A search for transiting companions in the J1407 (V1400 Cen) system (2106.15902v1)

Abstract: In 2007, the young star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a complex series of deep eclipses over 56 days. This was attributed to the transit of a ring system filling a large fraction of the Hill sphere of an unseen substellar companion. Subsequent photometric monitoring has not found any other deep transits from this candidate ring system, but if there are more substellar companions and they are coplanar with the potential ring system, there is a chance that they will transit the star as well. This young star is active and the light curves show a 5% modulation in amplitude with a dominant rotation period of 3.2 days due to star spots rotating in and out of view. We model and remove the rotational modulation of the J1407 light curve and search for additional transit signatures of substellar companions orbiting around J1407. We combine the photometry of J1407 from several observatories, spanning a 19 year baseline. We remove the rotational modulation by modeling the variability as a periodic signal, whose periodicity changes slowly with time over several years due to the activity cycle of the star. A Transit Least Squares (TLS) analysis searches for any periodic transiting signals within the cleaned light curve. We identify an activity cycle of J1407 with a period of 5.4 years. A Transit Least Squares search does not find any plausible periodic eclipses in the light curve, from 1.2% amplitude at 5 days up to 1.9% at 20 days. This sensitivity is confirmed by injecting artificial transits into the light curve and determining the recovery fraction as a function of transit depth and orbital period. J1407 is confirmed as a young active star with an activity cycle consistent with a rapidly rotating solar mass star. With the rotational modulation removed, the TLS analysis rules out transiting companions with radii larger than about 1 Jupiter.

• The paper analyzes 19 years of photometric data from the J1407 system to search for transiting companions, placing constraints on potential bodies larger than 1.1 planetary radii within periods of 5 to 20 days.
• The study uses data from multiple observatories, including TESS, over 19 years and applies the Transit Least Squares algorithm to search for periodic transit signatures in the cleaned light curve.
• The absence of detectable transits suggests that if other companions exist, they may have non-coplanar or eccentric orbits, highlighting the need for improved detection sensitivity or multi-wavelength observations.

Analysis of Transiting Companions in the J1407 System

The paper presents a detailed paper on the young star J1407, focusing primarily on the search for transiting substellar companions that may provide insights into complex ring systems and exoplanet characteristics. Previously observed in 2007, J1407 exhibited significant brightness variations attributed to the possible transit of a ring system surrounding an unseen substellar companion. This research aims to enhance understanding by refining the analysis of the J1407 light curve and assessing the presence of additional transiting bodies in this unique stellar system.

Methodology: Data Collection and Analysis

The authors employ a comprehensive methodological framework to refine the photometric data of J1407 collected over a 19-year span from various ground-based and space observatories, including TESS and several terrestrial telescopes. The process begins with correcting inherent stellar variabilities, notably the removal of rotational modulation due to the star’s activity cycle with a period of 5.4 years. Utilizing the Transit Least Squares (TLS) algorithm, the paper systematically searches for periodic transit signatures within the cleaned light curve to detect planetary or substellar bodies.

Findings: Constraints on Substellar Companions

Despite thorough analysis, the paper does not identify any definitive evidence of transiting companions within the parameters searched. Significant deductions from the research include:

• The absence of detectable transits for companions larger than approximately 1.1 planetary radii within periods ranging from 5 to 20 days.
• Confirming J1407 as a young and active star with a rotation-induced luminosity modulation of around 3.2 days derived from stellar spots.

Implications and Future Research Directions

The lack of observable transiting events around J1407 has important implications for our understanding of young stellar environments and planetary formation. The results suggest that if other substellar companions exist within the system, they either do not have coplanar orbits with the suspected ring system or possess characteristics making them difficult to detect with current photometric sensitivity limits. This implies potential research routes such as:

1. Improving Detection Sensitivity: Future endeavors might focus on refining the analytical methods or employing more sensitive observational instruments to capture finer details below current detection thresholds.
2. Exploring Eccentric Orbits: Given the need for high eccentricity in explaining the lack of periodic transits, further investigation into the orbital dynamics of J1407’s potential companions could yield fruitful insights.
3. Simultaneous Multi-Wavelength Observations: Incorporating data from infrared or other electromagnetic spectra might help discern qualities that are invisible to present techniques, given the atmospheric dynamics and complex activity cycles of younger stars like J1407.
4. Astrophysical Modeling: Continued development and testing of astrophysical models, including simulations of ring systems and stellar activity cycles, can provide more grounded predictions and corroborative data.

Conclusion

This research underlines the complexities involved in studying young stellar systems and their potential planets. The meticulous analysis serves as a cornerstone for future studies aiming to elucidate the mechanisms behind star-system development and offers a framework for improving transit detection methodologies. As observational capabilities progress, the findings from such comprehensive analyses will be pivotal in enhancing our understanding of the cosmos and the diverse characteristics of planets and substellar objects within it.