Abstract :

The planetary nebula (PN) NGC 3132 is a striking example of the dramatic but poorly understood mass-loss phenomena that (1-8) M _⊙ stars undergo during their death throes as they evolve into white dwarfs (WDs). From an analysis of JWST multiwavelength (0.9-18 μm) imaging of NGC 3132, we report the discovery of an extended dust cloud around the WD central star (CS) of NGC 3132, seen most prominently in the 18 μm image, with a surface-brightness-limited radial extent of ≳2″. We show that the A2V star located 1.″7 to CS's northeast (and 0.75 kpc from Earth) is gravitationally bound to the latter, as evidenced by the detection of relative orbital angular motion of 0.°24 ± 0.°045 between these stars over ~20 yr. Using aperture photometry of the CS extracted from the JWST images, together with published optical photometry and an archival UV spectrum, we have constructed the spectral energy distribution (SED) of the CS and its extended emission over the UV to mid-IR (0.091-18 μm) range. We find that fitting the SED of the CS and the radial intensity distributions at 7.7, 12.8, and 18 μm with thermal emission from dust requires a cloud that extends to a radius of ≳1785 au, with a dust mass of ~1.3 × 10^-2 M _⊕ and grains that are 70% silicate and 30% amorphous carbon. We propose plausible origins of the dust cloud and an evolutionary scenario in which a system of three stars-the CS, a close low-mass companion, and a more distant A2V star-forms a stable hierarchical triple system on the main sequence but becomes dynamically unstable later, resulting in the spectacular mass ejections that form the current, multipolar PN.

Publication : The Astrophysical Journal, Volume 943, Issue 2, id.110, 16 pp.
DOI : 10.3847/1538-4357/aca7ba
Bibcode : 2023ApJ...943..110S
Keywords : Circumstellar matter; Planetary nebulae nuclei; Stellar mass loss; White dwarf stars; Circumstellar dust; Planetary nebulae; James Webb Space Telescope; Hubble Space Telescope; Gaia; Ultraviolet spectroscopy; Close binary stars; Orbit determination; 241; 1250; 1613; 1799; 236; 1249; 2291; 761; 2360; 2284; 254; 1175; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Astrophysics of Galaxies