Migration and Evolution of giant ExoPlanets (MEEP) I: Nine Newly Confirmed Hot Jupiters from the TESS Mission (2401.05923v1)

Abstract: Hot Jupiters were many of the first exoplanets discovered in the 1990s, but in the decades since their discovery, the mysteries surrounding their origins remain. Here, we present nine new hot Jupiters (TOI-1855 b, TOI-2107 b, TOI-2368 b, TOI-3321 b, TOI-3894 b, TOI-3919 b, TOI-4153 b, TOI-5232 b, and TOI-5301 b) discovered by NASA's TESS mission and confirmed using ground-based imaging and spectroscopy. These discoveries are the first in a series of papers named the Migration and Evolution of giant ExoPlanets (MEEP) survey and are part of an ongoing effort to build a complete sample of hot Jupiters orbiting FGK stars, with a limiting Gaia $G$-band magnitude of 12.5. This effort aims to use homogeneous detection and analysis techniques to generate a set of precisely measured stellar and planetary properties that is ripe for statistical analysis. The nine planets presented in this work occupy a range of masses (0.55 Jupiter masses (M${\rm{J}}$) $<$ M${\rm{P}}$ $<$ 3.88 M${\rm{J}}$) and sizes (0.967 Jupiter radii (R${\rm{J}}$) $<$ R${\rm{P}}$ $<$ 1.438 R${\rm{J}}$) and orbit stars that range in temperature from 5360 K $<$ Teff $<$ 6860 K with Gaia $G$-band magnitudes ranging from 11.1 to 12.7. Two of the planets in our sample have detectable orbital eccentricity: TOI-3919 b ($e = 0.259^{+0.033}_{-0.036}$) and TOI-5301 b ($e = 0.33^{+0.11}_{-0.10}$). These eccentric planets join a growing sample of eccentric hot Jupiters that are consistent with high-eccentricity tidal migration, one of the three most prominent theories explaining hot Jupiter formation and evolution.

• The paper confirms nine TESS-detected hot Jupiters with masses ranging from 0.55 to 3.88 Jupiter masses and radii between 0.967 and 1.438 Jupiter radii.
• It employs a robust methodology that combines TESS photometry, radial velocity measurements, and high-resolution imaging to rigorously validate planetary candidates.
• The study reveals variations in orbital eccentricities, supporting high-eccentricity tidal migration as a key mechanism in shaping hot Jupiter evolution.

Overview of "Migration and Evolution of Giant Exoplanets (MEEP) I: Nine Newly Confirmed Hot Jupiters from the TESS Mission"

The paper presents the discovery and characterization of nine hot Jupiters, detected by NASA's TESS mission and confirmed through a combination of ground-based imaging and spectroscopy. This paper forms part of the broader Migration and Evolution of giant ExoPlanets (MEEP) survey, aimed at constructing a detailed sample of hot Jupiters to investigate their formation and evolutionary mechanisms.

Key Findings

The nine newly confirmed planets—TOI-1855 b, TOI-2107 b, TOI-2368 b, TOI-3321 b, TOI-3894 b, TOI-3919 b, TOI-4153 b, TOI-5232 b, and TOI-5301 b—are all classified as hot Jupiters due to their short orbital periods around their respective host stars. Their masses range from 0.55 to 3.88 Jupiter masses, and their radii range from 0.967 to 1.438 Jupiter radii. Notably, two of these planets, TOI-3919 b and TOI-5301 b, exhibit non-zero eccentricities, suggesting a complex orbital evolution likely influenced by high-eccentricity tidal migration mechanisms.

Techniques and Methodology

The observational strategy combined TESS's transit photometry with radial velocity measurements acquired from multiple ground-based telescopes and high-resolution imaging. This approach allowed the researchers to robustly confirm the planetary nature of the TESS-detected candidates, excluding possible false-positive signals such as those originating from eclipsing binaries. The comprehensive data set, analyzed using the EXOFASTv2 code, facilitated precise determinations of stellar and planetary parameters.

Implications

The diversity in eccentricities observed among the sample provides empirical support for multiple migratory scenarios influencing hot Jupiter evolution, including high-eccentricity tidal migration. The paper posits that understanding these mechanisms requires a statistically significant sample of exoplanets. A larger sample will better constrain the orbital dynamics and potential for companion bodies within these systems, which could inform models of planetary system evolution.

Speculation on Future Developments

Future studies should aim to expand this sample size to discern clearer statistical trends and refine theoretical models. An increase in the number of detected systems with measurable eccentricities can aid in deciphering the relative importance of different migration pathways. Additionally, continued development of high-precision spectroscopic instruments will enhance radial velocity measurements, increasing accuracy in mass determinations, thereby improving our understanding of planet compositions.

As the TESS mission continues, it is expected to significantly enhance the catalog of exoplanets. The data, combined with forthcoming observations from instruments like the James Webb Space Telescope (JWST), will enable deeper investigation into atmospheric properties and further elucidate the processes driving exoplanetary climates and evolution.

Conclusion

The findings presented in this paper contribute to the foundational knowledge of hot Jupiter characteristics and their formative and migratory histories. The ongoing MEEP survey will be pivotal in detailing the conditions and mechanisms influencing the architecture of planetary systems, thereby enriching the scientific narrative of planetary formation and migration in the cosmos.