- ID:
- ivo://CDS.VizieR/J/ApJ/774/75
- Title:
- Solar isotopic decomposition for nucleosynthesis
- Short Name:
- J/ApJ/774/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- All stellar evolution models for nucleosynthesis require an initial isotopic abundance set to use as a starting point. Generally, our knowledge of isotopic abundances of stars is fairly incomplete except for the Sun. We present a first model for a complete average isotopic decomposition as a function of metallicity. Our model is based on the underlying nuclear astrophysics processes, and is fitted to observational data, rather than traditional forward galactic chemical evolution modeling which integrates stellar yields beginning from big bang nucleosynthesis. We first decompose the isotopic solar abundance pattern into contributions from astrophysical sources. Each contribution is then assumed to scale as a function of metallicity. The resulting total isotopic abundances are summed into elemental abundances and fitted to available halo and disk stellar data to constrain the model's free parameter values. This procedure allows us to use available elemental observational data to reconstruct and constrain both the much needed complete isotopic evolution that is not accessible to current observations, and the underlying astrophysical processes. As an example, our model finds a best fit for Type Ia contributing =~0.7 to the solar Fe abundance, and Type Ia onset occurring at [Fe/H]=~-1.1, in agreement with typical values.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/500/L17
- Title:
- Spectral flux ratio of SN Ia
- Short Name:
- J/A+A/500/L17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new method to standardize Type Ia supernova (SN Ia) luminosities to ~<0.13mag using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotometry of 58 SNe Ia, we performed an unbiased search for flux ratios that correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R(642/443)=Flux(642nm)/Flux(443nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125+/-0.011mag, compared with 0.161+/-0.015mag when fit with the SALT2 light curve shape and color parameters x1 and c. The ratio R(642/443) is an effective correction factor for both extrinsic dust reddening and intrinsic variations such as those of SN 1991T-like and SN 1999aa-like SNe. When combined with broad-band color measurements, spectral flux ratios can standardize SN Ia magnitudes to ~0.12mag. These are the first spectral metrics that give robust improvements over the standard normalization methods based upon light curve shape and color, and they provide among the lowest scatter Hubble diagrams ever published.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A37
- Title:
- Spectral log of (i)PTF stripped-envelope SN
- Short Name:
- J/A+A/618/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of 507 spectra of 173 stripped-envelope (SE) supernovae (SNe) discovered by the untargeted Palomar Transient Factory (PTF) and intermediate PTF (iPTF) surveys. Our sample contains 55 TypeIIb SNe (SNeIIb), 45 TypeIb SNe (SNeIb), 56 TypeIc SNe (SNeIc), and 17 TypeIb/c SNe (SNeIb/c). We have compared the SE SN subtypes via measurements of the pseudo-equivalent widths (pEWs) and velocities of the HeI{lambda}{lambda}5876, 7065 and OI{lambda}7774 absorption lines. Consistent with previous work, we find that SNeIc show higher pEWs and velocities in OI{lambda}7774 compared to SNeIIb andIb. The pEWs of the HeI{lambda}{lambda}5876, 7065 lines are similar in SNeIb andIIb after maximum light. The HeI{lambda}{lambda}5876, 7065 velocities at maximum light are higher in SNeIb compared to SNeIIb. We identify an anticorrelation between the HeI{lambda}7065 pEW and OI{lambda}7774 velocity among SNeIIb andIb. This can be interpreted as a continuum in the amount of He present at the time of explosion.It has been suggested that SNeIb andIc have similar amounts of He, and that lower mixing could be responsible for hiding He in SNeIc. However, our data contradict this mixing hypothesis. The observed difference in the expansion rate of the ejecta around maximum light of SNeIc (V_m_=sqrt(2)E_k_/M_ej_~=15000km/s) and SNeIb (V_m_~=9000km/s) would imply an average He mass difference of ~1.4M_{sun}_, if the other explosion parameters are assumed to be unchanged between the SE SN subtypes. We conclude that SNeIc do not hide He but lose He due to envelope stripping.
