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Jozsef Vinko

Publications and source records attributed to Jozsef Vinko.

At least 37 records · Page 2Linked to original sources

SN 2016iyc: A Type IIb supernova arising from a low-mass progenitor

In this work, photometric and spectroscopic analyses of a very low-luminosity Type IIb supernova (SN) 2016iyc have been performed. SN 2016iyc lies near the faint end among the distribution of similar supernovae (SNe). Given lower ejecta mass ($M_{\rm ej}$) and low nickel mass ($M_{\rm Ni}$) from the literature, combined with SN 2016iyc lying near the faint end, one-dimensional stellar evolution models of 9 - 14 M$_{\odot}$ zero-age main-sequence (ZAMS) stars as the possible progenitors of SN 2016iyc have been performed using the publicly available code MESA. Moreover, synthetic explosions of the progenitor models have been simulated using the hydrodynamic evolution codes STELLA and SNEC. The bolometric luminosity light curve and photospheric velocities produced through synthetic explosions of ZAMS stars of mass in the range 12 - 13 M$_{\odot}$ having a pre-supernova radius $R_{\mathrm{0}} =$ (240 - 300) R$_{\odot}$, with $M_{\rm ej} =$ (1.89 - 1.93) M$_{\odot}$, explosion energy $E_{\rm exp} = $ (0.28 - 0.35) $\times 10^{51}$ erg, and $M_{\rm Ni} < 0.09$ M$_{\odot}$, are in good agreement with observations; thus, SN 2016iyc probably exploded from a progenitor near the lower mass limits for SNe IIb. Finally, hydrodynamic simulations of the explosions of SN 2016gkg and SN 2011fu have also been performed to compare intermediate- and high-luminosity examples among well-studied SNe IIb. The results of progenitor modelling and synthetic explosions for SN 2016iyc, SN 2016gkg, and SN 2011fu exhibit a diverse range of mass for the possible progenitors of SNe IIb.

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Seven Years of SN 2014C: a Multi-Wavelength Synthesis of an Extraordinary Supernova

SN 2014C was originally classified as a Type Ib supernova, but at phase ϕ = 127 d post-explosion strong Hα emission was observed. SN 2014C has since been observed in radio, infrared, optical and X-ray bands. Here we present new optical spectroscopic and photometric data spanning ϕ = 947 - 2494 d post-explosion. We address the evolution of the broadened Hα emission line, as well as broad [O III] emission and other lines. We also conduct a parallel analysis of all publicly available multi-wavelength data. From our spectra, we find a nearly constant Hα FWHM velocity width of {\sim}2000 km/s that is significantly lower than that of other broadened atomic transitions ({\sim}3000 - 7000 km/s) present in our spectra ([O I] λ6300; [O III] λλ4959,5007; He I λ7065; [Ca II] λλ7291,7324). The late radio data demand a fast forward shock ({\sim}10,000 km/s at ϕ = 1700 d) in rarified matter that contrasts with the modest velocity of the Hα. We propose that the infrared flux originates from a toroidal-like structure of hydrogen surrounding the progenitor system, while later emission at other wavelengths (radio, X-ray) likely originates predominantly from the reverse shock in the ejecta and the forward shock in the quasi-spherical progenitor He wind. We propose that the Hα emission arises in the boundary layer between the ejecta and torus. We also consider the possible roles of a pulsar and a binary companion.

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Progenitor mass constraints for the type Ib intermediate-luminosity SN 2015ap and the highly extinguished SN 2016bau

Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN~2016bau are discussed. Photometric properties of the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, synthesised nickel mass, and kinetic energy of the ejecta are calculated from their light-curve analysis. We also model and compare the spectra of SN~2015ap and SN~2016bau at various stages of their evolution. The P~Cygni profiles of various lines present in the spectra are used to determine the velocity evolution of the ejecta. To account for the observed photometric and spectroscopic properties of the two SNe, we have computed 12\,$M_\odot$ zero-age main sequence (ZAMS) star models and evolved them until the onset of core collapse using the publicly available stellar-evolution code {\tt MESA}. Synthetic explosions were produced using the public version of {\tt STELLA} and another publicly available code, {\tt SNEC}, utilising the {\tt MESA} models. {\tt SNEC} and {\tt STELLA} provide various observable properties such as the bolometric luminosity and velocity evolution. The parameters produced by {\tt SNEC}/{\tt STELLA} and our observations show close agreement with each other, thus supporting a 12\,$M_\odot$ ZAMS star as the possible progenitor for SN~2015ap, while the progenitor of SN~2016bau is slightly less massive, being close to the boundary between SN and non-SN as the final product.

