11 research outputs found
Optical studies of the low velocity gradient type Ia supernovae 2009an and 2009ig
UBVRI photometry and medium resolution spectroscopy of two Type Ia supernovae, SN 2009an and SN 2009ig, are presented. Their Δm15(B) indicate these two SNe marginally deviate from “normal” Type Ia events. Spectroscopically, both SNe belong to the low velocity gradient group. The estimated mass of 56Ni ejected is almost a factor of two different for these two objects, with the estimates being ~0.4M☉ for SN 2009an and ~0.8 M☉ for SN 2009ig
The Peculiar Type Ib Supernova 2006jc: A WCO Wolf-Rayet Star Explosion
We present a theoretical model for Type Ib supernova (SN) 2006jc. We
calculate the evolution of the progenitor star, hydrodynamics and
nucleosynthesis of the SN explosion, and the SN bolometric light curve (LC).
The synthetic bolometric LC is compared with the observed bolometric LC
constructed by integrating the UV, optical, near-infrared (NIR), and
mid-infrared (MIR) fluxes. The progenitor is assumed to be as massive as
on the zero-age main-sequence. The star undergoes extensive mass
loss to reduce its mass down to as small as , thus becoming a WCO
Wolf-Rayet star. The WCO star model has a thick carbon-rich layer, in which
amorphous carbon grains can be formed. This could explain the NIR brightening
and the dust feature seen in the MIR spectrum. We suggest that the progenitor
of SN 2006jc is a WCO Wolf-Rayet star having undergone strong mass loss and
such massive stars are the important sites of dust formation. We derive the
parameters of the explosion model in order to reproduce the bolometric LC of SN
2006jc by the radioactive decays: the ejecta mass , hypernova-like
explosion energy ergs, and ejected Ni mass . We
also calculate the circumstellar interaction and find that a CSM with a flat
density structure is required to reproduce the X-ray LC of SN 2006jc. This
suggests a drastic change of the mass-loss rate and/or the wind velocity that
is consistent with the past luminous blue variable (LBV)-like event.Comment: 12 pages, 11 figures. Accepted for publication in the Astrophysical
Journa
Optical studies of SN 2009jf: A type Ib supernova with an extremely slow decline and aspherical signature
Optical photometry and medium resolution spectroscopy of the type Ib
supernova SN 2009jf, during the period to +250days with respect to
the maximum are reported. The light curves are broad, with an extremely
slow decline. The early post-maximum decline rate in the band is similar to
SN 2008D, however, the late phase decline rate is slower than other studied
type Ib supernovae. With an absolute magnitude of
magnitude at peak, SN 2009jf is a normally bright supernova. The peak
bolometric luminosity and the energy deposition rate via Ni
Co chain indicate that
M of Ni was ejected during the explosion. He\,I 5876 \AA\ line
is clearly identified in the first spectrum of day , at a velocity of
km sec. The [O\,I] 6300-6364 \AA\ line seen in the nebular
spectrum has a multi-peaked and asymmetric emission profile, with the blue peak
being stronger. The estimated flux in this line implies \ga 1.34 M
oxygen was ejected. The slow evolution of the light curves of SN 2009jf
indicates the presence of a massive ejecta. The high expansion velocity in the
early phase and broader emission lines during the nebular phase suggest it to
be an explosion with a large kinetic energy. A simple qualitative estimate
leads to the ejecta mass of M M, and kinetic energy
E erg. The ejected mass estimate is indicative
of an initial main-sequence mass of \ga 20- 25 M.Comment: 14 pages, 13 figures; accepted for publication in MNRA
Optical photometry and spectroscopy of the type Ibn supernova SN 2006jc until the onset of dust formation
We present optical UBVRI photometric and spectroscopic data of the type Ibn
supernova SN 2006jc, until the onset of the dust forming phase. The optical
spectrum shows a blue continuum and is dominated by the presence of moderately
narrow (velocity ~2500 km/s) He I emission lines superimposed over a relatively
weak supernova spectrum. The helium lines are produced in a pre-existing He
rich circumstellar shell. The observed helium line fluxes indicate the
circumstellar shell is dense, with a density of ~10^9 - 10^{10} cm^{-3}. The
helium mass in this shell is estimated to be <~0.07 Msun. The optical light
curves show a clear signature of dust formation, indicated by a sharp decrease
in the magnitudes around day 50, accompanied by a reddening of the colours. The
evolution of the optical light curves during the early phase and that of the
uvoir bolometric light curve at all phases is reasonably similar to normal Ib/c
supernovae.Comment: Accepted for publication in MNRA
Spectroscopic Monotoring of the Symbiotic Star BX Monocerotis
Low resolution optical spectra of the symbiotic star BX Monocerotis in the 3500-9000 Å range obtained during 1999–2010 are described. the spectrum of BX Mon at all phases is dominated by the cool component, with a red continuum and TiO absorption. Emission lines, predominantly due to HI, He I, He II, Fe II, Ca II and [O III] are seen superimposed on the spectrum of the M5III star, with variable intensities. the observed variations in the spectra seem to be correlated with the orbital phases
A tale of two GRB-SNe at a common redshift of z=0.54
none74We present ground-based and Hubble Space Telescope optical observations of the optical transients (OTs) of long-duration Gamma Ray Bursts (GRBs) 060729 and 090618, both at a redshift of z=0.54. For GRB 060729, bumps are seen in the optical light curves (LCs), and the late-time broad-band spectral energy distributions (SEDs) of the OT resemble those of local Type Ic supernovae (SNe). For GRB 090618, the dense sampling of our optical observations has allowed us to detect well-defined bumps in the optical LCs, as well as a change in colour, that are indicative of light coming from a core-collapse SN. The accompanying SNe for both events are individually compared with SN1998bw, a known GRB supernova, and SN1994I, a typical Type Ic supernova without a known GRB counterpart, and in both cases the brightness and temporal evolution more closely resemble SN1998bw. We also exploit our extensive optical and radio data for GRB 090618, as well as the publicly available Swift-XRT data, and discuss the properties of the afterglow at early times. In the context of a simple jet-like model, the afterglow of GRB 090618 is best explained by the presence of a jet-break at t − to > 0.5 d.
