Evidence that the planetary candidate CVSO30c is a background star from optical, seeing-limited data

TL;DR

Optical imaging reveals that the exoplanet candidate CVSO30c is likely a background star, not a planetary object, based on its brightness and color inconsistent with a substellar companion.

Contribution

This study shows that optical seeing-limited data can effectively distinguish between true planetary candidates and background stars in young star-forming regions.

Findings

CVSO30c is much brighter in optical bands than expected for a substellar object.

Optical/infrared colors suggest CVSO30c is a background star, not a planet.

Color-magnitude analysis indicates CVSO30c is inconsistent with being a low-mass member of 25 Ori.

Abstract

We report serendipitous optical imaging of CVSO30c, an exoplanet candidate associated with the pre-main sequence T Tauri star CVSO30 resides in the 25 Ori stellar cluster. We perform PSF modeling on our seeing limited optical image to remove the lights from the host star (CVSO30), allowing us to extract photometry of CVSO30c to be g = 23.2+/-0.2 (statistic)+/-0.1 (systematic) and r = 21.5+/-0.1 (statistic)+/-0.1 (systematic) magnitudes, respectively. This is 170 and 80 times too bright in the g and r-band, respectively, if CVSO30c were an L0 substellar object as suggested by previous studies. The optical/infrared colors of CVSO 30c are indicative of a stellar, not substellar object, while the object's color-magnitude diagram position is strikingly inconsistent with expected values for a low mass member of 25 Ori. Broad-band photometry for CVSO30c is instead better fit by contaminants such as a background K3 giant or M subdwarf. Our study demonstrates that optical seeing limited data can help clarify the nature of candidate wide separation planet-mass companions in young star-forming regions.