Observation of Magnetized Soliton Remnants in the Wake of Intense Laser Pulse Propagation through Plasmas

Slowly evolving, regularly spaced patterns have been observed in proton projection images of plasma channels drilled by intense (greater than or similar to 10(19) W cm(-2)) short (similar to 1 ps) laser pulses propagating in an ionized gas jet. The nature and geometry of the electromagnetic fields generating such patterns have been inferred by simulating the laser-plasma interaction and the following plasma evolution with a two-dimensional particle-in-cell code and the probe proton deflections by particle tracing. The analysis suggests the formation of rows of magnetized soliton remnants, with a quasistatic magnetic field associated with vortexlike electron currents resembling those of magnetic vortices.

Dust and the type II-Plateau supernova 2004dj

We present mid-infrared (MIR) spectroscopy of a Type II-plateau supernova, SN 2004dj, obtained with the Spitzer Space Telescope, spanning 106--1393d after explosion. MIR photometry plus optical/near-IR observations are also reported. An early-time MIR excess is attributed to emission from non-silicate dust formed within a cool dense shell (CDS). Most of the CDS dust condensed between 50d and 165d, reaching a mass of $0.3x^(-5)Msun. Throughout the observations much of the longer wavelength (>10microns) part of the continuum is explained as an IR echo from interstellar dust. The MIR excess strengthened at later times. We show that this was due to thermal emission from warm, non-silicate dust formed in the ejecta. Using optical/near-IR line-profiles and the MIR continua, we show that the dust was distributed as a disk whose radius appeared to be slowly shrinking. The disk radius may correspond to a grain destruction zone caused by a reverse shock which also heated the dust. The dust-disk lay nearly face-on, had high opacities in the optical/near-IR regions, but remained optically thin in the MIR over much of the period studied. Assuming a uniform dust density, the ejecta dust mass by 996d was 0.5+/-0.1 x 10^(-4)Msun, and exceeded 10^(-4)Msun by 1393d. For a dust density rising toward the center the limit is higher. Nevertheless, this study suggests that the amount of freshly-synthesized dust in the SN 2004dj ejecta is consistent with that found from previous studies, and adds further weight to the claim that such events could not have been major contributors to the cosmic dust budget.

SUPERNOVA 2009kf: AN ULTRAVIOLET BRIGHT TYPE IIP SUPERNOVA DISCOVERED WITH PAN-STARRS 1 AND GALEX

We present photometric and spectroscopic observations of a luminous Type IIP Supernova (SN) 2009kf discovered by the Pan-STARRS 1 (PS1) survey and also detected by the Galaxy Evolution Explorer. The SN shows a plateau in its optical and bolometric light curves, lasting approximately 70 days in the rest frame, with an absolute magnitude of M-V = - 18.4 mag. The P-Cygni profiles of hydrogen indicate expansion velocities of 9000 km s(-1) at 61 days after discovery which is extremely high for a Type IIP SN. SN 2009kf is also remarkably bright in the near-ultraviolet (NUV) and shows a slow evolution 10-20 days after optical discovery. The NUV and optical luminosity at these epochs can be modeled with a blackbody with a hot effective temperature (T similar to 16,000 K) and a large radius (R similar to 1 x 10(15) cm). The bright bolometric and NUV luminosity, the light curve peak and plateau duration, the high velocities, and temperatures suggest that 2009kf is a Type IIP SN powered by a larger than normal explosion energy. Recently discovered high-z SNe (0.7

ESC observations of SN 2005cf - I. Photometric evolution of a normal Type Ia supernova

We present early-time optical and near-infrared photometry of supernova (SN) 2005cf. The observations, spanning a period from about 12 d before to 3 months after maximum, have been obtained through the coordination of observational efforts of various nodes of the European Supernova Collaboration and including data obtained at the 2-m Himalayan Chandra Telescope. From the observed light curve we deduce that SN 2005cf is a fairly typical SN Ia with a post-maximum decline [Delta m(15)(B)(true) = 1.12] close to the average value and a normal luminosity of M-B,M-max = -19.39 +/- 0.33. Models of the bolometric light curve suggest a synthesized Ni-56 mass of about 0.7 M-circle dot. The negligible host galaxy interstellar extinction and its proximity make SN 2005cf a good Type Ia SN template.

