Type Ib Supernova 2008D associated with the Luminous X-ray Transient 080109: An Energetic Explosion of a Massive Helium Star
Masaomi Tanaka, Nozomu Tominaga, Ken'ichi Nomoto, S. Valenti, D. K. Sahu, T. Minezaki, Y. Yoshii, M. Yoshida, G. C. Anupama, S. Benetti, G. Chincarini, M. Della… 展开作者
Masaomi Tanaka, Nozomu Tominaga, Ken'ichi Nomoto, S. Valenti, D. K. Sahu, T. Minezaki, Y. Yoshii, M. Yoshida, G. C. Anupama, S. Benetti, G. Chincarini, M. Della Valle, P. A. Mazzali, E. Pian
备注：
13 pages, 10 figures, Accepted for publication in ApJ, typos corrected
We present a theoretical model for supernova (SN) 2008D associated with the luminous X-ray transient 080109. The bolometric light curve and optical spectra of the SN are modelled based on the progenitor models and the explosion models obtained from hydrodynamic/nucleosynthetic calculations. We find that SN 2008D is a more energetic explosion than normal core-collapse supernovae, with an ejecta mass of Mej = 5.3 +- 1.0 Msun and a kinetic energy of E = 6.0 +- 2.5 x 10^{51} erg. The progenitor star of the SN has a 6-8 Msun He core with essentially no H envelope (< 5 x 10^{-4} Msun) prior to the explosion. The main-sequence mass of the progenitor is estimated to be Mms =20-25 Msun, with additional systematic uncertainties due to convection, mass loss, rotation, and binary effects. These properties are intermediate between those of normal SNe and hypernovae associated with gamma-ray bursts. The mass of the central remnant is estimated as 1.6 - 1.8 Msun, which is near the boundary between neutron star and black hole formation.
The extremely luminous supernova SN2006gy is explained in the same way as other SNIIn events: light is produced by a radiative shock propagating in a dense circumstellar envelope formed by a previous weak explosion. The problems in the theory and observations of multiple-explosion SNe IIn are briefly reviewed.
There is growing observational evidence that gamma-ray bursts (GRBs) are powered by black holes accreting rapidly through a disk. The supernova-like outburst that accompanies some gamma-ray bursts suggest that some long-duration GRBs may be driven by the accretion of a rotating stellar core onto a central black hole. Such a system can be produced when a compact remnant spirals into the helium core of its binary companion. During the inspiral, orbital angular momentum is injected into the core. By the time the compact remnant reaches the center of the helium core, it too has gained angular mome…
We explore the hypothesis, that helium stars in a certain mass range can evolve to a carbon core explosion similar to what is widely accepted as an explanation for the SN I phenomenon. This should happen when their carbon-oxygen core grows thanks to the helium shell burning above the core. We found that in the mass range of about 1.7-2.2 Msun, indeed this can happen. The main new insight we believe we gained is the crucial importance of an "early" off-center ignition of carbon, which at a later stage prevents the carbon which forms below the helium burning shell and ignites, from burning the c…
We have calculated the mass accumulation efficiency during helium shell flashes to examine whether or not a carbon-oxygen white dwarf (C+O WD) grows up to the Chandrasekhar mass limit to ignite a Type Ia supernova explosion. It has been frequently argued that luminous super-soft X-ray sources and symbiotic stars are progenitors of SNe Ia. In such systems, a C+O WD accretes hydrogen-rich matter from a companion and burns hydrogen steadily on its surface. The WD develops a helium layer underneath the hydrogen-rich envelope and undergoes periodic helium shell flashes. Using OPAL opacity, we have …
A few Type Ia supernovae (SNe Ia) have been suggested to be an explosion of a super-Chandrasekhar-mass white dwarf (WD) to account for their large luminosities, requiring a large amount of 56Ni. However, the candidate over-luminous SNe Ia 2003fg, 2006gz, and (moderately over-luminous) SN 1991T, have very different observational features: the characteristic time-scale and velocity are very different. We examine if and how the diversity can be explained, by 1D spherical radiation transport calculations covering a wide range of model parameters (e.g., WD mass). The observations of SN 2006gz are n…
Massive stars end their short lives in spectacular explosions, supernovae, that synthesize new elements and drive galaxy evolution. Throughout history supernovae were discovered chiefly through their delayed optical light, preventing observations in the first moments (hours to days) following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the br…
The extremely luminous supernova SN 2006gy challenges the traditional view that the collapse of a stellar core is the only mechanism by which a massive star makes a supernova, because it seems too luminous by more than a factor of ten. Here we report that the brightest supernovae in the modern Universe arise from collisions between shells of matter ejected by massive stars that undergo an interior instability arising from the production of electron-positron pairs. This "pair instability" leads to explosive burning that is insufficient to unbind the star, but ejects many solar masses of the env…
CCD UBVRI photometry is presented for type IIn SN 2005kd. The maximum luminosity exceeded Mv=-19.8, and SN remained brighter than -18 mag for about 400 days. While overall photometric evolution is quite similar to SN 1997cy, SN 2005kd shows a plateau at phases between 119 and 311 days past explosion, which is a unique feature for SN IIn.
