Photometric and spectroscopic data of the energetic Type Ic supernova (SN) 2002ap are presented, and the properties of the SN are investigated through models of its spectral evolution and its light curve. The SN is spectroscopically similar to the "hypernova" SN 1997ef. However, its kinetic energy [∼ ergs] and 51 (4-10) # 10 the mass ejected (2.5-5) are smaller, resulting in a faster evolving light curve. The SN synthesized M , ∼0.07 of 56 Ni, and its peak luminosity was similar to that of normal SNe. Brightness alone should not be M , used to define a hypernova, whose defining character, namely very broad spectral features, is the result of high kinetic energy. The likely main-sequence mass of the progenitor star was [20][21][22][23][24][25] , which is also lower than M , that of both hypernovae SN 1997ef and SN 1998bw. SN 2002ap appears to lie at the low-energy and low-mass end of the hypernova sequence as it is known so far. Observations of the nebular spectrum, which is expected to dominate by the summer of 2002, are necessary to confirm these values.

No abstract

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.

The impact cratering process on a comet is controversial but holds the key for interpreting observations of the Deep Impact collision with comet 9P/Tempel 1. Mid-infrared data from the Cooled Mid-Infrared Camera and Spectrometer (COMICS) of the Subaru Telescope indicate that the large-scale dust plume ejected by the impact contained a large mass (approximately 10(6) kilograms) of dust and formed two wings approximately +/-45 degrees from the symmetric center, both consistent with gravity as the primary control on the impact and its immediate aftermath. The dust distribution in the inner part of the plume, however, is inconsistent with a pure gravity control and implies that evaporation and expansion of volatiles accelerated dust.

We quantified eight parent volatiles (H 2 O, C 2 H 6 , HCN, CO, CH 3 OH, H 2 CO, C 2 H 2 , and CH 4 ) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy in the wavelength range 2.8 to 5.0 micrometers. The abundance ratio for ethane was significantly higher after impact, whereas those for methanol and hydrogen cyanide were unchanged. The abundance ratios in the ejecta are similar to those for most Oort cloud comets, but methanol and acetylene are lower in Tempel 1 by a factor of about 2. These results suggest that the volatile ices in Tempel 1 and in most Oort cloud comets originated in a common region of the protoplanetary disk.

No abstract

We describe recent results on the CO/C0 2 /H 2 0 composition of comets and compare these with models of the protoplanetary disk. We argue that the cometary observations require reactions on grain surfaces to convert CO to CO 2 and also require formation between the CO and CO 2 snow lines. This then requires very early mixing of cometesimals in the protoplanetary disk analogous to the mixing described for the asteroid belt by Walsh and Morbidelli (2011). We suggest that most comels formed in the region of the giant planets. the traditional source of the Oort-cloud comets but not of the Jupiter-family comets.

Coronagraphic imaging for the Herbig Ae star, HD 142527, was performed using the Coronagraphic Imager with Adaptive Optics (CIAO) on the 8.2 m Subaru Telescope. The images were obtained in the H 2 O ice filter (λ = 3.08 μm) using adaptive optics (AO), and in the L band without AO. Combining these data with previous observational results in the H and K bands, we derived the spectra of the scattered light from the circumstellar disk around HD 142527 and detected an H 2 O ice absorption feature in the spectra. This result can be explained by the presence of silicate and H 2 O ice grains of ∼ 1 μm in size, according to the prediction model by Inoue et al. This grain size is consistent with previous observational study by Fukagawa et al. and Fujiwara et al. The present result demonstrates that high-resolution imaging of disk-scattered light in the ice band is useful for detecting H 2 O ice grain distributions in circumstellar disks.