ﻻ يوجد ملخص باللغة العربية
We present the highest resolution single-dish submillimetre observations of the detached shell source U Antliae to date. The observations were obtained at $450~micron$ and $850~micron$ with SCUBA-2 instrument on the James Clerk Maxwell Telescope as part of the Nearby Evolved Stars Survey. The emission at $850~micron$ peaks at $40arcsec$ with hints of a second peak seen at $sim 20arcsec$. The emission can be traced out to a radius of $56arcsec$ at a $3sigma$ level. The outer peak observed at $850~micron$ aligns well with the peak observed at Herschel/PACS wavelengths. With the help of spectral energy distribution fitting and radiative transfer calculations of multiple-shell models for the circumstellar envelope, we explore the various shell structures and the variation of grain sizes along the in the circumstellar envelope. We determine a total shell dust mass of $(2.0 pm 0.3) times 10^{-5}$ M$_{odot}$ and established that the thermal pulse which gave rise to the detached shell occurred 3500 $pm$ 500 years ago.
Aims. Our goal is to characterize the intermediate age, detached shell carbon star U Antliae morphologically and physically in order to study the mass-loss evolution after a possible thermal pulse. Methods. High spatial resolution ALMA observations o
Most protostars have luminosities that are fainter than expected from steady accretion over the protostellar lifetime. The solution to this problem may lie in episodic mass accretion -- prolonged periods of very low accretion punctuated by short burs
During the protostellar phase of stellar evolution, accretion onto the star is expected to be variable, but this suspected variability has been difficult to detect because protostars are deeply embedded. In this paper, we describe a sub-mm luminosity
We present the JCMT Gould Belt Surveys first look results of the southern extent of the Orion A Molecular Cloud ($delta leq -5mathrm{:}31mathrm{:}27.5$). Employing a two-step structure identification process, we construct individual catalogues for la
Binary interactions dominate the evolution of massive stars, but their role is less clear for low- and intermediate-mass stars. The evolution of a spherical wind from an asymptotic giant branch (AGB) star into a nonspherical planetary nebula (PN) cou