SN 2011hs: a fast and faint Type IIb supernova from a supergiant progenitor

Bufano, F.; Pignata, G.; Bersten, Melina C.; Mazzali, P. A.; Ryder, S. D.; Margutti, R.; Milisavljević, D.; Morelli, L.; Benetti, S.; Cappellaro, E.; González–Gaitán, S.; Romero-Cañizales, C.; Stritzinger, M. D.; Walker, E. S.; Anderson, J. P.; Contreras, C.; Jaeger, Thomas de; Förster, F.; Gutiérrez, C. P.; Hamuy, M.; Hsiao, E. Y.; Morrell, N.; E., F. Olivares; Paillas, Enrique; Parker, S.; Pian, E.; Pickering, T. E.; Sanders, Nathan; Stockdale, C. J.; Turatto, M.; Valenti, S.; Fesen, Robert A.; Maza, J.; Nomoto, Ken’ichi; Phillips, M. M.; Söderberg, A. M.

doi:10.1093/mnras/stu065

Cited by 62 publications

(68 citation statements)

References 102 publications

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“…While the emission line is strong in the three Type IIb SNe studied here as well as in the Type IIb SNe 2011ei (Milisavljevic et al 2013) and 2011hs (Bufano et al 2014), it appears dim or absent in SN 2001ig (Silverman et al 2009) and SN 2003bg Mazzali et al 2009). Some Type Ib SNe also have spectra that exhibit this line (e.g.…”

Section: [N Ii] λλ6548 6583mentioning

confidence: 59%

Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh

Jerkstrand

Ergon

Smartt

et al. 2014

A&A

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We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modelling identifies the nuclear burning layers and physical mechanisms that produce the major emission lines, and the diagnostic potential of these. We compare the model calculations with data on the three best observed Type IIb SNe to-date − SN 1993J, SN 2008ax, and SN 2011dh. Oxygen nucleosynthesis depends sensitively on the main-sequence mass of the star and modelling of the [O I] λλ6300, 6364 lines constrains the progenitors of these three SNe to the M ZAMS = 12−16 M range (ejected oxygen masses 0.3−0.9 M ), with SN 2011dh towards the lower end and SN 1993J towards the upper end of the range. The high ejecta masses from M ZAMS 17 M progenitors give rise to brighter nebular phase emission lines than observed. Nucleosynthesis analysis thus supports a scenario of low-to-moderate mass progenitors for Type IIb SNe, and by implication an origin in binary systems. We demonstrate how oxygen and magnesium recombination lines may be combined to diagnose the magnesium mass in the SN ejecta. For SN 2011dh, a magnesium mass of 0.02−0.14 M is derived, which gives a Mg/O production ratio consistent with the solar value. Nitrogen left in the He envelope from CNO burning gives strong [N II] λλ6548, 6583 emission lines that dominate over Hα emission in our models. The hydrogen envelopes of Type IIb SNe are too small and dilute to produce any noticeable Hα emission or absorption after ∼150 days, and nebular phase emission seen around 6550 Å is in many cases likely caused by [N II] λλ6548, 6583. Finally, the influence of radiative transport on the emergent line profiles is investigated. Significant line blocking in the metal core remains for several hundred days, which affects the emergent spectrum. These radiative transfer effects lead to early-time blueshifts of the emission line peaks, which gradually disappear as the optical depths decrease with time. The modelled evolution of this effect matches the observed evolution in SN 2011dh.

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Section: [N Ii] λλ6548 6583mentioning

confidence: 59%

Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh

Jerkstrand

Ergon

Smartt

et al. 2014

A&A

Self Cite

152

249

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“…Thus, even if the remnants of these supernovae are bright in radio (at peak we expect almost 1000 Jy in L-band at 20 kpc Bufano et al 2014), they could be very faint in the optical due to the GP absorption: considering that m = A + M + µ, assuming a SN with a peak absolute magnitude of M = 17 mag, we would have an apparent magnitude as high as m ∼26 mag, having in the direction of SCORPIO an extinction A = 26.7 (Schlafly & Finkbeiner 2011) and a distance module, corresponding to 20 kpc, of µ ∼ 16.5. This means that it is possible for a supernova in our Galaxy to happen undiscovered but to leave a remnant bright enough to be detected at radio wavelength.…”

Section: Comparison With Atlasmentioning

confidence: 86%

SCORPIO – II. Spectral indices of weak Galactic radio sources

Cavallaro

Trigilio

Umana

et al. 2017

Monthly Notices of the Royal Astronomical Society

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In the next few years the classification of radio sources observed by the large surveys will be a challenging problem, and spectral index is a powerful tool for addressing it. Here we present an algorithm to estimate the spectral index of sources from multiwavelength radio images. We have applied our algorithm to SCORPIO (Umana et al. 2015), a Galactic Plane survey centred around 2.1 GHz carried out with ATCA, and found we can measure reliable spectral indices only for sources stronger than 40 times the rms noise. Above a threshold of 1 mJy, the source density in SCORPIO is 20 percent greater than in a typical extra-galactic field, like ATLAS (Norris et al. 2006), because of the presence of Galactic sources. Among this excess population, 16 sources per square degree have a spectral index of about zero, suggesting optically thin thermal emission such as Hii regions and planetary nebulae, while 12 per square degree present a rising spectrum, suggesting optically thick thermal emission such as stars and UCHii regions.

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“…For this purpose we used a one-dimensional Lagrangian LTE hydrodynamical code (Bersten et al 2011) applied to stellar evolution pre-SN structures (Nomoto & Hashimoto 1988) with different He core masses. The methodology is the same that we applied in previous analyses of SNe IIb (e.g., see Bersten et al 2012;Bufano et al 2014), i.e., we first derived global parameters focusing on the explosion of H-free structures to fit the main peak of the bolometric light curve and the expansion velocities, and then we used such parameters to analyze the effect on the early light curve of a thin H-rich envelope with different extensions. In order to compare models and observations on the same time frame, we adopted an explosion date of JD = 2,454,528.80 ± 0.15 from Taubenberger et al (2011).…”

Section: Hydrodynamical Modelsmentioning

confidence: 99%

THE PROGENITOR OF THE TYPE IIb SN 2008ax REVISITED

Folatelli

Bersten

Kuncarayakti

et al. 2015

ApJ

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Hubble Space Telescope observations of the site of the supernova (SN) SN 2008ax obtained in 2011 and 2013 reveal that the possible progenitor object detected in pre-explosion images was in fact multiple. Four point sources are resolved in the new, higher-resolution images. We identify one of the sources with the fading SN. The other three objects are consistent with single supergiant stars. We conclude that their light contaminated the previously identified progenitor candidate. After subtraction of these stars, the progenitor appears to be significantly fainter and bluer than previously measured. Post-explosion photometry at the SN location indicates that the progenitor object has disappeared. If single, the progenitor is compatible with a supergiant star of B to mid-A spectral type, while a Wolf-Rayet (W-R) star would be too luminous in the ultraviolet to account for the observations. Moreover, our hydrodynamical modeling shows that the pre-explosion mass was 4-5 M e and the radius was 30-50 R e , which is incompatible with a W-R progenitor. We present a possible interacting binary progenitor computed with our evolutionary models that reproduces all the observational evidence. A companion star as luminous as an O9-B0 main-sequence star may have remained after the explosion.

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SN 2011hs: a fast and faint Type IIb supernova from a supergiant progenitor

Cited by 62 publications

References 102 publications

Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh

Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh

SCORPIO – II. Spectral indices of weak Galactic radio sources

THE PROGENITOR OF THE TYPE IIb SN 2008ax REVISITED

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