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SN 2018zd: An Unusual Stellar Explosion as Part of the Diverse Type II Supernova Landscape

We present extensive observations of SN 2018zd covering the first $\sim450$\,d after the explosion. This SN shows a possible shock-breakout signal $\sim3.6$\,hr after the explosion in the unfiltered light curve, and prominent flash-ionisation spectral features within the first week. The unusual photospheric temperature rise (rapidly from $\sim 12,000$\,K to above 18,000\,K) within the earliest few days suggests that the ejecta were continuously heated. Both the significant temperature rise and the flash spectral features can be explained with the interaction of the SN ejecta with the massive stellar wind ($0.18^{+0.05}_{-0.10}\, \rm M_{\odot}$), which accounts for the luminous peak ($L_{\rm max} = [1.36\pm 0.63] \times 10^{43}\, \rm erg\,s^{-1}$) of SN 2018zd. The luminous peak and low expansion velocity ($v \approx 3300$ km s$^{-1}$) make SN 2018zd to be like a member of the LLEV (luminous SNe II with low expansion velocities) events originated due to circumstellar interaction. The relatively fast post-peak decline allows a classification of SN 2018zd as a transition event morphologically linking SNe~IIP and SNe~IIL. In the radioactive-decay phase, SN 2018zd experienced a significant flux drop and behaved more like a low-luminosity SN~IIP both spectroscopically and photometrically. This contrast indicates that circumstellar interaction plays a vital role in modifying the observed light curves of SNe~II. Comparing nebular-phase spectra with model predictions suggests that SN 2018zd arose from a star of $\sim 12\,\rm M_{\odot}$. Given the relatively small amount of $^{56}$Ni ($0.013 - 0.035 \rm M_{\odot}$), the massive stellar wind, and the faint X-ray radiation, the progenitor of SN 2018zd could be a massive asymptotic giant branch star which collapsed owing to electron capture.

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SN 2019ehk: A Double-Peaked Ca-rich Transient with Luminous X-ray Emission and Shock-Ionized Spectral Features

We present panchromatic observations and modeling of the Calcium-rich supernova 2019ehk in the star-forming galaxy M100 (d$\approx$16.2 Mpc) starting 10 hours 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 $\textit{Swift}$-XRT discovered X-ray emission ($L_x\approx10^{41}~\rm{erg~s^{-1}}$ at 3 days; $L_x \propto t^{-3}$), and a Shane/Kast spectral detection of narrow H$α$ and He II emission lines ($v \approx 500$ km/s) originating from pre-existent circumstellar material. We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at $r<10^{15}$ cm and the resulting cooling emission. We calculate a total CSM mass of $\sim$ $7\times10^{-3}$ $\rm{M_{\odot}}$ with particle density $n\approx10^{9}\,\rm{cm^{-3}}$. Radio observations indicate a significantly lower density $n < 10^{4}\,\rm{cm^{-3}}$ at larger radii. The photometric and spectroscopic properties during the second light curve peak are consistent with those of Ca-rich transients (rise-time of $t_r =13.4\pm0.210$ days and a peak B-band magnitude of $M_B =-15.1\pm0.200$ mag). We find that SN 2019ehk synthesized $(3.1\pm0.11)\times10^{-2} ~ \rm{M_{\odot}}$ of ${}^{56}\textrm{Ni}$ and ejected $M_{\rm ej} = (0.72\pm 0.040)~\rm{M_{\odot}}$ total with a kinetic energy $E_{\rm k}=(1.8\pm0.10)\times10^{50}~\rm{erg}$. Finally, deep $\textit{HST}$ pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (~10 $\rm{M_{\odot}}$) in binaries that lost most of their He envelope or white dwarfs. The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD + CO WD binaries.

