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—Portions of the HST FOS spectrum centered on SN 1987A, showing the narrow emission lines that originate from the NOR
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![FIG. 3.—NTT observations of the [O II] 3726, 3729 doublet. The bottom...](profile/Robert-Kirshner/publication/231064930/figure/fig2/AS:393599385653248@1470852814018/NTT-observations-of-the-O-II-3726-3729-doublet-The-bottom-and-central-panels-display_Q320.jpg)
![FIG. 6.—Intensity ratio I(N III] 1750)/I(C III] 1909) for the NOR over...](profile/Robert-Kirshner/publication/231064930/figure/fig3/AS:393599385653249@1470852814175/Intensity-ratio-IN-III-1750-IC-III-1909-for-the-NOR-over-the-value-for-the-inner_Q320.jpg)
We present recent Hubble Space Telescope (HST) Faint Object Spectrograph and ground-based spectroscopic observations of SN 1987A and its surroundings and discuss them in conjunction with HST Faint Object Camera and Wide Field Planetary Camera 2 narrowband imaging. We have determined the following properties of the outer rings around SN 1987A: (1) t...
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... absolute scale of the synthetic profiles has been adjusted to fit the observed peaks. Thus, we find that the intensity ratios of the [O II] doublet are I (3729)/I(3726) 0.53, 0.78, 0.72, and 1.4 for the inner ring, NOR, SOR, and background, respectively, with an uncertainty of 4% for the inner ring and 115% for the NOR, SOR, and background. Adopting a temperature of 12,000 K, these ratios correspond to average electron densities of 2600, 800, and less than 100 for the inner ring, both outer rings, and background gas, respectively, to within H0.1 dex. ...
Citations
... The Hubble Space Telescope ( HST ) R -band images in Fig. 1 , taken from Larsson et al. ( 2019 ), demonstrate the structures and evolution of the remnant of SN 1987A. The bright ring, which is often called the 'inner ring' or 'equatorial ring', is one of the circumstellar rings found in SN 1987A, with the other ring being fainter and farther (up to ∼5 arcsec in diameter) 'outer rings' (Panagia et al. 1996 ). The inner ring is composed of about 20 clumps within, while the ejecta appear as a central keyhole-shaped cloud, expanding in time. ...
At a distance of 50 kpc, Supernova 1987A is an ideal target to study how a young supernova (SN) evolves in time. Its equatorial ring, filled with material expelled from the progenitor star about 20,000 years ago, has been engulfed with SN blast waves. Shocks heat dust grains in the ring, emitting their energy at mid-infrared (IR) wavelengths We present ground-based 10–18 μm monitoring of the ring of SN 1987A from day 6067 to 12814 at a resolution of 0.5”, together with SOFIA photometry at 10–30 μm. The IR images in the 2000’s (day 6067–7242) showed that the shocks first began brightening the east side of the ring. Later, our mid-IR images from 2017 to 2022 (day 10952–12714) show that dust emission is now fading in the east, while it has brightened on the west side of the ring. Because dust grains are heated in the shocked plasma, which can emit X-rays, the IR and X-ray brightness ratio represent shock diagnostics. Until 2007 the IR to X-ray brightness ratio remained constant over time, and during this time shocks seemed to be largely influencing the east side of the ring. However, since then, the IR to X-ray ratio has been declining, due to increased X-ray brightness. Whether the declining IR brightness is because of dust grains being destroyed or being cooled in the post-shock regions will require more detailed modelling.
... Core collapse supernovae I start with the three rings of SN 1987A that I present in Fig. 8. The ejecta of SN 1987A has been strongly colliding with the inner ring for about 23 years (e.g., Fransson et al. 2013;Frank et al. 2016; rings were ejected ≈ 20, 000 yr before explosion (e.g., Panagia et al. 1996;. ...
I review studies of core collapse supernovae (CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets (with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae (SLSNe). I conclude that modelling of SLSNe lightcurves and bumps in the lightcurves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter (CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae (CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in supernova 1987A, and can power pre-explosion outbursts (precursors) in binary systems progenitors of CCSNe and CEJSNe. Binary interaction facilitate also the launching of post-explosion jets.
