The Cassiopeia A Supernova Was of Type IIb

Krause, O.; Birkmann, Stephan M.; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Rieke, G. H.; Misselt, K. A.

doi:10.1126/science.1155788

Cited by 286 publications

(264 citation statements)

References 30 publications

(36 reference statements)

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“…This strengthens the growing evidence for not having a WR phase during Cas A's progenitor life (Schure et al 2008;Krause et al 2008;Pérez-Rendón et al 2009). …”

Section: Discussionsupporting

confidence: 83%

“…Although recent studies (Schure et al 2008;Krause et al 2008) seem to suggest an extended progenitor star, the presence of a WR shell, i.e. the shell of red supergiant (RSG) wind material swept up by the fast WR wind, has been invoked to explain the presence of numerous slow moving (≤ 500 km/s van den Bergh & Kamper 1985) nitrogen rich knots, often called quasi-stationary flocculi (QSF).…”

Section: Send Offprint Requests To: B Van Veelenmentioning

confidence: 99%

“…In that case one would expect the supernova to be of Type Ib/c. However, recently Krause et al (2008) obtained a spectrum of the supernova by observing its light echo, identifying it as a Type IIb explosion. This indicates that the progenitor lost most, but not all of its hydrogen envelope.…”

Section: Introductionmentioning

confidence: 99%

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The hydrodynamics of the supernova remnant Cassiopeia A

Veelen

Langer

Vink

et al. 2009

A&A

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Aims. There are large differences in the proposed progenitor models for the Cas A SNR. One of these differences is the presence or absence of a Wolf-Rayet (WR) phase of the progenitor star. The mass loss history of the progenitor star strongly affects the shape of the Supernova remnant (SNR). In this paper we investigate whether the progenitor star of Cas A had a WR phase or not and how long it may have lasted.Methods. We performed two-dimensional multi-species hydrodynamical simulations of the CSM around the progenitor star for several WR life times, each followed by the interaction of the supernova ejecta with the CSM. We then looked at the influence of the length of the WR phase and compared the results of the simulations with the observations of Cas A. Results. The difference in the structure of the CSM, for models with different WR life times, has a strong impact on the resulting SNR. With an increasing WR life time the reverse shock velocity of the SNR decreases and the range of observed velocities in the shocked material increases. Furthermore, if a WR phase occurs, the remainders of the WR shell will be visible in the resulting SNR. Conclusions. Comparing our results with the observations suggests that the progenitor star of Cas A did not have a WR phase. We also find that the quasi-stationary flocculi (QSF) in Cas A are not consistent with the clumps from a WR shell that have been shocked and accelerated by the interaction with the SN ejecta. We can also conclude that for a SN explosion taking place in a CSM that is shaped by the wind during a short (≤ 15000 yr) WR phase, the clumps from the WR shell will be visible inside the SNR.

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“…This strengthens the growing evidence for not having a WR phase during Cas A's progenitor life (Schure et al 2008;Krause et al 2008;Pérez-Rendón et al 2009). …”

Section: Discussionsupporting

confidence: 83%

Section: Send Offprint Requests To: B Van Veelenmentioning

confidence: 99%

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The hydrodynamics of the supernova remnant Cassiopeia A

Veelen

Langer

Vink

et al. 2009

A&A

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“…Other observations had shown this before from X-ray measurements, for example, and especially from optical/IR light echo spectra, revealing this asymmetry in the supernova photosphere. Furthermore, it was shown by these light echoes that Cas A exploded as a type IIb supernova (Krause et al 2005(Krause et al , 2008Rest et al 2008Rest et al , 2011; see also discussion by Wheeler et al 2008). …”

