314 research outputs found
Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh
We investigate line formation processes in Type IIb supernovae (SNe) from 100
to 500 days post-explosion using spectral synthesis calculations. The modeling
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 modeling of the [O I] 6300, 6364
lines constrains the progenitors of these three SNe to the M_ZAMS=12-16 M_sun
range (ejected oxygen masses 0.3-0.9 M_sun), 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_sun progenitors give rise to brighter nebular phase
emission lines than observed. Nucleosynthesis analysis thus supports a scenario
of low/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 of 0.02-0.14 M_sun 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] 6548, 6583 emission lines that
dominate over H-alpha emission in our models. The hydrogen envelopes of Type
IIb SNe are too small and dilute to produce any noticeable H-alpha emission or
absorption after ~150 days, and nebular phase emission seen around 6550 A is in
many cases likely caused by [N II] 6548, 6583. Finally, the influence of
radiative transport on the emergent line profiles is investigated...(abridged)Comment: Published versio
Circumstellar interaction models for the early bolometric light curve of SN 2023ixf
SNe II show growing evidence of interaction with CSM surrounding their
progenitor stars as a consequence of enhanced mass loss during the last years
of the progenitor's life. We present an analysis of the progenitor mass-loss
history of SN2023ixf, a nearby SN II showing signs of interaction. We calculate
the early-time bolometric light curve (LC) for SN2023ixf based on the
integration of the observed flux covering UV, optical and NIR bands, and
black-body extrapolations for the unobserved flux. Our calculations spot the
sudden increase to maximum luminosity and temperature, in addition to the
subsequent fall, displaying an evident peak. This is the first time that this
phase can be precisely estimated for a SN II showing interesting
characteristics as: 1) slope changes during the rise to maximum luminosity; and
2) a very sharp peak with a maximum luminosity of 310erg
s. We use the bolometric LC of SN2023ixf to test the calibrations of
bolometric corrections against colours from the literature. In addition, we
include SN2023ixf into some of the available calibrations to extend their use
to earlier epochs. Comparison of the observed bolometric LC to SN II explosion
models with CSM interaction suggests a progenitor mass-loss rate of
310yr confined to 12000 and a wind
acceleration parameter of =5. This model reproduces the early bolometric
LC, expansion velocities, and the epoch of disappearance of interacting lines
in the spectra. This model indicates that the wind was launched 80yr
before the explosion. If the effect of the wind acceleration is not taken into
account, the enhanced wind must have developed over the final months to years
prior to the SN, which may not be consistent with the lack of outburst
detection in pre-explosion images over the last 20yr before explosion.Comment: Submitted to A&
Optical photometry and spectroscopy of the 1987A-like supernova 2009mw
We present optical photometric and spectroscopic observations of the
1987A-like supernova (SN) 2009mw. Our and photometry covers
167 days of evolution, including the rise to the light curve maximum, and ends
just after the beginning of the linear tail phase. We compare the observational
properties of SN 2009mw with those of other SNe belonging to the same subgroup,
and find that it shows similarities to several objects. The physical parameters
of the progenitor and the SN are estimated via hydrodynamical modelling,
yielding an explosion energy of foe, a pre-SN mass of , a progenitor radius as and a Ni mass
as . These values indicate that the progenitor of SN
2009mw was a blue supergiant star, similar to the progenitor of SN 1987A. We
examine the host environment of SN 2009mw and find that it emerged from a
population with slightly sub-solar metallicty.Comment: 11 pages, 12 figures, accepted for publication in MNRA
The Carnegie Supernova Project I: methods to estimate host-galaxy reddening of stripped-envelope supernovae
We aim to improve upon contemporary methods to estimate host-galaxy reddening
of stripped-envelope (SE) supernovae (SNe). To this end the Carnegie Supernova
Project (CSP-I) SE SNe photometry data release, consisting of nearly three
dozen objects, is used to identify a minimally reddened sub-sample for each
traditionally defined spectroscopic sub-types (i.e, SNe~IIb, SNe~Ib, SNe~Ic).
Inspection of the optical and near-infrared (NIR) colors and color evolution of
the minimally reddened sub-samples reveals a high degree of homogeneity,
particularly between 0d to +20d relative to B-band maximum. This motivated the
construction of intrinsic color-curve templates, which when compared to the
colors of reddened SE SNe, yields an entire suite of optical and NIR color
excess measurements. Comparison of optical/optical vs. optical/NIR color excess
measurements indicates the majority of the CSP-I SE SNe suffer relatively low
amounts of reddening and we find evidence for different R_(V)^(host) values
among different SE SN. Fitting the color excess measurements of the seven most
reddened objects with the Fitzpatrick (1999) reddening law model provides
robust estimates of the host visual-extinction A_(V)^(host) and R_(V)^(host).
In the case of the SE SNe with relatively low amounts of reddening, a preferred
value of R_(V)^(host) is adopted for each sub-type, resulting in estimates of
A_(V)^(host) through Fitzpatrick (1999) reddening law model fits to the
observed color excess measurements. Our analysis suggests SE SNe reside in
galaxies characterized by a range of dust properties. We also find evidence SNe
Ic are more likely to occur in regions characterized by larger R_(V)^(host)
values compared to SNe IIb/Ib and they also tend to suffer more extinction.