... These enhancements of helium and nitrogen in the nebular material, which was ejected from the envelope of Sk -69 • 202before its explosion, indicate that the star underwent H-burning through the CNO cycle during its evolution (Saio et al. 1988;Fransson et al. 1989;Sonneborn et al. 1997;France et al. 2011). Panagia et al. (1996) found that the outer rings are less enriched in N/C and N/O, by a factor of ∼ 3 than the corresponding values measured in the inner ring, thus concluding that the outer rings may have been ejected 10 kyr before the inner ring. These results were contested by Crotts & Heathcote (2000), who through a kinematic study, deduced that all three rings were expelled ∼ 20 kyr before the supernova explosion. ...
... These results were contested by Crotts & Heathcote (2000), who through a kinematic study, deduced that all three rings were expelled ∼ 20 kyr before the supernova explosion. Maran et al. (2000) further supported this result, through long-slit optical spectroscopic measurements of the CNO abundances of the rings and found no discrepancies between the inner and outer rings, stating that Panagia et al. (1996) may not have taken time-dependent line emissions from the outer rings in to account while measuring these abundances. ...
We present the results of a detailed, systematic stellar evolution study of binary mergers for blue supergiant (BSG) progenitors of Type II supernovae. In particular, these are the first evolutionary models that can simultaneously reproduce nearly all observational aspects of the progenitor of SN 1987A, $\text{Sk}-69\,^{\circ}202$, such as its position in the HR diagram, the enrichment of helium and nitrogen in the triple-ring nebula, and its lifetime before its explosion. The merger model, based on the one proposed by Podsiadlowski 1992 et al. and Podsiadlowski 2007 et al., consists of a main sequence secondary star that dissolves completely in the common envelope of the primary red supergiant at the end of their merger. We empirically explore a large initial parameter space, such as primary masses ($15\,\text{M}_{\odot}$, $16\,\text{M}_{\odot}$, and $17\,\text{M}_{\odot}$), secondary masses ($2\,\text{M}_{\odot}$, $3\,\text{M}_{\odot}$, ..., $8\,\text{M}_{\odot}$) and different depths up to which the secondary penetrates the He core of the primary during the merger. The evolution of the merged star is continued until just before iron-core collapse and the surface properties of the 84 pre-supernova models ($16\,\text{M}_{\odot}-23\,\mathrm{M}_{\odot}$) computed have been made available in this work. Within the parameter space studied, the majority of the pre-supernova models are compact, hot BSGs with effective temperature $>12\,\text{kK}$ and radii of $30\,\text{R}_{\odot}-70\,\mathrm{R}_{\odot}$ of which six match nearly all the observational properties of $\text{Sk}-69\,^{\circ}202$.
I review studies of core collapse supernovae (CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets (with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae (SLSNe). I conclude that modelling of SLSNe lightcurves and bumps in the lightcurves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter (CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae (CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in supernova 1987A, and can power pre-explosion outbursts (precursors) in binary systems progenitors of CCSNe and CEJSNe. Binary interaction facilitate also the launching of post-explosion jets.
We present narrow-band near-infrared images of a sample of 11 Galactic planetary nebulae (PNe) obtained in the molecular hydrogen (H$_{2}$) 2.122 $\mu$m and Br$\gamma$ 2.166 $\mu$m emission lines and the $K_{\rm c}$ 2.218 $\mu$m continuum. These images were collected with the Wide-field InfraRed Camera (WIRCam) on the 3.6m Canada-France-Hawaii Telescope (CFHT); their unprecedented depth and wide field of view allow us to find extended nebular structures in H$_{2}$ emission in several PNe, some of these being the first detection. The nebular morphologies in H$_{2}$ emission are studied in analogy with the optical images, and indication on stellar wind interactions is discussed. In particular, the complete structure of the highly asymmetric halo in NGC6772 is witnessed in H$_{2}$, which strongly suggests interaction with the interstellar medium. Our sample confirms the general correlation between H$_{2}$ emission and the bipolarity of PNe. The knotty/filamentary fine structures of the H$_{2}$ gas are resolved in the inner regions of several ring-like PNe, also confirming the previous argument that H2 emission mostly comes from knots/clumps embedded within fully ionized material at the equatorial regions. Moreover, the deep H$_{2}$ image of the butterfly-shaped Sh1-89, after removal of field stars, clearly reveals a tilted ring structure at the waist. These high-quality CFHT images justify follow-up detailed morpho-kinematic studies that are desired to deduce the true physical structures of a few PNe in the sample.