SN2003du: 480 days in the life of a normal type Ia supernova

Aims. We present a study of the optical and near-infrared (NIR) properties of the Type Ia Supernova (SNIa) 2003du.

A Spitzer space telescope study of Sn 2002hh: An infrared echo from a Type IIP supernova

We present late-time ( 590 - 994 days) mid-IR photometry of the normal but highly reddened Type IIP supernova SN 2002hh. Bright, cool, slowly fading emission is detected from the direction of the supernova. Most of this flux appears not to be driven by the supernova event but instead probably originates in a cool, obscured star formation region or molecular cloud along the line of sight. We also show, however, that the declining component of the flux is consistent with an SN-powered IR echo from a dusty progenitor CSM. Mid-IR emission could also be coming from newly condensed dust and/or an ejecta/CSM impact, but their contributions are likely to be small. For the case of a CSM-IR echo, we infer a dust mass of as little as 0.036 M-. with a corresponding CSM mass of 3.6(0.01/ r(dg)) M-., where rdg is the dust-to-gas mass ratio. Such a CSM would have resulted from episodic mass loss whose rate declined significantly about 28,000 years ago. Alternatively, an IR echo from a surrounding, dense, dusty molecular cloud might also have been responsible for the fading component. Either way, this is the first time that an IR echo has been clearly identified in a Type IIP supernova. We find no evidence for or against the proposal that Type IIP supernovae produce large amounts of dust via grain condensation in the ejecta. However, within the CSM-IR echo scenario, the mass of dust derived implies that the progenitors of the most common of core-collapse supernovae may make an important contribution to the universal dust content.

Early-time Spitzer observations of the type II plateau supernova SN 2004dj

We present mid-infrared observations with the Spitzer Space Telescope of the nearby Type II-P supernova SN 2004dj at epochs of 89 - 129 days. We have obtained the first mid-IR spectra of any supernova apart from SN 1987A. A prominent [Ni II] 6.64 mu m line is observed, from which we deduce that the mass of stable nickel must be at least 2.2 x 10(-4) M-.. We also observe the red wing of the CO fundamental band. We relate our findings to possible progenitors and favor an evolved star, most likely a red supergiant, with a probable initial mass between similar to 10 and 15 M-..

SN 2009jf: a slow-evolving stripped-envelope core-collapse supernova

We present an extensive set of photometric and spectroscopic data for SN 2009jf, a nearby Type Ib supernova (SN), spanning from ˜20 d before B-band maximum to 1 yr after maximum. We show that SN 2009jf is a slowly evolving and energetic stripped-envelope SN and is likely from a massive progenitor (25-30 Msun). The large progenitor's mass allows us to explain the complete hydrogen plus helium stripping without invoking the presence of a binary companion. The SN occurred close to a young cluster, in a crowded environment with ongoing star formation. The spectroscopic similarity with the He-poor Type Ic SN 2007gr suggests a common progenitor for some SNe Ib and Ic. The nebular spectra of SN 2009jf are consistent with an asymmetric explosion, with an off-centre dense core. We also find evidence that He-rich Ib SNe have a rise time longer than other stripped-envelope SNe, however confirmation of this result and further observations are needed. This paper is based on observations with several telescopes, including NTT(184.D-1151), VLT-UT1(085.D-0750,386.D-0126), NOT, WHT, TNG, PROMPT, Ekar, Calar Alto and Liverpool Telescope.