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Detecting Pair-Instability Supernovae at z<5 with the James Webb Space Telescope

Pair-instability supernovae (PISNe) are the ultimate cosmic lighthouses, capable of being observed at z<25 and revealing the properties of primordial stars at cosmic dawn. But it is now understood that the spectra and light curves of these events evolved with redshift as the universe became polluted with heavy elements because chemically enriched stars in this mass range typically lose most of their hydrogen envelopes and explode as bare helium cores. The light curves of such transients can be considerably dimmer in the near infrared (NIR) today than those of primordial PISNe of equal energy and progenitor mass. Here, we calculate detection rates for PISNe whose progenitors lost their outer layers to either line-driven winds or rotation at z<10, their detection limit in redshift for the James Webb Space Telescope (JWST). We find that JWST may be able to detect only Pop II (metal-poor) PISNe over the redshift range of z<4, but not their Pop III (metal-free) counterparts.

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SN 2010kd: Photometric and Spectroscopic Analysis of a Slow-Decaying Superluminous Supernova

This paper presents data and analysis of SN 2010kd, a low-redshift ($z = 0.101$) H-deficient superluminous supernova (SLSN), based on ultraviolet/optical photometry and optical spectroscopy spanning between $-$28 and +194 days relative to $\mathit{B}$ band maximum light. The $\mathit{B}$ band light curve comparison of SN 2010kd with a subset of well-studied SLSNe I at comparable redshifts indicates that it is a slow-decaying PTF12dam like SLSN. Analytical light-curve modeling using the $\mathtt{Minim}$ code suggests that the bolometric light curve of SN 2010kd favors circumstellar matter interaction for the powering mechanism. $\mathtt{SYNAPPS}$ modeling of the early-phase spectra does not identify broad H or He lines, whereas the photospheric-phase spectra are dominated by O I, O II, C II, C IV and Si II, particularly, presence of both low and high-velocity components of O II and Si II lines. The nebular-phase spectra of SN 2010kd are dominated by O I and Ca II emission lines similar to those seen in other SLSNe I. The line velocities in SN 2010kd exhibit flatter evolution curves similar to SN 2015bn but with comparatively higher values. SN 2010kd shows a higher single-zone local thermodynamic equilibrium temperature in comparison to PTF12dam and SN 2015bn, and it has an upper O I ejected mass limit of $\sim 10~M_\odot$. The host of SN 2010kd is a dwarf galaxy with a high star-formation rate ($\sim 0.18 \pm 0.04~M_\odot$ yr$^{-1}$) and extreme emission lines.

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SN 2017cfd: A Normal Type Ia Supernova Discovered Very Young

The Type~Ia supernova (SN~Ia) 2017cfd in IC~0511 (redshift z = 0.01209+- 0.00016$) was discovered by the Lick Observatory Supernova Search 1.6+-0.7 d after the fitted first-light time (FFLT; 15.2 d before B-band maximum brightness). Photometric and spectroscopic follow-up observations show that SN~2017cfd is a typical, normal SN~Ia with a peak luminosity MB ~ -19.2+-0.2 mag, Delta m15(B) = 1.16 mag, and reached a B-band maximum ~16.8 d after the FFLT. We estimate there to be moderately strong host-galaxy extinction (A_V = 0.39 +- 0.03 mag) based on MLCS2k2 fitting. The spectrum reveals a Si~II lambda 6355 velocity of ~11,200 kms at peak brightness. The analysis shows that SN~2017cfd is a very typical, normal SN Ia in nearly every aspect. SN~2017cfd was discovered very young, with multiband data taken starting 2 d after the FFLT, making it a valuable complement to the currently small sample (fewer than a dozen) of SNe~Ia with color data at such early times. We find that its intrinsic early-time (B - V)0 color evolution belongs to the "blue" population rather than to the distinct "red" population. Using the photometry, we constrain the companion star radius to be < 2.5 R_sun, thus ruling out a red-giant companion.

