UV Spectropolarimetry with Polstar: Protoplanetary Disks

TL;DR

Polstar is a proposed NASA mission that would use UV spectropolarimetry to study the geometry and physical conditions of protoplanetary disks, enabling new insights into star and planet formation processes.

Contribution

It introduces a novel UV spectropolarimeter for time-domain studies of protoplanetary disks, addressing key questions about accretion mechanisms and transient events.

Findings

Potential to distinguish accretion modes in young stars.

Ability to identify causes of transient events in disks.

Advances in understanding disk geometry and physics.

Abstract

Polstar is a proposed NASA MIDEX mission that would feature a high resolution UV spectropolarimeter capable of measure all four Stokes parameters onboard a 60cm telescope. The mission would pioneer the field of time-domain UV spectropolarimetry. Time domain UV spectropolarimetry offers the best resource to determine the geometry and physical conditions of protoplanetary disks from the stellar surface to <5 AU. We detail two key objectives that a dedicated time domain UV spectropolarimetry survey, such as that enabled by Polstar, could achieve: 1) Test the hypothesis that magneto-accretion operating in young planet-forming disks around lower-mass stars transitions to boundary layer accretion in planet-forming disks around higher mass stars; and 2) Discriminate whether transient events in the innermost regions of planet-forming disks of intermediate mass stars are caused by inner disk mis-alignments or from stellar or disk emissions.