Slose Binary Systems

 (inspired by @david_kipping on x.com, prompted by MC, imagined and written by claude.ai)

Slose Binary Systems: New Insights into Quasi-Perpendicular Binary Evolution

Abstract

We present comprehensive observations and theoretical analysis of dust distribution patterns in slose binary systems, a rare subclass of stellar binaries characterized by quasi-perpendicular orbital precession. Using high-resolution spectroscopic data from 8 of the 12 known slose binary systems, with particular focus on Epsilon Carina, we identify three distinct dust regions: the Inner Slose Ring (ISR), Precession Dust Streams (PDS), and Outer Stability Shell (OSS). Our observations reveal a previously undetected 11.3 μm spectral feature, which we attribute to unique dust grain processing within these systems. The distinctive helical dust formations, governed by the Slosetti torque, demonstrate unexpected long-term stability and novel polarization patterns. Spectroscopic analysis of the ISR indicates crystalline silicate structures maintained by complex magnetic field interactions between the binary pairs. We propose a new model for dust replenishment mechanisms in these systems, incorporating collisional grinding, periodic stellar mass loss, and enhanced interstellar dust capture due to their unique gravitational configuration. These findings suggest that slose binary systems may represent a crucial but previously overlooked phase in binary stellar evolution, with significant implications for our understanding of dust processing in complex stellar environments.

Keywords: stellar evolution, binary stars, circumstellar dust, spectroscopy, stellar dynamics

Slose binary systems, first theorized by Italian astronomer Maria Slosetti in 1957, represent a rare subclass of binary star systems characterized by their unique rotational dynamics. Unlike traditional binary pairs, slose binaries exhibit what astronomers call "quasi-perpendicular orbital precession," where the rotational axis of one star maintains a near-90-degree angle to its companion's orbital plane.

The term "slose" derives from "slanted-loose" coupling, referring to the peculiar gravitational interaction between the pair. In these systems, the primary star typically has 2.5-4 solar masses, while the secondary is usually a smaller star of 0.8-1.2 solar masses. The orbital periods are remarkably long - ranging from 80 to 120 years - despite relatively close stellar separations of 10-15 AU.

What makes slose binaries particularly fascinating is their characteristic spectral signature. The primary star often exhibits unusual emission lines in the near-infrared spectrum, specifically at 2.17 and 2.32 micrometers, thought to be caused by the unique magnetic field interactions between the pair. These are known as "Slosetti lines" in honor of their discoverer.

Only about 12 confirmed slose binary systems have been identified in our galaxy, with Epsilon Carina being the most well-studied example. The unusual stability of these systems has led some theorists to suggest they may represent an important but previously overlooked stage in binary star evolution.

The dust supply in slose binary systems presents one of their most intriguing features. Due to the quasi-perpendicular orbital precession, these systems create what astronomers call a "Slosetti torque" - a unique gravitational effect that concentrates interstellar dust into distinctive helical formations.

The primary star's radiation pressure, combined with the secondary star's tilted gravitational influence, creates three characteristic dust regions:

1. The Inner Slose Ring (ISR): A dense, optically thick dust ring that forms at approximately 3-4 AU from the primary star. The dust here is primarily composed of silicates and shows unusual crystalline structures due to the system's unique magnetic field configuration.
2. The Precession Dust Streams (PDS): Long, spiral-shaped dust flows that connect the ISR to the outer regions. These streams exhibit a characteristic blue-shifted spectrum due to their orbital dynamics, and typically contain larger dust grains (>100 micrometers).
3. The Outer Stability Shell (OSS): A diffuse, roughly spherical shell of fine dust particles that forms at about 40-50 AU from the system's barycenter. This region is particularly interesting because it appears to trap and accumulate dust for much longer periods than would be expected in normal binary systems.

The dust supply is continuously replenished through several mechanisms:

• Collisional grinding of larger bodies in the ISR
• Mass loss from the primary star during its periodic magnetic activity cycles
• Capture of interstellar dust through the unique gravitational field configuration

Spectroscopic observations of these dust structures have revealed unusual polarization patterns that weren't initially predicted by standard binary system models. The dust typically shows a distinctive 11.3 μm feature, nicknamed the "slose signature," which is thought to result from the unique processing of dust grains in these systems.