Knowing the Kerr parameters we can make quantitative calculations of the rotational energy of black holes. We show that Nova Sco (GRO J1655 - 40), Il Lupi (4U 1543 - 47), XTE J1550 - 564 and GS 2023 + 338 are relics of gamma-ray burst (GRB) and Hypernova explosions. They had more than enough rotational energy to power themselves. In fact, they had so much energy that they would have disrupted the accretion disk of the black hole that powered them by the communicated rotational energy, so that the energy delivery was self limiting. The most important feature in producing high rotational energy …
We report a radio detection of supernova SN 2004ip in the circumnuclear region of the luminous infrared galaxy IRAS 18293-3413, using Very Large Array (VLA) observations at 8.4 GHz on 11 June 2007. SN 2004ip had been previously discovered at near-infrared wavelengths using adaptive optics observations, but its nature (core-collapse or thermonuclear) could not be definitely established. Our radio detection, about three years after the explosion of the supernova, indicates a prominent interaction of the ejecta of SN 2004ip with the circumstellar medium, confirming that the supernova was a core-c…
We present optical spectra of the Type Ic supernova 1994I in M51 and preliminary non-LTE analysis of the spectra. Our models are not inconsistent with the explosions of C+O cores of massive stars. While we find no direct evidence for helium in the optical spectra, our models cannot rule out small amounts of helium. More than 0.1~\msol\ of helium seems unlikely.
With a view to understanding the formation of double neutron-stars (DNS), we investigate the late stages of evolution of helium stars with masses of 2.8 - 6.4 Msun in binary systems with a 1.4 Msun neutron-star companion. We found that mass transfer from 2.8 - 3.3 Msun helium stars and from 3.3 - 3.8 Msun in very close orbits (P_orb > 0.25d) will end up in a common-envelope (CE) and spiral-in phase due to the development of a convective helium envelope. If the neutron star has sufficient time to complete the spiraling-in process before the core collapses, the system will produce very tight DNS…
We present new observational results obtained for the Galactic non-thermal radio source G328.4+0.2 to determine both if this source is a pulsar wind nebula or supernova remnant, and in either case, the physical properties of this source. Using X-ray data obtained by XMM, we confirm that the X-ray emission from this source is heavily absorbed and has a spectrum best fit by a power law model of photon index=2 with no evidence for a thermal component, the X-ray emission from G328.4+0.2 comes from a region significantly smaller than the radio emission, and that the X-ray and radio emission are sig…
We present unfiltered photometric observations with ROTSE-III and optical spectroscopic follow-up with the HET and Keck of the most luminous supernova yet identified, SN 2005ap. The spectra taken about 3 days before and 6 days after maximum light show narrow emission lines (likely originating in the dwarf host) and absorption lines at a redshift of z=0.2832, which puts the peak unfiltered magnitude at -22.7 +/- 0.1 absolute. Broad P-Cygni features corresponding to H-alpha, CIII, NIII, and OIII, are further detected with a photospheric velocity of ~20,000 km/s. Unlike other highly luminous supe…
We revisit the formation of PSR J0737-3039, taking into account the most recent observational constraints. We show that the most likely kick velocity and progenitor parameters depend strongly on the consideration of the full five-dimensional PDF for the magnitude and direction of the kick velocity imparted to pulsar B at birth, the mass of pulsar B's pre-supernova helium star progenitor, and the pre-supernova orbital separation, and on the adopted prior assumptions. The priors consist of the transverse systemic velocity, the age of the system, and the treatment of the unknown radial velocity. …
From Hubble Space Telescope images with 0.05" resolution we identify four stars brighter than V=25 mag within 2.5" of SN 1993J in M81 which contaminated previous ground-based brightness estimates for the supernova progenitor. Correcting for the contamination, we find that the energy distribution of the progenitor is consistent with that of an early K-type supergiant star with M_V \~ -7.0 +/- 0.4 mag and an initial mass of 13--22 Msun. The brightnesses of the nearby stars are sufficient to account for the excess blue light seen from the ground in pre-explosion observations. Therefore, the SN 19…
