The white dwarf mass–orbital period relation under wind mass-loss

Abstract

Helium white dwarfs (HeWDs) are thought to form from low-mass red giant stars experiencing binary interaction. Because the helium core mass of a red giant star is closely related to the stellar radius, there exists well-known relation between the orbital period (Porb) and the mass (MWD) of the HeWDs, which is almost independent of the type of the companion star. Traditional derivation of the MWD–Porb relation generally neglected the effect of wind mass loss from the red giants, while observations show that wind mass loss from red giants in binary systems is systematically higher than that from isolated stars. In this work, we calculate binary evolution with tidally enhanced stellar wind (TEW) and find that it causes significantly scatter of the traditional MWD–Porb relation. The TEW can prevent the red giants from overflowing their Roche lobes and slow down the growth of the helium core, leaving a lower-mass HeWD for given orbital period. This scenario may account for some of the HeWD binaries that deviate from the traditional MWD–Porb relation. However, we point out that observations of more HeWD binaries in wide orbits are needed to test the TEW model and to constrain the enhanced wind factor.

On Its Way to the Neutron Star–White Dwarf Binary Graveyard, IGR J16194−2810, A First Ascent M Giant X-Ray Binary

“…Figure 9 shows the orbital period as a function of the core mass for the NS-He WD systems with well-established masses (Gao & Li 2023). A relation between period and WD mass can be established by modeling systems (Lin et al 2011), and this is also shown.…”

“…Table 5 contains no fully recycled pulsars, i.e., pulsars with spin periods less than 10 ms. Four systems contain a mildly (or close to mildly) recycled pulsar with spin periods  35 ms. Three systems, J0823+0159, J1803−2712, and J1822−0848, have spin periods > 300 ms. Long orbital period systems like IGR J16194−2810 are clearly not MSP progenitors. The absence in Table 5 of NS-He WD pulsars with orbital periods longer than 1000 days suggests that IGR J16194−2810 is at the long end of LMXB orbital periods 2 of Gao & Li 2023). Where the uncertainties in the mass are large enough to be plotted they are shown as a horizontal line.…”

The Common Envelope Evolution Outcome. II. Short-orbital-period Hot Subdwarf B Binaries Reveal a Clear Picture

“…However, for an individual binary, TS99 pointed out that P orb and M WD increase with increasing fractions of mass and angular momentum loss. Gao & Li (2023) studied the P orb -M WD relation under wind mass loss and pointed out that tidally enhanced wind can play an important role for helium WD binaries in wide orbits. In addition, the P orb -M WD relation is ascertained from a circular orbit.…”

Discovery of a Proto–White Dwarf with a Massive Unseen Companion

“…The final stage of the close binary evolution through Roche lobe overflow results in a relationship between the primary masses and the orbital periods. These values are shown in Figure 8, where we compare our target with ELM WD-WD binaries from an ELM survey (Brown et al 2020) and ELM WD-NS binaries from Gao & Li (2023). The short-period binaries (P < 8 hr) with a broad distribution of primary masses are from the common envelope channel, whereas the Roche lobe channel forms a relatively narrow locus of objects with a strong mass-period dependence.…”

“…Masses vs. orbital periods for ELM WDs binaries are plotted along with both solutions obtained for our target. Binaries with WD companions are selected fromBrown et al (2020), while binaries with NS companions are selected fromGao & Li (2023). The dashed line is the theoretical mass-orbital period relation for the Roche lobe channel fromGao & Li (2023).…”