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The Young and Nearby Normal Type Ia Supernova 2018gv: UV-Optical Observations and the Earliest Spectropolarimetry

The non-detection of companion stars in Type Ia supernova (SN) progenitor systems lends support to the notion of double-degenerate (DD) systems and explosions triggered by the merging of two white dwarfs. This very asymmetric process should lead to a conspicuous polarimetric signature. By contrast, observations consistently find very low continuum polarization as the signatures from the explosion process largely dominate over the pre-explosion configuration within several days. Critical information about the interaction of the ejecta with a companion and any circumstellar matter is encoded in the early polarization spectra. In this study, we obtain spectropolarimetry of SN\,2018gv with the ESO Very Large Telescope at $-$13.6 days relative to the $B-$band maximum light, or $\sim$5 days after the estimated explosion --- the earliest spectropolarimetric observations to date of any Type Ia SN. These early observations still show a low continuum polarization ($\lesssim$0.2\%) and moderate line polarization (0.30$\pm$0.04\% for the prominent \ion{Si}{2} $λ$6355 feature and 0.85$\pm$0.04\% for the high-velocity Ca component). The high degree of spherical symmetry implied by the low line and continuum polarization at this early epoch is consistent with explosion models of delayed detonations and is inconsistent with the merger-induced explosion scenario. The dense UV and optical photometry and optical spectroscopy within the first $\sim$100 days after the maximum light indicate that SN\,2018gv is a normal Type Ia SN with similar spectrophotometric behavior to SN\,2011fe.

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The mass and density of the dwarf planet (225088) 2007 OR10

The satellite of (225088) 2007 OR10 was discovered on archival Hubble Space Telescope images and along with new observations with the WFC3 camera in late 2017 we have been able to determine the orbit. The orbit's notable eccentricity, e$\approx$0.3, may be a consequence of an intrinsically eccentric orbit and slow tidal evolution, but may also be caused by the Kozai mechanism. Dynamical considerations also suggest that the moon is small, D$_{eff}$ $<$ 100 km. Based on the newly determined system mass of 1.75x10$^{21}$ kg, 2007 OR10 is the fifth most massive dwarf planet after Eris, Pluto, Haumea and Makemake. The newly determined orbit has also been considered as an additional option in our radiometric analysis, provided that the moon orbits in the equatorial plane of the primary. Assuming a spherical shape for the primary this approach provides a size of 1230$\pm$50 km, with a slight dependence on the satellite orbit orientation and primary rotation rate chosen, and a bulk density of 1.75$\pm$0.07 g cm$^{-3}$ for the primary. A previous size estimate that assumed an equator-on configuration (1535$^{+75}_{-225}$ km) would provide a density of 0.92$^{+0.46}_{-0.14}$ g cm$^{-3}$, unexpectedly low for a 1000 km-sized dwarf planet.

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Detection and classification of supernovae beyond z~2 redshift with the James Webb Space Telescope

Future time-domain surveys for transient events in the near- and mid-infrared bands will significantly extend our understanding about the physics of the early Universe. In this paper we study the implications of a deep (~27 mag), long-term (~3 years), observationally inexpensive survey with the James Webb Space Telescope (JWST) within its Continuous Viewing Zone, aimed at discovering luminous supernovae beyond z~2 redshift. We explore the possibilities for detecting Superluminous Supernovae (SLSNe) as well as Type Ia supernovae at such high redshifts and estimate their expected numbers within a relatively small (~0.1 deg^2) survey area. It is found that we can expect ~10 new SLSNe and ~50 SNe Ia discovered in the 1 < z < 4 redshift range. We show that it is possible to get relatively accurate (sigma_z < 0.25) photometric redshifts for Type Ia SNe by fitting their Spectral Energy Distributions (SED), redshifted into the observed near-IR bands, with SN templates. We propose that Type Ia SNe occupy a relatively narrow range on the JWST F220W-F440W vs F150W-F356W color-color diagram between +/- 7 rest-frame days around maximum light, which could be a useful classification tool for such type of transients. We also study the possibility of extending the Hubble-diagram of Type Ia SNe beyond redshift 2 up to z~4. Such high-z SNe Ia may provide new observational constraints for their progenitor scenario.

