Knowledge of the progenitors of core-collapse supernovae is a fundamental component in understanding the explosions. The recent progress in finding such stars is reviewed. The minimum initial mass ...that can produce a supernova (SN) has converged to 8 ± 1 M ⊙ from direct detections of red supergiant progenitors of II-P SNe and the most massive white dwarf progenitors, although this value is model dependent. It appears that most type Ibc SNe arise from moderate mass interacting binaries. The highly energetic, broad-lined Ic SNe are likely produced by massive, Wolf-Rayet progenitors. There is some evidence to suggest that the majority of massive stars above ∼20 M ⊙ may collapse quietly to black holes and that the explosions remain undetected. The recent discovery of a class of ultrabright type II SNe and the direct detection of some progenitor stars bearing luminous blue variable characteristics suggest some very massive stars do produce highly energetic explosions. The physical mechanism is under debate, and these SNe pose a challenge to stellar evolutionary theory.
The progenitors of many Type II core-collapse supernovae (SNe) have now been identified directly on pre-discovery imaging. Here, we present an extensive search for the progenitors of Type Ibc SNe in ...all available pre-discovery imaging since 1998. There are 12 Type Ibc SNe with no detections of progenitors in either deep ground-based or Hubble Space Telescope archival imaging. The deepest absolute BVR magnitude limits are between −4 and − 5 mag. We compare these limits with the observed Wolf-Rayet population in the Large Magellanic Cloud and estimate a 16 per cent probability that we have failed to detect such a progenitor by chance. Alternatively, the progenitors evolve significantly before core-collapse or we have underestimated the extinction towards the progenitors. Reviewing the relative rates and ejecta mass estimates from light-curve modelling of Ibc SNe, we find both incompatible with Wolf-Rayet stars with initial masses >25 M being the only progenitors. We present binary evolution models that fit these observational constraints. Stars in binaries with initial masses 20 M lose their hydrogen envelopes in binary interactions to become low-mass helium stars. They retain a low-mass hydrogen envelope until 104 yr before core-collapse; hence, it is not surprising that Galactic analogues have been difficult to identify.
ABSTRACT
The detection of the binary neutron star merger GW170817 together with the observation of electromagnetic counterparts across the entire spectrum inaugurated a new era of multimessenger ...astronomy. In this study, we incorporate wavelength-dependent opacities and emissivities calculated from atomic-structure data enabling us to model both the measured light curves and spectra of the electromagnetic transient AT2017gfo. Best fits of the observational data are obtained by Gaussian Process Regression, which allows us to present posterior samples for the kilonova and source properties connected to GW170817. Incorporating constraints obtained from the gravitational wave signal measured by the LIGO-Virgo Scientific Collaboration, we present a $90{{\ \rm per\ cent}}$ upper bound on the mass ratio q ≲ 1.38 and a lower bound on the tidal deformability of $\tilde{\Lambda } \gtrsim 197$, which rules out sufficiently soft equations of state. Our analysis is a path-finder for more realistic kilonova models and shows how the combination of gravitational wave and electromagnetic measurements allow for stringent constraints on the source parameters and the supranuclear equation of state.
Cao et al. reported a possible progenitor detection for the Type Ib supernovae iPTF13bvn for the first time. We find that the progenitor is in fact brighter than the magnitudes previously reported by ...approximately 0.7-0.2 mag with a larger error in the bluer filters. We compare our new magnitudes to our large set of binary evolution models and find that many binary models with initial masses in the range of 10-20...M... match this new photometry and other constraints suggested from analysing the supernova. In addition, these lower mass stars retain more helium at the end of the model evolution indicating that they are likely to be observed as Type Ib supernovae rather than their more massive, Wolf-Rayet counter parts. We are able to rule out typical Wolf-Rayet models as the progenitor because their ejecta masses are too high and they do not fit the observed SED unless they have a massive companion which is the observed source at the supernova location. Therefore only late-time observations of the location will truly confirm if the progenitor was a helium giant and not a Wolf-Rayet star. (ProQuest: ... denotes formulae/symbols omitted.)
Abstract
We present preexplosion optical and infrared (IR) imaging at the site of the type II supernova (SN II) 2023ixf in Messier 101 at 6.9 Mpc. We astrometrically registered a ground-based image ...of SN 2023ixf to archival Hubble Space Telescope (HST), Spitzer Space Telescope (Spitzer), and ground-based near-IR images. A single point source is detected at a position consistent with the SN at wavelengths ranging from HST
R
band to Spitzer 4.5
μ
m. Fitting with blackbody and red supergiant (RSG) spectral energy distributions (SEDs), we find that the source is anomalously cool with a significant mid-IR excess. We interpret this SED as reprocessed emission in a 8600
R
⊙
circumstellar shell of dusty material with a mass ∼5 × 10
−5
M
⊙
surrounding a
log
(
L
/
L
⊙
)
=
4.74
±
0.07
and
T
eff
=
3920
−
160
+
200
K RSG. This luminosity is consistent with RSG models of initial mass 11
M
⊙
, depending on assumptions of rotation and overshooting. In addition, the counterpart was significantly variable in preexplosion Spitzer 3.6 and 4.5
μ
m imaging, exhibiting ∼70% variability in both bands correlated across 9 yr and 29 epochs of imaging. The variations appear to have a timescale of 2.8 yr, which is consistent with
κ
-mechanism pulsations observed in RSGs, albeit with a much larger amplitude than RSGs such as
α
Orionis (Betelgeuse).
