Millimagnitude Optical Photometry for the Transiting Planetary Candidate OGLE-TR-109

Abstract

We present precise V-band photometry for the low-amplitude transit candidate star OGLE-TR-109. This is an extreme case among the transiting candidates found by the OGLE group because of the early spectral type of the star (F0V), of the low transit amplitude (A_I=0.008 mag), and of the very short period (P=0.58909 days) of the orbiting companion. Using difference image photometry, we are able to achieve millimagnitude errors in the individual data points. One transit of this star is well defined in our light curve. This confirms the OGLE detection and rules out the possibility of a false positive. The measurement of this transit allows to refine the transit amplitude (A_V=0.006 +/- 0.001 mag), and the ephemerides for this interesting system, as well as the radius of the possible orbiting companion (R_P=0.90 +/- 0.09 ~R_J), and the inclination of the orbit (i=77 +/- 5 deg). Two other transits observed at lower S/N confirm the period of this system measured by OGLE. There is no evidence for a blend of the F-type main sequence star with a redder eclipsing binary, or for secondary transits in the present observations. The absence of ellipsoidal modulation in the light curve of the primary rules out a low mass star companion or brown dwarf with M>14 +/- 8 M_J. The remaining possibilities for OGLE-TR-109 are a blend between the F-type star and a binary with a bluer primary star, or a new transiting extrasolar planet.

24 pages (including figures) submitteed to ApJ, Accepted. 1 replacement (updated references)

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Cited by in corpus (7)

• Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates III: Accurate Radius and Period for OGLE-TR-111-b
• The `666' collaboration on OGLE transits: I. Accurate radius of the planets OGLE-TR-10b and OGLE-TR-56b with VLT deconvolution photometry
• Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates: II. Transits of OGLE-TR-113-b in the Optical and Near-IR
• The VVV Infrared Variability Catalog (VIVA-I)
• Variability and stellar populations with deep optical-IR images of the Milky Way disk: matching VVV with VLT/VIMOS data
• Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates IV: The Puzzle of the Extremely Red OGLE-TR-82 Primary Solved
• Deep census of variable stars in a VLT/VIMOS field in Carina