These findings are consistent with work in the literature suggesting SNe Ic
tend to occur in regions of on-going star formation.Comment: Abstract abridged to fit allowed limit. Resubmitted to A&A, 34 pages,
19 figures, 6 tables. Constructive comments welcome
Properties of Newly Formed Dust Grains in The Luminous Type IIn Supernova 2010jl
Supernovae (SNe) have been proposed to be the main production sites of dust
grains in the Universe. Our knowledge on their importance to dust production
is, however, limited by observationally poor constraints on the nature and
amount of dust particles produced by individual SNe. In this paper, we present
a spectrum covering optical through near-Infrared (NIR) light of the luminous
Type IIn supernova (SN IIn) 2010jl around one and half years after the
explosion. This unique data set reveals multiple signatures of newly formed
dust particles. The NIR portion of the spectrum provides a rare example where
thermal emission from newly formed hot dust grains is clearly detected. We
determine the main population of the dust species to be carbon grains at a
temperature of ~1,350 - 1,450K at this epoch. The mass of the dust grains is
derived to be ~(7.5 - 8.5) x 10^{-4} Msun. Hydrogen emission lines show
wavelength-dependent absorption, which provides a good estimate on the typical
size of the newly formed dust grains (~0.1 micron, and most likely <~0.01
micron). We attribute the dust grains to have been formed in a dense cooling
shell as a result of a strong SN-circumstellar media (CSM) interaction. The
dust grains occupy ~10% of the emitting volume, suggesting an inhomogeneous,
clumpy structure. The average CSM density is required to be >~3 x 10^{7}
cm^{-3}, corresponding to a mass loss rate of >~0.02 Msun yr^{-1} (for a mass
loss wind velocity of ~100 km s^{-1}). This strongly supports a scenario that
SN 2010jl and probably other luminous SNe IIn are powered by strong
interactions within very dense CSM, perhaps created by Luminous Blue Variable
(LBV)-like eruptions within the last century before the explosion.Comment: 18 pages, 11 figures. Accepted by ApJ on 30 July 2013. The accepted
version was submitted on 8 July 2013, and the original version was submitted
on 3 March 201
Optical and near-infrared observations of SN 2011dh - The first 100 days
We present optical and near-infrared (NIR) photometry and spectroscopy of the
Type IIb supernova (SN) 2011dh for the first 100 days. We complement our
extensive dataset with SWIFT ultra-violet (UV) and Spitzer mid-infrared (MIR)
data to build a UV to MIR bolometric lightcurve using both photometric and
spectroscopic data. Hydrodynamical modelling of the SN based on this bolometric
lightcurve have been presented in Bersten (2012). We find that the absorption
minimum for the hydrogen lines is never seen below ~11000 km/s but approaches
this value as the lines get weaker. This suggests that the interface between
the helium core and hydrogen rich envelope is located near this velocity in
agreement with the Bersten et al. (2012) He4R270 ejecta model. Spectral
modelling of the hydrogen lines using this ejecta model supports the conclusion
and we find a hydrogen mass of 0.01-0.04 solar masses to be consistent with the
observed spectral evolution. We estimate that the photosphere reaches the
helium core at 5-7 days whereas the helium lines appear between ~10 and ~15
days, close to the photosphere and then move outward in velocity until ~40
days. This suggests that increasing non-thermal excitation due to decreasing
optical depth for the gamma-rays is driving the early evolution of these lines.
We also provide and discuss pre- and post-explosion observations of the SN site
which shows a reduction by 75 percent in flux at the position of the yellow
supergiant coincident with SN 2011dh. The B, V and r band decline rates of
0.0073, 0.0090 and 0.0053 mag/day respectively are consistent with the
remaining flux being emitted by the SN. Hence we find that the star was indeed
the progenitor of SN 2011dh as previously suggested by Maund et al. (2011) and
which is also consistent with the results from the hydrodynamical modelling.Comment: 38 pages, 27 figures, 18 tables, accepted for publication by A&
Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh
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 MZAMS = 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 MZAMS ≳ 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 Ã… 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.Facultad de Ciencias Astronómicas y GeofÃsicasInstituto de AstrofÃsica de La Plat
Disappearance of the Progenitor of Supernova iPTF13bvn
Supernova (SN) iPTF13bvn in NGC 5806 was the first Type Ib SN to have been
tentatively associated with a progenitor candidate in pre-explosion images. We
performed deep ultraviolet (UV) and optical Hubble Space Telescope (HST)
observations of the SN site 740 days after explosion. We detect an object in
the optical bands that is fainter than the pre-explosion object. This dimming
is likely not produced by dust absorption in the ejecta; thus, our finding
confirms the connection of the progenitor candidate with the SN. The object in
our data is likely dominated by the fading SN, which implies that the pre-SN
flux is mostly due to the progenitor. We compare our revised pre-SN photometry
with previously proposed progenitor models. Although binary progenitors are
favored, models need to be refined. In particular, to comply with our deep UV
detection limit, any companion star must be less luminous than a late-O star or
substantially obscured by newly formed dust. A definitive progenitor
characterization will require further observations to disentangle the
contribution of a much fainter SN and its environment.Comment: 8 pages, 3 tables, 3 figures. Accepted for publication in ApJ
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