo>,</mo> <mn>5</mn> <mo>/</mo> <mn>2</mn> </mrow> <mi mathvariant="normal">o</mi> </msubsup> </semantics> </math> </inline-formula> levels are in the order of one hour. Modeling indicates that a 10% uncertainty of the lifetime determination in this case corresponds to a 50% uncertainty of the density diagnostic. The available theoretical lifetime predictions scatter by much more than 10%. Considerations about an experimental approach are presented with the goal of instigating a measurement of the actual level lifetimes. |
| first_indexed | 2024-03-10T19:54:58Z |
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| spelling | doaj.art-ea9673c8aa444aa0bf8cc41c89ecfd702023-11-20T00:03:03ZengMDPI AGAtoms2218-20042020-05-01822110.3390/atoms8020021A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge IonsElmar Träbert0AIRUB, Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, GermanyEmission lines of singly charged ions populate many astrophysical spectra. However, the interpretation of the line intensities (usually line ratios) often depends on the transition rates of the decays of very long-lived low-lying levels. For example, the line ratio of two electric-dipole forbidden transitions in the 3s<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>2</mn> </msup> </semantics> </math> </inline-formula>3p<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>3</mn> </msup> </semantics> </math> </inline-formula> ground configuration of singly ionized sulfur (ion S<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>+</mo> </msup> </semantics> </math> </inline-formula>, spectrum S II) has been interpreted in terms of a density diagnostic for planetary nebulae, i.e., for densities in the order of 10<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>4</mn> </msup> </semantics> </math> </inline-formula> cm<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics> </math> </inline-formula>. The predicted lifetimes of the <inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mn>2</mn> </msup> </semantics> </math> </inline-formula>D<inline-formula> <math display="inline"> <semantics> <msubsup> <mrow></mrow> <mrow> <mn>3</mn> <mo>/</mo> <mn>2</mn> <mo>,</mo> <mn>5</mn> <mo>/</mo> <mn>2</mn> </mrow> <mi mathvariant="normal">o</mi> </msubsup> </semantics> </math> </inline-formula> levels are in the order of one hour. Modeling indicates that a 10% uncertainty of the lifetime determination in this case corresponds to a 50% uncertainty of the density diagnostic. The available theoretical lifetime predictions scatter by much more than 10%. Considerations about an experimental approach are presented with the goal of instigating a measurement of the actual level lifetimes.https://www.mdpi.com/2218-2004/8/2/21atomic spectroscopyion trapcomputationslaboratory astrophysics |
| spellingShingle | Elmar Träbert A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions Atoms atomic spectroscopy ion trap computations laboratory astrophysics |
| title | A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions |
| title_full | A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions |
| title_fullStr | A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions |
| title_full_unstemmed | A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions |
| title_short | A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions |
| title_sort | laboratory astrophysics problem the lifetime of very long lived levels in low charge ions |
| topic | atomic spectroscopy ion trap computations laboratory astrophysics |
| url | https://www.mdpi.com/2218-2004/8/2/21 |
| work_keys_str_mv | AT elmartrabert alaboratoryastrophysicsproblemthelifetimeofverylonglivedlevelsinlowchargeions AT elmartrabert laboratoryastrophysicsproblemthelifetimeofverylonglivedlevelsinlowchargeions |