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Hydrogen and helium traces in type Ib-c supernovae
Astrophysics · Submitted 22 Dec 2005
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim A low mass and thin hydrogen layer with very high ejection velocities above the helium shell, is thus the most likely scenario for Type Ib SNe.
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The abstract, sentence by sentence
The spectroscopic properties of a selected optical photospheric spectra of core collapse supernovae (CCSNe) are investigated.Special attention is devoted to traces of hydrogen at early phases. The generated spectra are found to match the observed ones reasonably well, including a list of only 23 candidate ions. Guided by SN Ib 1990I, the observed trough near 6300\AA is attributed to H$\alpha$ in almost all Type Ib events, although in some objects it becomes too weak to be discernible, especially at later phases. Alternative line identifications are discussed. Differences in the way hydrogen manifests its presence within CCSNe are highlighted. In Type Ib SNe, the H$\alpha$ contrast velocity (i.e. line velocity minus the photospheric velocity) seems to increase with time at early epochs, reaching values as high as 8000 km s$^{-1}$ around 15-20 days after maximum and then remains almost constant. The derived photospheric velocities, indicate a lower velocity for Type II SNe 1987A and 1999em as compared to SN Ic 1994I and SN IIb 1993J, while Type Ib events display a somewhat larger variation. The scatter, around day 20, is measured to be $\sim$5000 km s$^{-1}$. Following two simple approaches, rough estimates of ejecta and hydrogen masses are given. A mass of hydrogen of approximately 0.02 $M_\odot$ is obtained for SN 1990I, while SNe 1983N and 2000H ejected $\sim$0.008 $M_\odot$ and $\sim$0.08 $M_\odot$ of hydrogen, respectively. SN 1993J has a higher hydrogen mass, $\sim 0.7$ $M_\odot$ with a large uncertainty. A low mass and thin hydrogen layer with very high ejection velocities above the helium shell, is thus the most likely scenario for Type Ib SNe. Some interesting and curious issues relating to oxygen lines suggest future investigations.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The spectroscopic properties of a selected optical photospheric spectra of core collapse supernovae (CCSNe) are investigated.Special attention is devoted to traces of hydrogen at early phases. | contribution 0.96 | 0.84 | 0.04 | asserted 0.89 |
| s1 | The generated spectra are found to match the observed ones reasonably well, including a list of only 23 candidate ions. | result 0.96 | 0.91 | 0.05 | asserted 0.99 |
| s2 | Guided by SN Ib 1990I, the observed trough near 6300\AA is attributed to H$\alpha$ in almost all Type Ib events, although in some objects it becomes too weak to be discernible, especially at later phases. | result 0.66 | 0.69 | 0.27 | asserted 0.93 |
| s3 | Alternative line identifications are discussed. | contribution 0.67 | 0.66 | 0.02 | unclear 0.74 |
| s4 | Differences in the way hydrogen manifests its presence within CCSNe are highlighted. | result 0.67 | 0.69 | 0.06 | asserted 0.70 |
| s5 | In Type Ib SNe, the H$\alpha$ contrast velocity (i.e. line velocity minus the photospheric velocity) seems to increase with time at early epochs, reaching values as high as 8000 km s$^{-1}$ around 15-20 days after maximum and then remains almost constant. | result 1.00 | 0.86 | 0.16 | hedged possibility 0.78 |
| s6 | The derived photospheric velocities, indicate a lower velocity for Type II SNe 1987A and 1999em as compared to SN Ic 1994I and SN IIb 1993J, while Type Ib events display a somewhat larger variation. | result 1.00 | 0.90 | 0.05 | asserted 0.52 |
| s7 | The scatter, around day 20, is measured to be $\sim$5000 km s$^{-1}$. | result 1.00 | 0.91 | 0.03 | asserted 1.00 |
| s8 | Following two simple approaches, rough estimates of ejecta and hydrogen masses are given. | method 0.75 | 0.92 | 0.03 | asserted 0.82 |
| s9 | A mass of hydrogen of approximately 0.02 $M_\odot$ is obtained for SN 1990I, while SNe 1983N and 2000H ejected $\sim$0.008 $M_\odot$ and $\sim$0.08 $M_\odot$ of hydrogen, respectively. | result 1.00 | 0.88 | 0.06 | asserted 1.00 |
| s10 | SN 1993J has a higher hydrogen mass, $\sim 0.7$ $M_\odot$ with a large uncertainty. | result 1.00 | 0.86 | 0.05 | asserted 1.00 |
| s11 | A low mass and thin hydrogen layer with very high ejection velocities above the helium shell, is thus the most likely scenario for Type Ib SNe. | interpretation 1.00 | 0.78 | 0.71 | hedged possibility 0.98 |
| s12 | Some interesting and curious issues relating to oxygen lines suggest future investigations. | future work 1.00 | 0.35 | 0.02 | hedged possibility 0.84 |
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Original abstract
The spectroscopic properties of a selected optical photospheric spectra of core collapse supernovae (CCSNe) are investigated.Special attention is devoted to traces of hydrogen at early phases. The generated spectra are found to match the observed ones reasonably well, including a list of only 23 candidate ions. Guided by SN Ib 1990I, the observed trough near 6300\AA is attributed to H$\alpha$ in almost all Type Ib events, although in some objects it becomes too weak to be discernible, especially at later phases. Alternative line identifications are discussed. Differences in the way hydrogen manifests its presence within CCSNe are highlighted. In Type Ib SNe, the H$\alpha$ contrast velocity (i.e. line velocity minus the photospheric velocity) seems to increase with time at early epochs, reaching values as high as 8000 km s$^{-1}$ around 15-20 days after maximum and then remains almost constant. The derived photospheric velocities, indicate a lower velocity for Type II SNe 1987A and 1999em as compared to SN Ic 1994I and SN IIb 1993J, while Type Ib events display a somewhat larger variation. The scatter, around day 20, is measured to be $\sim$5000 km s$^{-1}$. Following two simple approaches, rough estimates of ejecta and hydrogen masses are given. A mass of hydrogen of approximately 0.02 $M_\odot$ is obtained for SN 1990I, while SNe 1983N and 2000H ejected $\sim$0.008 $M_\odot$ and $\sim$0.08 $M_\odot$ of hydrogen, respectively. SN 1993J has a higher hydrogen mass, $\sim 0.7$ $M_\odot$ with a large uncertainty. A low mass and thin hydrogen layer with very high ejection velocities above the helium shell, is thus the most likely scenario for Type Ib SNe. Some interesting and curious issues relating to oxygen lines suggest future investigations.
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A thin low mass hydrogen layer extending to very high ejection velocities above the helium shell, is found to be the most likely scenario for Type Ib SNe.
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