The Yellow Supergiant Progenitor of the Type II Supernova 2011dh in M51

We present the detection of the putative progenitor of the Type IIb SN 2011dh in archival pre-explosion Hubble Space Telescope images. Using post-explosion Adaptive Optics imaging with Gemini NIRI+ALTAIR, the position of the supernova (SN) in the pre-explosion images was determined to within 23 mas. The progenitor candidate is consistent with an F8 supergiant star (logL/L sun = 4.92 ± 0.20 and T eff = 6000 ± 280 K). Through comparison with stellar evolution tracks, this corresponds to a single star at the end of core C-burning with an initial mass of M ZAMS = 13 ± 3 M sun. The possibility of the progenitor source being a cluster is rejected, on the basis of: (1) the source not being spatially extended, (2) the absence of excess Ha emission, and (3) the poor fit to synthetic cluster spectral energy distributions (SEDs). It is unclear if a binary companion is contributing to the observed SED, although given the excellent correspondence of the observed photometry to a single star SED we suggest that the companion does not contribute significantly. Early photometric and spectroscopic observations show fast evolution similar to the transitional Type IIb SN 2008ax and suggest that a large amount of the progenitor's hydrogen envelope was removed before explosion. Late-time observations will reveal if the yellow supergiant or the putative companion star were responsible for this SN explosion.

Possible evidence of asymmetry in SN 2007rt, a type IIn supernova

An optical photometric and spectroscopic analysis of the slowly-evolving type IIn SN 2007rt is presented, covering a duration of 481 days after discovery. Its earliest spectrum, taken approximately 100 days after the explosion epoch, indicates the presence of a dense circumstellar medium, with which the supernova ejecta is interacting. This is supported by the slowly-evolving light curve. A notable feature in the spectrum of SN 2007rt is the presence of a broad He i 5875 line, not usually detected in type IIn supernovae. This may imply that the progenitor star has a high He/H ratio, having shed a significant portion of its hydrogen shell via mass-loss. An intermediate resolution spectrum reveals a narrow Ha P-Cygni profile, the absorption component of which has a width of 128 km s-1. This slow velocity suggests that the progenitor of SN 2007rt recently underwent mass-loss with wind speeds comparable to the lower limits of those detected in luminous blue variables. Asymmetries in the line profiles of H and He at early phases bears some resemblance to double-peaked features observed in a number of Ib/c spectra. These asymmetries may be indicative of an asymmetric or bipolar outflow or alternatively dust formation in the fast expanding ejecta. In addition, the late time spectrum, at over 240 days post-explosion, shows clear evidence for the presence of newly formed dust.

SN 2009md: another faint supernova from a low-mass progenitor

We present adaptive optics imaging of the core-collapse supernova (SN) 2009md, which we use together with archival Hubble Space Telescope data to identify a coincident progenitor candidate. We find the progenitor to have an absolute magnitude of V=-4.63+0.3-0.4 mag and a colour of V-I= 2.29+0.25-0.39 mag, corresponding to a progenitor luminosity of log L/L?similar to 4.54 +/- 0.19 dex. Using the stellar evolution code STARS, we find this to be consistent with a red supergiant progenitor with M= 8.5+6.5-1.5 M?. The photometric and spectroscopic evolution of SN 2009md is similar to that of the class of sub-luminous Type IIP SNe; in this paper we compare the evolution of SN 2009md primarily to that of the sub-luminous SN 2005cs. We estimate the mass of 56Ni ejected in the explosion to be (5.4 +/- 1.3) x 10-3 M? from the luminosity on the radioactive tail, which is in agreement with the low 56Ni masses estimated for other sub-luminous Type IIP SNe. From the light curve and spectra, we show the SN explosion had a lower energy and ejecta mass than the normal Type IIP SN 1999em. We discuss problems with stellar evolutionary models, and the discrepancy between low observed progenitor luminosities (log L/L?similar to 4.35 dex) and model luminosities after the second dredge-up for stars in this mass range, and consider an enhanced carbon burning rate as a possible solution. In conclusion, SN 2009md is a faint SN arising from the collapse of a progenitor close to the lower mass limit for core collapse. This is now the third discovery of a low-mass progenitor star producing a low-energy explosion and low 56Ni ejected mass, which indicates that such events arise from the lowest end of the mass range that produces a core-collapse SN (78 M?).