We then compare the rest-frame, peak V-band absolute magnitudes of all of the GRB and X-Ray Flash (XRF)-associated SNe with a large sample of local Type Ibc SNe, concluding that, when host extinction is considered, the peak magnitudes of the GRB/XRF-SNe cannot be distinguished from the peak magnitudes of non-GRB/XRF SNe.noneZ. Cano; D. Bersier; C. Guidorzi; R. Margutti; K.M Svensson; S. Kobayashi;
A. Melandri; K. Wiersema; A. Pozanenko; A.J. van der Horst; G. G. Pooley;
A. Fernandez-Soto; A.J. Castro-Tirado; A. de Ugarte Postigo; M. Im;
A.P. Kamble; D. Sahu; M. Alexander; Jorge Alonso-Lorite; G. Anupama;
J. L. Bibby; M. J. Burgdorf; N. Clay; P.A. Curran; T. A. Fatkhullin;
A. S. Fruchter; P. Garnavich; A. Gomboc; J. Gorosabel; J. F. Graham;
U. Gurugubelli; J. Haislip; K. Huang; A. Huxor; M. Ibrahimov; Y. Jeon;
Y-B. Jeon; K. Ivarsen; D. Kasen; E. Klunko; C. Kouveliotou; A. LaCluyze;
A. J. Levan; V. Loznikov; P.A. Mazzali; C. Mottram; C. G. Mundell;
P.E. Nugent; M. Nysewander; P. T. OBrien; W. -K. Park; V. Peris;
E. Pian; D. Reichart; J. E. Rhoads; E. Rol; V. Rumyantsev;
V. Scowcroft; D. Shakhovskoy; E. Small; R. J. Smith; V. V. Sokolov;
R.L.C. Starling; I. Steele; R. Strom; N. R. Tanvir; Y. Tsapras; Y. Urata;
O. Vaduvescu; A. Volnova; A. Volvach; R. A. M. J. Wijers; S. E. Woosley;
D. R. YoungZ., Cano; D., Bersier; Guidorzi, Cristiano; R., Margutti; K. M., Svensson; S., Kobayashi; A., Melandri; K., Wiersema; A., Pozanenko; A. J., van der Horst; G. G., Pooley; A., Fernandez Soto; A. J., Castro Tirado; A., de Ugarte Postigo; M., Im; A. P., Kamble; D., Sahu; M., Alexander; Jorge Alonso, Lorite; G., Anupama; J. L., Bibby; M. J., Burgdorf; N., Clay; P. A., Curran; T. A., Fatkhullin; A. S., Fruchter; P., Garnavich; A., Gomboc; J., Gorosabel; J. F., Graham; U., Gurugubelli; J., Haislip; K., Huang; A., Huxor; M., Ibrahimov; Y., Jeon; Y. B., Jeon; K., Ivarsen; D., Kasen; E., Klunko; C., Kouveliotou; A., Lacluyze; A. J., Levan; V., Loznikov; P. A., Mazzali; C., Mottram; C. G., Mundell; P. E., Nugent; M., Nysewander; P. T., Obrien; W. K., Park; V., Peris; E., Pian; D., Reichart; J. E., Rhoads; E., Rol; V., Rumyantsev; V., Scowcroft; D., Shakhovskoy; E., Small; R. J., Smith; V. V., Sokolov; R. L. C., Starling; I., Steele; R., Strom; N. R., Tanvir; Y., Tsapras; Y., Urata; O., Vaduvescu; A., Volnova; A., Volvach; R. A. M. J., Wijers; S. E., Woosley; D. R., Youn