Forbidden hugs in pandemic times

Pastorello, A.; Fraser, M.; Valerin, G.; Reguitti, A.; Itagaki, K.; Ochner, P.; Williams, S. C.; Jones, David; Munday, James; Smartt, S. J.; Smith, K.; Srivastav, Shubham; Elias‐Rosa, N.; Kankare, E.; Karamehmetoglu, E.; Lundqvist, Peter; Mazzali, P. A.; Munari, U.; Stritzinger, M. D.; Tomasella, L.; Anderson, J. P.; Chambers, K.; Rest, A.

doi:10.1051/0004-6361/202039952

Cited by 30 publications

(42 citation statements)

References 78 publications

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“…The light curve is characterized by an initial peak of high luminosity and short duration 1 week followed by longer duration plateau lasting several months. Such double-peaked light curve behavior is common in LRNe (MacLeod et al 2017;Pastorello et al 2021a; Fig. 1).…”

Section: Example Light Curvesmentioning

confidence: 63%

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Matsumoto¹,

Metzger²

2022

Preprint

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The process of unstable mass transfer in a stellar binary can result in either a complete merger of the stars or successful removal of the donor envelope leaving a surviving more compact binary. "Luminous red nova" (LRN) are the class of optical transients believed to accompany such merger/common envelope events. Past works typically model LRNe using analytic formulae for supernova light curves which make assumptions (e.g., radiation dominated ejecta, neglect of hydrogen recombination energy) not justified in stellar mergers due to the lower velocities and specific thermal energy of the ejecta. We present a one-dimensional model of LRN light curves, which accounts for these effects. Consistent with observations, we find that LRNe typically possess two light curve peaks, an early phase powered by initial thermal energy of the hot, fastest ejecta layers and a later peak powered by hydrogen recombination from the bulk of the ejecta. We apply our model to a sample of LRNe to infer their ejecta properties (mass, velocity, and launching radius) and compare them to the progenitor donor star properties from pre-transient imaging. We define a maximum luminosity achievable for a given donor star in the limit that the entire envelope is ejected, finding that several LRNe violate this limit. Shock interaction between the ejecta and pre-dynamical mass-loss, may provide an additional luminosity source to alleviate this tension. Our model can also be applied to the merger of planets with stars or stars with compact objects.

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Section: Example Light Curvesmentioning

confidence: 63%

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Matsumoto¹,

Metzger²

2022

Preprint

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“…We make use of the modeled progenitor masses, radii, luminosities, and effective temperatures reported in the literature for eight transients: V4332 Sgr (Martini et al 1999), V838 Mon (Munari et al 2002;Bond et al 2003;Tylenda 2005;Tylenda et al 2005b), V1309 Sco (Mason et al 2010;Tylenda et al 2011), NGC4490-OT2011 (Smith et al 2016), M31 LRN 2015 (Williams et al 2015;Kurtenkov et al 2015;MacLeod et al 2017;Blagorodnova et al 2020), M101 LRN 2015(Blagorodnova et al 2017, SN Hunt 248 (Mauerhan et al 2015), and AT2018 bwo (Blagorodnova et al 2021). The extragalactic transients AT 2018hso (Cai et al 2019), AT 2019zhd (Pastorello et al 2021a), AT 2020hat and AT 2020kog (Pastorello et al 2021b) also have pre-outburst absolute magnitudes and colors, but no comparisons to stellar model tracks have been made.…”

Section: Luminous Red Nova Samplementioning

confidence: 99%

Dusty, Self-Obscured Transients from Stellar Mergers and Common Envelope Phases

MacLeod¹,

De²,

Loeb³

2022

Preprint

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We discuss the central role that dust condensation plays in shaping the observational appearance of outflows from coalescing binary systems. As binaries enter into a common envelope phase or merger, they shock-heat and expel material into their surroundings. Depending on the properties of the merging system, this material can expand to the point where molecules and dust form, dramatically increasing the gas opacity. We use the existing population of Luminous Red Novae (LRNe) to constrain the thermodynamics of these ejecta, then apply our findings to the progressive obscuration of merging systems in the lead in to their coalescence. Compact progenitor stars near the main sequence or in the Hertzsprung gap along with massive progenitor stars have sufficiently hot circumstellar material to remain unobscured by dust. By contrast, more extended, low-mass giants should become completely optically obscured by dust formation in the circumbinary environment. We predict that approximately half of stellar merger and common envelope transients for solar-mass stars will be dusty, infraredluminous sources. The dusty, infrared transients will selectively trace the population of systems that may successfully eject their common envelopes, while the unobscured, optical transients correspond to the LRNe population of stellar mergers.

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“…For the fit of the photometric points, we perform a Monte Carlo simulation for each epoch, fitting with the python tool curve_fit 5 200 sets of fluxes randomly generated with a Gaussian distribution centered on the measured value, and 𝜎 equal to the measured error. Such procedure is described in detail in Pastorello et al (2021). Both in the spectroscopic and photometric fits, we exclude the regions heavily affected by line blanketing, since they would misleadingly reduce the estimated temperature.…”

Section: Blackbody Fittingmentioning

confidence: 99%

Low luminosity Type II supernovae -- IV. SN 2020cxd and SN 2021aai, at the edges of the sub-luminous supernovae class

Valerin,

Pumo,

Pastorello

et al. 2022

Preprint

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Photometric and spectroscopic data for two Low Luminosity Type IIP Supernovae (LL SNe IIP) are presented. SN 2020cxd reaches a peak absolute magnitude 𝑀 𝑟 = -13.90 ± 0.05 mag two days after explosion, subsequently settling on a plateau for ∼120 days. Through the luminosity of the late light curve tail, we infer a synthesized 56 Ni mass of (1.8±0.5) × 10 −3 M . During the early evolutionary phases, optical spectra show a blue continuum (𝑇 > 8000 K) with broad Balmer lines displaying a P Cygni profile, while at later phases Ca II, Fe II, Sc II and Ba II lines dominate the spectra. Hydrodynamical modelling of the observables yields 𝑅 575 𝑅 for the progenitor star, with 𝑀 𝑒 𝑗 = 7.5 M and 𝐸 0.097 foe emitted during the explosion. This low-energy event originating from a low-mass progenitor star is compatible with both the explosion of a red supergiant (RSG) star and with an Electron Capture Supernova arising from a super asymptotic giant branch star. SN 2021aai reaches a maximum luminosity of 𝑀 𝑟 = -16.4 mag (correcting for 𝐴 𝑉 =1.9 mag), and displays a remarkably long plateau (∼140 days). The estimated 56 Ni mass is (1.4±0.5) × 10 −2 M . The expansion velocities are compatible with those of other LL SNe IIP (few 10 3 km s −1 ). The physical parameters obtained through hydrodynamical modelling are 𝑅 575 R , 𝑀 𝑒 𝑗 = 15.5 M and 𝐸 = 0.4 foe. SN 2021aai is therefore interpreted as the explosion of a RSG, with properties that bridge the class of LL SNe IIP with standard SN IIP events.

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Forbidden hugs in pandemic times

Cited by 30 publications

References 78 publications

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Dusty, Self-Obscured Transients from Stellar Mergers and Common Envelope Phases

Low luminosity Type II supernovae -- IV. SN 2020cxd and SN 2021aai, at the edges of the sub-luminous supernovae class

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