The Progenitor of Supernova 1993J Revisited (original) (raw)
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SN 1987A - Presupernova Evolution and the Progenitor Star
1997
Ten years later, astronomers are still puzzled by the stellar evolution that produced SN 1987A --- a blue supergiant. In single star models, the new OPAL opacities make blue solutions more difficult to achieve, though still possible for certain choices of convection physics. We also consider rotation, which has the desirable effect of producing large surface enhancements of nitrogen and helium, but the undesirable effect of increasing the helium-core mass at the expense of the envelope. The latter makes blue solutions more difficult. Still, we seek a model that occurs with high probability in the LMC and for which the time-scale for making the last transition from red to blue, sim\simsim 20,000 years, has a physical interpretation --- the Kelvin-Helmholtz time of the helium core. Single star models satisfy both criteria and might yet prove to be the correct explanation for Sk -69 202, provided new rotational or convection physics can simultaneously give a blue star and explain the ring ...
Monthly Notices of the Royal Astronomical Society, 2012
We present optical photometry and spectroscopy of the peculiar Type IIn/Ibn supernova (SN) 2011hw. Its optical light curve exhibits a slower decline rate than that of normal SNe Ibc, with a peak absolute magnitude of −19.5 (unfiltered) and a secondary rise 20-30 d later of −18.3 mag (R). Spectra of SN 2011hw are highly unusual compared to those of normal SN types, most closely resembling the spectra of SNe Ibn. We centre our analysis on comparing SN 2011hw to the well-studied Type Ibn SN 2006jc. While the two SNe have many important similarities, the differences are quite telling: compared to SN 2006jc, SN 2011hw has weaker He I and Ca II lines and relatively stronger H lines, its light curve exhibits a higher visual-wavelength luminosity and slower decline rate, and emission lines associated with the progenitor's circumstellar material (CSM) are narrower. One can reproduce the unusual continuum shape of SN 2011hw with roughly equal contributions from a 6000-K blackbody and a spectrum of SN 2006jc. We attribute this blackbody-like emission component and many other differences between the two SNe to a small amount of additional H in SN 2011hw, analogous to the small H mass that makes SNe IIb differ from SNe Ib. Slower speeds in the CSM and somewhat elevated H content suggest a connection between SN 2011hw's progenitor and Ofpe/WN9 stars, which have been associated with luminous blue variables (LBVs) in their hot quiescent phases, and are H poor-but not H free like classical Wolf-Rayet (WR) stars. Comparisons between SN 2011hw and SN 2006jc can be largely understood if their progenitors exploded at different points in the transitional evolution from an LBV to a WR star.
Massive star evolution: luminous blue variables as unexpected supernova progenitors
Astronomy & Astrophysics, 2013
Stars more massive than about 8 M ⊙ end their lives as a Supernova (SN), an event of fundamental importance Universe-wide. Theoretically, these stars have been expected to be either at the red supergiant, blue supergiant, or Wolf-Rayet stage before the explosion. We performed coupled stellar evolution and atmospheric modeling of stars with initial masses between 20 M ⊙ and 120 M ⊙ . We found that the 20 M ⊙ and 25 M ⊙ rotating models, before exploding as SN, have spectra that do not resemble any of the aforementioned classes of massive stars. Rather, they have remarkable similarities with rare, unstable massive stars known as Luminous Blue Variables (LBV). While observations show that some SNe seem to have had LBVs as progenitors, no theoretical model had yet predicted that a star could explode at this stage. Our models provide theoretical support for relatively low-luminosity LBVs exploding as SN in the framework of single stellar evolution. This is a significant shift in paradigm, meaning that a fraction of LBVs could be the end stage of massive star evolution, rather than a transitory evolutionary phase. We suggest that type IIb SN could have LBV as progenitors, and a prime example could be SN 2008ax.
THE TYPE IIb SUPERNOVA 2011dh FROM A SUPERGIANT PROGENITOR
The Astrophysical Journal, 2012
A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature of SN 2011dh. Our modeling suggests that a large progenitor star-with R ∼ 200 R -is needed to reproduce the early light curve (LC) of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the supernova (SN) in deep pre-explosion images is the progenitor star. From the main peak of the bolometric LC and expansion velocities, we constrain the mass of the ejecta to be ≈2 M , the explosion energy to be E = (6-10) × 10 50 erg, and the 56 Ni mass to be approximately 0.06 M . The progenitor star was composed of a helium core of 3-4 M and a thin hydrogen-rich envelope of ≈0.1M with a main-sequence mass estimated to be in the range of 12-15 M . Our models rule out progenitors with helium-core masses larger than 8 M , which correspond to M ZAMS 25M . This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.