Some extragalactic SNRs are more than two orders of magnitude more luminous than the young Galactic SNR Cas A. These SNRs are called super-luminous or ultra-luminous SNRs. Their high luminosities can be caused by chance superpositions of multiple objects, interactions with a very dense environment, or unusually powerful supernova explosions. Four super-luminous SNRs are known: one in NGC 4449, one in NGC 6946, and two in M101. The two remnants in M101, NGC 5471B and MF83, are recently suggested to be "hypernova remnants" possibly connected to the GRBs. We have obtained new or archival HST WFPC…
We systematically examine how the presence in a binary affects the final core structure of a massive star and its consequences for the subsequent supernova explosion. Interactions with a companion star may change the final rate of rotation, the size of the helium core, the strength of carbon burning and the final iron core mass. Stars with initial masses larger than \sim 11\Ms that experiece core collapse will generally have smaller iron cores at the time of the explosion if they lost their envelopes due to a previous binary interaction. Stars below \sim 11\Ms, on the other hand, can end up wi…
We present spectroscopic and photometric observations of the luminous narrow- line Type IIP (plateau) supernova 1994W. After the plateau phase (t >120 days), the light curve dropped by 3.5 mag in V in only 12 days. Between 125 and 197 days after explosion the supernova faded substantially faster than the decay rate of Co-56, and by day 197 it was 3.6 magnitudes less luminous in R compared to SN 1987A. The low R-luminosity could indicate less than 0.0026 {+0.0017}/ {-0.0011} Msun of Ni-56 ejected at the explosion, but the emission between 125 and 197 days must then have been dominated by an add…
The most massive Galactic globular cluster, Omega centauri, appears to have multiple populations. Its bluest main sequence and extended horizontal branch stars are suggested to have the common origin, that is, an extremely high helium abundance of Y ~ 0.4. The high helium abundance is most often attributed to asymptotic giant branch (AGB) stars. In this study we test the AGB hypothesis. We simulate the maximum-AGB models where the impact of AGB stars is maximised by assuming that supernova explosions do not affect the chemical evolution of the proto cloud. We compare the enrichment history of …
Recently the observationally derived stellar-wind mass-loss rates for Wolf-Rayet stars, or massive naked helium stars, have been revised downwards by a substantial amount. We present evolutionary calculations of helium stars incorporating such revised mass-loss rates, as well as mass transfer to a close compact binary companion. Our models reach final masses well in excess of 10 Msun, consistent with the observed masses of black holes in X-ray binaries. This resolves the discrepancy found with previously assumed high mass-loss rates between the final masses of stars which spend most of their h…
By means of population synthesis we model the Galactic ensemble of helium stars. It is assumed that all helium stars are formed in binaries. Under this assumption, single helium stars are produced by the mergers of helium remnants of components of close binaries (mainly, by merging helium white dwarfs) and by disruption of binaries with helium components in supernovae explosions. The estimate of the total birthrate of helium stars in the Galaxy is 0.043 yr$^{-1}$, their total number is estimated as $4 \times 10^6$. The rate of binarity in the total sample is 76%. We construct a subsample of lo…
We have recently measured the angle between the spin and orbital angular momenta of PSR B1534+12 to be either 25+/-4 deg or 155+/-4 deg. This misalignment was almost certainly caused by an asymmetry in the supernova explosion that formed its companion neutron star. Here we combine the misalignment measurement with measurements of the pulsar and companion masses, the orbital elements, proper motion, and interstellar scintillation. We show that the orbit of the binary in the Galaxy is inconsistent with a velocity kick large enough to produce a nearly antialigned spin axis, so the true misalignme…
