Anomalous flux event in the TESS Sector 43 light curve of the white dwarf photometric standard HZ 4 was caused by a passing asteroid

TL;DR

An anomalous flux variation observed in TESS data of the white dwarf HZ 4 was identified as caused by asteroid 4382 Stravinsky passing through the pixels, confirming HZ 4's reliability as a standard star.

Contribution

This study demonstrates that asteroid transits can cause apparent flux anomalies in TESS data, clarifying the nature of the flux variation in HZ 4.

Findings

Flux variation caused by asteroid 4382 Stravinsky.

HZ 4 remains a reliable photometric standard.

Asteroid transits can mimic stellar flux anomalies.

Abstract

Frymire & Ardila (2023) reported an anomalous flux variation in the Transiting Exoplanet Survey Satellite (TESS) Sector 43 light curve of the white dwarf HZ 4. We show that this flux variation was caused by the main-belt asteroid 4382 Stravinsky traversing the nearby TESS pixels, and it is therefore not a cause for concern regarding the continued use of HZ 4 as a photometric standard star.