Gravity-Darkened Seasons: Insolation Around Rapid Rotators

Abstract

I model the effect of rapid stellar rotation on a planet's insolation. Fast-rotating stars have induced pole-to-equator temperature gradients (known as gravity-darkening) of up to several thousand Kelvin that affect the star's luminosity and peak emission wavelength as a function of latitude. When orbiting such a star, a planet's annual insolation can strongly vary depending on its orbit inclination. Specifically, inclined orbits result in temporary exposure to the star's hotter poles. I find that gravity-darkening can drive changes in a planet's equilibrium temperature of up to $\sim 15\%$ due to increased irradiance near the stellar poles. This effect can also vary a planet's exposure to UV radiation by up to $\sim 80\%$ throughout its orbit as it is exposed to an irradiance spectrum corresponding to different stellar effective temperatures over time.

8 pages, 6 figures, accepted for publication in ApJ

References in corpus (8)

• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Imaging the Surface of Altair
• Effects of gravitational darkening on the determination of fundamental parameters in fast rotating B-type stars
• The habitability of Proxima Centauri b. I. Irradiation, rotation and volatile inventory from formation to the present
• Inflating and Deflating Hot Jupiters: Coupled Tidal and Thermal Evolution of Known Transiting Planets
• On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays
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• Spin-Orbit Alignment For 110-Day-Period KOI368.01 From Gravity Darkening

Cited by in corpus (3)

• KELT-9 b's Asymmetric TESS Transit Caused by Rapid Stellar Rotation and Spin-Orbit Misalignment
• Gravity-Darkening Analysis of Misaligned Hot Jupiter MASCARA-4 b
• The Habitable Zones of Rapidly Rotating Main Sequence A/F Stars