We show that a fast wind that expands into a bipolar nebula composed of two opposite jet-inflated bubbles can form a pair of bipolar rings around giant stars. Our model assumes three mass loss episodes: a spherical slow and dense shell, two opposite jets, and a spherical fast wind. We use the FLASH hydrodynamical code in three-dimensions to simulate the flow, and obtain the structure of the nebula. We assume that the jets are launched from an accretion disk around a stellar companion to the giant star. The accretion disk is assumed to be formed when the primary giant star and the secondary star suffer a strong interaction accompanied by a rapid mass transfer process from the primary to the secondary star, mainly a main sequence star. Later in the evolution the primary star is assumed to shrink and blow a fast tenuous wind that interacts with the dense gas on the surface of the bipolar structure. We assume that the dense mass loss episode before the jets are launched is spherically symmetric. Our results might be applicable to some planetary nebulae, and further emphasize the large variety of morphological features that can be formed by jets. But we could not reproduce some of the properties of the outer rings of SN1987A. It seems that some objects, like SN1987A, require a pre-jets mass loss episode with a mass concentration at mid-latitudes.
Aims: We investigate the physical properties and structure of the outer rings of SN 1987A to understand their formation and evolution. Methods: We used low resolution spectroscopy from VLT/FORS1 and high resolution spectra from VLT/UVES to estimate the physical conditions in the outer rings, using nebular analysis for emission lines such as [O II], [O III], [N II], and [S II]. We also measured the velocity at two positions of the outer rings to test a geometrical model for the rings. Additionally, we used data from the HST science archives to check the evolution of the outer rings of SN 1987A for a period that covers almost 11 years. Results: We measured the flux in four different regions, two for each outer ring. We chose regions away from the two bright neighbouring stars and as far as possible from the inner ring and created light curves for the emission lines of [O III], Halpha, and [N II]. The light curves display a declining behaviour, which is consistent with the initial supernova-flash powering of the outer rings. The electron density of the emitting gas in the outer rings, as estimated by nebular analysis from the [O II] and [S II] lines, is ≲ 3 × 103 cm-3, has not changed over the last ~15 years, and the [N II] temperature remains also fairly constant at ~1.2 × 104 K. We find no obvious difference in density and temperature for the two outer rings. The highest density, as estimated from the decay of Halpha, could be ~5 × 103 cm-3 however, and because the decay is somewhat faster in the southern outer ring than it is in the northern, the highest density in the outer rings may be found in the southern outer ring. For an assumed distance of 50 kpc to the supernova, the distance between the supernova and the closest parts of the outer rings could be as short as ~1.7 × 1018 cm. Interaction between the supernova ejecta and the outer rings could therefore start in less than ~20 years. We do not expect the outer rings to show the same optical display as the equatorial ring when this happens. Instead soft X-rays should provide a better way of observing the ejecta - outer rings interaction. Based on observations made with ESO Telescopes at the Paranal Observatory, Chile (ESO Programs 70.D-0379, and 082.D-0273A)
We have performed a detailed study of the morphology and kinematics of the hourglass-shaped nebula around the blue supergiant Sher 25 in the galactic giant H II region NGC 3603. Near-infrared high-resolution adaptive optics images in the Br? line and HST/NICMOS images in the He I 1.08 ?m line were compared with isovelocity maps in the H? and [N II] lines.
