New Extinction and Mass Estimates of the Low-mass Companion 1RXS 1609 B with the Magellan AO System: Evidence of an Inclined Dust Disk

TL;DR

This study used advanced imaging to refine the properties of the low-mass companion 1RXS 1609 B, revealing a higher temperature, significant dust extinction, and evidence of a dusty disk, suggesting a star-like formation process.

Contribution

First direct imaging at bluest wavelengths of 1RXS 1609 B, providing improved temperature and extinction estimates, and evidence of a dusty disk around a low-mass companion.

Findings

Temperature estimated at 2000 K with dust extinction of A_V=4.5 mag.

Mass estimated between 0.012-0.015 solar masses, likely a brown dwarf.

Evidence of a dusty disk around the companion.

Abstract

We used the Magellan adaptive optics system to image the 11 Myr substellar companion 1RXS 1609 B at the bluest wavelengths to date (z' and Ys). Comparison with synthetic spectra yields a higher temperature than previous studies of $T_\mathrm{eff}=2000\pm100\mathrm{K}$ and significant dust extinction of $A_V=4.5^{+0.5}_{-0.7}$ mag. Mass estimates based on the DUSTY tracks gives 0.012-0.015 Msun, making the companion likely a low-mass brown dwarf surrounded by a dusty disk. Our study suggests that 1RXS 1609 B is one of the 25% of Upper Scorpius low-mass members harboring disks, and it may have formed like a star and not a planet out at 320 AU.