Eccentricities of Close Stellar Binaries
Orbits of stellar binaries are in general eccentric. These eccentricities encode information about their early lives. Here, we use thousands of main-sequence binaries from the Gaia DR3 catalog to reveal that binaries inward of a few astronomical units exhibit a simple Rayleigh distribution with a mo...
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astrophysical Journal Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/2041-8213/adb751 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Orbits of stellar binaries are in general eccentric. These eccentricities encode information about their early lives. Here, we use thousands of main-sequence binaries from the Gaia DR3 catalog to reveal that binaries inward of a few astronomical units exhibit a simple Rayleigh distribution with a mode of σ _e ≃ 0.3. We find the same distribution for binaries from M to A spectral types, and from tens of days to thousands of days (possibly extending to tens of astronomical units). This observed distribution is most likely primordial and its invariance suggests a single universal process. One possibility is eccentricity excitation by circumbinary disks. Another, as is suggested by the Rayleigh form, is weak scattering and ejection of brown-dwarf objects. We explore this latter scenario and find that the binary eccentricities reach an equipartition value of ${\sigma }_{e}\simeq \sqrt{{M}_{\mathrm{BD}}/{M}_{* }}$ . So to explain the observed mode, the brown dwarfs will have to be of order one-tenth the stellar masses, and be at least as abundant in the Galaxy as in the close binaries. The veracity of both proposals remains to be tested. |
|---|---|
| ISSN: | 2041-8205 |