The adaptive optics observations clearly resolved the width of the ring (09, i.e., 0.027 pc), yielding ?R/R = 1/8. We show that the H? and [N II] lines trace the entire silhouette of the hourglass. The bipolar lobes of the hourglass expand at 70 km s⁻¹, whereas the ring around the waist of the hourglass expands at 30 km s⁻¹. Both the ring and the bipolar lobes have about the same dynamical age, indicating a common origin and a major outburst and mass-loss event 6630 yr ago. The ionized mass within the hourglass is between 0.3 and 0.6 M??quite comparable to the total mass suggested for the expanding (presupernova) shell around SN 1987A.
The hourglass structure around Sher 25 is similar to that of SN 1987A in spatial extent, mass, and velocity. The major differences between these two nebulae might arise from environmental effects. Both internal and external ionization sources are available for Sher 25's nebula. Furthermore, Sher 25 and its hourglass-shaped nebula appear to be moving to the southwest with respect to the ambient interstellar medium, and ram pressure has apparently deformed the hourglass. We conclude that the circumstellar nebulae around SN 1987A and Sher 25 are very similar and define a new class of nebulae around blue supergiants in their final evolutionary stage.
The Hubble Space Telescope 2000-8000 Å spectrum of SN 1987A observed on 1995 January 7 (7.87 yr after the explosion) is dominated by Hα and UV lines, including Mg II-Mg I λ2825 (equal to Hα in luminosity), Fe II UV 2 (two-thirds the intensity of Hα), Fe II UV 3 (one-half the intensity of Hα), and a 3730 Å emission feature identified with a blend of [O II] λ3727 and Fe I emission lines. [O I] λ6300 and lines of [Ca II] and Na I, as well as some Fe II optical forbidden and permitted lines are present at visual wavelengths. Also present are a number of weak emission features, which are presumably metal lines produced by photon degradation as a result of reprocessing of UV radiation into metal lines. Modeling the Mg II-Mg I lines provides the velocity of the outer visible radius of the envelope, 9000 ± 500 km s-1 in the Mg II λ2800 line, which is consistent with the earlier direct HST imaging at near-UV wavelengths. The UV/optical emission lines originate from the radioactive luminescence of the cool gas (T ≈ 130-160 K). The metal lines reflect the instantaneous reprocessing of the energy deposited from 44Ti radioactive decays through collisions with fast electrons, while the Hα emission primarily comes from the recombination of previously ionized hydrogen. The overall luminosity of the Fe II emission lines, ~1035 ergs s-1, can be explained if the bulk of the positrons from a mass (1-2) × 10-4 M☉ of 44Ti release their energy in the iron-rich material, which suggests the presence of a magnetic field B > 5 × 10-13 G prohibiting the escape of positrons into oxygen and hydrogen gas. The ionized fraction in the iron-rich material is small (0.2-0.3), and the total UV/optical emission from Fe I should be comparable to that from Fe II. Most of the 1036 ergs s-1 deposited by the 44Ti positrons should be emitted in the Fe II 26 μm line. The observed Hα luminosity decrease, by 5 orders of magnitude between the ages of 1 to 8 yr, is reproduced in a time-dependent model of ionization and cooling with the "standard" amount of radioactive nuclides. However, an additional source of energy at the present epoch with a deposition rate 30 ergs s-1 g-1 (≈ 1036 ergs s-1 in the whole envelope) is not ruled out. The present average temperature in the hydrogen envelope predicted by the time-dependent model is 130 K, which is lower than the value T ≈ 350 K obtained from the observed Balmer continuum shape. However, the shape is affected by a possible contribution of metal lines to the Balmer continuum. The luminosity of the [O I] λ6300 doublet is consistent with that expected for the deposited energy of γ-rays from (1-2) × 10-4 M☉ of 44Ti for an assumed 1.5-2 M☉ of oxygen. If the oxygen mass does not exceed 2 M☉, 1 × 10-4 M☉ is a lower limit for the amount of 44Ti in SN 1987A. The maximum fraction of the 44Ti positron energy deposited into oxygen-rich material does not exceed 5%, which is consistent with positron trapping in Fe-rich material. The [O I] λ6300 line intensity rules out the presence of a central source of γ-radiation (hν > 100 keV) with a luminosity Lγ > 4 × 1036 ergs s-1.