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Observations of SN 2017ein Reveal Shock Breakout Emission and A Massive Progenitor Star for a Type Ic Supernova

We present optical and ultraviolet observations of nearby type Ic supernova SN 2017ein as well as detailed analysis of its progenitor properties from both the early-time observations and the prediscovery Hubble Space Telescope (HST) images. The optical light curves started from within one day to $\sim$275 days after explosion, and optical spectra range from $\sim$2 days to $\sim$90 days after explosion. Compared to other normal SNe Ic like SN 2007gr and SN 2013ge, \mbox{SN 2017ein} seems to have more prominent C{\footnotesize II} absorption and higher expansion velocities in early phases, suggestive of relatively lower ejecta mass. The earliest photometry obtained for \mbox{SN 2017ein} show indications of shock cooling. The best-fit obtained by including a shock cooling component gives an estimate of the envelope mass as $\sim$0.02 M$_{\odot}$ and stellar radius as 8$\pm$4 R$_{\odot}$. Examining the pre-explosion images taken with the HST WFPC2, we find that the SN position coincides with a luminous and blue point-like source, with an extinction-corrected absolute magnitude of M$_V$$\sim$$-$8.2 mag and M$_I$$\sim$$-$7.7 mag.Comparisons of the observations to the theoretical models indicate that the counterpart source was either a single WR star or a binary with whose members had high initial masses, or a young compact star cluster. To further distinguish between different scenarios requires revisiting the site of the progenitor with HST after the SN fades away.

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Circumstellar Interaction Models for the Bolometric Light Curve of SN 2017egm

We explore simple semi-analytic fits to the bolometric light curve of Gaia17biu/SN 2017egm, the most nearby hydrogen-deficient superluminous supernova (SLSN I) yet discovered. SN 2017egm has a quasi-bolometric light curve that is uncharacteristic of other SLSN I by having a nearly linear rise to maximum and decline from peak, with a very sharp transition. Magnetar models have difficulty explaining the sharp peak and may tend to be too bright 20 d after maximum. Light curves powered only by radioactive decay of nickel fail on similar grounds and because they demand greater nickel mass than ejecta mass. Simple models based on circumstellar interaction do have a sharp peak corresponding to the epoch when the forward shock breaks out of the optically-thick circumstellar medium or the reverse shock reaches the inside of the ejecta. We find that models based on circumstellar interaction with a constant-density shell provide an interesting fit to the bolometric light curve from 15 d before to 15 d after peak light of SN 2017egm and that both magnetar and radioactive decay models fail to fit the sharp peak. Future photometric observations should easily discriminate basic CSI models from basic magnetar models. The implications of a CSI model are briefly discussed.

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Abundance Tomography of Type Iax SN 2011ay with TARDIS

We present a detailed spectral analysis of Type Iax SN 2011ay. Our spectra cover epochs between -3 and +19 days with respect to the maximum light in B-band. This time range allows us to employ a so-called abundance tomography technique. The synthetic spectral fitting was made with the 1D Monte Carlo radiative transfer code TARDIS. In this paper, we describe our method to fit multiple epochs with a self-consistent, stratified atmospheric model. We compare our results to previously published SYN++ models and the predictions of different explosion scenarios. Using a fixed density profile (exponential fit of W7), we find that a uniform abundance model cannot reproduce the spectral features before maximum light because of the emergence of excessively strong Fe lines. In our best-fit TARDIS model, we find an abundance profile that separated into two different regimes: a well-mixed region under 10,000 km s$^{-1}$ and a stratified region with decreasing IGE abundances above 10,000 km s$^{-1}$. Based on a detailed comparative analysis, our conclusion is that the available pure deflagration models cannot fully explain either the observed properties of SN 2011ay or the results of our TARDIS modeling. Further examinations are necessary to find an adequate explanation for the origin of this object.

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After the Fall: Late-Time Spectroscopy of Type IIP Supernovae

Herein we analyse late-time (post-plateau; 103 < t < 1229 d) optical spectra of low-redshift (z < 0.016), hydrogen-rich Type IIP supernovae (SNe IIP). Our newly constructed sample contains 91 nebular spectra of 38 SNe IIP, which is the largest dataset of its kind ever analysed in one study, and many of the objects have complementary photometric data. We determined the peak and total luminosity, velocity of the peak, HWHM intensity, and profile shape for many emission lines. Temporal evolution of these values and various flux ratios are studied. We also investigate the correlations between these measurements and photometric observables, such as the peak and plateau absolute magnitudes and the late-time light curve decline rates in various optical bands. The strongest and most robust result we find is that the luminosities of all spectral features (except those of helium) tend to be higher in objects with steeper late-time V-band decline rates. A steep late-time V-band slope likely arises from less efficient trapping of gamma-rays and positrons, which could be caused by multidimensional effects such as clumping of the ejecta or asphericity of the explosion itself. Furthermore, if gamma-rays and positrons can escape more easily, then so can photons via the observed emission lines, leading to more luminous spectral features. It is also shown that SNe IIP with larger progenitor stars have ejecta with a more physically extended oxygen layer that is well-mixed with the hydrogen layer. In addition, we find a subset of objects with evidence for asymmetric Ni-56 ejection, likely bipolar in shape. We also compare our observations to theoretical late-time spectral models of SNe IIP from two separate groups and find moderate-to-good agreement with both sets of models. Our SNe IIP spectra are consistent with models of 12-15 M_Sun progenitor stars having relatively low metallicity (Z $\le$ 0.01).