We present panchromatic observations and modeling of the Calcium-rich supernova (SN) 2019ehk in the star-forming galaxy M100 (d 16.2 Mpc) starting 10 hr after explosion and continuing for ∼300 days. ...SN 2019ehk shows a double-peaked optical light curve peaking at t = 3 and 15 days. The first peak is coincident with luminous, rapidly decaying Swift-XRT-discovered X-ray emission ( at 3 days; Lx ∝ t−3), and a Shane/Kast spectral detection of narrow H and He ii emission lines (v 500 ) originating from pre-existent circumstellar material (CSM). We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at r < 1015 cm and the resulting cooling emission. We calculate a total CSM mass of ∼7 × 10−3 (MHe/MH 6) with particle density n 109 cm−3. Radio observations indicate a significantly lower density n < 104 cm−3 at larger radii r > (0.1-1) × 1017 cm. The photometric and spectroscopic properties during the second light-curve peak are consistent with those of Ca-rich transients (rise-time of tr = 13.4 0.210 days and a peak B-band magnitude of MB = −15.1 0.200 mag). We find that SN 2019ehk synthesized (3.1 0.11) × 10−2 of and ejected Mej = (0.72 0.040) total with a kinetic energy Ek = (1.8 0.10) × 1050 erg. Finally, deep HST pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (∼10 ) in binaries that lost most of their He envelope or white dwarfs (WDs). The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD+CO WD binaries.
Using images from the Hubble Space Telescope and the Gemini Telescope, we confirmed the disappearance of the progenitors of two type II supernovae (SNe) and evaluated the presence of other stars ...associated with them. We found that the progenitor of SN 2003gd, an M-supergiant star, is no longer observed at the SN location and determined its intrinsic brightness using image subtraction techniques. The progenitor of SN 1993, a K-supergiant star, is also no longer present, but its B-supergiant binary companion is still observed. The disappearance of the progenitors confirms that these two supernovae were produced by red supergiants.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
We study the sudden optical and ultraviolet (UV) brightening of 1ES 1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar ...class of "true Type-2" AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appearance of a blue, featureless continuum, followed several weeks later by the appearance of broad Balmer emission lines. This timescale is generally consistent with the expected light travel time between the central engine and the broadline emission region in (persistent) broadline AGN. Hubble Space Telescope spectroscopy reveals no evidence for broad UV emission lines (e.g., C iv λ1549, C iii λ1909, Mg ii λ2798), probably owing to dust in the broadline emission region. To the best of our knowledge, this is the first case where the lag between the change in continuum and in broadline emission of a "changing look" AGN has been temporally resolved. The nature and timescales of the photometric and spectral evolution disfavor both a change in line-of-sight obscuration and a change of the overall rate of gas inflow as driving the drastic spectral transformations seen in this AGN. Although the peak luminosity and timescales are consistent with those of tidal disruption events seen in inactive galaxies, the spectral properties are not. The X-ray emission displays a markedly different behavior, with frequent flares on timescales of hours to days, and will be presented in a companion publication.
The massive star that underwent a collapse of its core to produce supernova (SN)1993J was subsequently identified as a non-variable red supergiant star in images of the galaxy M81 taken before ...explosion. It showed an excess in ultraviolet and B-band colours, suggesting either the presence of a hot, massive companion star or that it was embedded in an unresolved young stellar association. The spectra of SN1993J underwent a remarkable transformation from the signature of a hydrogen-rich type II supernova to one of a helium-rich (hydrogen-deficient) type Ib. The spectral and photometric peculiarities were best explained by models in which the 13-20 solar mass supergiant had lost almost its entire hydrogen envelope to a close binary companion, producing a 'type IIb' supernova, but the hypothetical massive companion stars for this class of supernovae have so far eluded discovery. Here we report photometric and spectroscopic observations of SN1993J ten years after the explosion. At the position of the fading supernova we detect the unambiguous signature of a massive star: the binary companion to the progenitor.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
SN 2016gkg is a nearby SN IIb discovered shortly after explosion. Like several other Type IIb events with early-time data, SN 2016gkg displays a double-peaked light curve, with the first peak ...associated with the cooling of a low-mass extended progenitor envelope. We present unprecedented intranight-cadence multi-band photometric coverage of the first light curve peak of SN 2016gkg obtained from the Las Cumbres Observatory Global Telescope network, the Asteroid Terrestrial-impact Last Alert System, the Swift satellite, and various amateur-operated telescopes. Fitting these data to analytical shock-cooling models gives a progenitor radius of ∼40-150 with ∼2-40 × 10−2 of material in the extended envelope (depending on the model and the assumed host-galaxy extinction). Our radius estimates are broadly consistent with values derived independently (in other works) from HST imaging of the progenitor star. However, the shock-cooling model radii are on the lower end of the values indicated by pre-explosion imaging. Hydrodynamical simulations could refine the progenitor parameters deduced from the shock-cooling emission and test the analytical models.
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