We present the colibri code for computing the evolution of stars along the thermally pulsing asymptotic giant branch (TP-AGB) phase. Compared to purely synthetic TP-AGB codes, colibri relaxes a ...significant part of their analytic formalism in favour of a detailed physics applied to a complete envelope model, in which the stellar structure equations are integrated from the atmosphere down to the bottom of the hydrogen-burning shell. This allows us to predict self-consistently: (i) the effective temperature, and more generally the convective envelope and atmosphere structures, correctly coupled to the changes in the surface chemical abundances and gas opacities; (ii) the conditions under which sphericity effects may significantly affect the atmospheres of giant stars; (iii) the core mass-luminosity relation and its possible break-down due to the occurrence of hot-bottom burning (HBB) in the most massive AGB stars, by taking properly into account the nuclear energy generation in the H-burning shell and in the deepest layers of the convective envelope; (iv) the HBB nucleosynthesis via the solution of a complete nuclear network (including the pp chains, and the CNO, NeNa and MgAl cycles) coupled to a diffusive description of mixing, suitable to follow also the synthesis of 7Li via the Cameron-Fowler beryllium transport mechanism; (v) the intershell abundances left by each thermal pulse via the solution of a complete nuclear network applied to a simple model of the pulse-driven convective zone (PDCZ); (vi) the onset and quenching of the third dredge-up, with a temperature criterion that is applied, at each thermal pulse, to the result of envelope integrations at the stage of the post-flash luminosity peak.
At the same time, colibri pioneers new techniques in the treatment of the physics of stellar interiors, not yet adopted in full TP-AGB models. It is the first evolutionary code ever to use accurate on-the-fly computation of the equation of state (EoS) for roughly 800 atoms, ions, molecules and of the Rosseland mean opacities throughout the atmosphere and the deep envelope. This ensures a complete consistency, step by step, of both EoS and opacity with the evolution of the chemical abundances caused by the third dredge-up and HBB. Another distinguishing aspect of colibri is its high computational speed, which allows to generate complete grids of TP-AGB models in just a few hours. This feature is absolutely necessary for calibrating the many uncertain parameters and processes that characterize the TP-AGB phase.
We illustrate the many unique features of colibri by means of detailed evolutionary tracks computed for several choices of model parameters, including initial star masses, chemical abundances, nuclear reaction rates, efficiency of the third dredge-up, overshooting at the base of the PDCZ, etc. Future papers in this series will deal with the calibration of all these and other parameters using observational data of AGB stars in the Galaxy and in nearby systems, a step that is of paramount importance for producing reliable stellar population synthesis models of galaxies up to high redshift.
ABSTRACT Extensive photometric and spectroscopic observations are presented for SN 2014cx, a Type IIP supernova (SN) exploding in the nearby galaxy NGC 337. The observations are performed in optical ...and ultraviolet bands, covering from −20 to +400 days from the peak light. The stringent detection limit from prediscovery images suggests that this supernova was actually detected within about one day after explosion. Evolution of the very early time light curve of SN 2014cx is similar to that predicted from a shock breakout and post-shock cooling decline before reaching the optical peak. Our photometric observations show that SN 2014cx has a plateau duration of ∼100 days, an absolute V-band magnitude of mag at days, and a nickel mass of 0.056 0.008 . The spectral evolution of SN 2014cx resembles that of normal SNe IIP like SN 1999em and SN 2004et, except that it has a slightly higher expansion velocity (∼4200 at 50 days). From the cooling curve of photospheric temperature, we derive that the progenitor has a pre-explosion radius of ∼640 R , consistent with those obtained from SuperNova Explosion Code modeling (∼620 R ) and hydrodynamical modeling of the observables (∼570 R ). Moreover, the hydrodynamical simulations yield a total explosion energy of erg, and an ejected mass of ∼8 . These results indicate that the immediate progenitor of SN 2014cx is likely a red supergiant star with a mass of ∼10 .
ABSTRACT We present extensive ultraviolet, optical, and near-infrared observations of the Type IIP supernova (SN IIP) 2013ej in the nearby spiral galaxy M74. The multicolor light curves, spanning ...from ∼8-185 days after explosion, show that it has a higher peak luminosity (i.e., MV ∼ −17.83 mag at maximum light), a faster post-peak decline, and a shorter plateau phase (i.e., ∼50 days) compared to the normal Type IIP SN 1999em. The mass of 56Ni is estimated as 0.02 0.01 M from the radioactive tail of the bolometric light curve. The spectral evolution of SN 2013ej is similar to that of SN 2004et and SN 2007od, but shows a larger expansion velocity (i.e., vFe ii ∼ 4600 km s−1 at t ∼ 50 days) and broader line profiles. In the nebular phase, the emission of the H line displays a double-peak structure, perhaps due to the asymmetric distribution of 56Ni produced in the explosion. With the constraints from the main observables such as bolometric light curve, expansion velocity, and photospheric temperature of SN 2013ej, we performed hydrodynamical simulations of the explosion parameters, yielding the total explosion energy as ∼0.7× 1051 erg, the radius of the progenitor as ∼600 R , and the ejected mass as ∼10.6 M . These results suggest that SN 2013ej likely arose from a red supergiant with a mass of 12-13 M immediately before the explosion.
