Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates

Abstract: Context. The 16 Myr old star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a series of complex eclipses in May 2007, interpreted as the transit of a giant Hill sphere filling debris ring system around a secondary companion, J1407b. No other eclipses have since been detected, although other measurements have constrained but not uniquely determined the orbital period of J1407b. Finding another eclipse towards J1407 will help determine the orbital period of the system, the geometry of the proposed ring system and enable planning of further observations to characterize the material within these putative rings. Aims. We carry out a search for other eclipses in photometric data of J1407 with the aim of constraining the orbital period of J1407b. Methods. We present photometry from archival photographic plates from the Harvard DASCH survey, and Bamberg and Sonneberg Observatories, in order to place additional constraints on the orbital period of J1407b by searching for other dimming and eclipse events. Using a visual inspection of all 387 plates and a period-folding algorithm we performed a search for other eclipses in these data sets. Results. We find no other deep eclipses in the data spanning from 1890 to 1990, nor in recent time-series photometry from 2012-2018. Conclusions. We rule out a large fraction of putative orbital periods for J1407b from 5 to 20 years. These limits are still marginally consistent with a large Hill sphere filling ring system surrounding a brown dwarf companion in a bound elliptical orbit about J1407. Issues with the stability of any rings combined with the lack of detection of another eclipse, suggests that J1407b may not be bound to J1407.

• The paper uses over a century of archival photographic plates and photometric data, combined with a period-folding algorithm, to search for additional eclipses of the ringed companion J1407b.
• The absence of new eclipses rules out 90% of J1407b's possible orbital periods between 10 and 20 years and strongly constrains periods beyond 22 years, suggesting a plausible range of 11 to 18 years.
• This analysis significantly narrows the potential orbital parameters for J1407b and emphasizes the need for future observations, such as direct imaging, to refine its period and understand the stability of its massive ring system.

Constraining the Period of the Ringed Secondary Companion to the Young Star J1407

The paper presents an analysis of photometric data to constrain the orbital period of J1407b, a secondary companion to the young star 1SWASP J140747.93-394542.6 (V1400 Cen), also known as J1407. The companion, suspected to possess an extensive ring system, was initially identified through its complex eclipse of J1407 in 2007. Since then, efforts to establish its orbital characteristics have been ongoing.

Methodology and Data Sources

The researchers use a combination of archival photographic plates and CCD photometry covering over a century to search for additional eclipses. Sources include the Harvard DASCH survey, Bamberg and Sonneberg Observatories, AAVSO, KELT, SuperWASP, and PROMPT. A total of 868 plates were visually inspected or processed through archival methods, yielding a robust dataset for analysis. The absence of further eclipses in this extensive dataset informs the constraints on J1407b’s orbital period.

A period-folding algorithm (PFA) is employed to deduce possible orbital periods by testing assumed periods against the timing of the 2007 eclipse. The PFA accounts for multiple transit windows approximated from the 2007 light curve to search for overlaps with other observational epochs.

Results and Analysis

No new eclipses of J1407b are observed in the available data. The PFA rules out 90% of possible orbital periods between 10 and 20 years, with significant constraints placed on periods beyond 22 years. The analysis suggests plausible orbital periods likely range from 11 to 18 years, with the data supporting higher probabilities around 16 to 17 years. Such findings indicate a high ellipticity for J1407b’s orbit if it is gravitationally bound, as more circular orbits would necessitate implausibly long periods given the system's dynamics.

The study also entertains the hypothesis of a retrograde ring system to account for the challenges posed by stability considerations during periastron passage. Retrograde orbits may offer a viable dynamic solution within the constraints established.

Implications and Future Directions

This work advances our understanding of the J1407 system by narrowing possible orbital configurations through extensive retrospective analysis. The speculative nature of J1407b’s substantial ring system warrants further investigation, primarily whether such rings remain stable under proposed orbital constraints.

Future work is needed to refine these orbital parameters, possibly through direct imaging endeavors capable of detecting radiation from the ring system itself using facilities like ALMA. Anticipating the next eclipse will also benefit from continued photometric surveillance, which should be strategically planned based on the refined orbital constraints discussed here.

In conclusion, while the absence of additional eclipse events prevents definitive confirmation of J1407b’s orbital nature, this research significantly narrows the range of potential periods and underscores the complexity of studying distant ring systems akin to J1407b.