J. Zendejas

Max Planck Institute for Extraterrestrial Physics

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Jayne Birkby

University of Oxford

D. J. Pinfield

University of Hertfordshire

M. Cappetta

Max Planck Institute for Extraterrestrial Physics

P. Cruz

Centro de Astrobiología

R. P. Saglia

Ludwig-Maximilians-Universität München

D. Barrado

Centro de Astrobiología

Brigitta Sipőcz

Infrared Processing and Analysis Center

S. T. Hodgkin

University of Cambridge

J. Koppenhoefer

Max Planck Institute for Extraterrestrial Physics

E. L. Martı́n

Instituto de Astrofísica de Canarias

Cooperative Institutions

University of Hertfordshire

Centre National de la Recherche Scientifique

University of Cambridge

Consejo Superior de Investigaciones Científicas

Max Planck Society

Centro de Astrobiología

Instituto de Astrofísica de Canarias

Universidad de La Laguna

Leiden University

Institute of Astronomy

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Erratum: The first planet detected in the WTS: an inflated hot-Jupiter in a 3.35 day orbit around a late F-star

Monthly Notices of the Royal Astronomical Society (2020)

M. Cappetta R. P. Saglia Jayne Birkby J. Koppenhoefer D. J. Pinfield

Jupiter (rocket family)

Orbit (dynamics)

Star (game theory)

10.1093/mnras/staa1912

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Citations (0)

WTS-2 b: a hot Jupiter orbiting near its tidal destruction radius around a K dwarf

Monthly Notices of the Royal Astronomical Society (2014)

Jayne Birkby M. Cappetta P. Cruz J. Koppenhoefer O. Ivanyuk

We report the discovery of WTS-2 b, an unusually close-in 1.02-day hot Jupiter (Mp=1.12MJ, Rp=1.363RJ) orbiting a K2V star, which has a possible gravitationally-bound M-dwarf companion at 0.6 arcsec separation contributing ~20 percent of the total flux in the observed J-band light curve. The planet is only 1.5 times the separation from its host star at which it would be destroyed by Roche lobe overflow, and has a predicted remaining lifetime of just ~40 Myr, assuming a tidal dissipation quality factor of Q'*=10^6. Q'* is a key factor in determining how frictional processes within a host star affect the orbital evolution of its companion giant planets, but it is currently poorly constrained by observations. We calculate that the orbital decay of WTS-2 b would correspond to a shift in its transit arrival time of T_shift~17 seconds after 15 years assuming Q'*=10^6. A shift less than this would place a direct observational constraint on the lower limit of Q'* in this system. We also report a correction to the previously published expected T_shift for WASP-18 b, finding that T_shift=356 seconds after 10 years for Q'*=10^6, which is much larger than the estimated 28 seconds quoted in WASP-18 b discovery paper. We attempted to constrain Q'* via a study of the entire population of known transiting hot Jupiters, but our results were inconclusive, requiring a more detailed treatment of transit survey sensitivities at long periods. We conclude that the most informative and straight-forward constraints on Q'* will be obtained by direct observational measurements of the shift in transit arrival times in individual hot Jupiter systems. We show that this is achievable across the mass spectrum of exoplanet host stars within a decade, and will directly probe the effects of stellar interior structure on tidal dissipation.

Hot Jupiter

Orbital period

Jupiter (rocket family)

Gas giant

Orbital decay

Roche lobe

Eclipse

Radial velocity

10.1093/mnras/stu343

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Citations (76)

Erratum: The first planet detected in the WTS: an inflated hot-Jupiter in a 3.35 d orbit around a late F star

Monthly Notices of the Royal Astronomical Society (2014)

M. Cappetta R. P. Saglia Jayne Birkby J. Koppenhoefer D. J. Pinfield

We report the discovery of WTS-1b, the first extrasolar planet found by the WFCAM Transit Survey, which began observations at the 3.8-m United Kingdom Infrared Telescope (UKIRT) in August 2007. Light curves comprising almost 1200 epochs with a photometric precision of better than 1 per cent to J ~ 16 were constructed for ~60000 stars and searched for periodic transit signals. For one of the most promising transiting candidates, high-resolution spectra taken at the Hobby-Eberly Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main sequence dwarf (V=16.13) with possibly slightly subsolar metallicity, and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the substellar companion of 3.35 days, a planetary mass of 4.01 +- 0.35 Mj and a planetary radius of 1.49+0.16-0.18 Rj. WTS-1b has one of the largest radius anomalies among the known hot Jupiters in the mass range 3-5 Mj. The high irradiation from the host star ranks the planet in the pM class.