SN 2013ab: a normal Type IIP supernova in NGC 5669 Bose, Subhash; Valenti, Stefano; Misra, Kuntal ...
Monthly notices of the Royal Astronomical Society,
07/2015, Letnik:
450, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We present densely sampled ultraviolet/optical photometric and low-resolution optical spectroscopic observations of the Type IIP supernova 2013ab in the nearby (∼24 Mpc) galaxy NGC 5669, from 2 to ...190 d after explosion. Continuous photometric observations, with the cadence of typically a day to one week, were acquired with the 1–2 m class telescopes in the Las Cumbres Observatory Global Telescope network, ARIES telescopes in India and various other telescopes around the globe. The light curve and spectra suggest that the supernova (SN) is a normal Type IIP event with a plateau duration of ∼80 d with mid-plateau absolute visual magnitude of −16.7, although with a steeper decline during the plateau (0.92 mag 100 d−1 in V band) relative to other archetypal SNe of similar brightness. The velocity profile of SN 2013ab shows striking resemblance with those of SNe 1999em and 2012aw. Following the Rabinak & Waxman prescription, the initial temperature evolution of the SN emission allows us to estimate the progenitor radius to be ∼800 R⊙, indicating that the SN originated from a red supergiant star. The distance to the SN host galaxy is estimated to be 24.3 Mpc from expanding photosphere method. From our observations, we estimate that 0.064 M⊙ of 56Ni was synthesized in the explosion. General relativistic, radiation hydrodynamical modelling of the SN infers an explosion energy of 0.35 × 1051 erg, a progenitor mass (at the time of explosion) of ∼9 M⊙ and an initial radius of ∼600 R⊙.
The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this ...gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA.
We present the COLIBRI code for computing the evolution of stars along the TP-AGB phase. Compared to purely synthetic TP-AGB codes, COLIBRI relaxes a significant part of their analytic formalism in ...favour of a detailed physics applied to a complete envelope model, in which the stellar structure equations are integrated from the atmosphere down to the bottom of the hydrogen-burning shell. This allows to predict self-consistently: (i) the effective temperature, and more generally the convective envelope and atmosphere structures, correctly coupled to the changes in the surface chemical abundances and gas opacities; (ii) sphericity effects in the atmospheres; (iii) the core mass-luminosity relation and its break-down due to hot bottom burning (HBB) in the most massive AGB stars, (iv) the HBB nucleosynthesis via the solution of a complete nuclear network (pp chains, and the CNO, NeNa, MgAl cycles), including also the production of 7Li via the Cameron-Fowler beryllium transport mechanism; (v) the chemical composition of the pulse-driven convective zone; (vi) the onset and quenching of the third dredge-up, with a suitable temperature criterion. At the same time COLIBRI pioneers new techniques in the treatment of the physics of stellar interiors. It is the first evolutionary code ever to use accurate on-the-fly computation of the equation of state for roughly 800 atoms, ions, molecules, and of the Rosseland mean opacities throughout the deep envelope. Another distinguishing aspect of COLIBRI is its high computational speed. This feature is necessary for calibrating the uncertain parameters and processes that characterize the TP-AGB phase, a step of paramount importance for producing reliable stellar population synthesis models of galaxies up to high redshift. (abridged)
We present extensive ultraviolet, optical, and near-infrared observations of the type IIP supernova (SN IIP) 2013ej in the nearby spiral galaxy M74. The multicolor light curves, spanning from ...\(\sim\) 8--185 days after explosion, show that it has a higher peak luminosity (i.e., M\(_{V}\) $\sim$$-\(17.83 mag at maximum light), a faster post-peak decline, and a shorter plateau phase (i.e., \)\sim\( 50 days) compared to the normal type IIP SN 1999em. The mass of \)^{56}\(Ni is estimated as 0.02\)\pm\(0.01 M\)_{\odot}\( from the radioactive tail of the bolometric light curve. The spectral evolution of SN 2013ej is similar to that of SN 2004et and SN 2007od, but shows a larger expansion velocity (i.e., \)v_{Fe II} \sim\( 4600 km s\)^{-1}\( at t \)\sim\( 50 days) and broader line profiles. In the nebular phase, the emission of H\)\alpha\( line displays a double-peak structure, perhaps due to the asymmetric distribution of \)^{56}\(Ni produced in the explosion. With the constraints from the main observables such as bolometric light curve, expansion velocity and photospheric temperature of SN 2013ej, we performed hydrodynamical simulations of the explosion parameters, yielding the total explosion energy as \)\sim\(0.7\)\times\( 10\)^{51}\( erg, the radius of the progenitor as \)\sim\(600 R\)_{\odot}\(, and the ejected mass as \)\sim\(10.6 M\)_{\odot}\(. These results suggest that SN 2013ej likely arose from a red supergiant with a mass of 12--13 M\)_{\odot}$ immediately before the explosion.