Hydrogen and helium in the spectra of Type Ia supernovae
Monthly Notices of the Royal Astronomical Society, 2013
We present predictions for hydrogen and helium emission line luminosities from circumstellar matter around Type Ia supernovae (SNe Ia) using time dependent photoionization modelling. Early high-resolution ESO/Very Large Telescope (VLT) optical echelle spectra of the SN Ia 2000cx were taken before and up to ∼70 d after maximum to probe the existence of such narrow emission lines from the supernova. We detect no such lines, and from our modelling place an upper limit on the mass-loss rate for the putative wind from the progenitor system, M 1.3 × 10 −5 M yr −1 , assuming a speed of 10 km s −1 and solar abundances for the wind. If the wind would be helium-enriched and/or faster, the upper limit onṀ could be significantly higher. In the helium-enriched case, we show that the best line to constrain the mass-loss would be He I λ10 830. In addition to confirming the details of interstellar Na I and Ca II absorption towards SN 2000cx as discussed by Patat et al., we also find evidence for 6613.56 Å diffuse interstellar band absorption in the Milky Way. We also discuss measurements of the X-ray emission from the interaction between the supernova ejecta and the wind and we re-evaluate observations of SN 1992A obtained ∼16 d after maximum by Schlegel & Petre. We find an upper limit ofṀ ∼ 1.3 × 10 −5 M yr −1 which is significantly higher than that estimated by Schlegel & Petre. These results, together with the previous observational work on the normal SNe Ia 1994D and 2001el, disfavour a symbiotic star in the upper mass-loss rate regime (so-called Mira-type systems) from being the likely progenitor scenario for these SNe. Our model calculations are general, and can also be used for the subclass of SNe Ia that do show circumstellar interaction, e.g. the recent PTF 11kx. To constrain hydrogen in late-time spectra, we present ESO/VLT and ESO/New Technology Telescope optical and infrared observations of SNe Ia 1998bu and 2000cx in the nebular phase, 251−388 d after maximum. We see no signs of hydrogen line emission in SNe 1998bu and 2000cx at these epochs, and from the absence of Hα with a width of the order of ∼10 3 km s −1 , we argue from modelling that the mass of such hydrogen-rich gas must be 0.03 M for both supernovae. Comparing similar upper limits with recent models of Pan et al., it seems that hydrogen-rich donors with a separation of 5 times the radius of the donor may be ruled out for the five SNe Ia 1998bu, 2000cx, 2001el, 2005am and 2005cf. Larger separation, helium-rich donors, or a double-degenerate origin for these supernovae seems more likely. Our models have also been used to put the limit on hydrogen-rich gas in the recent SN 2011fe, and for this supernova, a double-degenerate origin seems likely.
SN 1998A: explosion of a blue supergiant
Monthly Notices of the Royal Astronomical Society, 2005
We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue supergiant. However, the comparison with SN 1987A also highlights some important differences: SN 1998A is more luminous and the spectra show bluer continua and larger expansion velocities at all epochs. These observational properties indicate that the explosion of SN 1998A is more energetic than SN 1987A and more typical of SNe II. Comparing the observational data to simulations, we deduce that the progenitor of SN 1998A was a massive star (∼ 25 M ⊙ ) with a small pre-supernova radius ( < ∼ 6 × 10 12 cm). The Ba II lines, unusually strong in SN 1987A and some faint II-P events, are almost normal in the case of SN 1998A, indicating that the temperature plays a key role in determining their strength.
The Astrophysical Journal, 2009
We present a theoretical model for supernova (SN) 2008D associated with the luminous X-ray transient 080109. The bolometric light curve and optical spectra of the SN are modelled based on the progenitor models and the explosion models obtained from hydrodynamic/nucleosynthetic calculations. We find that SN 2008D is a more energetic explosion than normal core-collapse supernovae, with an ejecta mass of M ej = 5.3 ± 1.0 M ⊙ and a kinetic energy of E K = 6.0 ± 2.5 × 10 51 erg. The progenitor star of the SN has a 6 − 8M ⊙ He core with essentially no H envelope (< 5 × 10 −4 M ⊙) prior to the explosion. The main-sequence mass of the progenitor is estimated to be M MS = 20 − 25 M ⊙ , with additional systematic uncertainties due to convection, mass loss, rotation, and binary effects. These properties are intermediate between those of normal SNe and hypernovae associated with gamma-ray bursts. The mass of the central remnant is estimated as 1.6 − 1.8M ⊙ , which is near the boundary between neutron star and black hole formation.
A BLUE POINT SOURCE AT THE LOCATION OF SUPERNOVA 2011DH
The Astrophysical Journal, 2014
We present Hubble Space Telescope (HST) observations of the field of the Type IIb supernova (SN) 2011dh in M51 performed at ≈1161 rest-frame days after explosion using the Wide Field Camera 3 and near-UV filters F225W and F336W. A star-like object is detected in both bands and the photometry indicates it has negative (F225W − F336W) color. The observed object is compatible with the companion of the now-vanished yellow supergiant progenitor predicted in interacting binary models. We consider it unlikely that the SN is undergoing strong interaction and thus estimate that it makes a small contribution to the observed flux. The possibilities of having detected an unresolved light echo or an unrelated object are briefly discussed and judged unlikely. Adopting a possible range of extinction by dust, we constrain parameters of the proposed binary system. In particular, the efficiency of mass accretion onto the binary companion must be below 50%, if no significant extinction is produced by newly formed dust. Further multiband observations are required in order to confirm the identification of the object as the companion star. If confirmed, the companion star would already be dominant in the UV-optical regime, so it would readily provide a unique opportunity to perform a detailed study of its properties.