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Published February 1, 2014 | Supplemental Material + Published + Accepted Version
Journal Article Open

Trawling for transits in a sea of noise: a search for exoplanets by analysis of WASP optical light curves and follow-up (SEAWOLF)

Abstract

Studies of transiting Neptune-sized planets orbiting close to nearby bright stars can inform theories of planet formation because mass and radius and therefore mean density can be accurately estimated and compared with interior models. The distribution of such planets with stellar mass and orbital period relative to their Jovian-mass counterparts can test scenarios of orbital migration, and whether 'hot' (period <10 d) Neptunes evolved from 'hot' Jupiters as a result of mass loss. We searched 1763 late K and early M dwarf stars for transiting Neptunes by analysing photometry from the Wide Angle Search for Planets and obtaining high-precision (≤10^(−3)) follow-up photometry of stars with candidate transit signals. One star in our sample (GJ 436) hosts a previously reported hot Neptune. We identified 92 candidate signals among 80 other stars and carried out 148 observations of predicted candidate transits with 1–2 m telescopes. Data on 70 WASP signals rules out transits for 39 of them; 28 other signals are ambiguous and/or require more data. Three systems have transit-like events in follow-up photometry and we plan additional follow-up observations. On the basis of no confirmed detections in our survey, we place an upper limit of 10.2 per cent on the occurrence of hot Neptunes around late K and early M dwarfs (95 per cent confidence). A single confirmed detection would translate to an occurrence of 5.3 ± 4.4 per cent. The latter figure is similar to that from Doppler surveys, suggesting that GJ 436b may be the only transiting hot Neptune in our sample. Our analysis of Kepler data for similar but more distant late-type dwarfs yields an occurrence of 0.32 ± 0.21 per cent. Depending on which occurrence is applicable, we estimate that the Next Generation Transit Survey will discover either ∼60 or ∼1000 hot Neptunes around late K- and early M-type dwarfs.

Additional Information

© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 October 23. Received 2013 August 9; in original form 2013 July 10. Published: 09 December 2013. EG and KC acknowledge support from NASA grants NNX10AI90G (Astrobiology: Exobiology & Evolutionary Biology) and NNX11AC33G (Origins of Solar Systems). GM acknowledges support from the State Scholarships Foundation of Greece in the form of a scholarship and fruitful discussions with E. Paleologou. AZ acknowledges the Foundation for Research and Technology-Hellas. Space astrophysics in Crete is supported in part by EU REGPOT project number 206469. NN acknowledges support by an NAOJ Fellowship, NINS Program for Cross-Disciplinary Study, and Grant-in-Aid for Scientific Research (A) (No. 25247026) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. EC and JB were supported by NASA/University of Hawaii Space Grant fellowships. The SuperWASP-N Camera was constructed and operated with funds made available from WASP Consortium universities and the UK Science and Technology Facilities Council (STFC). We extend our thanks to the Director and staff of the Isaac Newton Group of Telescopes for their support of SuperWASP-N operations. We thank the staff of the MDM and Skinakas observatories for their invaluable and courteous assistance during many observing runs. The Las Cumbres Observatory Network operates Faulkes Telescope North, ELP at McDonald Observatory, and the Byrne Observatory; the last is located on the Sedgwick Reserve, a part of the University of California Natural Reserve System.

Attached Files

Published - stt2078.pdf

Accepted Version - 1310.7586.pdf

Supplemental Material - 998747_Supplementary_Data.zip

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Additional details

Created:
August 19, 2023
Modified:
October 18, 2023