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Register a new userATCA observations of the very young Planetary Nebula SAO 244567
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The radio emission from the youngest known Planetary nebula, SAO244567, has been mapped at 1384, 2368, 4800, 8640, 16832 and 18752 MHz by using the Australian Telescope Compact Array (ATCA). These observations constitute the first detailed radio study of this very interesting object, as they allow us to obtain the overall radio morphology of the source and to compute, for the first time, the radio spectrum up to millimetre range. Radio emission is consistent with free-free from a wind-like shell, which is also the region where most of the [OIII] comes from as revealed by HST images. Physical parameters of the radio nebula and of the central star were derived, all consistent with SAO 244567 being a very young Planetary Nebula still embedded in the dusty remnant of the AGB phase. The optically thin radio flux density appear to decrease when compared to data from the literature. Even very appealing, the variability of the radio emission, probably related to the evolution of the central object, needs further investigations.
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We have carried out a detailed analysis of the interesting and important very young planetary nebula (PN) Hen3-1357 (Stingray Nebula) based on a unique dataset of optical to far-IR spectra and photometric images. We calculated the abundances of nine elements using collisionally excited lines (CELs) and recombination lines (RLs). The RL C/O ratio indicates that this PN is O-rich, which is also supported by the detection of the broad 9/18 um bands from amorphous silicate grain. The observed elemental abundances can be explained by asymptotic giant branch (AGB) nucleosynthesis models for initially 1-1.5 Msun stars with Z = 0.008. The Ne overabundance might be due to the enhancement of 22Ne isotope in the He-rich intershell. By using the spectrum of the central star synthesized by Tlusty as the ionization/heating source of the PN, we constructed the self-consistent photoionization model with Cloudy to the observed quantities, and we derived the gas and dust masses, dust-to-gas mass ratio, and core-mass of the central star. About 80 % of the total dust mass is from warm-cold dust component beyond ionization front. Comparison with other Galactic PNe indicates that Hen3-1357 is an ordinary amorphous silicate rich and O-rich gas PN. Among other studied PNe, IC4846 shows many similarities in properties of the PN to Hen3-1357, although their post-AGB evolution is quite different from each other. Further monitoring observations and comparisons with other PNe such as IC4846 are necessary to understand the evolution of Hen3-1357.
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Radio observations of the region surrounding PSR J1301-6305 at 5.5 GHz and 7.5 GHz were conducted with ATCA on September 5th, 2013. They were dedicated to the search of the radio counterpart of the evolved pulsar wind nebula HESS J1303-631, detected in X-rays and GeV-TeV gamma-rays. The collected data do not reveal any significant extended emission associated with PSR J1301-6305. In addition, archival 1.384 GHz and 2.368 GHz data do not show any evidence for a radio counterpart of HESS J1303-631. Archival 1.384 GHz observations reveal a detection of an extended structure centred at an angular distance of 190 from the pulsar. This extended structure might be a Supernova remnant (SNR) and a potential birth place of PSR J1301-6305. The implications of the lack of radio counterpart of HESS J1303-631 on the understanding of the nature of the PWN are discussed.
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