Hot Jupiter

Gas giant

Radial velocity

Orbital period

10.1093/mnras/stu1662

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Citations (0)

Four ultra-short-period eclipsing M-dwarf binaries in the WFCAM Transit Survey

Monthly Notices of the Royal Astronomical Society (2012)

S. V. Nefs Jayne Birkby I. A. G. Snellen S. T. Hodgkin D. J. Pinfield

We report on the discovery of four ultra-short-period (P ≤ 0.18 d) eclipsing M-dwarf binaries in the Wide-Field Camera (WFCAM) Transit Survey. Their orbital periods are significantly shorter than that of any other known main-sequence binary system, and are all significantly below the sharp period cut-off at P ∼ 0.22 d as seen in binaries of earlier-type stars. The shortest-period binary consists of two M4-type stars in a P = 0.112 d orbit. The binaries are discovered as part of an extensive search for short-period eclipsing systems in over 260 000 stellar light curves, including over 10 000 M-dwarfs down to J = 18 mag, yielding 25 binaries with P ≤ 0.23 d. In a popular paradigm, the evolution of short-period binaries of cool main-sequence stars is driven by the loss of angular momentum through magnetized winds. In this scheme, the observed P ∼ 0.22 d period cut-off is explained as being due to time-scales that are too long for lower-mass binaries to decay into tighter orbits. Our discovery of low-mass binaries with significantly shorter orbits implies that either these time-scales have been overestimated for M-dwarfs, e.g. due to a higher effective magnetic activity, or the mechanism for forming these tight M-dwarf binaries is different from that of earlier-type main-sequence stars.

Orbital period

Low Mass

Orbit (dynamics)

10.1111/j.1365-2966.2012.21338.x

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Citations (39)

The first planet detected in the WTS: an inflated hot Jupiter in a 3.35 d orbit around a late F star

Monthly Notices of the Royal Astronomical Society (2012)

M. Cappetta R. P. Saglia Jayne Birkby J. Koppenhoefer D. J. Pinfield

We report the discovery of WTS-1b, the first extrasolar planet found by the WFCAM Transit Survey, which began observations at the 3.8-m United Kingdom Infrared Telescope (UKIRT) in 2007 August. Light curves comprising almost 1200 epochs with a photometric precision of better than 1 per cent to J ∼ 16 were constructed for ∼60 000 stars and searched for periodic transit signals. For one of the most promising transiting candidates, high-resolution spectra taken at the Hobby–Eberly Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main-sequence dwarf (V = 16.13) with possibly slightly subsolar metallicity, and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the substellar companion of 3.35 d, a planetary mass of 4.01 ± 0.35 MJ and a planetary radius of RJ. WTS-1b has one of the largest radius anomalies among the known hot Jupiters in the mass range 3–5 MJ. The high irradiation from the host star ranks the planet in the pM class.

Hot Jupiter

Radial velocity

Gas giant

Orbital period

Jupiter (rocket family)

10.1111/j.1365-2966.2012.21937.x

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Citations (47)

Atmospheric mass loss by stellar wind from planets around main sequence M stars

Icarus (2010)

J. Zendejas Antígona Segura A. C. Raga

Stellar collision

Atmospheric models

10.1016/j.icarus.2010.07.013

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Citations (89)

A sensitivity analysis of the WFCAM Transit Survey for short-period giant planets around M dwarfs

Monthly Notices of the Royal Astronomical Society (2013)

Gábor Kovács S. T. Hodgkin Brigitta Sipőcz D. J. Pinfield D. Barrado

The WFCAM Transit Survey (WTS) is a near-infrared transit survey running on the United Kingdom Infrared Telescope (UKIRT), designed to discover planets around M dwarfs. The WTS acts as a poor-seeing backup programme for the telescope, and represents the first dedicated wide-field near-infrared transit survey. In this paper we describe the observing strategy of the WTS and the processing of the data to generate lightcurves. We describe the basic properties of our photometric data, and measure our sensitivity based on 950 observations. We show that the photometry reaches a precision of ~4mmag for the brightest unsaturated stars in lightcurves spanning almost 3 years. Optical (SDSS griz) and near-infrared (UKIRT ZYJHK) photometry is used to classify the target sample of 4600 M dwarfs with J magnitudes in the range 11-17. Most have spectral-types in the range M0-M2. We conduct Monte Carlo transit injection and detection simulations for short period (<10 day) Jupiter- and Neptune-sized planets to characterize the sensitivity of the survey. We investigate the recovery rate as a function of period and magnitude for 4 hypothetical star-planet cases: M0-2+Jupiter, M2-4+Jupiter, M0-2+Neptune, M2-4+Neptune. We find that the WTS lightcurves are very sensitive to the presence of Jupiter-sized short-period transiting planets around M dwarfs. Hot Neptunes produce a much weaker signal and suffer a correspondingly smaller recovery fraction. Neptunes can only be reliably recovered with the correct period around the rather small sample (~100) of the latest M dwarfs (M4-M9) in the WTS. The non-detection of a hot-Jupiter around an M dwarf by the WFCAM Transit Survey allows us to place an upper limit of 1.7-2.0 per cent (at 95 per cent confidence) on the planet occurrence rate.

Gas giant

Hot Jupiter

Neptune

Jupiter (rocket family)

Infrared telescope

10.1093/mnras/stt571

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Citations (13)