- ID:
- ivo://CDS.VizieR/J/ApJ/699/L139
- Title:
- Spectral parameters of SNe Ia
- Short Name:
- J/ApJ/699/L139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the observables of 158 relatively normal Type Ia supernovae (SNe Ia) by dividing them into two groups in terms of the expansion velocity inferred from the absorption minimum of the SiII{lambda}6355 line in their spectra near B-band maximum brightness. One group ("Normal") consists of normal SNe Ia populating a narrow strip in the SiII velocity distribution, with an average expansion velocity <{nu}>=10600+/-400km/s near B maximum; the other group ("HV") consists of objects with higher velocities, {nu}>~11800km/s. Compared with the Normal group, the HV one shows a narrower distribution in both the peak luminosity and the luminosity decline rate {Delta}m_15_. In particular, their B-V colors at maximum brightness are found to be on average redder by ~0.1mag, suggesting that they either are associated with dusty environments or have intrinsically red B-V colors. The HV SNe Ia are also found to prefer a lower extinction ratio RV~1.6 (versus ~2.4 for the Normal ones). Applying such an absorption-correction dichotomy to SNe Ia of these two groups remarkably reduces the dispersion in their peak luminosity from 0.178mag to only 0.125mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/108
- Title:
- Spectral properties of Type Ic & Ic-bl SNe
- Short Name:
- J/ApJ/832/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first systematic investigation of spectral properties of 17 Type Ic Supernovae (SNe Ic), 10 broad-lined SNe Ic (SNe Ic-bl) without observed gamma-ray bursts (GRBs), and 11 SNe Ic-bl with GRBs (SN-GRBs) as a function of time in order to probe their explosion conditions and progenitors. Using a number of novel methods, we analyze a total of 407 spectra, which were drawn from published spectra of individual SNe as well as from the densely time-sampled spectra of Modjaz+ (2014, J/AJ/147/99). In order to quantify the diversity of the SN spectra as a function of SN subtype, we construct average spectra of SNe Ic, SNe Ic-bl without GRBs, and SNe Ic-bl with GRBs. We find that SN 1994I is not a typical SN Ic, contrasting the general view, while the spectra of SN 1998bw/GRB 980425 are representative of mean spectra of SNe Ic-bl. We measure the ejecta absorption and width velocities using a new method described here and find that SNe Ic-bl with GRBs, on average, have quantifiably higher absorption velocities, as well as broader line widths than SNe without observed GRBs. In addition, we search for correlations between SN-GRB spectral properties and the energies of their accompanying GRBs. Finally, we show that the absence of clear He lines in optical spectra of SNe Ic-bl, and in particular of SN-GRBs, is not due to them being too smeared-out due to the high velocities present in the ejecta. This implies that the progenitor stars of SN-GRBs are probably free of the He-layer, in addition to being H-free, which puts strong constraints on the stellar evolutionary paths needed to produce such SN-GRB progenitors at the observed low metallicities.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/11
- Title:
- Spectra of SN 2017eaw 545 & 900 days after explosion
- Short Name:
- J/ApJ/900/11
- Date:
- 14 Mar 2022 07:13:15
- Publisher:
- CDS
- Description:
- SN 2017eaw, the tenth supernova observed in NGC6946, was a normal Type II-P supernova with an estimated 11-13M{sun} red supergiant progenitor. Here we present nebular-phase spectra of SN 2017eaw at +545 and +900days post-max, extending approximately 50-400days past the epochs of previously published spectra. While the +545day spectrum is similar to spectra taken between days +400 and +493, the +900day spectrum shows dramatic changes both in spectral features and emission-line profiles. The H{alpha} emission is flat-topped and boxlike with sharp blue and red profile velocities of ~-8000 and +7500km/s. These late-time spectral changes indicate strong circumstellar interaction with a mass-loss shell, expelled ~1700yr before explosion. SN 2017eaw's +900day spectrum is similar to those seen for SN2004et and SN2013ej observed 2-3yr after explosion. We discuss the importance of late-time monitoring of bright SNeII-P and the nature of presupernova mass-loss events for SNII-P evolution.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A142
- Title:
- Spectra of 5 Type II supernovae
- Short Name:
- J/A+A/555/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Core-collapse Supernovae (CC-SNe) descend from progenitors more massive than about 8M_{sun}_. Because of the young age of the progenitors, the ejecta may eventually interact with the circumstellar medium (CSM) via highly energetic processes detectable in the radio, X-ray, ultraviolet (UV) and, sometimes, in the optical domains. In this paper we present ultraviolet, optical and near infrared observations of five type II SNe, namely SNe 2009dd, 2007pk, 2010aj, 1995ad, and 1996W. Together with few other SNe they form a group of moderately luminous type II events. We investigate the photometric similarities and differences among these bright objects. We also attempt to characterise them by analysing the spectral evolutions, in order to find some traces of CSM-ejecta interaction. We collected photometry and spectroscopy with several telescopes in order to construct well-sampled light curves and spectral evolutions from the photospheric to the nebular phases. Both photometry and spectroscopy indicate a degree of heterogeneity in this sample. Modelling the data of SNe 2009dd, 2010aj and 1995ad allows us to constrain the explosion parameters and the properties of the progenitor stars. The light curves have luminous peak magnitudes (-16.95<M_B}_-18.70). The ejected masses of ^56^Ni for three SNe span a wide range of values (2.8x10^-2^M_{sun}<M(^56^Ni)<1.4x10^-1^M_{sun}_), while for a fourth (SN2010aj) we could determine a stringent upper limit (7x10^-3^M_{sun}_). Clues of interaction, such as the presence of high velocity (HV) features of the Balmer lines, are visible in the photospheric spectra of SNe 2009dd and 1996W. For SN2007pk we observe a spectral transition from a type IIn to a standard type II SN. Modelling the observations of SNe 2009dd, 2010aj and 1995ad with radiation hydrodynamics codes, we infer kinetic plus thermal energies of about 0.2-0.5 foe, initial radii of 2-5x10^13^cm and ejected masses of ~5.0-9.5M_{sun}_. These values suggest moderate-mass, super-asymptotic giant branch (SAGB) or red super-giants (RSG) stars as SN precursors, in analogy with other luminous type IIP SNe 2007od and 2009bw.
- ID:
- ivo://CDS.VizieR/J/ApJ/690/1358
- Title:
- Spectra of unusual optical transient SCP 06F6
- Short Name:
- J/ApJ/690/1358
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of SCP 06F6, an unusual optical transient discovered during the Hubble Space Telescope Cluster Supernova Survey. The transient brightened over a period of ~100 days, reached a peak magnitude of ~21.0 in both i_775_ and z_850_, and then declined over a similar timescale. There is no host galaxy or progenitor star detected at the location of the transient to a 3{sigma} upper limit of i_775_>=26.4 and z_850_>=26.1, giving a corresponding lower limit on the flux increase of a factor of ~120. Multiple spectra show five broad absorption bands between 4100{AA} and 6500{AA}, and a mostly featureless continuum longward of 6500{AA}. The shape of the light curve is inconsistent with microlensing. The transient's spectrum, in addition to being inconsistent with all known supernova types, does not match any spectrum in the Sloan Digital Sky Survey database. We suggest that the transient may be one of a new class.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/58
- Title:
- Spectrophotometric time series obs. of twin SNIa
- Short Name:
- J/ApJ/815/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce a method for identifying "twin" Type Ia supernovae (SNeIa) and using them to improve distance measurements. This novel approach to SN Ia standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). We begin with a well-measured set of SNe, find pairs whose spectra match well across the entire optical window, and then test whether this leads to a smaller dispersion in their absolute brightnesses. This analysis is completed in a blinded fashion, ensuring that decisions made in implementing the method do not inadvertently bias the result. We find that pairs of SNe with more closely matched spectra indeed have reduced brightness dispersion. We are able to standardize this initial set of SNfactory SNe to 0.083+/-0.012mag, implying a dispersion of 0.072+/-0.010mag in the absence of peculiar velocities. We estimate that with larger numbers of comparison SNe, e.g., using the final SNfactory spectrophotometric data set as a reference, this method will be capable of standardizing high-redshift SNe to within 0.06-0.07mag. These results imply that at least 3/4 of the variance in Hubble residuals in current SN cosmology analyses is due to previously unaccounted-for astrophysical differences among the SNe.
- ID:
- ivo://CDS.VizieR/J/AJ/143/126
- Title:
- Spectroscopy of 462 nearby Type Ia supernovae
- Short Name:
- J/AJ/143/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. (2006PASP..118..560B) and Wang et al. (2009, Cat. J/ApJ/699/L139). The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic SiII{lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ~0 to ~400km/s/day considering the instantaneous velocity decline rate at maximum light.
