Investigation of a transiting planet candidate in Trumpler 37: An astro‐physical false positive eclipsing spectroscopic binary star *

Abstract

We report our investigation of the first transiting planet candidate from the YETI project in the young (∼4 Myr old) open cluster Trumpler 37. The transit-like signal detected in the lightcurve of F8V star 2M21385603+5711345 repeats every 1.364894 ± 0.000015 days, and has a depth of 54.5 ± 0.8 mmag in R. Membership in the cluster is supported by its mean radial velocity and location in the color-magnitude diagram, while the Li diagnostic and proper motion are inconclusive in this regard. Follow-up photometric monitoring and adaptive optics imaging allow us to rule out many possible blend scenarios, but our radial-velocity measurements show it to be an eclipsing single-lined spectroscopic binary with a late-type (mid-M) stellar companion, rather than one of planetary nature. The estimated mass of the companion is 0.15-0.44 M . The search for planets around very young stars such as those targeted by the YETI survey remains of critical importance to understand the early stages of planet formation and evolution.

THE ROTATION PERIOD DISTRIBUTIONS OF 4–10 Myr T TAURI STARS IN ORION OB1: NEW CONSTRAINTS ON PRE-MAIN-SEQUENCE ANGULAR MOMENTUM EVOLUTION

“…The advantage of this method is that it directly produces light curves for all the stars referenced to this synthetic standard star. Each night was processed independently using this scheme, and following Errmann et al (2014) the data from different nights was combined using the night-to-night differences of the of stars selected as constant standards.…”

Search for transiting exoplanets and variable stars in the open cluster NGC 7243

“…The cluster with its 698 pc distance, 21 angular diameter and 211 cluster members is an ideal YETI target, observable from most YETI observatories. On the other hand, compared to Trumpler 37, also observed within YETI (Errmann et al 2014b), we can expect less discoveries on NGC 7243 since it has fewer members (614 versus 211). The estimate of the number of expected transiting planets N p can be parameterized as :…”

“…The data were reduced using IRAF 7 as described in Errmann et al (2014b). The first step was the dark and flat correction (and an overscan correction in the case of the data obtained from Jena).…”

“…To check whether the candidate is a low-mass or stellar companion, we also searched for a secondary eclipse in the data. In the case of the stellar companion we should probably also see a small dip roughly at phase 0.5 if the orbit is circular (see Fig 3. in Errmann et al 2014b). Figure 2 (right) shows the full phase-folded light curve of the exoplanet candidate.…”

“…The first target cluster of YETI was Trumpler 37, where a periodic (1.364894(15) days) transit-like signal (ΔR = 0.054 mag) was detected at a late F-type star. Subsequently, the follow-up observations showed that the candidate is an astrophysical false positive rather than a true planet (Errmann et al 2014b). The 25 Ori cluster was also monitored by the project.…”