# Grazing envelope evolution toward Type IIb supernovae

## TL;DR

This paper proposes a new binary evolution scenario called grazing envelope evolution (GEE) that can lead to Type IIb supernovae by efficiently removing the hydrogen envelope through jets, expanding the conditions under which these supernovae can occur.

## Contribution

It introduces the GEE scenario where jets prevent common envelope evolution, increasing the parameter space for Type IIb supernova progenitors.

## Key findings

- GEE can last from hundreds to tens of thousands of years.
- Jets effectively remove the hydrogen envelope during GEE.
- GEE expands the range of binary systems that produce SNe IIb.

## Abstract

I propose a scenario where the majority of the progenitors of type IIb supernovae (SNe IIb) lose most of their hydrogen-rich envelope during a grazing envelope evolution (GEE). In the GEE the orbital radius of the binary system is about equal to the radius of the giant star, and the more compact companion accretes mass through an accretion disk. The accretion disk is assumed to launch two opposite jets that efficiently remove gas from the envelope along the orbit of the companion. The efficient envelope removal by jets prevents the binary system from entering a common envelope evolution, at least for part of the time. The GEE might be continuous or intermittent. I crudely estimate the total GEE time period to be in the range of about hundreds of years, for a continuous GEE, and up to few tens of thousands of years for intermittent GEE. The key new point is that the removal of envelope gas by jets during the GEE prevents the system from entering a common envelope evolution, and by that substantially increases the volume of the stellar binary parameter space that leads to SNe IIb, both to lower secondary masses and to closer orbital separations.