Accounting for planet-shaped planetary nebulae

Abstract

By following the evolution of several observed exoplanetary systems we show that by lowering the mass loss rate of single solar-like stars during their two giant branches, these stars will swallow their planets at the tip of their asymptotic giant branch (AGB) phase. This will most likely lead the stars to form elliptical planetary nebulae (PNe). Under the traditional mass loss rate these stars will hardly form observable PNe. Stars with a lower mass loss rate as we propose, about 15 per cent of the traditional mass loss rate of single stars, leave the AGB with much higher luminosities than what traditional evolution produces. Hence, the assumed lower mass loss rate might also account for the presence of bright PNe in old stellar populations. We present the evolution of four exoplanetary systems that represent stellar masses in the range of 0.9 − 1.3M . The justification for this low mass loss rate is our assumption that the stellar samples that were used to derive the traditional average single-star mass loss rate were contaminated by stars that suffer binary interaction.

The two promising scenarios to explode core collapse supernovae

“…A star that along its entire evolution does not acquire angular momentum from a stellar companion or a sub-stellar companion, or that the angular momentum it acquires is less than the maximum value it can have on the main sequence, is termed an angular momentum isolated star, or an J-isolated star (Sabach & Soker 2017) J dep J MS,max for a J − isolated star.…”

“…Binary stars with a large orbital separation, such that the companion does not spin-up the primary star, are J-isolated stars. Single low mass stars that have close and massive planets can become non-J-isolated stars if they are spun-up by such a planet to the degree that J dep J MS,max (Sabach & Soker 2017).…”

Jsolated Stars of Low Metallicity

“…We have also shown that such Jsolated stars have implications related to the puzzle of the bright end cut-off in the PN luminosity function (PNLF) of old stellar populations ( [1,2]; for studies on the PNLF see, e.g., [16][17][18][19][20][21][22]). It was observed that both young and old populations have a steep bright end cut-off in the PNLF in [OIII] emission lines at M * 5007 −4.5 mag.…”

“…Jsolated stars are stars that do not gain much angular momentum along their post main sequence evolution from a companion, either stellar or substellar, thus resulting with a lower mass-loss rate compared to non-Jsolated stars [1]. As previously stated in Sabach and Soker [1,2], the fitting formulae of the mass-loss rates for red giant branch (RGB) and asymptotic giant branch (AGB) single stars are set empirically by contaminated samples of stars that are classified as "single stars" but underwent an interaction with a companion early on, increasing the mass-loss rate to the observed rates. The mass-loss rate on the giant branches has extensive effects on stellar evolution and on the resulting planetary nebula (PN) in low and intermediate mass stars.…”

“…In Sabach & Soker [2] we focused on the implications of a reduced mass-loss rate on stellar evolution of solar-type stars and the shaping of elliptical PNe by a companion. In Sabach & Soker [1] we set the term Jsolated stars and studied the possible solution for the puzzling finding of bright PNe in old stellar populations, where the stellar mass is up to 1.2 M .…”