Section: Introductionmentioning

confidence: 78%

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

Siegert

Diehl

Krause

et al. 2015

A&A

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Context. The 340-yr old supernova remnant Cassiopeia A, located at 3.4 kpc distance, is the best-studied young core-collapse supernova remnant. Nucleosynthesis yields in radioactive isotopes have been studied with different methods, in particular for production and ejection of 44 Ti and 56 Ni, which originate in the innermost regions of the supernova. 44 Ti was first discovered in this remnant, but is not seen consistently in other core-collapse sources. Aims. We aim to measure radioactive 44 Ti ejected in Cassiopeia A and to place constraints on velocities of these ejecta by determining X-and γ-ray line-shape parameters of the emission lines. Methods. We analyzed the observations made with the SPI spectrometer on INTEGRAL together with an improved instrumental background method, to achieve a high spectroscopic resolution that enables interpretation for a velocity constraint on 44 Ti ejecta from the 1.157 MeV γ-ray line of the 44 Sc decay. Results. We observe both the hard X-ray line at 78 keV and the γ-ray line at 1157 keV from the 44 Ti decay chain at a combined significance of 3.8σ. Measured fluxes are (2.1 ± 0.4) × 10 −5 ph cm −2 s −1 and (3.5 ± 1.2) × 10 −5 ph cm −2 s −1 , which corresponds to (1.5 ± 0.4) × 10 −4 and (2.4 ± 0.9) × 10 −4 M of 44 Ti, respectively. The measured Doppler broadening of the lines implies expansion velocities of 4300 and 2200 km s −1 , respectively. By combining our results with previous studies, we determine a more precise estimate of ejected 44 Ti of (1.37 ± 0.19) × 10 −4 M . Conclusions. The measurements of the two lines are consistent with previous studies. The flux in the line originating from excited 44 Ca is significantly higher than the flux determined in the lines from 44 Sc. Cosmic-ray acceleration within the supernova remnant may be responsible for an additional contribution to this line from nuclear de-excitation following energetic particle collisions in the remnant and swept-up material.

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“…There are in the case of Cas A several indications of large scale mixing and instabilities, both from the morphology and the elemental abundance distribution (e.g., Reed et al 1995;Wheeler et al 2008). It is, however, likely that Cas A was a type IIb SN (Krause et al 2008), with only a small amount of hydrogen left, which influences the instabilities and the general dynamic structure of the ejecta. In this paper we discuss recent observations of SN 1987A, showing the spatial distribution of the inner ejecta still powered by radioactive decays.…”

Section: Introductionmentioning

confidence: 99%

The 3-D structure of SN 1987A's inner ejecta

Kjaer¹,

Leibundgut

Fransson

et al. 2010

A&A

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Context. Observing the inner ejecta of a supernova is possible only in a handful of nearby supernova remnants. The core-collapse explosion mechanism has been extensively explored in recent models and predict large asymmetries. SN 1987A is the first modern stellar explosion that has been continuously observed from its beginning to the supernova remnant phase. Twenty years after the explosion, we are now able to observe the three-dimensional spatially resolved inner ejecta of this supernova. Aims. Detailed mapping of newly synthesised material and its radioactive decay daughter products sheds light on the explosion mechanism. This may reveal the geometry of the explosion and its connection to the equatorial ring and the outer rings around SN 1987A. Methods. We have used integral field spectroscopy to image the supernova ejecta and the equatorial ring in the emission lines of [Si I] + [Fe II] (λ1.64 μm) and He I (λ2.058 μm). The spectral information can be mapped into a radial velocity image revealing the expansion of the ejecta both as projected onto the sky and perpendicular to the sky plane. Results. The inner ejecta are spatially resolved in a North-South direction and are clearly asymmetric. Like the ring emission, the northern parts of the ejecta are blueshifted, while the material projected to the South of the supernova centre is moving away from us. We argue that the bulk of the ejecta is situated in the same plane as defined by the equatorial ring and does not form a bipolar structure as has been suggested. The exact shape of the ejecta is modelled and we find that an elongated triaxial ellipsoid fits the observations best. The velocity measured in the [Si I] + [Fe II] line corresponds to ∼3000 km s −1 and is the same as the width of the IR [Fe II] line profiles during the first years. From our spectral analyses of the ejecta spectrum we find that most of the He I, [Si I] and [Fe I-II] emission originates in the core material which has undergone explosive nucleosynthesis. The He I emission may be the result of α-rich freeze-out if the positron energy is deposited locally. Conclusions. Our observations clearly indicate a non-symmetric explosion mechanism for SN 1987A. The elongation and velocity asymmetries point towards a large-scale spatial non-spherical distribution as predicted in recent explosion models. The orientation of the ejecta in the plane of the equatorial ring argues against a jet-induced explosion through the poles due to stellar rotation.

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The Cassiopeia A Supernova Was of Type IIb

Cited by 286 publications

References 30 publications

The hydrodynamics of the supernova remnant Cassiopeia A

The hydrodynamics of the supernova remnant Cassiopeia A

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A

The 3-D structure of SN 1987A's inner ejecta

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The Cassiopeia A Supernova Was of Type IIb

Cited by 286 publications

References 30 publications

The hydrodynamics of the supernova remnant Cassiopeia A

The hydrodynamics of the supernova remnant Cassiopeia A

Revisiting INTEGRAL/SPI observations of44Ti from Cassiopeia A

The 3-D structure of SN 1987A's inner ejecta

Contact Info

Product

Resources

About

Revisiting INTEGRAL/SPI observations of⁴⁴Ti from Cassiopeia A