ON THE PROGENITOR AND EARLY EVOLUTION OF THE TYPE II SUPERNOVA 2009kr

We identify a source coincident with SN 2009kr in Hubble Space Telescope pre-explosion images. The object appears to be a single point source with an intrinsic color V - I = 1.1 +/- 0.25 and M-V = -7.6 +/- 0.6. If this is a single star, it would be a yellow supergiant of log L/L-circle dot similar to 5.1 and a mass of 15(-4)(+5) M-circle dot. The spatial resolution does not allow us yet to definitively determine if the progenitor object is a single star, a binary system, or a compact cluster. We show that the early light curve is similar to a Type IIL SN, but the prominent H alpha P-Cygni profiles and the signature of the end of a recombination phase are reminiscent of a Type IIP. The evolution of the expanding ejecta will play an important role in understanding the progenitor object.

SN 1999ga: a low-luminosity linear type II supernova?

Context. Type II-linear supernovae are thought to arise from progenitors that have lost most of their H envelope by the time of the explosion, and they are poorly understood because they are only occasionally discovered. It is possible that they are intrinsically rare, but selection effects due to their rapid luminosity evolution may also play an important role in limiting the number of detections. In this context, the discovery of a subluminous type II-linear event is even more interesting.

VLT DETECTION OF A RED SUPERGIANT PROGENITOR OF THE TYPE II-P SUPERNOVA 2008bk

We report the identification of a source coincident with the position of the nearby Type II-P supernova (SN) 2008bk in high-quality optical and near-infrared preexplosion images from the ESO Very Large Telescope (VLT). The SN position in the optical and near-infrared preexplosion images is identified to within about +/- 70 and +/- 40 mas, respectively, using postexplosion-band images obtained with the NAOS CONICA adaptive optics system K-s on the VLT. The preexplosion source detected in four different bands is precisely coincident with SN 2008bk and is consistent with being dominated by a single point source. We determine the nature of the point source using the STARS stellar evolutionary models and find that its colors and luminosity are consistent with the source being a red supergiant progenitor of SN 2008bk with an initial mass of 8.5 +/- 1.0 M-circle dot.

SUPERNOVA 1996cr: SN 1987A's WILD COUSIN?

We report on new VLT optical spectroscopic and multiwavelength archival observations of SN 1996cr, a previously identified ultraluminous X-ray source known as Circinus galaxy X-2. Our optical spectrum confirms SN 1996cr as a bona fide Type IIn supernova, while archival imaging from the Anglo-Australian Telescope archive isolates the explosion date to between 1995 February 28 and 1996 March 16. SN 1996cr is one of the closest SNe (approximate to 3.8 Mpc) in the last several decades, and in terms of flux ranks among the brightest radio and X-ray SNe ever detected. The wealth of optical, X-ray, and radio observations that exist for this source provide relatively detailed constraints on its postexplosion expansion and progenitor history, including a preliminary angular size constraint from VLBI. Archival X-ray and radio data imply that the progenitor of SN 1996cr evacuated a large cavity just prior to exploding: the blast wave likely spent similar to 1-2 yr in relatively uninhibited expansion before eventually striking the dense circumstellar material which surrounds SN 1996cr. The X-ray and radio emission, which trace the progenitor mass-loss rate, have respectively risen by a factor of greater than or similar to 2 and remained roughly constant over the past 7 years. This behavior is reminiscent of the late rise of SN 1987A, but 1000 times more luminous and much more rapid to onset. SN 1996cr may likewise provide us with a younger example of SN 1978K and SN 1979C, both of which exhibit flat X-ray evolution at late times. Complex oxygen line emission hints at a possible concentric shell or ringlike structure. The discovery of SN 1996cr suggests that a substantial fraction of the closest SNe observed in the last several decades have occurred in wind-blown bubbles, and argues for the phenomena being widespread.