The accretion disk of SS 433?

TL;DR

This paper analyzes infrared spectra of SS 433, revealing episodic outbursts and clarifying that observed disk features do not necessarily indicate a low-mass compact object, challenging previous assumptions.

Contribution

It demonstrates that Brackett series outbursts are episodic and that the observed disk profiles do not imply a low-mass accretion disk, refining understanding of SS 433's system.

Findings

Brackett series outbursts are episodic in SS 433

Disk profiles at ~200 km/s are not from the accretion disk

Mass of the compact object is not less than 2.2 solar masses

Abstract

I discuss two points concerning recent Brackett series spectra of SS 433. The first is that outbursts to red and blue episodic in the Balmer series are now shown to be episodic in the far infrared Brackett series. The second point is that while in quiet times the Brackett profiles are characteristic of a disk rotating at ~ 200 km/s, such a disk is not the accretion disk and it should not be claimed that these profiles require a compact object mass less than 2.2 solar masses.