Transit Timing Variations in TESS lightcurves — Unraveling the planetary system TOI-2556

Abstract

Exoplanetary research has flourished since the landmark discovery of the first exoplanet detection in 1992 (Wolszczan & Frail, 1992), with over 5500 confirmed exoplanets expanding our understanding of planetary systems beyond our solar system. Population-level analyses have revealed a diverse array of exoplanetary systems, including hot Jupiters—gas giants orbiting close to their host stars (Mayor & Queloz, 1995; Dawson & Johnson, 2018). The discovery of hot Jupiters has challenged traditional planetary formation theories, prompting a reevaluation of our understanding of planetary systems. Here, I outline the foundational techniques used to detect and characterize exoplanets, namely, the transit, radial velocity (RV) and transit timing variation (TTV) methods. These methods are then employed to study and characterize the system TOI-25561. Previous analyses suggest that TOI-2556 harbors a transiting planet. In this study, I confirm and validate the presence of an 8-day transiting signal, referred to as TOI-2556.01,using TESS photometry. Additionally, spectroscopic data analysis reveals an 8-day periodic signal, suggesting a planetary mass of around 0.5 Jupiter masses, classifying TOI-2556.01 as a hot Jupiter. Furthermore, I analyze transit timing variations leveraging 19 observed transit center epochs, uncovering a pronounced sinusoidal TTV signal. I explore several scenarios known to produce TTVs and find that the signal is likely being induced by a planetary perturber, which I refer to as TOI-2556.02. N-body simulations across various masses and eccentricities provide evidence favoring a inner Super-Earth to Neptune mass perturber with an orbital period around 4 days. These results are in line with analytical models derived by Nesvorn`y & Vokrouhlick`y (2016) for co-planar systems in resonance. My results suggest that TOI-2556 could be the second known system, after TOI-1130, to feature a hot Jupiter in resonance with an inner, smaller planet. Investigating such systems will advance our comprehension of planetary architectures, particularly those housing hot Jupiters and smaller companions. I suggest that future observational efforts should prioritize refining the characterization of the RV signal to constrain the eccentricity of TOI-2556.01 as well as searching for a signal induced by the perturber. Additionally, conducting transit spectroscopy on TOI-2556 could shed light on the system’s formation history. Expanding the dataset through future photometric observations will refine the TTV curve, potentially revealing insights into the system’s evolutionary processes. Given its intriguing complexities, this unique system stands as a promising target for future studies.

Popular Abstract

Imagine looking out into space and seeing not just stars, but entire planets—worlds beyond our solar system, each with its own story to tell. This incredible reality, once the stuff of science fiction, has become an exciting frontier in modern astronomy. But how do we figure out what these distant planets are like? Indirect methods are essential for studying exoplanets because they are generally too faint to observe directly. Instead, we rely on techniques like the transit and radial velocity methods to unveil their secrets.

For the transit method, we observe the "shadow" cast by a planet as it passes in front of its host star, causing a slight dimming in the star’s brightness. Meanwhile, the RV method detects the subtle gravitational pull exerted by a planet on its star, providing valuable information about the planet’s properties and orbit.

These methods have completely changed how we see exoplanets, showing us a huge variety of worlds out there. From gas giants orbiting closely around their stars to icy super-Earths nestled in the distant corners of space, each discovery expands our understanding of the universe’s incredible diversity. Hot Jupiters—giant gas planets orbiting remarkably close to their stars—are among the most captivating discoveries. They challenge our understanding of planetary formation and compel us to reconsider the workings of planetary systems.

In this work, I look a particularly interesting system—a distant place full of possibilities. By studying the timing of transits and carefully analyzing the data, I’ve found some intriguing hints that there might not just be a Hot Jupiter hiding there, but a smaller Neptune-mass planet as well. This process isn’t merely about analyzing data; it’s about carefully assembling each piece of information, like fitting together the missing parts of a puzzle. And with each revelation, our understanding of the planetary systems deepens.

In a universe as vast and enigmatic as ours, delving into the study of exoplanets offers a glimpse into the
astonishing diversity of worlds beyond our own.

• author: Vernharðsson, Kristján Ríkarður
• supervisor: Judith Korth; Alexander Mustill
• organization: Astrophysics; Department of Physics
• course: ASTM32 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Physics and Astronomy
• keywords: Exoplanetary science, TTV, TESS, transit method, radial velocity method, planetary detection, dynamics, exoplanet
• report number: 2024-EXA229
• language: English
• id: 9167096
• date added to LUP: 2024-11-05 08:24:06
• date last changed: 2024-11-05 08:24:06