The HIP 54515 b Superjovian Planet as an Early, Critical Look at the Roman Coronagraph's Performance in the Faint Target Star, Small IWA Limit

TL;DR

This paper evaluates the Roman Coronagraph's ability to image a faint superjovian planet near its inner working angle, providing insights into its performance for future rocky planet imaging around nearby stars.

Contribution

It presents an initial performance assessment of the Roman Coronagraph in challenging faint star and small IWA conditions using the HIP 54515 b system.

Findings

Demonstrates the coronagraph's capability to detect a superjovian planet near the IWA

Provides data on contrast performance as a function of thermal environment

Assesses the potential for imaging rocky planets around K and M stars

Abstract

The Roman Coronagraph's capabilities in the faint star, small IWA limit has enormous scientific (programmatic) impacts. Testing its performance in this limit provides a first look at challenges that may be encountered with the Habitable Worlds Observatory in imaging rocky planets around the nearest K and M stars. We propose such a rigorous test with the HLC/575nm targeting a newly-discovered superjovian planet HIP 54515 b, whose predicted contrast is $\sim$4.7 $\times$10$^{-8}$--2.5 $\times$10$^{-7}$. The companion lies close to the coronagraph IWA (well interior to the TTR5 performance region) and orbits a V = 6.8 star, near the limit for which the coronagraph may yield deep contrasts. Multiple reference stars are available that will further test CGI's performance as a function of $\Delta$ pitch angle to assess how the telescope's thermal environment impacts contrasts.