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Possible detection of singly-ionized oxygen in the Type Ia SN 2010kg

We present direct spectroscopic modeling of 11 high-S/N observed spectra of the Type Ia SN 2010kg, taken between -10 and +5 days with respect to B-maximum. The synthetic spectra, calculated with the SYN++ code, span the range between 4100 and 8500 Å. Our results are in good agreement with previous findings for other Type Ia SNe. Most of the spectral features are formed at or close to the photosphere, but some ions, like Fe II and Mg II, also form features at ~2000 - 5000 km s$^{-1}$ above the photosphere. The well-known high-velocity features of the Ca II IR-triplet as well as Si II $λ$6355 are also detected. The single absorption feature at ~4400 Å, which usually has been identified as due to Si III, is poorly fit with Si III in SN 2010kg. We find that the fit can be improved by assuming that this feature is due to either C III or O II, located in the outermost part of the ejecta, ~4000 - 5000 km s$^{-1}$ above the photosphere. Since the presence of C III is unlikely, because of the lack of the necessary excitation/ionization conditions in the outer ejecta, we identify this feature as due to O II. The simultaneous presence of O I and O II is in good agreement with the optical depth calculations and the temperature distribution in the ejecta of SN 2010kg. This could be the first identification of singly ionized oxygen in a Type Ia SN atmosphere.

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High-Velocity Features of Calcium and Silicon in the Spectra of Type Ia Supernovae

"High-velocity features" (HVFs) are spectral features in Type Ia supernovae (SNe Ia) that have minima indicating significantly higher (by greater than about 6000 km/s) velocities than typical "photospheric-velocity features" (PVFs). The PVFs are absorption features with minima indicating typical photospheric (i.e., bulk ejecta) velocities (usually ~9000-15,000 km/s near B-band maximum brightness). In this work we undertake the most in-depth study of HVFs ever performed. The dataset used herein consists of 445 low-resolution optical and near-infrared (NIR) spectra (at epochs up to 5 d past maximum brightness) of 210 low-redshift SNe Ia that follow the "Phillips relation." A series of Gaussian functions is fit to the data in order to characterise possible HVFs of Ca II H&K, Si II λ6355, and the Ca II NIR triplet. The temporal evolution of the velocities and strengths of the PVFs and HVFs of these three spectral features is investigated, as are possible correlations with other SN Ia observables. We find that while HVFs of Ca II are regularly observed (except in underluminous SNe Ia, where they are never found), HVFs of Si II λ6355 are significantly rarer, and they tend to exist at the earliest epochs and mostly in objects with large photospheric velocities. It is also shown that stronger HVFs of Si II λ6355 are found in objects that lack C II absorption at early times and that have red ultraviolet/optical colours near maximum brightness. These results lead to a self-consistent connection between the presence and strength of HVFs of Si II λ6355 and many other mutually correlated SN~Ia observables, including photospheric velocity.

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A semi-analytical light curve model and its application to type IIP supernovae

The aim of this work is to present a semi-analytical light curve modeling code which can be used for estimating physical properties of core collapse supernovae (SNe) in a quick and efficient way. To verify our code we fit light curves of Type II SNe and compare our best parameter estimates to those from hydrodynamical calculations. For this analysis we use the quasi-bolometric light curves of five different Type IIP supernovae. In each case we get appropriate results for the initial pre-supernova parameters. We conclude that this semi-analytical light curve model is useful to get approximate physical properties of Type II SNe without using time-consuming numerical hydrodynamic simulations.

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