Observational Signatures of Planetary Tidal Disruption Events Around Solar-Mass Stars

TL;DR

This work models planetary tidal disruption events (TDEs) around a solar-mass star, focusing on Jupiter-like and Neptune-like planets, and explores how pre-disruption orbital eccentricity shapes debris morphology and emission. Using 2D hydrodynamic simulations with the FARGO3D code, an $\a$-disk viscosity, and a time-dependent energy equation, the authors predict bolometric and multi-band light curves for circular ($e=0$) and eccentric ($e=0.5$) encounters. They find that light-curve morphology is highly sensitive to planet mass and eccentricity: a Jupiter-like planet on an eccentric orbit yields a very fast, volatile peak, while a Neptune-like planet with eccentricity experiences a delayed, broader peak; a robust blue-when-brighter color trend accompanies the evolution in all cases. The results provide a predictive framework for identifying planetary TDEs in time-domain surveys (e.g., LSST) and for inferring both orbital parameters and planetary internal structure from observed light curves, while acknowledging that future 3D radiation-hydrodynamics will further refine these predictions.

Abstract

The tidal disruption of planets by their host stars represents a growing area of interest in transient astronomy, offering insights into the final stages of planetary system evolution. We model the hydrodynamic evolution and predict the multi-wavelength observational signatures of planetary TDEs around a solar-mass host, focusing on Jupiter-like and Neptune-like progenitors and examining how different eccentricities of the planet's pre-disruption orbit shape the morphology and emission of the tidal debris.We perform 2D hydrodynamic simulations using the FARGO3D code to model the formation and viscous evolution of the resulting debris disk. We employ a viscous alpha-disk prescription and include a time-dependent energy equation to compute the disk's effective temperature and subsequently derive the bolometric and multi-band photometric light curves.Our simulations show that planetary TDEs produce a diverse range of luminous transients. A Jupiter-like planet disrupted from a circular orbit at the Roche limit generates a transient peaking at $L_{bol} \approx 10^{38}$ erg s$^{-1}$ after a 12-day rise. In contrast, the same planet on an eccentric orbit (e=0.5) produces a transient of comparable peak luminosity but on a much shorter timescale, peaking in only 1 day and followed by a highly volatile light curve. We find that the effect of eccentricity is not universal, as it accelerates the event for Jupiter but delays it for Neptune. A robust "bluer-when-brighter" colour evolution is a common feature as the disk cools over its multi-year lifetime. The strong dependence of light curve morphology on the initial orbit and progenitor mass makes these events powerful diagnostics. This framework is crucial for identifying planetary TDEs in time-domain surveys.

Figures (7)

• Figure 1: Evolution of the surface density (left column) and effective temperature (right column) for the fiducial Jupiter model ($e=0$). Each row corresponds to a key epoch: the initial compact clump, the shock-heating phase during the rising TDE, the hot peak disk phase, and the viscously relaxed state at late times.
• Figure 2: Synthetic imaging of the fiducial Jupiter TDE at $\lambda = 1.0\,\mu$m observed from $d=140$ pc. The four panels show the morphological evolution from the initial compact debris (a) and the formation of the primary spiral arm during the rise (b), to the turbulent peak (c) and the relaxed disk (d). To enhance the visibility of the emission structure, the intensity is scaled radially by $(r/0.07\,\mathrm{au})^3$. For reference, the total physical flux density of the system at the peak epoch (c) is $\sim 1.7 \times 10^2$ Jy.
• Figure 3: Comparison of bolometric light curves. Left: Fiducial models ($e=0$). The Jupiter model (gold) shows a higher peak and faster decay, while the Neptune model (blue) is fainter but longer-lived. Right: Eccentric models ($e=0.5$). The effect of eccentricity is markedly different for Jupiter (faster, more volatile peak) and Neptune (slower, broader, and more luminous peak).
• Figure 4: Comparison of the thermal evolution. Left: In the fiducial ($e=0$) run, the temperature evolution is smooth post-peak. Right: In the eccentric ($e=0.5$) run, the evolution is highly variable and spiky, especially for the Jupiter model, which reaches a higher peak temperature, indicating a more violent initial energy dissipation.
• Figure 5: Luminosity--temperature tracks for the Jupiter model. Left: The fiducial ($e=0$) case shows a relatively smooth track with well-defined loops near the peak, characteristic of a quasi-stable evolution. Right: The eccentric ($e=0.5$) case displays a substantially more scattered and chaotic track, reflecting a highly unstable hydrodynamic evolution following the initial disruption.