Extensive photometric and spectroscopic observations are presented for SN 2014cx, a type IIP supernova (SN) exploding in the nearby galaxy NGC 337. The observations are performed in optical and ...ultraviolet bands, covering from -20 to +400 days from the peak light. The stringent detection limit from prediscovery images suggests that this supernova was actually detected within about 1 day after explosion. Evolution of the very early-time light curve of SN 2014cx is similar to that predicted from a shock breakout and post-shock cooling decline before reaching the optical peak. Our photometric observations show that SN 2014cx has a plateau duration of ~ 100 days, an absolute V-band magnitude of ~ -16.5 mag at t~50 days, and a nickel mass of 0.056+-0.008 Msun. The spectral evolution of SN 2014cx resembles that of normal SNe IIP like SN 1999em and SN 2004et, except that it has a slightly higher expansion velocity (~ 4200 km/s at 50 days). From the cooling curve of photospheric temperature, we derive that the progenitor has a pre-explosion radius of ~ 640 Rsun, consistent with those obtained from SNEC modeling (~ 620 Rsun) and hydrodynamical modeling of the observables (~ 570 Rsun). Moreover, the hydrodynamical simulations yield a total explosion energy of ~ 0.4*10e51 erg, and an ejected mass of ~ 8 Msun. These results indicate that the immediate progenitor of SN 2014cx is likely a red supergiant star with a mass of ~ 10 Msun.
We present densely-sampled ultraviolet/optical photometric and low-resolution optical spectroscopic observations of the type IIP supernova 2013ab in the nearby (\(\sim\)24 Mpc) galaxy NGC 5669, from ...2 to 190d after explosion. Continuous photometric observations, with the cadence of typically a day to one week, were acquired with the 1-2m class telescopes in the LCOGT network, ARIES telescopes in India and various other telescopes around the globe. The light curve and spectra suggest that the SN is a normal type IIP event with a plateau duration of \( \sim80 \) days with mid plateau absolute visual magnitude of -16.7, although with a steeper decline during the plateau (0.92 mag 100 d\( ^{-1} \) in \( V \) band) relative to other archetypal SNe of similar brightness. The velocity profile of SN 2013ab shows striking resemblance with those of SNe 1999em and 2012aw. Following the Rabinak & Waxman (2011) prescription, the initial temperature evolution of the SN emission allows us to estimate the progenitor radius to be \( \sim \) 800 R\(_{\odot}\), indicating that the SN originated from a red supergiant star. The distance to the SN host galaxy is estimated to be 24.3 Mpc from expanding photosphere method (EPM). From our observations, we estimate that 0.064 M\(_{\odot}\) of \(^{56}\)Ni was synthesized in the explosion. General relativistic, radiation hydrodynamical modeling of the SN infers an explosion energy of \( 0.35\times10^{51} \) erg, a progenitor mass (at the time of explosion) of \( \sim9 \) M\(_{\odot}\) and an initial radius of \( \sim600 \) R\(_{\odot}\).
Astron.Astrophys.447:641-647,2006 Using a new s-nucleosynthesis code, coupled with the stellar evolution code
Star2003, we performed simulations to study the impact of the convection
treatment on the ...s-process during core He-burning of a 25 Msun star (ZAMS mass)
with an initial metallicity of Z=0.02. Particular attention was devoted to the
impact of the extent of overshooting on the s-process efficiency. The results
show enhancements of about a factor 2-3 in s-process efficiency (measured as
the average overproduction factor of the 6 s-only nuclear species with
$60\lesssim A\lesssim 90$) with overshooting parameter values in the range
0.01-0.035, compared to results obtained with the same model but without
overshooting. The impact of these results on the p-process model based on type
II supernovae is discussed.
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